Aixun T3A misbehaving on grounded PCBs - Page 1
Forum section: electronics / general

author: tony359
author_rank: Frequent Contributor
timestamp: September 15, 2023, 08:56:47 am
content: Hi all,Just got this Aixun T3A and I'm experiencing a pretty severe issue. Basically if the PCB I am working on is grounded, some (not all) joints will cause the station to lose connection with the tip (NO TOOLS displayed on screen).This happens with multiple tips.Also the handle is buzzing which is... concerning?I am not on very latest FW, I downgraded to 1.33 as with 1.34 the temperatures are all over the place.This is brand new so I can ask for warranty support (wish me luck) but I'm curious if anybody else is experiencing the same or has an idea of what is going on?Thanks!

author: slavoy
author_rank: Regular Contributor
timestamp: September 15, 2023, 09:37:12 am
content: Touching the grounding point with the tip of the soldering iron shorts one of the thermocouple leads in the tip, causing the station to be unable to read the correct temperature during that cycle, which results in reporting a tip error or behaving erratically. It's the same in Quick soldering stations, for example. This is due to the design and temperature measurement method, and apparently, during the temperature reading period, the thermocouple cannot be shorted to the ground.

author: tony359
author_rank: Frequent Contributor
timestamp: September 15, 2023, 10:13:24 am
content: That’s not the case though. If I touch ground with the tip, nothing happens.Only if I touch some solder joints of a grounded PCB.So are you saying this station cannot be used on grounded equipment? I had that board on a pre-heating station - which is grounded. Are you saying I can’t use it in that scenario? It limits the case use of the station massively.Also, what is the purpose of the ground alligator lead enclosed in the box of grounding the PCB causes that issue?I’m still very puzzled.

author: slavoy
author_rank: Regular Contributor
timestamp: September 15, 2023, 10:29:04 am
content: I think this way you create a loop to ground, which introduces interference into the thermocouple signal.QuoteIt's meant to connect to the ESD point, but internally, it's directly connected to the ground in the case without any resistor.

author: tony359
author_rank: Frequent Contributor
timestamp: September 15, 2023, 10:52:33 pm
content: T3A owners: have you seen this on your station?

author: drksy
author_rank: Regular Contributor
timestamp: September 18, 2023, 12:20:56 am
content: Quote from: tony359 on September 15, 2023, 10:52:33 pmI tried it on my unit. Grounded some board to mains earth and touched the tip of the iron to some ground point. I couldn't reproduce the effect. Nothing happened.

author: tony359
author_rank: Frequent Contributor
timestamp: September 18, 2023, 02:28:20 pm
content: I appreciate the time you spent on this, thanks!However, it's not ground that triggers the issue.It's SOME pins on a GROUNDED board. I can touch ground with my tip and nothing happens as well.As I am measuring 0.95VDC at the tip, that is enough to activate some junctions and I suspect that some combination of components might trigger some unexpected feedback.

author: thm_w
author_rank: Super Contributor
timestamp: September 18, 2023, 10:36:31 pm
content: Looks like you've cross posted here:https://forum.allaboutcircuits.com/threads/aixun-t3a-issue-on-grounded-pcbs.196084/You are measuring 1VDC from the tip wrt ground right? What is the tip resistance to earth?I tried with Aifen that I've earthed the tip on, and it gives a similar voltage and a heater error if I ground the tip via another path. The stock config was floating tip which was not nice, I prefer this configuration. Its probably a common issue with JBC clones. JBC itself has a ton of circuitry inside to deal with this, in addition to the linear transformer which might have less noise. I remember bskull dealing with a similar issue:https://www.eevblog.com/forum/projects/jbc-clone-with-good-ground-noise-immunity/What you probably want is a proper ESD mat (not silicone) and then ground the ESD mat and not the circuit board itself.

author: tony359
author_rank: Frequent Contributor
timestamp: September 19, 2023, 09:34:37 am
content: Yes apologies for cross-posting but I don't get much feedback on thisTip to earth is zero ohms but only when not heating. When heating I'm reading OL - to measure that I had to go from cold to 400C so the tip is being heated for several seconds.During the "trickle" heating I see the resistance jumping around but that's my Fluke not fast enough to read OL I guess.Yes it's 1VDC measuring from tip to ground.Thanks for the link. Things are getting clearer. However, if I touch ground with the tip nothing happens. It's when I touch SOME joints on a GROUNDED PCB.Many have commented on why I would need to ground a PCBs and I don't normally do that. But as I said I discovered this issue while soldering a PCB which was sitting on a (obviously) grounded pre-heater. The PCB touches the metal chassis of the pre-heater so it becomes grounded.If this behaviour is expected, I can take precautions and shield the resting points of the pre-heater. It just baffles me that nobody has seen this before, I noticed that 20 minutes into using this stationAlso, wouldn't 1V/1.5A be potentially dangerous for some more delicate components?Thanks for your input!

