T12 STM32 V2.1S Soldering Station Controller - schematic etc. - Page 1
Forum section: electronics / general

author: floobydust
author_rank: Super Contributor
timestamp: June 05, 2019, 06:34:51 am
content: Here's a schematic I drew of the KSGER soldering station controller V2.1SPlease PM for any corrections and I will keep it updated.Known Issues:-The RTC battery goes dead in a few weeks. Remove resistor R10 10k, it adds unnecessary 0.28mA load.-The encoder body is not grounded which is a problem for ESD.-The heater and wand cable has ~4uH inductance and -ve spikes occur switching which stress the MOSFET and thermocouple amplifier. A small cap C8 is across the MOSFET to absorb this, but I added a fast recovery reverse diode across the heater.- The vacuum desoldering pump MOSFETs/diodes/connectors are not populated.- Silkscreen has duplicate ref. designators.- JBC option likely doesn't work, T245 thermocouple overloads op-amp and option R11 pcb trace is wrong on some boards.- S/W 2.10 my cold junction temperature from NTC is not working despite A/D voltage changing.A replacement controller works.Controller board H/W versions:OLED-V3.0 (black PCB) same as 2.1S but no pump control, 6-pin OLED, no R20 battery killer, ref. designators shuffled, no resistor packs, battery on board, JBC option R0 may be fixed. Looks like a cheaper build.2.1S (blue PCB) has pump control and buck-converter. JBC option is bungled, I think you must cut a trace.2.1S (green PCB) has pump control and SPX2954 LDO for 3.3V2.1 (sometimes called 2.1S) has no pump control and an LDO for 3.3V, not buck-converter.2.01 fixed the (2.0) LDO overheating, added copper-pour heatsink.2.0 is a failed design using SOT-89 LDO for 3.3V that overheated from no heatsinking, and no snubber on the MOSFET.1.5 oddball design using dual buck/LDO vregs, 4-pin GX12 connector like Quicko, and dual op-amp for thermocouple amp.PT Dreamer's Blogreverse engineered it and made custom open firmware for it.Lately, firmware needs an activation key first run. STM32 CPU ID1, ID2 and then activation codes.The T12 thermocouple is oddball metallurgy, measured empirically in HakkoPatent US6087631Afor the look up table, 20-21uV/°C accurate from 200°-600°C. Exact curves hereUS6054678A.edit: uploaded the wrong sch (huge file), fixed, added thermocouple info, V1.5 url.edit2: updated sch Rev. 2 - 8/2020 added JBC pinout and fixed the JBC thermocouple breakout, my pcb has the trace on wrong side of R11. Other boards do not have this error.

author: bitwelder
author_rank: Super Contributor
timestamp: June 06, 2019, 10:41:45 am
content: Voltlog was showing some of the station issues in his recent videohttps://youtu.be/QESGY5LzPPw

author: android
author_rank: Regular Contributor
timestamp: June 06, 2019, 11:53:25 am
content: You might want to preemptively replace C8 (Chongx brand 100μF 35V electro) with something from Japan. Mine was open circuit. Edit: oops I meant C4

author: voltlog
author_rank: Regular Contributor
timestamp: June 06, 2019, 05:18:39 pm
content: After a hint I got from another user on twitter, I assume R10 was intended as protection to prevent reverse leakage current from flowing through the diode into the battery when system vcc (3V3) is present. This is sometimes shown in RTC chip datasheets but KSGER somehow got that wrong and the resistor is slowly draining the battery. I have removed R10 on my unit, problem solved.Another known issue (but related to the power supply, not the controller board) is poor isolation between primary and secondary, caused by the output diode heatsink which extends on the top side from the primary high voltage tracks up to the secondary low voltage side.

author: floobydust
author_rank: Super Contributor
timestamp: June 06, 2019, 09:51:01 pm
content: Power Supply schematicsI drew of the KSGER soldering station, V2.04 and V2.05, 24VDC.KSGER 96W 24V 5A Electric Power Supply Unit For STM32 STC OLED T12 Digital DIY Soldering Station Controller.KSGER did change their power supply's PC board grounding.Soldering Power V2.05 (black pcb) has mains PE ground from IEC connecting to a large pad and open jumper/pin3 output connector, to the 24VDC secondary side GND, sothe controller board and heating-element are NOT grounded.The enclosure is not either. They fixed the PCB trace HV spacings to the heatsink, larger 82uF primary cap.Safety mod is to connect that jumper, and add a ground wire to the case which also covers ESD to the knob/encoder.Soldering Power V2.04 (green pcb) has mains PE ground from IEC connecting to the 24VDC secondary side GND, so the controller board and heating-element is grounded. The enclosure is not.Safety mod is add a ground wire to the case, which also covers ESD to the knob/encoder. The heatsink over the HV PCB trace, add some Kapton insulating tape or lift the heatsink for some airgap.If you want your soldering iron floating and trust the "double insulation" of the power transformer etc. add a 1MEG resistor from PE to DC GND. There's no safety approvals here, no idea how the transformer is wound if it would pass the few kV hipot test for the double-insulated test. Butthis did not work,seescope traces122Vpk so I'd definitely just add a wire as a hard ground.To check, just measure ACV tip-PE when it's running to confirm the tip is not floating up to some high voltage that can damage semiconductors or people.*Caution there are no bleeder resistors for the big primary cap, so always ensure it is discharged (check with a voltmeter) and safe to poke around before going in.edit Feb. 26, 2022: updated both PSU schematics- had X-cap in the wrong spot.EEVblog member Hugo.Froh has contributed PSU V2.05 voltage measurements, pics, annotated schematic, and at different loads with the V2.05 PSU.

author: Hemi345
author_rank: Contributor
timestamp: June 07, 2019, 05:33:32 pm
content: @voltlog, I believe the delay you mentioned in your video on power up might be related to initializing the OLED display. I've played a bit with these OLEDs and found that I needed to include a 1-2 second pause in my program at startup to give the display some time before I sent the initialization commands to it. KSGER might be a bit generous in the startup delay to make sure the display is definitely ready to go before trying to initialize it and display something. Only a theory. Maybe @PT_Dreamer can chime in on the startup delay as I believe that person wrote alternative firmware for some of these stations.

author: floobydust
author_rank: Super Contributor
timestamp: June 07, 2019, 07:47:30 pm
content: The power supply takes 3 seconds (on 120VAC) to come up, and then the controller another 3 seconds before the OLED is lit up.So for 6 seconds I wonder if I have the thing plugged in or turned on. Both delays are too long.edit: the long boot time 3 seconds is apparently the copy protection and RTOS delay. The power supply is another 3 seconds even after replacing capacitor.

author: Hemi345
author_rank: Contributor
timestamp: June 09, 2019, 02:42:44 am
content: I see the power LED on the power supply board light up on mine in less than a second, but no signs of life on the front for a few seconds (with my 2.01 station) so I wonder if it got unplugged too. It's kind of annoying. But other than that, I'm enjoying this station. For the money, it works well.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 11, 2019, 10:33:04 am
content: Nice workfloobydust. OneWARNINGto users of the KSGER V2.1S is that, if you put the station to sleep and power is interrupted and then comes back, the station will come back up ON! At least mine does.I'm drawing up a replacement PCB for this, does anyone have the dimensions for the GX12-M5 connector (pins) (I measured this from a new part and the PCB but confirmation would be good.Any part number suggestions for the beeper and the small locking connectors would be helpful tooI figured out the rotary encoder; it's a Bourns PEC11R-4120K-S0018 (the 20K is 20mm shaft length knurled and I could go with a 25mm 25K but they are not as easily available)The AT24C08N 8k I2C flash memory IC is obsolete and there is no stock at Digikey or Mouser; if this design is going to take PTdreamer's code, is the memory actually required? If yes, then can we switch to a SPI device?

author: Hemi345
author_rank: Contributor
timestamp: July 11, 2019, 03:33:09 pm
content: Quote from: Gandalf_Sr on July 11, 2019, 10:33:04 amThe default initial state is "ON" when the unit is powered up so that sounds like normal behavior to me. I have my unit's initial state set to "StandBy" when powered on because sometimes I'm not actually ready to solder when I first turn it on, habit of turning on the soldering iron while getting ready from years of using my old Weller. It'll also maybe offer a little fire protection in the event it gets powered up without the handle in the stand.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 11, 2019, 04:49:01 pm
content: Oh, can you change the initial state? My point was a safety issue where I had been leaving my KSGER T12 station on standby and then there was a glitch in power and next thing I notice is that my iron is 300 C.

author: floobydust
author_rank: Super Contributor
timestamp: July 12, 2019, 03:38:23 am
content: Quote from: Gandalf_Sr on July 11, 2019, 10:33:04 amMenu 12 to set the power-up state, but it must be Boeing software. If it was sleeping when power goes off, it must only look at Menu 12 setting to run, on power up?Quote from: Gandalf_Sr on July 11, 2019, 10:33:04 amGX12-5 I never found decent mech. dimensions and had to reverse engineer it for the pin radius or was it from a Japanese mfgr I forgot. The PCB has 1.6mm holes for 1.5mm pins, tight fit.I wouldn't solder a PCB to it- it's murder to desolder to get your board out, if you can do it. The GX mounting nut locks it in.Quote from: Gandalf_Sr on July 11, 2019, 10:33:04 amThe encoder seems to be a chinese clone ofAlps EC1117.5mm shaftI measure. It's an odd length to match the knob. Watch the underbelly has sharp edges that short to soldermask and short out, you need some keepouts. ESD hits the housing too so it needs some path to GND, a cap or resistor.Quote from: Gandalf_Sr on July 11, 2019, 10:33:04 amSTM32 family has no internal EEPROM, so you have to add one to store settings and calibration for your project or maybe you can use a block of FLASH. There are many other mfgr 24C08 parts i.e. M24C08 ST or AT24C08D Microchip.A lithium battery is something silly for a soldering station, I could care less what time it is.

author: Hemi345
author_rank: Contributor
timestamp: July 12, 2019, 04:14:21 pm
content: Quote from: Gandalf_Sr on July 11, 2019, 04:49:01 pmYeah, in your situation, I'd probably set the intial power state to Sleep (I think that's an option), so if that happens again, it'll just boot up to the iron being off. Note that these OLEDs can burn in the image when left on for long periods of time. It does that little race track animation after a while (also configurable in the menu) but I'm not sure all the pixels go dark for very long. Not that it would be hard to swap out the old screen with a new on for a few $ if that happens.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 12, 2019, 09:02:09 pm
content: Thanks for all the info. I've done some work on the schematic today with component selection, here's some notes:1. There are multiple 1.3" OLEDs available and some have the order of VCC, GND reversed so I have incorporated a cross-patch 0603 resistor setup to handle either.2. The STM32F103C8T processor is crazy expensive ($6) so I'm considering a Cypress CY8C4025AZI-S403 in its place, I've worked extensively with this processor and they're $2 in 100's3. The alternative suggestion for the 8k EEPROM was good, I chose a M24C08-RDW6TP which is dirt cheap (15 cents).What do you guys think about the new processor or could you care less? Changing CPU would mean I'd have to port over the code but I can handle that or share the work with you guys.I tried to unsolder the GX12 from one of my KSGER's I have a Hakko desoldering tool with a 1.6 mm tip which would seem perfect but I gave up in the end; I can see the advantage from a manufacturer's perspective of having the connector solder to the PCB as it almost makes it impossible to remove without destroying the PCB (maybe a feature rather than a bug?)

