hybridfree/eevblog-posts huggingface dataset:
Korad KWR103 (TENMA 72-13360) PSU burnt parts identification - Page 1
Forum section: electronics / repair

author: abyrvalg
author_rank: Frequent Contributor
timestamp: January 24, 2022, 04:14:10 pm
content: Hello everyone,We’ve got a KWR103 burnt presumably from a wrong 110/220V switch setting. Both primary side MOSFETs went short, burning several surrounding SMD resistors so their markings couldn’t be read (R35, R37, R46, R55, see the photo). Perhaps some happier owner could help identifying them?Thanks in advance.

author: fzabkar
author_rank: Super Contributor
timestamp: January 24, 2022, 04:21:34 pm
content: That area of the circuit looks like a copy of the area between Q17 and D6.

author: abyrvalg
author_rank: Frequent Contributor
timestamp: January 27, 2022, 06:38:53 pm
content: fzabkar, unfortunately that Q17-D6 area is burned too (R46, R55 I’ve mentioned already)
Korg DJ Mixer Crossfader Woes - Page 1
Forum section: electronics / repair

author: Timmox
author_rank: Contributor
timestamp: January 18, 2021, 02:31:28 pm
content: Hello everyone,First of all thank you for taking time to look at my problem. I’ve quite a lot of experience repairing electronics with relatively simple issues. However, this one is seems to be a bit more complex and beating me at the moment.The offending bit of gear is the 2002 Korg KM2 Kaoss Mixer. The main issue is when the crossfader is fully left it only reduces the level of Channel 2 to around 75% rather than 0%. If you move the crossfader to the right it cuts level from Channel 1 to 0% as you expect.Of course, the first thing I did to remedy this problem was replace the crossfader. The replacement was purchased from Korg UK who amazingly had it in stock. This however did not resolve the problem.I then set out to try and find the service manual online but to no avail.After some probing, I came to the conclusion that the audio signal probably doesn’t actually pass though the faders and they are more likely remote controlling preamp with voltage. With this in mind, I traced all the faders back to a HC4053 Triple 2-Channel Analog Multiplexer IC. So I replaced this but sadly again it made no difference.At this point I thought I am out of my depth now and should get some advice.If anyone can offer any advice it would be gratefully received.Thanks in advance,Tim.
Korg DTR-1000 POS Rackmount Tuner - Page 1
Forum section: electronics / repair

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 28, 2025, 04:58:44 am
content: A friend of mine ruined 3 Korg DTR-1000 tuners when running the tuners from a DI box output. The symptoms appear to be the same as described here:https://www.freestompboxes.org/viewtopic.php?t=32209The tuner front panelappearsto work and responds to button presses. The LEDs switch from static or strobe tuning as normal. Mute LED turns on or off with the switch. Neither input jack gets any signal to the tuner. All the LEDs light up in "test mode."In the linked thread, they needed to replace the front board, and I think the assumption was that the M37540M4FP chip was bad. However, I dunno if that makes great sense or not. The LEDs are all controlled by that chip, and the fact that they behave as normal doesn't sound right if the chip is bad.Any ideas of what would cause this? DI level is lower voltage than instrument level. So not overvoltage from the input.Schematic attached.Unfortunately, I don't have access to an oscilloscope right now to trace the audio signal path. All normal passives on the rear input board tested as expected. Voltage on the 5V regular was +5V and ~+10V, so obviously the rectifier was working fine.Thoughts?Thanks,JoshPS. For the record, I know these tuners are mediocre at best. I'm interested in the repair more than the tuner.

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 28, 2025, 06:05:05 am
content: What else should I need to drive the front panel? I assume all the real work happens there... +9V at CN7-2, +5V at CN7-4. Signal at CN8-1 and GND at CN8-2.Both +5V and +9V draw current in test mode with the LEDs flashing. LED18 is a little week, the rest appear fine.I'm attempting to feed the tuner with a signal from my AWG at CN8-1. I've tried sine and square waves at 440Hz. What voltage level would that op amp put out? I don't want to go too high and make things worse.
Korg i3 - faulty power on mute? - Page 1
Forum section: electronics / repair