author: thm_w
author_rank: Super Contributor
timestamp: September 20, 2023, 12:05:22 am
content: Thats a good point about the grounded preheater, if you have traces near the edge. I guess options for you are:- Add teflon washers or rails to insulate the board on the preheater, and rely on the station being earthed- Get another soldering ironIf you measure 1V and shorted out providing 1.5A then yes there is a very small chance some components could be damaged. But if you are also measuring zero ohms to earth, I don't think the current would be that high. There are some measurements in the aixun thread where 0.4A short circuit is seen:https://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg4417474/#msg4417474still fairly high I guess...One of the JBC schematics was reverse engineered here:https://www.eevblog.com/forum/testgear/jbc-soldering-station-cd-2bc-complete-schematic-analysis/You can see two 0.22 ohm resistors and a fuse from the tip to earth ground, then a circuit that senses earth leakage. I don't know if an Aixun schematic exists anywhere, and if any mods can be done.

author: tony359
author_rank: Frequent Contributor
timestamp: September 20, 2023, 09:13:54 am
content: thank you @thm_wYou're the first in the whole internet who has actually pointed me to what I think is the right direction.c0d3z3r0 is measuring the same things I am and he's experiencing the same issues I am. It sounds like there is a reason for this station to cost a fraction of a JBC - what annoys me a bit is that none of the reviews I've watched have mentioned any of this potential issues.Let's see what Aixun comes back with (meanwhile they have confirmed that my station is genuine at least and they will help if they can), then I'll draw my conclusions.I did put some kapton tape on the rails where the PCB sits while on the pre-heating plate but inevitably you end up with some metal parts touching something. I guess I'll have to decide whether to live with it or not.Thanks for now!

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: September 20, 2023, 03:58:45 pm
content: Quote from: thm_w on September 20, 2023, 12:05:22 amSchematics can be found here:https://github.com/c0d3z3r0/aixun_t3a_rev/blob/master/schematics/aixun_t3a.pdf

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: September 20, 2023, 04:19:30 pm
content: I believe that the grounded tip + heating through DC/PWM instead of AC + the way T3A is measuring temperature is the root cause.This is how the cartridge is connected:GX12-5 pin handle / tip5 + ---------------- heater (middle)4 GND ------+-------- GND (top metal)|3 ID ------+2 T(EMP) ---------------- temp (lower spike)Temperature is measured between the outer connector (GND) of the cartridge and the spike / center connector.Heating happens through outer connector (GND) and the middle connector.JBC stations measure between the outer connector (GND) and the middle connector, while heating is done through middle connector and center connector. (Oh well, there are different opinions on that topic btw. Some people say JBC is heating through middle connector - outer connector. When I looked at the reversed engineered JBC schematics, I had the impression that it's middle + center)

author: tony359
author_rank: Frequent Contributor
timestamp: September 20, 2023, 04:46:36 pm
content: @c0d3z3r0Thanks for your reports on this issue - as I said you are the first I am reading about that.What is your opinion on this, do you see this as a major issue with the T3A or just something I should try to mitigate by insulating the PCBs I am soldering? And what about the voltages and currents you measured? I measured 1.5A in DC between tip and ground, I believe you only measures 0.4A.Thanks!

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: September 20, 2023, 04:59:38 pm
content: Quote from: tony359 on September 20, 2023, 04:46:36 pmWow, 1.5A o.OWell, I usually don't ground any boards I am soldering. Since I also solder highly-ESD-sensitive stuff and I have not yet fried any board (or... at least I'm not aware of any issues yet - ESD might cause damage that only shows at some later time), I would say it's fine for me.However, if anyone finds a proper solution/fix/hack/... for these weird behaviours of the T3A, I'd be more than happy

author: tony359
author_rank: Frequent Contributor
timestamp: September 20, 2023, 06:05:09 pm
content: I don't either - my pre-heating board happens to be grounded though, that's how I discovered that!Thanks for your input, gives me a little peace of mind!Are all those copycat cartridge stations like that? Is the famous KSGER the same? Just wondering.

author: thm_w
author_rank: Super Contributor
timestamp: September 20, 2023, 11:01:03 pm
content: As noted above, Aifen was worse if anything (tip is ungrounded), and then the same behavior after the mod. Ksger I have one portable one, same issue where the temperature can bounce around due to induced noise.With a pure T12 clone you wouldn't have this issue as the tip earth and heater are completely separate, so the T12 KSGER can be OK (assuming the tip is earthed inside).There is an "i2c" station with a toroidal transformer but I don't know the results of that one. Aixun has theirhigh end modelas well.Its a tradeoff with the JBC design I guess, to get that performance the thermocouple has to be bonded electrically to the tip, making isolation difficult.Quote from: tony359 on September 20, 2023, 09:13:54 amYes, as you can see with codezeros schematic, its built to be about as cheap as possible in terms of control and measurement. Single opamp single FET.If you are a professional, don't mess around with cheap clones, get a name brand station.I'm still not sure why the current is this high though.. the secondary is isolated right? The tip should be earthed via an isolated supply so it can float. But I guess the issues are all related to inductive or capacitive coupling in this case?The filtering in the Aixun schematic: C27 then R33, if that is right it seems backwards, I would expect RC filter on the temperature sense input not CR. In the JBC schematic you can see two op-amps, and an normal RC filter at the output of the second one.