author: Hemi345
author_rank: Contributor
timestamp: July 13, 2019, 04:52:25 am
content: Quote from: Gandalf_Sr on July 12, 2019, 09:02:09 pmMy hot air station made quick work of removing the GX12 when KSGER sent me a replacement controller (replace the board with the crappy SOT-89 LDO w/one that has the switch mode regulator).It'd probably be better to design it to use wire for connections if you put standoff holes on the board to fasten it to the case. Or are you planning to use the KSGER case and face plates with your design? If so, the GX12 soldered to the PCB, keeps the PCB/screen aligned in the case, where as I've seen the screen tilted on the 2.1S because it's only held on one side by the rotary encoder.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 13, 2019, 09:45:33 am
content: Yes, I am sure I could remove the GX12 connector using a hot air rework station but it's kind of a weird design. I'm thinking that Iwillmatch the form factor for the KSGER as many will prefer this (and I can get all the components onto the PCB) but the PCB could still be put in a more ergonomic case. In the KSGERs I own, the PCB includes holes to feed wires from so that the GX12-5 can be remotely mounted but they are there because the GX12 connector can be sawn off and anyone could simply run wires from the GX12-5 footprint to the connector.I looked atPTdreamer's schematicyesterday and he's doing something weird with the drain of Q1 where he seems to be measuring the signal across a diode which, I think, is to do with allowing use of JBC tips - any comments on this and whether or not I should incorporate that into my PCB?So, I think position of display and controls will allow use in KSGER case but I'll add features that maybe allow for a bigger display.

author: floobydust
author_rank: Super Contributor
timestamp: July 13, 2019, 07:20:24 pm
content: I would start a new thread for OSHW requirements and design of a soldering iron controller, or porting PT Dreamer's code to these existing controllers. His board is old V1.5 and oddball I would not use it.GX12-5 footprint I took the 4-pin part and trigonometry to get the pin radius as 3.536mm (9/64"?), hole 1.6mm, pad 2.1mm. Let me know what you find.The problem is JST connectors to the GX12 pcb can't handle 3A. So it's directly soldered to the PCB which means you will never remove the board and I would rather the solder 5 wires.The open-source soldering iron controllers I see support 936, T12, JBC. I can help with the schematics for something low cost and not Fendi or Gucci.These stations use the popular 88mm extrusion out of china for an enclosure.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 15, 2019, 11:53:48 am
content: Quote from: floobydust on July 13, 2019, 07:20:24 pmFor 'pin radius', do you mean to the radius to the outer edges of the pins? If yes then I concur, my measurements have the radius to the center of the pins at 2.5 mm

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2019, 07:04:59 pm
content: Good, hard to find the dimensions with pin radius.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: July 16, 2019, 10:15:51 am
content: Nice find floobydust. That clearly shows that the pin diameter for the 5-pin GX12 is 5 mm so my radius is good at 2.5 mm. I have been doing some more work on the design, I'm leaning towards designing a board that is the same dimensions as the KSGER one so it could be a replacement but that doesn't mean that it can't be made to fit in a different case; I can also change the PCB layout at any time I like.I also think I'll start a new thread when I've done a bit more work - anyone want to volunteer to port the code over to PSoC Creator? I've already started the project in that IDE.

author: mematyi
author_rank: Contributor
timestamp: October 18, 2019, 09:27:22 pm
content: Hi!I just received this station from Banggood today, and it has a "Ve2.12S" marked pcb. It still shows 2.1S in the menu, but the board is a bit revised. The components moved a little bit, and R10 is simply missing from the board. My RTC battery came fully charged.Power Supply is still a 2.04 thing.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: October 19, 2019, 12:56:17 am
content: Cool, any change of a photo? I should pull my finger out and finish the design for my replacement PCB.

author: mematyi
author_rank: Contributor
timestamp: November 04, 2019, 08:11:05 pm
content: Hi!Sorry for the late reply.Here it is. That Famous R10 resistor is completely missing.

author: tszaboo
author_rank: Super Contributor
timestamp: November 04, 2019, 08:45:06 pm
content: Thanks for the schematic. I cannot believe I even considered buying this. Not even a fuse on the output or on the input. if you micro locks up, the iron becomes hotter than the sun. or if ESD kills Q2 gate. Not to mention all the routing and assembly problems. What a piece of junk.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 07, 2019, 02:27:36 am
content: Quote from: NANDBlog on November 04, 2019, 08:45:06 pmI do think you're being a little harsh in your criticism and since I haven't contributed very much to these forums of late, I'll explain why and add a little balance to counter this criticism. Incidentally, do you have any reason to think the gate of Q2 is particularly at risk of ESD damage? It's location in the circuit, as far as can see, makes it no more vulnerable to ESD than anything else within that Faraday Cage enclosure, earthed or not.It's true the control unit, as delivered, has some serious electrocution hazard risks due to the kakameemee diode heatsink choice and layout and absence of connection of the PE to the metal casing and ground bonding issues to the controller PCB but these are issues readily addressed by anyone buying one of these controllers as an upgrade to an existing soldering iron collection (and hey! at least the soldering tip is grounded making it ESD safe).Anyone who has had even just one previous experience of Chinese Kwality in regard of mains powered kit will be well aware of the need to open these things up to make sure that they're actually safe to use (either by them uncharacteristically already being safe, or more likely requiring a few simple alterations to ensure all the ESD, electrical fire and electrocution hazards have been neutered).Such modifications are fairly trivial to apply and well worth the additional work by anyone into electronics and DIY repairs/modifications to get their hands on such cheap Chinese bargain versions of kit that could otherwise easily cost ten times as much from Western manufacturers (who can't always be trusted to employ even minimal safety measures - Weller being a case in point with at least one current model of soldering station that has no protective fusing whatsoever).As for your "What if?" concern over the cpu locking up and the lack of protective fusing leading to the possibility of a T12/T15 tip glowing "hotter than the sun", that's always been an ever present but vanishingly small risk with any such control systems. The Lord Murphy is forever hovering in the background waiting His chance to punish Humanity for such hubris in believing they have made a totally safe and reliable 'gadget'.Most sensible designers (but not the Chinese it seems) don't aim for complete perfection, just enough 'perfection' to avoid suffering punishment of the "Capital kind" at the hands of Our Lord Murphy (i.e. minimal fire or electrocution risk). The Chinese don't seem to be able to distinguish between the level of consequences from their carelessness in design and manufacture of such electrical goodies, hence the safety check on Chinese electrical gadgets being SOP for the seasoned purchaser of such items.When you refer to the lack of fusing on the input and output, you neglected to specify the object in question. The PSU for all its faults, unlike the aforementioned Weller soldering station, actually has not one but two mains voltage fuses (a user replaceable fuse in the C14 socket assembly and the obligatory soldered in safety fuse on the smpsu board itself). Since smpsus typically incorporate overcurrent protection on their outputs, I can only assume you're reference is the controller board attached to the front panel itself.If this is the case, this is a situation where it would be impossible for any simple fuse protection (on the input or the output of the controller board) to protect against "the iron becomes hotter than the sun." risk. Since it's extremely unlikely that the iron could reach a temperature in excess of 2000K whilst the Sun's surface temperature is reckoned to be three times this at 6000K, this hyperbole detracts somewhat from your expressed concern over the lack of such protection.Quite frankly, the only situation where I can see such an event leading to loss of life or financial ruin is where the user needs to be under tight supervision by a competent adult. Making the reasonable assumption that any such soldering tools will normally only be used in a safe working environment by persons with a reasonable level of awareness of the risks in their inappropriate use, the worst outcome will be merely that of a ruined soldering iron. No biggy in the case of a cheap T12 clone and merely an annoyance in the case of an overpriced Hakko T12 or T15 tip - it's only money after all!Personally, if I ever saw my clone T12 tip starting to glow bright cherry red, I'd make a grab for my camera and use the opportunity to record just where the heating element is placed within these "Direct Drive Cartridge Tips" before hitting the off switch. Sacrificing even a genuine Hakko tip is far cheaper than investing in a relatively low resolution infrared camera to obtain such information at normal soldering temperatures. Besides which, photographic or even movie evidence can be useful when making a warranty claim against KSGER or their sales agent.Although power transistors have become somewhat more robust during the past half century, that truism about such semiconducting devices being defined as "Transistor - a ten dollar device designed to protect a ten cent fuse", still rings true today. Ordinary fuses, as I've already mentioned, don't offer effective protection against a lock up state that results in the iron overheating. Carefully crafted slow blow thermal fuses, accurately matched to the anticipated fault current in such a scenario could provide some limited form of protection against such an eventuality.Considering the rarity of such events (I can't recall anyone reporting such an event with these KSGER soldering stations), such provision of slow blow thermal fusing seems extremely unlikely as well as an unnecessary complication. It's a risk of failure I'm happy enough to accept, especially when I'm not going to be using the iron in such a way as to elevate such a risk to a life threatening level. I would be very surprised if other members contributing to this thread don't also take a similar view of this risk.You seem to forget that this product is aimed at a market demographic that will not only be all too grateful to get their hands on such a cheap clone soldering station based on Hakko's T12/T15 soldering iron direct drive cartridge tips but also have the necessary skills to render it safe and reliable for everyday use by applying the most basic of remedial measures.However, this does mean it can't really be recommended as a first time purchase to a soldering virgin without access to help from an experienced mentor, prepared to apply such remedial work on their behalf or to guide them in the necessary reworking by way of a practical lesson in soldering (using ordinary soldering tools of course!).Your concerns may be genuine if a little misplaced. Regardless of whether they were genuine or not, I thank you for giving me the opportunity to laud both the vices and the virtues of KSGER's cheap T12 soldering station. There are plenty here who see more of the virtue than the vice to go beyond mere remedial work and into the realm of applying hardware modifications to improve on KSGER's own efforts. I think your concerns may have fallen on deaf ears in this thread since I appear to be the only one so far, foolish enough to go where Angels fear to tread and make a reply. I'd seen an "illuminating" video on Youtube recently which demonstrated the 'glowing red hot' T12 tip but this was the result of mis-wiring a replacement temperature control module inside one of those combined spot welder/soldering station controller units. It was "illuminating" in that it showed just how close to the end of the tip the heating element was (extending just under 20mm from behind where the tip proper starts - impressively compact and right up against the tip itself). It seems I'd slightly misremembered that youtube video demonstration as you can see here:https://youtu.be/E9eZTspkV0I?t=241Nevertheless, it was literally illuminating, demonstrating just how compact and close to the business end of the tip the actual heating element is. I noticed he was careful to use the most commonly supplied K tip which so many reviewers tend to disparage out of hand. Close inspection shows that the heat is somehow being concentrated over the last 8mm or so of the heating element section which may or may not be typical for the K type tips.Since the K tip originally supplied with the soldering station appears to have become unstable and I'm now using the one from the pack of ten assorted tips I'd included in my initial order, I might sacrifice the original to a similar test run, seeing as I now finally have a Longwei 30v 10A bench supply to hand (after more than a month's wait for Banggood's "Priority Airmail" to belatedly fulfil its promise).This might actually cure it of its instability (or, more likely, kill it). At the moment it's like Schrödinger's cat, neither dead or alive so I'd prefer to force the issue one way or another and this seems a more fruitful way to resolve it (kill or cure - either is good, as in "All's Well that Ends", there's no need for it to end "Well", just as long as it ends).JBG

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: November 07, 2019, 07:30:57 pm
content: Johnny B GoodThanks for the brief summary in defense of the KSGER design. I would appreciate if you could outline your suggestions for 'upgrades' perhaps as bullet points.

author: mematyi
author_rank: Contributor
timestamp: November 07, 2019, 09:39:01 pm
content: Great point!As many people are purchasing the iron these days, it would be great to have a summary/guide of all the modifications at one place.With the help of this thread, I removed the heatsink from the PSU, clipped the side of it, and removed the soldered legs. Now it has at least 3mm of clearance from the HV side. I also connected the chassis to the PE, and verified that the PE goes to the tip. It does, because the PSU's 0V output is tied to the PE, and the 0V is connected to the iron handle minus and Earth as well on the pcb.According to the schematic published here, the iron actually has a separate GND and Earthing up to the controller. I think it would be great to separate those, and connect the chassis and controller board to the PE, but add a small resistor between the Iron Earth and PE, to limit the possible current. Does it make any sense?

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 08, 2019, 05:22:00 am
content: Quote from: mematyi on November 07, 2019, 09:39:01 pmBefore purchasing mine last August from Banggood (who had uncharacteristically shipped it out to me from their Chinese warehouse - cheapest option- in just 8 days!), I'd looked at countless youtube review videos so was well prepared to tackle the remedial work on the PSU and that 10K R10 battery draining resistor (as well as the need to fettle the wiring of the supplied 9501 handle which had guided my choice of soldering station - the alternative handle options had all looked rather naff to my mind).It turned out that this resistor had not been placed on the control board in mine, neatly explaining the 3.16v reading I saw when checking the plug in CR2032 cell which had been stuck to the side of the diode heatsink rather than jammed between the top of the psu transformer and the case lid - I relocated mine to the base of the case just under the LV end of the psu board, clear of any PTH wires.Since I had a 180W Parkside soldering gun stored unused since I'd purchased it from Lidl a year earlier, I decided to put it to use to sweat the heatsink off the board and reshape all three fins that overhung the "Isolation Slot" using a junior hacksaw and file to provide a healthy airgap to that 340vdc trace coming from the BFO smoothing cap rather than just ease it up enough to slide a layer of insulation tape in between said trace and the heatsink fin. I didn't have any kapton tape otherwise I may have used that method instead. Either way works - I just happened to have a BFO soldering gun to hand is all.Compared to that rather scary reliance on just a thin layer of solder resist mask to insulate the heatsink from a source of 340vdc, the 2mm creepage clearance between the retaining lug and mains voltage seemed positively generous so I left it alone. It's not ideal but the risk is low enough once the case is earthed.However, I must admit that it hadn't occurred to me to check whether the aluminium case had any earth connection until seeing another video review shortly after getting it "all sorted" as I'd thought in a moment of hubris, so I landed up stripping it apart yet again to rectify that particular Chinese sin of omission. Then, a little later on again, I discovered that the oval TPH which the unsoldered rotary encoder retaining tabs passed through weren't actually connected to the groundplane so had to solder short straps to nearby grounded points on the board for good measure.Which now reminds me that it might be a good idea to run an additional earthing wire from the soldered up retaining tabs as a belt to my braces soldering of an earthing strap from the PE tag directly onto the GX12-5 socket's barrel (I hadn't wanted to drill a hole into the case just to fit an earthing tag).I'm not sure (I've lost track of all the various sources of such useful information on these mods) but this last one may have been a floobydust inspired mod since I think I did the ground bootstrap diode mod across the heater element suggested by him to suppress voltage spikes at the same time.I used one of three BY298 diodes that I'd had in my parts bin for the past four decades just waiting to be put to good use - this seemed a golden opportunity to finally get some return on whatever my initial investment had been. Whether it makes any difference is hard to tell but I'm sure anything that suppresses voltage spikes on the input circuitry of an opamp dealing with mV level thermocouple signals is no bad thing.The one constant in all of this was the fact that the soldering iron tip was always fully grounded via the PE connection in the C14 mains socket (the only thing in fact thatwasactually earthed!). I know the idea of using a 1MR static drain resistance connection to the tip is largely deprecated by most, including myself but I can see where this could be useful in those rare usage cases such as working on ancient live telecoms kit running off 52 volt DC power to have an insulated tip with not even a static drain connection to ground for ESD protection. TBH, I can't see any such need these days with modern modular telecoms or IT kit nor with any other kit you might find yourself working with.Unless you have an essential need to work on live low voltage kit, you'd be better off with a low resistance earth connection to the soldering iron tip and work on circuit boards only when they are disconnected from their power source. You could try fitting a 1MR static drain with a bypass switch to let you choose whatever option seems best but this does leave room for mistakes. If you are going to use a resistive connection to earth the tip, just ensure that everything else (0v rail and the case metalwork) remains connected to the safety earth (PE tag in the C14 socket).I guess if such an option is desired you could use a two pole switch so you can light up a warning lamp to indicate when it's safe to use on live low voltage kit and when it's not safe. Even with such an indication scheme, the risk of getting the setting wrong still remains.In this case, using a low voltage DC (or AC) supply to power the heating element allows you to use a lowish value resistance, such as 10KR to 100KR, in place of the more usual 1MR static drain to earth with an acceptably low risk of damage to any unpowered delicate electronic components you may be working with. You could embellish such an arrangement with a leakage voltage detector circuit to trigger a warning of the presence of any undesirable voltage on the tip that could arise out of a breakdown of the insulation between the heating element and the tip itself - your call.The full earth contact to provide an ESD safe soldering iron is really an inheritance from soldering irons using mains voltage heating elements where the issue was not only one of ESD risk but also one of safety against the risk of electrocution.In the case of this KSGER T12 soldering station, you have some freedom to DIY whatever ESD protection scheme you fancy but it's best to avoid unnecessary complexity. The general advice here is "Make it no more complex than it absolutely needs to be (and, ideally, less complex than that)", which usually boils down to in this case, leave it as it is (the tip stays directly connected to the PE tag on the C14 socket).One alternative that could neatly address the occasional need to work on live kit is to add a socket so you can run the station off a 5s or 6s LiPo pack with the mains disconnected. Depending on your choice of battery pack, you could get several hours of use per charge, especially if you take full advantage of the low temperature standby and power down modes.Unless I'm very much mistaken, the smpsu should tolerate the application of battery voltage on its output when powered off (disconnected completely from the mains), leaving only the need to use a suitable diode in series with the battery supply to eliminate the risk of accidental backfeed should you power it up from the mains without unplugging the battery pack.If you use a 5s LiPo pack you could include a basic battery charging controller to let you use the smpsu to recharge the battery pack. You could do the same with a 6s pack but the charge controller will need to provide a small voltage boost which may make it a little more expensive an option. In this case, I'm assuming the use of a LiPo cell balancing and overcharge protection circuit in or attached to the battery pack.I've seen several examples of such battery powered stations built from KSGER kits but I can't recall seeing any based on the addition of a battery pack to an existing mains powered station. It might be worth taking a look, even if it's just to get some ideas on how to provide a battery power option to the existing mains only powered T12 soldering station if such an alternative has any appeal (freedom to work away from the mains supply with no troublesome earth contact to interfere with low voltage live circuits).JBG

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: November 08, 2019, 03:00:41 pm
content: JBG.That all makes sense but a picture showing all these improvements would also be a great help. Any chance?

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 08, 2019, 05:28:39 pm
content: Quote from: Gandalf_Sr on November 08, 2019, 03:00:41 pmI do regret not making a photographic record of the various modifications (before and after shots) so when I next take it apart to add that extra earth strap I mentioned, I'll rectify that omission and attach a few key photos to highlight not only the extra earth strap addition but also the modifications I'd applied since purchasing it.I'll try to fulfil this request for "photographic evidence" with a little more alacrity than your previous respondent had managed. Normally, my expertise in the fine art of procrastination doesn't bode well for such an outcome I'm sorry to say and you could probably place a large value order with Banggood and have it actually delivered before seeing any photos. However, since it's such a trivial modification and safety related, I might surprise us both in the next day or so.No promises but I'll do my best.JBG

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: November 08, 2019, 07:59:39 pm
content: JBG, NBD, FYI, JPGs

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: November 08, 2019, 08:13:54 pm
content: So to aid in the cryptic post above, the problem is that the 300+ Vdc track highlighted isreallyclose to the heatsink for the diode on the low voltage side. Here's the steps to ameliorate:1. Make sure the 400 volt capacitor is discharged2. Carefully remove the heatsink (I used a Hakko FR301 desoldering gun - awesome piece of kit)3. Remove the corners of the 2 heatsink splines as shown - this can be done with a good pair of cutters as the aluminum (similar to aluminium) is really soft4. Place a small amount of Kapton tape as shown (electrical tape, aka insulating tape in Blighty, will do)5. Refit the heatsink using a small amount of heatsink compound on the diode6. Use soldering station with less risk of self-electrocutionAs you can see, I'm bi-lingual

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 08, 2019, 11:59:04 pm
content: Nice photos!I took mine apart earlier this evening to take a few pictures (I'll sort out the extra earth strap tomorrow) and took exactly the same shot as your third image. It's a tricky shot to get right, especially if you're using macro to get close in as I think both of us did.I don't think I took any "before and after" shots of any of my previous modifications but I'll have a search just in case I did as a "Just might be worth documenting this work" thing and just put them out of mind, having done what I'd needed to do without any further thought of doing a "Show and Tell" session. If I find any previous pictures, I'll include a choice selection with my latest batch once I've recorded this, hopefully, final earthing modification work.JBG

author: BlackICE
author_rank: Regular Contributor
timestamp: November 09, 2019, 05:36:03 am
content: I took my heatsink off with a FR 301 too. Without it would have been a PITA since my other solder station is a Weller 1010NA. That and solder wick probably would work too well. I did add a fuse for the primary on the Weller.I didn't connect the negative of the secondary's output to PE. Is that necessary? I presume of the heating coil malfunctions the grounded tip cause a fuse to blow. Likewise as long as you ground the case if the heatsink shorts to the HV trace it will likely not causes an immediate problem (if the case is closed) as the diode has a non-conductive plastic case. Of course I'm only using 120v AC not 240 like some do with much more risk.IMO the mods in priority order are.1. GND the case to PE.2. Better isolate the heatsink from the HV trace.3. GND the negative of the sencondary to PE.Any think else? Some people did something to better protect the output MOSFET.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: November 09, 2019, 10:28:16 am
content: Quote from: Johnny B Good on November 08, 2019, 11:59:04 pmThanks. Believe it or not, they were taken on my iPhone 7+ on 'x2' which uses the second camera - the phone was very close to the subject and I touched the screen right at the point I was interested in to set focus and exposure at that point. The resolution has been reduced to make the file size smaller.