author: tony359
author_rank: Frequent Contributor
timestamp: September 21, 2023, 10:35:30 am
content: Thanks.I'm not a professional, I really cannot justify spending £500 on a JBC.As long as I am not damaging anything, I'm happy with the T3A.The T420 looks interesting - but will it be free from bugs? The T3A has stellar reviews online, nobody has mentioned any issues. So not sure I want to experiment with another mode. As I said, as long as I am not damaging things, I can live with the T3A. Opinions?

author: tony359
author_rank: Frequent Contributor
timestamp: September 21, 2023, 11:16:13 am
content: stumbled into this comment on a T3A review video.So clearly not just me.

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: September 21, 2023, 11:37:09 am
content: Quote from: thm_w on September 20, 2023, 11:01:03 pmWell, the genuine JBC station uses AC for heating, which probably simply does not interact with DC GND / earth. I guess the main problem is using common GND for earth, heating and the TC. It's just a gut feeling, though.Quote from: thm_w on September 20, 2023, 11:01:03 pm

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: September 21, 2023, 12:07:55 pm
content: Quote from: thm_w on September 20, 2023, 11:01:03 pmNot sure if that is meant to be a RC filter. Check out this one:https://taaralabs.eu/tag/t245/"Series resistor and reverse diode on the input of the Op-Amp are used for the protection against possible voltage spikes from the iron."

author: LuisBe
author_rank: Newbie
timestamp: September 21, 2023, 01:00:48 pm
content: Hi, I don't know if my contribution will help but I recently had the following problem with the ground of my workbench.The output of my signal generator (it was on but the output was disabled) gave me a voltage of 3Vac (measured with a multimeter). The problem is that an old power supply (switched off but connected to the same socket) was feeding 10Vac into my ground and some of it was going to my generator. I removed the power supply cable and my ground was clean. I don't know if you have tried just having the soldering station in the main socket and doing the test.Best regards and good luck.

author: thm_w
author_rank: Super Contributor
timestamp: September 21, 2023, 09:34:55 pm
content: Quote from: tony359 on September 21, 2023, 10:35:30 amYeah you'll probably be good then.I wouldn't spend £500 on new JBC either, the T420 is $230, will it be bug free, who knows. I already buy used Metcal for ~$240 so I'm not interested in the aixun at that price point.Quote from: c0d3z3r0 on September 21, 2023, 12:07:55 pmOK, makes sense. Though any external signal coming into an onboard ADC I would expect an RC filter to also be present. The signal we care about is very slow (temperature).Quote from: c0d3z3r0 on September 21, 2023, 11:37:09 amYeah most likely you are right.Whether it matters if its DC or AC, I don't think it does as long as switching is not too hard. With DC, you would have a main 24V supply that only goes to the heater. Then an isolated 24V:5V brick to run your mcu and control. And differential sensing of the TC, not using common ground. Might work.

author: mastershake
author_rank: Frequent Contributor
timestamp: September 24, 2023, 10:03:40 pm
content: i will not be back to the office till at least tues or wed but i will test this on the 420 and see. also we have 14 of the t3a here so ill test a few of them and see if i assume it will but more then one will do this same thing. i dont ground like code says i will to the esd mat but that does not seem to effect it like this.

author: thm_w
author_rank: Super Contributor
timestamp: September 25, 2023, 09:44:03 pm
content: Good teardown of a Weller station was just posted:https://www.eevblog.com/forum/reviews/weller-wxr-3-rework-station-teardown/They are using DC and have a FET for each output (24V, 12V, and 12V). So clearly DC itself is fine. Although they've still gone with the linear transformer instead of a switch mode.

author: mahi
author_rank: Regular Contributor
timestamp: September 26, 2023, 06:30:46 am
content: thm_w:Indeed, the Weller WXR 3 switches DC as well, but one major difference is that the Weller switches a non-filtered full-wave rectified signal at the zero crossings whereas the Aixun T3A switches a regulated DC signal. So, one results into a smooth(ish) full-wave sine and the other into a harsh square wave.And even the full-wave sine of the Weller WXR 3 seems to be a step back from the older generations that used triacs to switch the transformer AC directly (also at the zero crossings). When heating up I can hear a faint buzzing noise from the WXMT soldering tweezers. I guess the sharp "bottoms" of the full-wave sine are to blame for that.Note that using linear transformers and switching AC at the zero crossings is not guaranteed silent either. Transformers, especially non-toroidal, can hum and several Weller soldering stations show that.

author: tony359
author_rank: Frequent Contributor
timestamp: October 04, 2023, 05:09:28 pm
content: other "real life" examples of when this issue happens.- Equipment is unpowered but still connected to a serial port which is connected to the laptop which is connected to a device via USB which is connected to ground.- Oscilloscope clip is still attached to the chassis.With this I mean that there are a variety of cases where this issue happens.