author: mematyi
author_rank: Contributor
timestamp: November 09, 2019, 11:03:15 am
content: Hi!Can you describe this Bootstrap diode mod?You placed a diode across the heater, but in which orientation?I think it might actually beneficial to do, as many of my T12 tips have fluctuating temperature reading on higher temps. They have been broken in and calibrated, only this is the (mainly aesthetical) problem.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 09, 2019, 03:40:25 pm
content: Quote from: mematyi on November 09, 2019, 11:03:15 amIf you look at floobydust's starter post to this thread (https://www.eevblog.com/forum/reviews/t12-stm32-v2-1s-soldering-station-controller-schematic-etc/msg2463234/#msg2463234), he mentions adding a ground clamping diode (not bootstrap diode - my bad in sloppy choice of wording) which is shown in the bottom left quadrant of the circuit diagram he posted this link to:https://www.eevblog.com/forum/reviews/t12-stm32-v2-1s-soldering-station-controller-schematic-etc/?action=dlattach;attach=755412Once I've added the extra ground strap later today, I'll post a photo showing how I'd added a BY298 diode substitute for his suggested RS1M smd diode to my controller board.I can't really say with any certainty whether this modification improves the behaviour of the controller. All I can say is that it won't (and appears not to) do any harm. Its presence reduces stress on the input protection filtering circuit of the TC opamp which could otherwise create a reliability issue in the longer term. It may be nothing more than a 'snake oil' placebo effect but if so, at least it'scheap"snake oil".As for this business of having to "burn in" these clone/fake T12 tips before they lose their initial instability, my best guess is that it's the result of galvanic action from residual moisture which gets driven out of the heater/thermocouple cartridge assembly after several minutes of first time use.This behaviour with virgin clone/fake T12 tips seems to be a universal experience amongst users of these cheap tips. So far, I've not seen anyone stepping forward to announce whether genuine brand new Hakko T15 (or T12) tips show exactly the same initial behaviour or not.It may simply be that Hakko have merely thought to run a final drying out stage in their production process which the Chinese clone manufacturers deem unnecessary, leaving their customers to deal with it as a commissioning "Burn In" operation.If I'm right in this hypothesis of residual damp and transient galvanic effects (there could be a completely different mechanism at work here but damp and galvanic seems the most likely cause), that implies some initial electrolytic corrosion effect taking place during this brief running in / drying out process from the use of DC current by these KSGER units.How deleterious this may be to the long term life of the cartridge heater/thermocouple assembly is unknown but initialising these tips using a 12.6v ac valve(vacuum tube) heater transformer supply to minimise such potential electrolytic corrosion could provide a useful extension to the service life of these clone/fake tips (assuming all the other shortfalls in quality don't kill these tips first).Even if such a low voltage ac drying out/burning in setup makes little difference to the long term life of these tips, if you're in the habit of buying your clone tips in packs of ten, it might be worth trying, if only to let you commission your clone tips in bulk without tying up your soldering station with this task, especially if you already have a suitable low voltage (8 to 12vac 20VA) transformer to hand (with perhaps suitable dropper resistors to extend your transformer voltage options a little further).You could even repurpose an ancient car battery charger to this task, perhaps one with a burnt out rectifier which will be redundent in this case, giving it a new lease of life. For anyone intrigued enough by the thought of safely commissioning their new clone tips without tying up their soldering station with such an otherwise unproductive use, such a setup needn't cost them a penny in materials and only an hour or so's worth of their (usually ample) spare time to run such an experiment.I'd run this experiment but ICBA to simply for lack of time (and, quite honestly, motivation) but don't let my own lack of 'get up and go' put you off the idea. If I could get a round tuit, I'd do it myself. The problem is that up to now, I haven't quite reached the 'bulk soldering up' stage with any of my own projects to justify the modest time investment required.It's just an idea for a little side project that I've put on the back burner to simmer whilst I try and sort out my real project, a basic DIY GPSDO which I've been working off and on during the past six months or so (along with some unfinished work on an already much modified Feeltech FY6600 signal generator).Anyone's welcome to run with this "neat idea" of mine if they're looking for a potentially useful experiment to play around with. It may prove a complete waste of time but even a "failed experiment" (strictly speaking, there's no such thing as a "failed experiment" unless it stops a money earning project dead in its tracks) will tell you something new.JBG

author: floobydust
author_rank: Super Contributor
timestamp: November 09, 2019, 05:53:13 pm
content: The extra clamp diode goes across the heating element at pin 4,5 on the GX12-5.This protects the mosfet and tip temp circuit from -ve voltage spikes due to back-EMF or ESD. Any fast recovery or 40V Schottky diode 1N5819 would work.For +ve voltage spikes, the mosfet's internal diode covers that.C8 provides a little coverage but it's absent on many controller boards.

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 09, 2019, 08:50:11 pm
content: As promised, a whole bunch of photo attachments from today's earthing modification. I think it'll take more than one posting to deliver the 20 image files Iselected.JBG

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 09, 2019, 08:53:42 pm
content: Here's the next bunch of pictures:

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 09, 2019, 08:56:32 pm
content: Here's the next five photos

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: November 09, 2019, 09:00:05 pm
content: And, finally! The last three photos.I renamed them with a descriptive title which should explain what each one is. You can always ask for clarification if desired.JBG

author: Zanadar
author_rank: Newbie
timestamp: January 09, 2020, 12:15:10 pm
content: Hi JohnnyFirstly, appreciate all the advice on here regarding this soldering iron.However I have a couple of questions regarding your earthing modifications.1) What is the purpose of the second earthing wire from the rotary encoder, when one earth wire connected from AC plug to controller board ground (with rotary encoder and handle socket connected to controller ground also of course) would seemingly suffice?2) Are you certain that by earthing at the handle socket, the entire case is earthed? My copy of this soldering iron has no continuity between the case and the handle socket.Cheers

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: January 10, 2020, 01:20:22 am
content: Quote from: Zanadar on January 09, 2020, 12:15:10 pmThe answer to question one is that having subsequently discovered that the oval through plated holes used by the encoder's retaining tags which I had previously soldered to improve the earth connection of the encoder's metal frame didn't actually have any connection to the control board's ground plane requiring that I run a wire strap to a convenient ground plane connection to remedy this strange omission in the board's design, I'd decided to also take the opportunity to double up on my safety earth wiring to create a 'belt and braces' solution to give me extra peace of mind.When I did the original safety earthing modification, using the socket as an oversized earthing tag bolt, I had to scrape away the black anodizing around the socket aperture and the four fixing screw holes in the front and rear panels and around the threaded holes at both ends of the top and bottom panels to ensure a trustworthy enough contact between all the component parts of the case.This scraping away of the anodizing is also required if using a separate conventional earthing tag as others have done by drilling a dedicated earthing bolt hole in the base of the case. It's also worth taking note of the fact that I'd relocated the nylon spacing washer onto the outside of the front panel (primarily to parallel up the control board with the front panel), allowing the fixing nut to establish a very low resistance contact between the socket and the case front panel.Although the solder joint onto the socket barrel seemed to be very well formed, I felt a lot happier once I'd used the rotary encoder to provide a second earthing connection to the PE tag on the C14 mains socket. Although it's possible to have too much of a "Good Thing", I rather thought that in this case it would be the lesser of two evils should one of the two earth wires somehow manage to come adrift and make contact with full mains voltage.TBH, knowing what I now know about the isolated oval TPH used by the rotary encoder's retaining tags, I wouldn't bother trying to use the socket barrel to provide an earthing connection. The rotary encoder is a much better bet for this additional function regardless of whether or not you bother to strap the tags to the controller board's ground plane.Personally, I think it's a good idea to strap the retaining tags to the ground plane - I'm just surprised that the TPHs used to retain the rotary encoder didn't have any connection to the ground plane to begin with.JBG

author: Zanadar
author_rank: Newbie
timestamp: January 10, 2020, 11:52:50 am
content: Thanks for the explanation Johnny, the requirement to remove the anodising was what I thought you would say as I was about to do so myself.I will still ground the handle socket also, already did the encoder body.

author: canoemoose
author_rank: Newbie
timestamp: February 03, 2020, 04:57:15 pm
content: Hey all, long time lurker but finally registered!Recieved my KSGER T12 station this week, thought I'd better just test before making all of the sensible safety modifications above - However, it appeared to be stuck in a bootloop which was actually chased to the PSU cycling on and off. The controller works fine on a bench supply, but the PSU is not well.The output of my SMPS looks like a sawtooth from 17.8 to 24.5V with a period of .58s.Any ideas as to where I should begin looking? I'm not new to electronics, but I'm not so familiar with troubleshooting switched-mode supplies... Nothing looks like a bad joint, but I might just go over them all with an iron anyway. I've also told Banggood, but I have no idea if that'll get anywhere so I'd almost rather fix it mysef - at least at the moment I know what I have, which is the "better" version as received by Voltlog, Floobydust et al.

author: mpbrock
author_rank: Contributor
timestamp: February 06, 2020, 02:51:50 pm
content: Quote from: Johnny B Good on November 07, 2019, 02:27:36 amLMAOIs this Iron actually worth investing in as a cheapie can't be bothered walking down to the lab to use the PACE gear type situations or is the TS100 type better for that? (Or maybe I should just buy another PACE)...

author: BlackICE
author_rank: Regular Contributor
timestamp: February 07, 2020, 12:24:28 am
content: I bought one from Amazon and it works great. I did the safety upgrades and bought a genuine hakko tips. I also have a welder 1010. I prefer the T12 clone because the handle is smaller and more maneuverable and heats up faster. Have not done a head-to-head comparison but in my opinion they are least comprable and the T12 about 2/3 the cost. Although unsafe as it comes from the factory. Buying from Amazon allows you to return it at no cost if you happen to get a defective one from the factory. Buying from China your mileage may vary.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: February 09, 2020, 10:09:10 am
content: Quote from: mpbrock on February 06, 2020, 02:51:50 pmNot everyone has the luxury to "walk down to the lab" and use the super-deluxe, James Bond, high-falutin' soldering equipment. Maybe you need a new 33GHz 'scope but want to save a few quid so why not buythis one from eBay?I bought one of these T12s and liked it so much I bought another. I highly recommend them.

author: mpbrock
author_rank: Contributor
timestamp: February 09, 2020, 10:21:29 am
content: The office where all my dev gear is upstairs, so thats where all the actual debugging etc.. goes on.. outside is where the machinery/soldering/chemical/"dirty" (you get the idea) stuff lives.. i don't want to be debugging micros in the same room thats full of flux fumes.. been there, done that at a previous job.. sitting in the same room as large Heller ovens, noisy production gear etc.. trying to debug a USB stack or something isn't great for the productivity.The problem comes with my current setup if i've got a prototype hooked up to the PC (Logic analyser or something) and i need to tack on a wire or quickly remove something, having to unhook everything, take it outside, do the work, then bring it all back in, hook up, rinse and repeat, it becomes annoying real fast!The PACE gear (ADS200) is pretty reasonably priced, or get a second hand good-name unit (<£100) - plenty of Metcals, Wellers, PACE etc.. kicking about at the same price as the Chinese clones - its just making that decision, do i go Chinese clone or second-hand good brand.

author: dreamcat4
author_rank: Frequent Contributor
timestamp: February 09, 2020, 11:40:21 am
content: Still chasing that dream of the JCB on the cheap with a 3rd party controller such as the KSGER T12. Which personally I think is best. Just the thing with the firmware being difficult to flash because it's an ST device although i've heard that on linux its possible via OpenOCD. And also the open firmware (that is up on github)... being written for an earlier board revision which raises issues in regards to the compatibility to get it working etc.I also have some alternative options in that area however thanks to the efforts of this guy elsewhere on Romanian forum xDaduNow neverminding that: if you are so inclined the PACE is a great lower-performance alternative. And there is nothing wrong with that at the price so long as you are happy with the performance that is being offered by it. However in the same ballpark is this other thing is available and I happen to think it's worth a gamble due to the supporting background evidence that it should be pretty good:https://www.tindie.com/products/soguklehim/soldering-iron-controller-v33-for-jbc-t245c245/Which then you get for about $40 the T245 handle on aliexpress + another $12 - $15 for a C245 tip. And whatever 24 high current DC supply. I have one also from aliexpress which is 20A which was less than $30. It's probably similar price to the pace overall. Just more of a gamble but potentially going to give you that greater JBC performance.

author: mpbrock
author_rank: Contributor
timestamp: February 09, 2020, 11:51:15 am
content: Getting side tracked, not ventured into STM32 dev yet, why is it “hard to flash”? Is it the STM32 or some problem on the pcb?I’ve just sold my JBC di2860 station maybe I should of kept thatjust feels like I need a cheap reliable iron in the office.

author: dreamcat4
author_rank: Frequent Contributor
timestamp: February 09, 2020, 12:32:28 pm
content: because the st development tools on windows are notoriously convoluted and they make it far more complicated than it needs to be to simply flash some simple little mcu with a binary blob of precompiled firmware. via the st link device and its windows driver... all that crap unnecessary bs you have to put up with. Why i also why i mention openocd open source tool. Like how complicated should it be to just write a string of bytes into the flash.

author: Icelvlan88
author_rank: Newbie
timestamp: February 09, 2020, 04:43:39 pm
content: Hello,Hoping someone can help me.I believe my unit died due to ESP. I cannot be certain, but I was working with it all night. Took a break, saw a shock on the case when turning it back on and it didn't turn on.I opened the case, saw that I'm still getting 24-26V from the power board to the controller board. Is there something else I can try it swap out on the controller board to bring it back to life? or am I better off just replacing? I saw on many forums that grounding the case is a good idea, but only afterwards...Thanks!

author: floobydust
author_rank: Super Contributor
timestamp: February 09, 2020, 07:08:27 pm
content: You could start a new thread for repair of the board.An ESD hit to an ungrounded case is bad, it would likely arc at the encoder's pins. That is another reason to ground the case and secondary-side, to give ESD coverage.Some versions of T12 controllers are junk because the 24V-3.3V regulator overheats and fails. The PC board copper for cooling is not there, or the regulator is a low quality chip.

author: Icelvlan88
author_rank: Newbie
timestamp: February 09, 2020, 09:17:33 pm
content: I ended up just ordering another board.What do you mean by the secondary side?Is there a thread with pictures and such of all the improvements that could be made on the V2.1S?Are there any improved 3rd party controller boards?Thanks!

author: Johnny B Good
author_rank: Frequent Contributor
timestamp: February 14, 2020, 02:48:10 pm
content: Quote from: Icelvlan88 on February 09, 2020, 09:17:33 pmSorry for the late reply but I've been rather preoccupied these past few weeks finalising my very first DIY (simple?) GPSDO and I'm currently trying to figure out why my 5 element Chebyshev LPF (to convert the 10MHz square wave into some semblence of a sine wave) appears to be defying all the known laws of Physics.In case you haven't already figured it out by now, this is it! (the thread you were looking for!). I think you'll find all you need to know if you read it from the very beginning. At the very least, you'll find some useful links to other sources of information. A visit to youtube will also prove fruitful if you enter KSGR12 into the search box - lots and lots of technical reviews to peruse. The more useful reviews tend to be in the 20 to 50 minute runtime range - save the shorter ones till after you've mined out all the reviewing goodness of the longer ones.JBG

author: MikeyG
author_rank: Newbie
timestamp: June 08, 2020, 01:20:40 pm
content: Hi, having just purchased a T12 station from Banggood, I found this blog and decided to follow the advice given here to make the unit safer. As noted earlier by mematyi, the latest board does not have an R10. As for the psu, rather than unsolder the heatsink to cut/file the bottom edge, I found it easier to remove the HV cap beside it and then snip the bottom edge off the heatsink. However, I noticed another trace disappearing under the heatsink opposite. This can be clearly seen at the bottom of Johnny B Good's photo 19 (many thanks JBG for extensive descriptions and photos). I measured the voltage on this trace at 141v AC (rms) - same as the trace already identified in this thread, but I have not seen any mention of potential danger from the proximity of this trace which passes beneath the other heatsink. This would be harder to fix (so have left it for now), and the heatsink would need to be removed and a bridge cut into the bottom edge.Am I right in thinking this is a hazard too, and has anyone attempted to fix it?

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 08, 2020, 02:24:54 pm
content: Quote from: MikeyG on June 08, 2020, 01:20:40 pmI fixed an issue with a high voltage track right under a heatsink, it'shere on the previous pagecomplete with before and after pictures.Is the one you're talking about different?

author: MikeyG
author_rank: Newbie
timestamp: June 09, 2020, 04:40:14 pm
content: Hi Gandalf-Sr, thanks for the response. I have fixed that heatsink issue - as I say by snipping the bottom corner without removing it. It was in doing this that I noticed a track under the opposite heatsink. I am attaching (hopefully) an edited version of Johnny B Good's photo 19 showing a blue circle around the track you identify, and a red circle around the track under the heatsink opposite. As I don't have a whopping 180 watt iron, I am not sure how I can remove that heatsink for "adjustment". I believe both tracks carry the same HV but have not traced them out.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 10, 2020, 09:08:42 am
content: Quote from: MikeyG on June 09, 2020, 04:40:14 pmI just got another one (my third) and, after proving it worked, I did the mod to clip the corner off the heatsink. I have a Hakko solder removal gun which helped but a T12-K bit running at 300 C will melt the soldered posts and allow remove of the heatsink. I looked at the area you point out but the track to it seems to come from the '-' terminal of the bridge rectifier via a 300resistor so I am not convinced that it's an issue, what's really needed it to understand where you marked point is on the schematic.My new one came with an updated bit holder that has a screw-on bit retainer, it seems fine. I'll post pictures later.

author: MikeyG
author_rank: Newbie
timestamp: June 10, 2020, 02:00:47 pm
content: You are right Gandalf-Sr, the track under the lower (in the pic, red circle) heatsink comes from the top of R6 which connects to the -ve from the bridge. The track under the upper (in the pic, blue circle) heatsink comes from the top of R3 and C7 which I think is the +ve from the bridge. Relative to GND (my measurements) both are reading about 143v AC (ie half wave mains). Are you saying the 300 ohm R6 mitigates the danger of a short to the heatsink? I think I would prefer to play safe and carve a bridge in that lower heatsink too.

author: Gandalf_Sr
author_rank: Super Contributor
timestamp: June 10, 2020, 05:01:47 pm
content: Quote from: MikeyG on June 10, 2020, 02:00:47 pmI did have the thought about the resistor providing some protection but it won't do any harm to put a bridge in the heatsink.

author: MikeyG
author_rank: Newbie
timestamp: June 10, 2020, 06:48:06 pm
content: Decided to leave this be for now. This heatsink is nowhere near anything else - unlike the one first identified which runs close to the LV circuitry. Thanks anyway.

author: dreamcat4
author_rank: Frequent Contributor
timestamp: June 14, 2020, 10:25:35 am
content: @floobydust suggested changes to update your 1st post:Quote from: floobydust on June 05, 2019, 06:34:51 amAlso in schematic add:"AO4409"underQ1as 2nd alternative mosfet.Sorry for cross posting across different threads. Other post about it:https://www.eevblog.com/forum/reviews/stm32-oled-digital-soldering-station-for-t12-handle/msg3095988/#msg3095988

author: pvhoof
author_rank: Newbie
timestamp: June 23, 2020, 01:00:09 am
content: I just received mine I plugged it in and after about 3 seconds the display came on, another 5 seconds and a pop it went dark. Upon opening it I found resistor R1 burned and open. I did not try to replace it yet since I suspect U2 got a blast of the 160v dc on pin 6 and I suspect for some reason the mosfet stays on.Any suggestions on how to proceed would be welcome.Peter

author: floobydust
author_rank: Super Contributor
timestamp: June 23, 2020, 01:07:41 am
content: I suggest to start a new thread in Repair and if you can post a pic of the power supply because there are a few variations.

author: BlackICE
author_rank: Regular Contributor
timestamp: June 23, 2020, 04:11:06 am
content: Ask for full refund or replacement.

author: nephilim
author_rank: Newbie
timestamp: February 14, 2021, 07:44:32 pm
content: Hi,I got my T12 v2.1s a few days ago and did the recommended actions to ground it properly. I found this thread and since I haven't seen this elsewhere I would like to ask how & where to apply the following fixQuote from: floobydust on June 05, 2019, 06:34:51 amThanksTorstenP. S. Oh dear, I just read this thread again and the info is of course there already. Apologies!

author: Mindstorm88
author_rank: Contributor
timestamp: April 03, 2022, 07:33:49 pm
content: Hi Guys , just received my T12 from Ksger on Ali, on the board it is written V2.1S but i doubt it is just a V2.1 here a picture for future reference as i have not seen it anywhere on the net.

author: floobydust
author_rank: Super Contributor
timestamp: April 05, 2022, 12:38:35 am
content: Everyone is copying everyone and confusing a model number with a PCB revision number. The "S" was the optional desoldering-pump control that has been removed.Your board looks pretty much the same, a few changes like the 78L08 regulator U6 powering something, seems odd.Note your mosfet Q1's soldering looks not well. Are the pins soldered OK?

author: Mindstorm88
author_rank: Contributor
timestamp: April 05, 2022, 02:24:21 am
content: i thought i had an original as i bought it from this store ''KSGER Official Store" , soldering of Q1 is not perfect but ok, i may redo it. the 78L08 is a pre step down for the AMS1117 3.3 . If i find time i will draw the schematic of it .

author: floobydust
author_rank: Super Contributor
timestamp: April 05, 2022, 05:30:47 pm
content: The power section of the controller boards has been a struggle for years. Dropping 24VDC down to 3.3V either makes heat (linear regulator) or noise (buck converter) and the priority is of course low cost. Earlier boards overheated, failed then it settled down OK with the JW5026 buck converter - but no stock it could be the semi shortage forcing this change.Your controller is usingAMS1117-3.3but max. Vin is only 15V, so they use a 78L08 to first drop it down. As well as the two 6R8 resistors and diode.I would just finger check the temperatures of the parts to see if it's a decent solution. I think the 78L08 will run hot, maybe 0.5W dissipation is alot for the SOT-89 and that small copper fill. The controller board's version number is usually written on the other side, sometimes under the OLED and hard to read.

author: Mindstorm88
author_rank: Contributor
timestamp: April 05, 2022, 07:07:39 pm
content: Yes the version is on the other side . it is written V2.1S

author: floobydust
author_rank: Super Contributor
timestamp: April 06, 2022, 07:22:19 pm
content: It's the station model number "V2.1S" china confuses soldering station model number, revision number for the controller, firmware version etc. which adds to the confusion.I hate shopping on Aliexpress because only the pictures tell you the details, ad text is a bunch of lies lol.Your board looks like it has higher quality components, compared to many others. I can help with a schematic if you trace out the power section, the rest looks the same.Check the soldering station is correctly PE grounded- the V2.05 power supply is not. So the tip will float to voltages too high for semiconductors, it's ungrounded which is a no-no. The "G" terminal on the controller board needs to be wired to the IEC, or PSU PE ground jumper put in. The V2.04 PSU secondary was grounded though. Check with an ohmmeter.

author: Mindstorm88
author_rank: Contributor
timestamp: April 08, 2022, 12:05:14 am
content: Here the schematic of my model.- the driver for the mosfet is a NPN , no resistor to the STM- R1B a pullup of 910k, never seen on other model, maybe to help with temp measurement.