author: floobydust
author_rank: Super Contributor
timestamp: October 04, 2023, 05:55:16 pm
content: sorry I cross-posted your video in the other threadhttps://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg5094360/#msg5094360What markings are on your thermocouple amp IC? "541E"? Many different op-amps are used in T12 clone controllers and I'll bet that's part of the problem. What ver controller board you got?I would tack on a wire to observe the TC amp output with a scope and see it is probably oscillating or picking up HF noise due to a grounding or SMPS problem. Legendary firmware based on Boeing's MCAS seems to keep the displayed tip temp fake. Terrible.I'll see if I can sketch a schematic of that controller board V1.1 based on pics to see if anything else in the hardware is wonky.

author: dreamcat4
author_rank: Frequent Contributor
timestamp: October 04, 2023, 07:20:16 pm
content: hello i have recently checked my aixun t3a smps v2 and can say the ground is solid through the smps to the negative (ground floodplane) on the controller. which is then the gnd on the cartridge. so its a solid ground.so like tim says, to do isolated work, consider the matter that i have tested this t3a station on dc power working (soldering things) from 24v down all the ways to about 15-16v. and it can still function and solder even that low. perhaps taking more current or less performance at lowest voltage level. then the controller board has some precise cut off like 15.25v or something particularly exact.so for this isolation purpose: to direct power dc from a battery rather than through smps. for example can install some physical toggle switch, simply add wiring to switch and reuse existing dc power jack as instead input connector on the back (rather than output, which is not a recommended purpose). this can then isolate for this station. and then see if solves issue.if you can open up station, then this is more easy to run a/b test case to grounded boards. to make sure that the theory works correct.for my own purpose, i believe to mod xtc30 or similar dc power input to back, and then connect to 18v power tool battery. which is ideal because nominally the fully charged voltage on makita lxt is about 21 or 22v. then the most empty voltage coming from these battery is still 15 or 16 volts. so this is pretty good and simple. and convenient to recharge, or shared with other makita power tools. that you already have the batteries anyhow.

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 04, 2023, 09:53:05 pm
content: Quote from: floobydust on October 04, 2023, 05:55:16 pmWell, there is a schematic for 1.2. The only difference in 1.1 was D7 or D8 being added and the Zener diode being part of the layout (not hackysoldered anymore).https://github.com/c0d3z3r0/aixun_t3a_rev/blob/master/schematics/aixun_t3a.pdf

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 04, 2023, 09:56:28 pm
content: Quote from: thm_w on September 25, 2023, 09:44:03 pmWell, what I meant is the combination of using DC + common ground for heater, tc versus AC + common ground. That makes a hughe difference. So, a relevant question is if the Weller tips have that setup (common connector).

author: thm_w
author_rank: Super Contributor
timestamp: October 04, 2023, 10:40:29 pm
content: Quote from: c0d3z3r0 on October 04, 2023, 09:56:28 pmPeople used to debate here that DC would ruin a tip "designed" for AC which is clearly BS.Anyway, the poster in that thread noted: "With the equipotential bonding jack (bottom right corner of the PCB), you can choose different bondings like potential free (floating tip) or a different earth reference. Some hand pieces have TIP and GND connected, others keep them apart. I don't know why that is."The weller RT tips themselves have a common gnd, heater, and TC pin (3 pins total).

author: floobydust
author_rank: Super Contributor
timestamp: October 05, 2023, 02:50:40 am
content: Quote from: c0d3z3r0 on October 04, 2023, 09:53:05 pmCapacitor C23 is a very bad idea, and C27 is in the wrong spot should be other side of R33. I hope neither is big like 0.1uF. The TC op-amp "541E" looks to be a TC1541 but the markings are different. No idea if this op-amp is well behaved with HF noise coming in or phase-reversal with -ve input voltages which I suspect is aggravating things here as far as the ground problem. The IC datasheet is all unicorns and rainbows which of course is la bull.Does that make sense? HF noise coming into the op-amp (from the SMPS and Y-cap) at the tip with C23 are possibly causing it to oscillate, or the DC ground loop making it phase-invert. Then the firmware freaks out.

author: dreamcat4
author_rank: Frequent Contributor
timestamp: October 07, 2023, 08:09:53 am
content: it does sound like some set of possible scenarios. and especially as you noted what with how these chinese designs and components are not such a bedrock to ignore. to get to the bottom it seem affected users needs to connect up oscilloscope to there etc. and that introduction (scope probes) will not interfere to observe or ignore/dissapear such oscillations?