author: floobydust
author_rank: Super Contributor
timestamp: April 09, 2022, 09:10:33 pm
content: Does the 78L08 run hot?PCB trace J1 is for the JBC option.Q2 should be a mosfet (and is on some other 2.1S boards), I agree there's no base-drive limiting resistor which might be hard on the MCU pin.R1B 910k is a pullup for open-thermocouple detection, it works without it but picks up noise and the controller looks like it's spazzin if there is no tip in the handle.

author: Mindstorm88
author_rank: Contributor
timestamp: April 10, 2022, 02:22:28 pm
content: for Q2 according to marking J3Y it is a S8050 NPN and after vérification with a meter it is confirmed a NPNthe 78l08 in heating mode, i put a TC on its gnd tab, it reached 66 C. May have to do a mod on the long run !!

author: floobydust
author_rank: Super Contributor
timestamp: April 10, 2022, 07:30:49 pm
content: Other boards, Q2 is []url=http://aosmd.com/res/data_sheets/AO3422.pdf]AO3422 (same pinout as BJT) and likely what they ran out of. Hard to know if the firmware is using PBO open-drain/40k RPu or just under the MCU max. rating of 25mA.If the 78L08 could run a bit cooler, the OLED wouldn't need the resistor R2 on 3.3V feeding it and could be brighter?Old boards with no copper pour at all roasted their LDO, it would shut down or burn up. But this board looks OK at least the parts are better quality and aren't black-topped. It's hard to compete, would you lower quality and price or not? russian forums complain KSGER quality is lower but it seems their best doesn't always go there.

author: Mindstorm88
author_rank: Contributor
timestamp: April 10, 2022, 07:55:08 pm
content: for now display brightness is good enough for me. For Q2 i'm sure i have some mosfet pin compatible in stock. If the 78l08 dies, i wil put a small buck step down module to replace it, but as this is not my main soldering station , i'm pretty sure it will live long !!!

author: floobydust
author_rank: Super Contributor
timestamp: April 10, 2022, 09:13:16 pm
content: Last question - is the soldering tip grounded to mains earth-ground, or floating?

author: Mindstorm88
author_rank: Contributor
timestamp: April 10, 2022, 11:41:47 pm
content: The tip is grounded to mains earth-ground , psu is a Rev 2.04.Wire has been added to case and encoder.

author: floobydust
author_rank: Super Contributor
timestamp: April 11, 2022, 04:14:52 am
content: Good, the V2.05 PSU ungrounded things which is a mistake.

author: Ricks_Radio
author_rank: Contributor
timestamp: April 25, 2022, 10:51:02 pm
content: Many thanks to all who have put this gold mine of information together. I have recently purchased a KSGER soldering station and I have used the info posted here to upgrade the V2.05 power supply.My KSGER T12 is the current V3.1S and has a different controller board. It is Ver-20. Yes that's 20 not 2.0? I am attaching a photo for comparison purposes. As you can see R10 (4.7k) is there in all it's glory. Unfortunately I've never seen a photo of the Ver 2.0 board so I have no idea if this is the same beast?Any insight would be appreciated. Thanks.Rick

author: floobydust
author_rank: Super Contributor
timestamp: April 27, 2022, 06:34:53 am
content: As I've mentioned- the soldering station model number, controller H/W version number, software version all seem to get blended. The chinese copy each other along with mistakes.I would say your board is yet another copy of the Ver2.0 controllers out there, with some changes.Not from the "KSGER" store.edit: yes it's from theKSGER Storeas "OLED V2.01" board says "T12-V20".The linear voltage regulator overheated in many Ver2.0 designs, yours at least has a little copper heatsinking I think it's an LM317EMP but I would say it will run hot. The AO4409 mosfet seemed to fail for some people, it has no thermal pad underneath. Don't hot swap tips with power on. It's difficult because sometimes the semi's are low quality. Yours look decent marking though.Definitely check what you've got for grounding and add the PE ground wire. You can do a finger test for how hot the Vreg and mosfet get.

author: Ricks_Radio
author_rank: Contributor
timestamp: April 28, 2022, 04:08:56 am
content: Thanks for getting back Floobydust. It's disappointing that they coupled this old controller board with the latest software and power supply. I'll mention that in my review of the product. I agree it is likely an LM317EMP. It might be possible to add a small piece of copper at right angles to the board near the regualtor to help with the heat dissapation. (If I give it a try I'll post a photo.)Has anyone posted a schematic of the Ver 2.0 controller board? The PE is now grounded and the regulator is running cool to the touch.I've encountered another "problem" this one seems to be a firmware glitch. The TIPs menu seems to think I have a J02 tip. I don't and there's no way that I have found to un-check that tip from the menu. I've tried everything I can think of including a complete reset. This is not a big deal .... more a slight inconvenience.Thanks again.Rick

author: floobydust
author_rank: Super Contributor
timestamp: April 28, 2022, 05:42:26 pm
content: Let us know if the Vreg runs too hot. And it's got the battery drain resistor? I also see the cold junction thermistor NTC R21 on board, which is rare.I have a few V2.0 controller schematics. There's no big difference with the latest OLED V3.0 or V3.1 controllers aside from the 3.3V power supply being done with a buck-converter, the JW5026 is out of stock for a while now and more likely why KSGER rolled back- component shortages.As far as the tip list, I thought it needs to have at least one in the list, so first try add another to the list and then select it.

author: yelkvi
author_rank: Regular Contributor
timestamp: April 28, 2022, 06:15:53 pm
content: Quote from: floobydust on April 28, 2022, 05:42:26 pmWhat is the point of NTC on the board if the "cold" end of the thermocouple itself is in the soldering iron handle?Why measure the temperature inside the soldering station case? It will also be different from the one in the handle. And, accordingly, thermal compensation will not work correctly. This is a mistake of Chinese manufacturers, for whom the main thing is to sell goods,without understanding how it works.

author: omega9380
author_rank: Newbie
timestamp: May 05, 2022, 06:55:10 pm
content: OK, so after reading thru this thread and wanting a "definitive T12 board", I took a look at both floobydust and Mindstorm88s schematics, and kinda zoned out for a few daysHere's the results. I have created a KiCAD schematic and board, complete with JLCPCB part numbers.I want to stress a point that I am not an electronics engineer. In fact, my day job is an IT administrator. I play with KiCAD as a hobby. I'm not formerly trained in electronics or PCB design, so be gentle with the pitchforks when you see my trace routingI would like to get this board manufactured but I wanted to send it to the experts here on EEVBlog Forums first. Please tell me if this will burn down my house, blow up my computer, or steal my wife and car.The full design files are up on GitHub:https://github.com/omega9380/KSGER-CoverplatesI'm attaching the board renders and the schematic PDF for all to see.Happy soldering!

author: floobydust
author_rank: Super Contributor
timestamp: May 05, 2022, 08:12:10 pm
content: Welcome to the forums. I think it best to start a new thread for your design review, to not derail this thread about the OEM parts. I could not find the schematic pdf.Right off the bat, power traces are too thin for the heater and mosfet, thermal reliefs as well, for the many amps of current. It's best to keep the high current section close together. How can you put a GX connector on the front panel and not have it hit the board? If you're planning on using the original aluminum enclosure I could also see the four corner mounting holes not working out, hitting the extrusion housing. The original boards have a cutout/space for the GX and four corners.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 05, 2022, 09:21:47 pm
content: Those mosfet 0.1mm tracksCheckthis example, keep power traces as short and thicker as possible.Move the transistor closer to the connector.Also increase the width of VDD tracks, just a little, about 12-15th.Add more decoupling capacitors to the stm32, in every VDD/VDDA pin. This also happens in the original crappy design.Place the decoupling capacitors closer! C3 placement is terrible, rotate it 90° so the positive is much closer.Add more vias to join the ground planes, specially close to the stm32, regulator, amplifier... Avoid those barely connected islands like in U3, adjust the traces so the plane isn't broken everywhere.

author: omega9380
author_rank: Newbie
timestamp: May 06, 2022, 10:54:23 am
content: Thanks for the feedback folks!@flobbydust, I did go ahead and create a new thread so not to take over this one:https://www.eevblog.com/forum/projects/t12-soldering-iron-controller-board-based-on-ksger-board-v2-1s/To answer some of your questions, I wasn't designing the board to be exactly like the original KSGER one, nor for it's case. I have an aluminum project box that I was designing the board for, planning on getting custom endcaps made for it based on the board I'm designing. I mostly wanted the schematics up on GitHub for anyone to fork who wants a custom made T12 controller.@DavidAlfa, thanks, this is the exact feedback I was looking for! My board design experiance is mostly relegated to YouTube vids, like the ones Dave posted on board design. Again, I'm not an engineer, just someone who likes to play around with this stuff. As stated above, I created a seperate post for this project. Also, are you the same as "deividAlfa" that forked PTDreamer's custom firmware? I plan on using yours for the new board, and I want to put it on my current KSGER v2.1s...as soon as I remember how I flashed that one in the first place......

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 06, 2022, 12:41:33 pm
content: Neither am I am enginner!Ah yes, davidalfa was already taken, not willing to make davidalfa1234, I took the phonetic pronunciation of "David" in english, but written in spanish. That's a common way to friendly call Davids here. Like Jimmy for James.Check the readme in Github, you have programming, etc... I think everything is pretty clear there?

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 01:36:44 pm
content: A year ago I bought my welder on aliexpress, it has an OLED screen and on the board you can read Oled-V3.0, it has worked for me for a long time without any problem until suddenly it has not turned on anymore, neither the screen nor the buzzer. Yes, before it took about 5-10 seconds to start but now there is no way, if I connect it I don't read voltage on the screen pins, but on the input capacitor.The power supply I use is 24V and 160W.Thank you very much!Enric

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 01:41:50 pm
content: Show a photo of your board (on a large scale). I will show in the picture at which points to measure the voltage.Then we will analyze what is broken.are there any similar ones? -P.S. Board photo taken fromhttps://github.com/deividAlfa/stm32_soldering_iron_controller/tree/master/BOARDS/KSGER/%5Bv3%5D/SchematicI hope DavidAlfa doesn't get offended

author: mastershake
author_rank: Frequent Contributor
timestamp: May 15, 2022, 03:47:07 pm
content: typically the oled v3.0 board is the same as the 3.1 and 3.0 versions except some had the battery either in a different place, on leads, socketed, or not installed at all. i have a few styles here of that board.

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 04:22:39 pm
content: There is none similar, this is the photo of the back, I have measured the electrolyte capacitor and the display, and the display does not give voltage.Thank you very much for your quick response!

author: mastershake
author_rank: Frequent Contributor
timestamp: May 15, 2022, 04:26:34 pm
content: yours is the same as the bottom v3.1 the differences are in the battery in the corner. yours has the spot for it to be attached to the pcb where the v3.1 has a socket for a lead otherwise they should be the same thing

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 04:42:59 pm
content: Yes, I see that it is very similar but I wanted to confirm just in case I am not receiving wrong advice and wasting your time.So where can I find the voltage measurement points?

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 04:45:37 pm
content: Connect 24 volts to the board. Measure the voltage at point "1" and at point "2" (relative to "-").What is written on the chip "3"?Take a higher quality photo of the board.

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 04:54:45 pm
content: Here is a diagram of your board (or similar):

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 04:56:11 pm
content: on the point 1, read 24Von the point 2, read 0Vand the chip "3" is a very small, with a magnifying glass I read "jwbmj 9ya4l" but doesn't found nothing on the internet.

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 05:04:05 pm
content: Great, I think this is the one that is dead since I don't read 3.3V at the output, what can I do?

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 05:14:19 pm
content: Chip "3" is a DC/DC step down converter. Looks like JW5026 (datasheet for it in the file).Pins "5" and "4" should have an input voltage of 24 volts. And after the inductor "L1" - 3.3V.If there is no voltage 3.3, then several options are possible:1. Closing the circuit after "L1". To check this, you need to measure the resistance from the "L1" coil to "-".2. The breakage of the coil itself - measure its resistance - should be almost "0".3. Bad soldering - carefully look through all the small radio components around this microcircuit under a magnifying glass.4. The chip itself is faulty - it needs to be replaced (if there is no JW5206, then pick up an analogue).

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 05:44:26 pm
content: okey!in the pass nº1 I measure 0.6Ohm without voltage.2- 0.8 ohm3 i iew all ok4 the most possible.is possible put a 3.3V with an external power supply? to make it easier, can I connect it to the vcc of the display?If it worked like this, could you remove the chip and put a 3.3V AMS117? I know the footprint doesn't fit but I could mount it on another plate or aerial.

author: DavidAlfa
author_rank: Super Contributor
timestamp: May 15, 2022, 05:57:04 pm
content: Now remove the coil and check at which side the short is.Could be just bad capacitor.

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 06:00:02 pm
content: Quote from: Enric on May 15, 2022, 05:44:26 pmThis is not good. Very little.I read one topic on a Russian site. Many users had a problem with a soldering station, where the 3.3 voltage regulator is made like yours. I'm sorry, but the STM32 chip itself failed.If possible, unsolder the controller. If the resistance increases, then the STM.Moreover, they wrote on that forum that the stabilizer microcircuit was also out of order.Most likely, at first it failed, and then 24 volts entered the STM.To make the circuit more reliable, the step down converter must be set to 5 volts, and after it, set 1117 to 3.3V

author: Enric
author_rank: Newbie
timestamp: May 15, 2022, 06:39:28 pm
content: Ok, tomorrow I'm going to go find another welder and I'm going to try it.Thank you all very much.

author: floobydust
author_rank: Super Contributor
timestamp: May 15, 2022, 06:52:17 pm
content: Best to start a new repair thread for your controller. The JW5026 appears to be sole-sourced, I did not see any alternate part.

author: yelkvi
author_rank: Regular Contributor
timestamp: May 15, 2022, 06:55:37 pm
content: If you are going to buy a new STM32F103 chip, then pay attention that you need it with 64 pin (16 pin on one side). Because there are 48 pins (12 pins per side).

author: Dickysoe
author_rank: Contributor
timestamp: October 20, 2022, 02:29:29 pm
content: Hi All,I'm not very good in electronics. And i got a JWBHJ chip burnt uon connecting to 6S lipo battery.Can you please help me find a direct replacement for JWBHJ or JW5026?I cannot find them anywhere here in Indonesia.

author: yelkvi
author_rank: Regular Contributor
timestamp: October 21, 2022, 02:39:36 pm
content: The JW5026 is a current mode monolithic buck switching regulator

author: Dickysoe
author_rank: Contributor
timestamp: October 21, 2022, 03:43:48 pm
content: Yes, i was looking for alternatives. But don't know which one available in my country.I tried purchasing AOZ1282CI & MP2451DT. Hopefully those 2 IC can be used. They have the same package SOT23-6 and pin order.Can you please help me, i need information whether those 2 IC can be used or not.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 21, 2022, 03:50:57 pm
content: You need to ensure few things:- Same pinout.- Similar current and input voltage capabilities.- Similar switching frecuency.- Same reference voltage, but not really critical as long as you replace the feedback resistors to match the same output voltage.

author: yelkvi
author_rank: Regular Contributor
timestamp: October 21, 2022, 03:51:55 pm
content: If these microcircuits are not available in your country, then you can buy them on Aliexpress. They are there. Inexpensive.

author: Dickysoe
author_rank: Contributor
timestamp: October 21, 2022, 05:28:30 pm
content: Hi thank you for your reply.I just bought today some that might be compatible. Can you please help me choose the safer bet to replace JW5026?JW5026- monolithic buck regulator- 4.7V to 40V- 1A output current- Output 0.8V to Vin-3V- 1.1 MHz switching freqand I bought 3 types :AOZ1282CI (SOT23-6, same pin layout as JW5026)- High Freq Buck Regulator- 4.5V to 36V- 1.2 A cont output current- 450 KHz PWM operation- output voltage adj to 0.8V to 0.85*Vin- 420 mOhm MosfetMP2451 (SOT23-6, same pin layout as JW5026)- High Freq step down switching regulator- 2.2V to 36V- 0.6A high efficient output- 2MHz switching freq- Adj output 0.8V to 0.8*Vin- 500 mOhm mosfetMP2456GJ (SOT23-6, same pin layout as JW5026)- Monolithic switch step down converter- 4.5V to 50V- 0.5A output- Fixed 1.2 MHz freq- adjustable output 0.81V to 0.91*Vin- 1 Ohm mosfetThank you for your help.

author: Dickysoe
author_rank: Contributor
timestamp: October 21, 2022, 05:30:50 pm
content: Just checked on Aliexpress.they cost in lot of 10 pcs.not expensive. but the shipping is so expensive, let alone the Indonesian import tax, which is quite high based on my experience on servicing under warranty to fatshark goggle Australia. they charged me a lot of money.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 21, 2022, 06:28:04 pm
content: I think any of these would work.I'd probably start with the MP2451, the increased frequency shouln't be an issue.

author: Dickysoe
author_rank: Contributor
timestamp: October 22, 2022, 12:03:16 am
content: Will try it as soon as it arrived.Thank you so much for your help and advise.

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 22, 2022, 12:12:59 am
content: An advice: Try isolating the output, so it doesn't fry everything if it sends 20V instead of 3.However it must be done after the coil and the first capacitor, what's your board?

author: Dickysoe
author_rank: Contributor
timestamp: October 23, 2022, 03:05:13 am
content: i looked at the diagram for 3.3V for each, and notice that I need to change 2 resistors :one between SW and FB pin and another one between FB and GND pinall the ICs have different value of resistor compared to JW5026.I cannot find the board diagram anywhere on the internet.but assuming from the datasheet table for 3.3V, I need to to change 2 resistor i doddle with yellow on the pics in order to get 3.3V output.am I correct?

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 23, 2022, 08:32:30 am
content: Not si critical as long as the relation is the same.

author: Dickysoe
author_rank: Contributor
timestamp: October 23, 2022, 05:14:13 pm
content: So, is it OK if I just replace JWBHJ with other buck converter IC only? The output voltage should be read on SW pin?

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 23, 2022, 05:20:30 pm
content: No, it's a switching regulator (SW makes 24V pulses) the voltage will be seen at the output of the coil, measure at C4 (the side with a line mark)

author: Dickysoe
author_rank: Contributor
timestamp: October 23, 2022, 05:54:42 pm
content: Will try changing the IC tomorrow. Thank you for you help. Hopefully nothing blow up tomorrow.

author: Dickysoe
author_rank: Contributor
timestamp: October 24, 2022, 08:32:42 am
content: Tried today. And fried yhe chip.And when I tried to replace the buck IC, the pad came off.I think I'll buy a new solder then.Thanks All.Quote from: Dickysoe on October 23, 2022, 05:54:42 pm

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 24, 2022, 10:57:58 am
content: So there was another problem that blew the first regulator.Could be a short, have you checked it?

author: Dickysoe
author_rank: Contributor
timestamp: October 24, 2022, 11:00:14 am
content: Honestly, I don't have a proper knowledge in electronics.but now that the pad got pull off. is it beyond saved?

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 24, 2022, 11:53:11 am
content: Normally you can track where it went and simply solder a small wire, unless it's a very complex board (Not the case).Are you sure you didn't solder it in the wrong orientation?Check attached picture. Check 1 and C4 for shorts (Shouldn't).L1 must measure like a short.Repalce the IC again, but before powerign on, check the connections with the multimeter!Ensure there're no shorts between the pins and there's connection with the surrounding components.Use the multimeter in continuity mode (That one that beeps when shorting the tips).

author: Dickysoe
author_rank: Contributor
timestamp: October 24, 2022, 03:09:19 pm
content: Pin1 of the new chip (MP2456GJ) aligned with the red dot on your mark.I also changed the resistor according do datasheet :7.5 KOhm to 124 Kohm2.4 KOhm to 39 KOhmthen I connect to power source, but the unit didn't come to live.the not long after, the new chip got burnt.Amazing how you can trace it (mark on the pics) without a diagram.Quote from: DavidAlfa on October 24, 2022, 11:53:11 am

author: DavidAlfa
author_rank: Super Contributor
timestamp: October 24, 2022, 03:38:15 pm
content: If the recommend resistors are higher, using lower ones is rarely a problem as long as the ratio is the same.This is mostly to reduce power consumption...But if the IC suggest lower resistor values, this is usually to compensate for the feedback input current.7.5/2.4=3.125, (0.8*(1+3.125)= 3.30V124/39=3.18, (0.8*(1+3.18)=3.34VThe difference would be only about 43mV, absolutely irrelevant.

author: xfint34
author_rank: Contributor
timestamp: July 02, 2023, 04:37:40 pm
content: Recent purchase to Canada. Sold as KSGER T12 v2.1s . Controller board looks the same as Mindstorm88. Power supply is v2.2. I have not seen this posted before. The tip of the iron goes to PE.The case is not grounded.There are dabs of hot glue holding the power board in place at the corners of the board.Edit: A couple more things to mention.The power supply has through-hole marked PE. You can see it peeking out the capacitor on the right in my photo.The controller board I have has a different chip markings than Mindstorm88. Perhaps both of these two are some combination of real / fake chips. Both fake? Both real? One or the other? Who knows. I don't have a programmer board myself.The fuse is all glass. No metal end caps like I've seen every where else.

author: xfint34
author_rank: Contributor
timestamp: July 20, 2023, 08:42:53 pm
content: CPU ID: 20036410Does this mean it's a genuine STM32? Is there any other trickery that could be going on?

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 20, 2023, 10:52:13 pm
content: Apparently it's genuine, though nothing keep clones from copying that. Thankfully they don't use to.And yeah, that marking is suspicious.You have original firmware backups, so there's nothing to worry about if you want to test other firmwares.

author: Ian Dall
author_rank: Newbie
timestamp: July 21, 2023, 03:44:55 pm
content: This has been a most informative thread!I purchased a T12 from the Aliexpress "KSGER Official Store". It is a V3.1S and they make a feature of "case is grounded" which they achieve with a banana jack on the back panellinked to the IEC-C14 connector. The anodising on the case, made the earthing a bit dodgy and the iron tip was still not grounded at all. So this was my approach:Insert 3mm internal start washers between the back and front panels and the extrusions.To avoid gaps, I recessed the corners of the extrusion with some careful filing.This worked well, but placing the washers makes assemble a bit fiddly.The earth banana jack was a normal insulated banana jack with both parts of the plastic insulating bush on the same side of the panel. I thought it better to remove the plastic altogether and add an internal star washer between the earth lug and the panel.There is a pad labeled PE on both the power supply board and the controller board. I soldered 2.8mm Quick Disconnect tabs to both to take a removable jumper wire.I also added a fixed flexible jumper from the PE on the controller board to the encoder frame. The PE on the controller board connects to the soldering iron tip.Place a 12mm internal star washer on the GX12 connector and the front panel.Also the controller board was not parallel to the front panel, so I added a washer between the panel and the encoder frame and reworked the soldering of the header pins connecting to the display board. This is just to satisfy my OCD.This all seemed to work well[ Specified attachment is not available ] and I'm pretty confident it is at least safe!

author: floobydust
author_rank: Super Contributor
timestamp: July 21, 2023, 04:51:51 pm
content: But is the tip grounded? The 24VDC common needs a PSU jumper/solder bridge on V2.05 I thought.Photos in the threadhttps://www.eevblog.com/forum/repair/ksger-mini-t-12-station-doa/show a solder bridge between pins 3,4 for this and your controller does not have it.

author: Ian Dall
author_rank: Newbie
timestamp: July 22, 2023, 07:07:46 am
content: Not as delivered. The tip is connected to pin3 on the GX12 connector, which is connected to the PE pad on the controller board. Adding a jumper between that and the PE pad on the power supply board grounds the tip, albeit with a relatively high resistance of about 4 ohms. I didn't include a picture of the actual jumper, but it goes between the Quick Disconnect tabs I soldered in.