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 09, 2023, 10:24:08 am
content: Quote from: floobydust on October 05, 2023, 02:50:40 amNo. The op-amp is a AO4413.https://aosmd.com/sites/default/files/res/data_sheets/AO4413.pdfEDIT: Sorry, brainfart....... AO4413 is the mosfetThe closest match I could find was TP1541Ahttps://datasheet.lcsc.com/szlcsc/3PEAK-TP1542A-SR_C99005.pdf

author: floobydust
author_rank: Super Contributor
timestamp: October 09, 2023, 06:23:51 pm
content: I was trying a LTSpice sim of the mosfet switch circuit and changing the resistor values helps a tiny bit for switching times- at the expense of them heating up.More important is the heater and handle inductance causes the mosfet to ring/oscillate at RF extending turnoff. This could explain OP's observations of oddball sensitivity when the tip is being grounded in a loop. I imagine it also causes issues reading the thermocouple voltage right at the edge.Like I've said a few times, adding a Schottky or fast recovery diode across the heater (backside of GX connector) stops all that. Try a 1N5819, SS24 or ES1B etc. what you have lying around in the junkbox.There was drama with using cheaper TC op-amps in the T12 clones, so the 541E or 541LE mystery part could be part of the problem as well.edit: added pic

author: tony359
author_rank: Frequent Contributor
timestamp: October 10, 2023, 08:32:55 am
content: meanwhile after many days of silence Aixun has replied to my message saying that their technical team are looking into the problem and trying to find a solution.Finger crossed.

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 10, 2023, 02:32:30 pm
content: Quote from: floobydust on October 09, 2023, 06:23:51 pmI always thought "Naaah, no problem. I don't solder live circuits anyway". Now, how shall I solder that damn diode to the positive connector to the T3A itself while it's tip is negative?!

author: floobydust
author_rank: Super Contributor
timestamp: October 10, 2023, 03:54:20 pm
content: Quote from: tony359 on October 10, 2023, 08:32:55 amThe "Golden Week" holiday has ended so they'll be getting back to work now...Quote from: c0d3z3r0 on October 10, 2023, 02:32:30 pmYou don't own enough soldering irons lol

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 10, 2023, 04:19:18 pm
content: Quote from: floobydust on October 10, 2023, 03:54:20 pmYeah, obviously. Looks like I need to hook up my McGyver soldering station againhttps://www.eevblog.com/forum/reviews/any-opinions-on-the-aixun-t3a/msg4412704/#msg4412704

author: c0d3z3r0
author_rank: Regular Contributor
timestamp: October 16, 2023, 06:23:48 pm
content: Quote from: floobydust on October 09, 2023, 06:23:51 pmCan you give more insights on how one would select the "right" diode for that job? What values are important, besides recovery time? Max. Voltage, current, peak reverse voltage?

author: thm_w
author_rank: Super Contributor
timestamp: October 16, 2023, 09:10:27 pm
content: There is not a ton of value in analyzing it IMO, flooby's given recommendations that are safe: iron is 24V, so 40V is a reasonable and common max voltage rating.1A is overkill for the amount of energy, but, that is a standard diode rating. You won't find much below 1A unless you get a tiny package.Not quite the same as its for motors but:https://electronics.stackexchange.com/questions/357392/selecting-flyback-diode-for-inductive-load

author: tony359
author_rank: Frequent Contributor
timestamp: October 20, 2023, 11:11:31 am
content: another "real world" scenario where the iron misbehaves:- removing SMD capacitors using two irons, one being a traditional GROUNDED one. On some components the issue happens and the tip reaches 500C.Still no answer from Aixun.

author: eliocor
author_rank: Unknown
timestamp: October 26, 2023, 01:50:00 pm
content: Please take a look to the following post:https://www.eevblog.com/forum/reviews/aixun-t3b-strange-behavior-(must-invert-liveneutral)/msg5135604/#msg5135604and (if possible) check if even the T3A behave at the same manner, thanks

author: floobydust
author_rank: Super Contributor
timestamp: October 26, 2023, 06:39:27 pm
content: Quote from: tony359 on October 20, 2023, 11:11:31 amIf I owned a Aixun T3A, I would do a test if it's HF noise upsetting the temp readings. Capacitance from the tip to PE (such as when soldering a board with scenarios OP mentions), not necessarily a direct ground loop. Prob. it's own SMPS noise gets into the op-amp.Just try it - take a 0.1uF cap and touching the tip to one lead, the other lead is grounded - should have no effect at all - unless the TC op-amp flips out, and then the software propaganda campaign cover up fails, which is what I think is going on. It ignores TC temperatures wildly out of range - causing the usual head in the sand (ostrich) problem... tip temp is skyrocketing... that crappy algo is a total fail and needs a rewrite.Quote from: c0d3z3r0 on October 16, 2023, 06:23:48 pmThe back-EMF diode should be fast-recovery and take peak current of what the heater gets (for usec though) and PIV of well over 24V.1N581940V 1A 25A peak 1/2 sine is plenty overkill. For SMT consider B140 or SS14 (SMA package) or bigger SMB B360, SS24 etc.It does two things: clamps -ve spikes from ESD and the heater/cable inductance from damaging things like MCU inputs, as well as blowing the power mosfet. As well it will help with the op-amp input recovery time but it's a mystery part they are using with no noise filtering either.Another T12 clone controller just put a 0.1uF? capacitor across the heater, as a cheap sort of snubber. We need to save micropennies here.I say it's at least two problems - noisy hardware and the Eversolder software algo.

author: tony359
author_rank: Frequent Contributor
timestamp: October 29, 2023, 05:20:25 pm
content: I went to make a video review today and when I tried to re-create this issue, it would not happen anymore.the tip still overshoots, I see the spike in power but it then stops (it's likely being detected now) but if I measure with a thermometer, it's +100C than the set temp.I re-upgraded from 1.33 to 1.34. It looks like Aixun secretly changed 1.34 to make it better!!

author: tony359
author_rank: Frequent Contributor
timestamp: November 01, 2023, 09:38:33 pm
content: I made a video on this issue (and more generally to compare the T3A to a more traditional soldering iron). Let me know what you think!

author: thm_w
author_rank: Super Contributor
timestamp: November 01, 2023, 10:56:23 pm
content: Good demo. Showing the overshoot on the display is of course better than hiding it.

author: tony359
author_rank: Frequent Contributor
timestamp: November 01, 2023, 11:13:57 pm
content: Thank you!Indeed. At least I know it happened and maybe give the tip a few extra seconds to cool down.

author: Icchan
author_rank: Regular Contributor
timestamp: November 06, 2023, 11:10:40 pm
content: Quote from: drksy on September 18, 2023, 12:20:56 amCan you check the hardware version of your unit? I have 1.0 (at least if the aixun software is to be believed) and I'm wondering if that matters..If PCB was easier to take out (you need to heat up the front panel and tear the double sided tape, could crack the glass if not using suction cup method) I'd ask you to do that and take pictures of the PCB so we coudl check if this truly is hardware and not software issue...Thanks

author: Icchan
author_rank: Regular Contributor
timestamp: November 06, 2023, 11:12:15 pm
content: Quote from: tony359 on November 01, 2023, 09:38:33 pmDid you check what happens if you have 1Mohm to the ground like with ESD-mats/ESD-wristbands or if the item is "grounded" through an ESD-mat if that causes the issue as well?

author: Icchan
author_rank: Regular Contributor
timestamp: November 07, 2023, 01:22:51 am
content: Quote from: floobydust on October 09, 2023, 06:23:51 pmI have bunch of 1N5819's, I'll make sure my unit is affected and if this mod helps. I'd appreciate everyone else affected to also try it and report to the thread.

author: tony359
author_rank: Frequent Contributor
timestamp: November 07, 2023, 11:40:55 pm
content: my software also says 1.0 and I'm not thinking of opening that thing for now for the reasons you mentioned!

author: tony359
author_rank: Frequent Contributor
timestamp: November 19, 2023, 04:28:58 pm
content: I am so disappointed by the T3A.Today I did a large PCB, 100+ SMD capacitors so I'm using two irons, one being an older, more "traditional" one.On almost every capacitor on the power rails the T3A displayed the "no tool" issue, temperature skyrocketing and tip discolouring because of the heat. When I did an identical board weeks ago, it only happened once, today it happened on 40% of capacitors. The PCB is not grounded and my pre-heating station is insulated with tape. But the other soldering iron is, obviously, grounded.I tried downgrading to much older versions but1. The display is messed up, I suppose the latest FW works with a different version of the display2. the issue still happens even though with a different behaviour (is it better? who knows).I cannot recommend such a tool, it's pointless. I am really tempted to break the bank, get a JBC and forget about those issues.

author: ndarjo21
author_rank: Regular Contributor
timestamp: November 19, 2023, 10:20:24 pm
content: Try mechanic brand. C211

author: tony359
author_rank: Frequent Contributor
timestamp: November 20, 2023, 10:46:46 am
content: do you have direct experience with it?

author: ndarjo21
author_rank: Regular Contributor
timestamp: November 20, 2023, 11:58:20 am
content: Nah, cause you have far more money than me, i hope you can give the testimony. Lol. Sorry for that suggestion. JBC is a way to go fo yoy. Or perhaps metcal is another alternative

author: tony359
author_rank: Frequent Contributor
timestamp: November 20, 2023, 01:14:55 pm
content: I don't mean to be harsh but what is the point in recommending something you don't know?

author: ndarjo21
author_rank: Regular Contributor
timestamp: November 20, 2023, 01:35:54 pm
content: I wanna buy that. And i dont have enough money to buy it right now. So, i hope someone which have more money will try it to fullfill my desire and curiosity. Thats the truth.

author: Zero999
author_rank: Super Contributor
timestamp: November 20, 2023, 01:54:42 pm
content: Wow. I can't believe anyone would design a soldering iron which leaks current to earth and malfunctions, when the tip is grounded!Are there any other soldering irons which do this? It would be good to know, that way I can avoid buying one.

author: hasbihal
author_rank: Contributor
timestamp: November 21, 2023, 05:09:59 am
content: @Tony did you try plugging in a 3.5mm jack for ESD? I just read somewhere else that an old system used to have grounded tips but as soon as plugging in even a blank 3.5mm jack into the ESD jack, the tip was not grounded anymore. Try that

author: tony359
author_rank: Frequent Contributor
timestamp: November 23, 2023, 11:13:59 am
content: on the T3A?The T3A has a banana jack at the back, not a 3.5mm jack. I'm not sure I'm following.I've been thinking of cutting the ground of my traditional solder iron to avoid the issue but I don't think it's a good idea. It could be dangerous for the PCB I reckon?