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 22, 2023, 01:21:09 pm
content: 4ohm high resistence?Damn it can only take 60amps @ 240V, definitely useless for ESD protection

author: floobydust
author_rank: Super Contributor
timestamp: July 22, 2023, 07:07:48 pm
content: The power supply V2.05 ground jumper (quick-connect) you soldered in should connect the 24VDC(-) to PE.The tip needs to be grounded or else it will float to weak ~60VAC due to the Y-capacitor in the power supply. You can measure it with a multimeter on ACV.

author: Ian Dall
author_rank: Newbie
timestamp: July 23, 2023, 12:58:49 pm
content: The 5 ohms is OK, but I don't think the very narrow trace in the handle would handle the current until the circuit breaker trippedI'm thinking that is what the ELCB is for.

author: Ian Dall
author_rank: Newbie
timestamp: July 23, 2023, 01:19:04 pm
content: The tip is definitely grounded. At the line input end, the PS board is connected to the IEC connector ground and it looks like a fairly wide trace. I measure essentially zero ohms (within measurement error lacking a 4 terminal ohm meter) between pin 3 of the GX12 connector and the mains earth. There is an extra couple of ohms from the GX12 connector to the actual tip. With the thing powered up I get 26mV AC at the tip with one multi-meter and 2mV AC with another.The 24V -Ve is not connected to the PE on the power supply board, but it is on the controller board.

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 23, 2023, 02:19:38 pm
content: How could it be? Several ohms in a solid 15" long AWG26 wire directly connected to the tip case?Try wetting the tip with some alcohol, then inserting it several times to clean the socket connections.

author: Ian Dall
author_rank: Newbie
timestamp: July 25, 2023, 03:20:40 am
content: Yes, of course it is not the actual wire. Opening the handle it is low resistance (<< 1 Ohm), from the main earth, right up to the contact in the handle. With fiddling, I can get the resistance right up to the tip less than 1 Ohm, but not consistently. More typically it is 2 or 3 and up to 5 Ohms, even up to infinity sometimes!It raises the question of how good the contacts are to the heater/thermocouple, but they appear to be a different metal than the barrel, which looks like stainless steel. Anyhow, I'm not investing any more time on it unless it proves to be a problem.

author: xfint34
author_rank: Contributor
timestamp: August 20, 2023, 07:16:03 pm
content: I tried to make a schematic of the V2.2 power supply. I used as a template the layout from schematics made by floobydust. I'm sure there are technical errors. I don't normally do this stuff.The circuit looks the same as the previous versions. The differences I noticed are some of the components they put on this board compared to v2.04 and v2.05. In particular the rectifier and MOSFET have a lower rated specifications in datasheet.Bridge rectifier: KBL307 vs KBP310MOSFET: FQPF20N60C vs CEP10N6Y1 capacitor: JNC222M vs N222MOptocoupler: FL817 vs PC817The PE ground trace on the bottom side of board looks much thinner than the v2.04 board. There is no big copper fill on the +24VDC.I don't know if these differences have significant implications on performance.

author: Keeboudi
author_rank: Newbie
timestamp: October 24, 2023, 05:04:08 pm
content: I have been using one of these stations for a number of years on a daily basis in an audio electronics workshop. It has been reliable and works mostly fine but we have one issue: We often pick up (switching?) noise on the equipment we are working on, especially stages with high gain and am/fm receivers etc. I was wondering whether anyone else has noticed this and if there is a solution to cure it?

author: RayRay
author_rank: Frequent Contributor
timestamp: October 24, 2023, 05:51:06 pm
content: Quote from: Keeboudi on October 24, 2023, 05:04:08 pmFirst of, welcome to the forum!Secondly, do note that most T12 stations use a metal case with only partial grounding (the iron itself is grounded, but not the case) There are of course ways to address it. It might help if you'd make a video though, to make the issue more clear

author: Jono434
author_rank: Contributor
timestamp: November 14, 2023, 09:15:33 am
content: I wasn't sure what thread to ask this in.Does anyone know the front panel dimensions of the cut outs? Is there a picture or a file floating around somewhere?I'm looking at using KSGER V2.1S Controller board for example, but mounting the GX12 connector on the rear and having the 12mm hole at the front be for a push button. And potentially using plexiglass/acrylic for the front panel painted black on the opposite side.The main thing is the size in mm of the display cut out. Is it 32 X 17mm? And also the distance from the edge of the display to the center of the encoder knob hole. This is hard to measure when assembled, but even measuring the center of the knob would give a general idea.In the attached image, I understand these numbers are probably wrong.. but it gives an idea of what I am talking about.

author: Pfeffernuss
author_rank: Newbie
timestamp: December 03, 2023, 04:39:14 pm
content: Hello everyone!I just registered here after some time of passively following your discussion about the ksger soldering stations.Meanwhile, I own one of these stations and have some questions concerning the model with V2.2 power supply. (User xfint34 has posted some pictures of this one in posts #131 and #143.)I will just state my questions below, hoping for some answers from you.1. As I understand from xfint34's photos, the known issue with the heatsink overlapping the HV trace is not existent in this version, right? Also, the space between the aluminum posts of the heatsink and other traces is sufficient, right?2. At the other end of the mentioned heatsink, there is a mid-sized electrolyte capacitor very close to the heatsink. In my case it is directly in contact with the heatsink (see photo below). Is this a problem, concerning temperature of the capacitor? Otherwise it shouldn't be a problem, to cut the fin of the heatsink, so that it wouldn't touch the capacitor any more.3. As xfint34 already wrote, the gnd-trace on the backside of the pcb is significantly thinner than in the common versions. Is it still thick enough to ensure some security in case the soldering tip would touch a part under current?4. As you can see on the photos of my station below, the case is already connected to PE with a relatively thin black cable. Is this thick enough, or should I use a thicker one?5. Are there any other obvious security issues in this version of the power supply, I should fix, before using the station?Greetings and thank you in advance.Chris

author: floobydust
author_rank: Super Contributor
timestamp: January 16, 2024, 09:24:10 pm
content: Welcome to the ForumsSorry I did not see your post, it gets busy here.Important - is the tip grounded to PE? You don't want the tip floating up with stray voltage, or being a possible shock hazard if the PSU insulation fails. They have no safety approvals with these PSU's. Yours looks well made (transformer insulation) but I see a lot of junk builds copying the KSGER name.The danger with the older PSU was the PCB trace has HVDC, with the heatsink on top of itit is also on top of secondary-side PCB traces so that's why I hit the horn. It would fail a hi-pot test.Soldermask is not a proper insulator. At least they moved the trace over a little bit by R3 as an improvementI see the enclosure is PE-grounded which is another improvement. The ground wire should be thick enough to clear the fuse, it looks reasonable.It's OK the output cap is touching the heatsink, the heatsink does not have hazardous live on it.My second concern would be the thickness of the GND trace from PE to the 24VDC secondary side, again it needs to be high current. I don't see a wire or jumper it must be a run on the underside of the board. Maybe post a few more pics, I can draw a schematic for this V2.2-220610 PSU then.

author: geonicz
author_rank: Contributor
timestamp: April 27, 2024, 09:23:15 pm
content: Hi everyone!Hope someone can help me with my trouble. I've just bought one more pcb from China, cause they're like leftovers from the past and cost much less than other versions without docs, with strange controllers onboard and without ability to flash devidAlfa's firmware. So, it was a good looking choice. I had one for long enough and deividAlfa's firmware forced me buy one more. Mostly for c245 and c210 tips. It's called the "2.1S original pcb" sometimes. At least in dreamcat4's project.Here is a photoof this controller.Schematicsis also there. I've flashed firmware, connected t12 tip, connected c210 tip. Everything works fine. But the problem is with the c245 tip. I don't know how to connect it to this controller correctly to work with this firmware. Don't know which traces should be cut and which resistors where should be added to support c245 tips. Maybe someone can help with it?

author: DavidAlfa
author_rank: Super Contributor
timestamp: April 27, 2024, 09:33:08 pm
content: Always post pictures,or no help!Search "245" here:https://www.eevblog.com/forum/reviews/stm32-oled-digital-soldering-station-for-t12-handle/

author: floobydust
author_rank: Super Contributor
timestamp: April 27, 2024, 10:16:54 pm
content: I thought the 245 thermocouple has 2 junctions and thus too much output for the usual T12 op-amp configuration.

author: analityk
author_rank: Regular Contributor
timestamp: May 05, 2025, 12:44:26 am
content: My cusin sent me fired up KSGER solder station.During repair I've realized that this 78L50 regulator makes 5 volts only for LM1117-3.3 V regulator.I have no idea why someone takes smaller regulator for dissipating a lot of heat and then use post-regulator where amount of heat is insignificant.I've replaced 78L05 with one in DPAK case but still in 5 V and it can not replace bigger copper polygon.Second problem is lacking of backward diode in 78L05. 24 V can be lost very quickly when power mosfet is on (short times after power switch turns off station), so there is still possible to current can flow in wrong direction by this reg.I have no idea if newer version of this design exist but there is still some engineer work to do.

author: floobydust
author_rank: Super Contributor
timestamp: May 05, 2025, 01:16:19 am
content: The voltage reg overheating, failing - it is the weakness in of most of versions of the T12 control boards.If you have to drop 24V at 40mA down to 3.3V at 40mA... linear regs... that is 0.83W of heat to shed. Way too much for a SOT-89.Your board, they spread it out between the two regulator IC's and R14/D2. Most boards have a 78L09. R14 as 15ohms or so, which does not really help.Diode D2 prevents backfeed if the 24V is shorted during a cartridge swap.You are right, most of the heat 78L05 0.71W or 78L09 0.55W is dissipated in the first (pre) regulator. That's a lot. I've seen russians just put a TO-220 part there lol.Controller boards using buck-converter IC JW5026 is better for not heating up, but noisier for thermocouple readings. That IC was not available during the pandemic so they rolled back to using linear regs I guess, and bungling the required heatsinking.

author: Mattii
author_rank: Newbie
timestamp: September 14, 2025, 04:46:36 pm
content: Hi, i bought this ksger t12 v2.1 and i have purple pcb and can some one tell is this real stm32https://imgur.com/a/IZ8PZDu

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 15, 2025, 04:30:34 am
content: https://github.com/deividAlfa/stm32_soldering_iron_controller?tab=readme-ov-file#ksger-self-resetting