author: run_rabbit
author_rank: Newbie
timestamp: November 25, 2023, 10:48:22 pm
content: A new version is up, have you tested it?https://aixun-updates.github.io/#t3a

author: Icchan
author_rank: Regular Contributor
timestamp: December 04, 2023, 10:11:16 am
content: Plot thickens... I believe floobys solution would fix all of this:https://www.youtube.com/shorts/6rK7ACrbukIBecause it all makes sense.

author: floobydust
author_rank: Super Contributor
timestamp: December 04, 2023, 08:46:19 pm
content: OMG AiXun T3 tip has enough PWM noise enough to make a speaker buzz?!Too cheap china, too cheap on the cable, or maybe they wired the handle wrong.It would take 1 minute with a scope to figure out this drama.

author: ohmware
author_rank: Newbie
timestamp: December 09, 2023, 11:53:29 am
content: what is the name of this pin?

author: ohmware
author_rank: Newbie
timestamp: December 09, 2023, 12:21:09 pm
content: is this a ground pin or earth pin?

author: GnomeZA
author_rank: Regular Contributor
timestamp: December 30, 2023, 07:44:41 am
content: Quote from: tony359 on November 19, 2023, 04:28:58 pmSo here is my problem with the JBC stations1.They recent had the debacle with silently dropping features2.Quality control issues where the DDE has splattered solder over the unit3."Chang" capacitors on overpriced JBC unit4.JBC unit with a through hole capacitor bodged onto a SMD pad with tons of flux still on the board!What this tells me is that JBC has a serious quality control problem. And they have NO qualms about sending out bodge or dodgy things to their customers.I got one of the Aixun T420 stations and it is identical to SDGs station, so he didn't just get a cherry picked review sample. Some highlights from that unit include:1. Very good quality toroidal transformer (JBC units are using EI core transformer)2. PCB and internal build are on point, not a single bodge, not even left over flux you usually see in cheap Chinese parts. It really is very well made IMO.3. T115, T210 and T245 from a single station, huge selling point, you absolutely need to spend a fortune to get this with JBC. The prices are nowhere near comparable.As such I'm at a point where it feels like the Chinese clone is starting to even one-up JCB in terms of assembly quality.I also very much share the concerns about the temperature overshoots but Aixun actually seems to make firmware improvements based on these reach outs.Their latest T420D updates have added "temperature compensation" menus, so I assume they've listened to people asking to turn these off.Every YouTube video I've watched with people who has a JBC station has said dealing with JBC has been an absolute nightmare.So although your experience with Aixun is not great, it seems to be on par to what you would get with JBC (if not better), not great as it is.I also suspect they can't fix this problem with the Aixun T3A, so they probably haven't responded because what can they say "Oops we f#cked up".Anyway, my assessment on the lay of the land.I don't think perfect exists at this point.Would love to hear what you ended up going for?Btw. any chance you could comment on that diode fix proposed in this thread, did you try it and did it do anything for you?

author: floobydust
author_rank: Super Contributor
timestamp: January 02, 2024, 04:36:28 am
content: The diode-add across the heater is clamp inductive spikes and protect the mosfet, it's running near max. I don't see it helping with this grounding problem but the TC op-amp is an alien so it might help it a bit.My guess is it's the SMPS noise as well as crap firmware.

author: tony359
author_rank: Frequent Contributor
timestamp: January 14, 2024, 10:01:06 am
content: I ended up buying a JBC - Yes, I could agree it's a bit overpriced but... it works and because I am doing some paid work with my solder iron, I couldn't tolerate all those flaws I was having with the T3A and I didn't want to experiment more with other Chinese clones. It doesn't mean there are no other alternatives of course!I made a quick comparison between the Aixun and the T3A.Some of my viewers said they cannot measure voltage at the tip and they cannot make the speaker "sing" with their 6 months old station. Are there multiple HW revisions? Have they changed the design in worse?

author: tony359
author_rank: Frequent Contributor
timestamp: January 23, 2024, 12:09:16 pm
content: Someone has brought this to my attention:Check at 3:30. I believe Tony at NWR is using a T3A - but regardless, this is another example where "ground is in the way". There is NO WAY I want to see my expensive 245 tips glowing red like that. Shocking! It must be one of those FW where the station keeps spiking and never stops. Fair enough, later versions will detect and stop the uncontrolled burst, but will also hide the real temp at the tip.

author: GnomeZA
author_rank: Regular Contributor
timestamp: January 24, 2024, 11:51:24 pm
content: Quote from: tony359 on January 23, 2024, 12:09:16 pmWhat is actually a bit sad is that they didn't fix this on the T320.They went again for trying to solve the problem in software.I've certainly not deep dived this issue to the extreme, but I'm fairly certain no amount of software can make a millivolt differential amplifier that is being interfered with suddenly reliable through software alone when you have no other information.

author: tony359
author_rank: Frequent Contributor
timestamp: January 25, 2024, 09:52:03 am
content: Indeed, I saw the review and it still shows issues.I'm no electronic wizard but I agree with you, if the thermocouple is reporting rubbish you can only "mitigate" - that is, prevent the station from dumping 100's of watts into the tip. The tip won't glow red but it's unlikely it'll keep its setpoint.I'm wondering whether they're fixing this quietly while they get rid of the old stock or developing a newer model or simply ignoring this whole matterMy curiosity is: is this an unavoidable side effect of using an SMPS or could this be avoided with a different HW design?

author: elektryk
author_rank: Regular Contributor
timestamp: January 25, 2024, 10:03:30 am
content: QuoteI've got some custom stations SMPS powered and I didn't noticed such problems.There were some good reviews about T3. I even thought about it, but the reviews here confirm that DIY was a good option.EDIT:Well, I was able to reproduce problem with my DIY station when negative output from SMPS (which also acts as tip grounding) was hard wired to the earth connection and touched metal central heating pipe with tip.Problem didn't occur when I touched earth pin from power strip, which also made a ground loop but smaller, so it turns out that there was extraneous potential on the pipes and it did some mess.

author: tony359
author_rank: Frequent Contributor
timestamp: January 25, 2024, 09:09:31 pm
content: Keep in mind that to reproduce the grounding issue I have to touch SOME pins of a GROUNDED circuit - not necessarily ground. (Even though when I later tested that, it would also misbehave when touching ground which was NOT happening before. No idea why)It feels to me that some circuits might have the right combination of components and traces to create some noise which upsets the station.When I was using the T3A with my Hakko knock-off to remove SMD caps, I knew the ones which would cause the T3A to get crazy. Always the same caps. Not the others. Ever.

author: mebel
author_rank: Regular Contributor
timestamp: January 28, 2024, 12:25:07 pm
content: For me it's always ground issue. Try soledering for examplecopper platewithout grounding then do the same with grounding.Then do the same with grounding through 1Mohm resistor - it couses that there's no grounding issiue on T3A.

author: Gediminas
author_rank: Regular Contributor
timestamp: July 03, 2024, 06:57:44 am
content: Solution to temperature spikes:I have studied original JBC and Aixun t320 schematics, and found that the only way to get rid of temperature spikes on Aixun, is to ground the station through a 10-15 ohm resistor (should also work on T3A, T3B stations). This will completely eliminate temperature spikes.You will still have one volt on the tip, but it will be much less current flowing to the ground (if you touch the ground with the tip), it will be pulses of 30 milliamps instead of 1,2-1,4 amps.It is also possible to reduce voltage on the tip and make current negligible with further modification.For that we need to replace the 3 core handle cable with 4 core cable (possible to buy at AliExpress), fourth additional core needs to be connected to the cartridges outer shell/tip contact in the handle and other end needs to be connected to the ground at the station (to the real ground, not the ground after 10-15 ohm resistor from which station are grounded).It could be good if someone will verify that the resistor mod works on T3A, T3B stations (I have checked only on T320, because this station I own).

author: alex843
author_rank: Contributor
timestamp: June 21, 2025, 12:34:50 pm
content: Quote from: tony359 on January 14, 2024, 10:01:06 amI'm not sure why others can't see anything. I have posted in another thread about my own observations with the T3AS and firmware 1.36 here:https://www.eevblog.com/forum/reviews/aixun-t3as-vs-t3a/msg5931114/#msg5931114Quick summary:1. Static grounding test with a multimeter shows a low resistance from tip to ground.- So the lesson here is that when you are on youtube or forums, don't just ask "is the tip grounded", because that doesn't give the full picture.2. On a grounded board, soldering on the ground plane I observed temperature overshoot. This was on a 350 C setting, and at times I saw peaks of 430 C on the display.- There shouldn't be an 80 C overshoot, maybe a smaller amount would be acceptable.3. Using an oscilloscope connected to the board, I could see voltage spikes of around 1.2V to 1.5V, and maybe a few spikes larger than that.- This needs to be a peak or pk-pk measurement to appreciate the problem.- voltages of 1.2V or 1.5V are not desirable and since the voltage appears to have a low impedance source, this could lead to harmful currents flowing in sensitive devices if there is a path to ground.

author: ftg
author_rank: Frequent Contributor
timestamp: June 24, 2025, 07:42:51 am
content: Apparently this is not fixed in A9E either, because I'm seeing effects similar to what alex843 gets.10ms long bursts on the tip that can have up to 3 volts on them.I made two short videos of the station blinking some LED's.

author: Basileus
author_rank: Regular Contributor
timestamp: July 02, 2025, 12:50:46 am
content: Double confirm on Aifen A9e, DC resistance between tip and C16 inlet of the station is ~0.5ohm, i havent probed the situation with my oscilloscope yet but i can confirm i had 1W leds light up while soldering them, while not grounded on top of a block of wood. Weird things. I hope it's fixable or not too problematic at least