author: drhayes
author_rank: Newbie
timestamp: July 20, 2020, 02:21:47 pm
content: Hi there,I have a Korg i3 which is misbehaving. Directly up front: I may be an idiot, so please always assume that I don't really know what I'm talking about.The symptom: all outputs are quiet. With extreme amplification you can hear digital noise and the correctly produced sounds. I think I have tracked the issue down to the power on mute circuit, but I seem to have a problem understanding, what is happening, or what is supposed to happen.I assume that the Power On Mute rail is supposed to initially be high and then to drop to ground. Why do I think so? Because if I short POM to ground, all outputs work fine.The muting of the signals is done with transistors - 6 of these units:So, as much as I believe to understand, if the base of Q3 is positive, the signal is pulled to ground, if the base is ground, the transistor is inactive and the signal goes through.Butthe power on mute goes to 4.2V and slowly drops (if forced to ground shortly) to 2.8V. If I look at the circuit, I have a hard time understanding how it would ever reach 0 V. As much as I understand, the circuit does exactly the opposite. The 5 Volt charge C40 through R41 slowly raising the voltage on the base on Q7. While Q7 hasn't switched on, we have -12V on the power on mute rail. As soon as Q7 switches on, the POM rail goes up - and stays there.Measuring all components in circuit shows that all are within specs, except for C40, which measures as 110 µF.Edit:I have desoldered C40 now, out-of-circuit my multimeter shows the capacity to expect.Now my questions: what is it that I don't understand?

author: Zoli
author_rank: Frequent Contributor
timestamp: July 22, 2020, 05:08:46 am
content: Did you considered that Q7 is PNP(=raising base voltage will switch it off)?As recommandation: measure the voltage on the positive sides of C39 and C40, once the system is up;those voltages will give you a good indication where the fault lies.

author: drhayes
author_rank: Newbie
timestamp: July 22, 2020, 12:32:34 pm
content: Hi Zoli,apparently I have not considered the type of Q7. Thank you for pointing out where I had the mistake in my analysis.C40 apparently was bleeding current to ground, so the voltage never went above 3.3V. Replaced that with a new cap, and the voltage rises to 4.7V a few seconds after turning the synth on. And then - as you correctly mentioned - Q7 switches off and I get a nice low POM (haven't measured it now, but all muting stops after a few seconds).Cheers!
Korg microKORG - Page 1
Forum section: electronics / repair

author: squigley
author_rank: Contributor
timestamp: October 10, 2024, 09:29:13 am
content: Hello, I am trying to diagnose and hopefully fix this synthFirst, the power is stupid reverse polarity which is probably why I am here..Immediately after the power jack is an inductor which I removed and tested to be dead shorted (I should qualify that this is a 4 pole inductor with both positive and negative running through it, and all 4 legs are dead shorted).I continued checking and found a cap to be shorted so I removed it. I then found 2 diodes misbehaving so I removed those.Things still may be shorted so I don't want to apply any power.Has anyone worked on one of these before?

author: squigley
author_rank: Contributor
timestamp: October 10, 2024, 04:49:44 pm
content: I bypassed the questionable input section, and applied 9v directly to the ground plane and positive rail.It powers up, the audio in 1 and 2 LEDs light up for about 2 seconds, and then go off. That's the only sign of life.

author: squigley
author_rank: Contributor
timestamp: October 10, 2024, 04:50:34 pm
content: This is all is does, for about 2 seconds.

author: squigley
author_rank: Contributor
timestamp: October 11, 2024, 12:18:37 am
content: I found someone on Reddit with the same problem, but no solution :-(https://www.reddit.com/r/synthesizers/s/2NOUiwO9Hs

author: squigley
author_rank: Contributor
timestamp: October 11, 2024, 07:46:03 pm
content: I found this which provided some clues..http://www.korgforums.com/forum/phpBB2/viewtopic.php?t=23125&postdays=0&postorder=asc&start=0The audio in LEDs coming on just basically indicates that the 5v rail is working.The issue is that the 3v3 rail is not.I checked the pwm switching chip and found it to all be shorted and passing 9v straight through :-(The fet also seems suspect.And the fuse between the switching chips and the 3v3 circuit is blown.I applied 3v3 to the after side of the fuse, and all that happed was that briefly one of the switches lit up, and then nothing, except the CPU got hot enough to almost give me a 3rd degree burn.So it looks like I need to source a replacement CPU, and the 3v3 switching components.I am hoping that only the CPU got blown, and it protected the ram and flash chips and the DSP etc.

author: fzabkar
author_rank: Super Contributor
timestamp: October 11, 2024, 11:54:03 pm
content: FWIW ...https://elektrotanya.com/showresult?what=microkorg&kategoria=All&kat2=All
Korg Triton SMPS fault - Page 1
Forum section: electronics / repair

author: Graham Tinkers
author_rank: Newbie
timestamp: December 21, 2021, 01:23:58 pm
content: Hi All,I am trying to repair a SMPS out of a Korg Triton, I am not having much luck as I don't usually work on mains stuff so I thought I would turn to the forum for assistance. The outputs are +5, +15 and -15, all the voltages read correct but when under load the voltages drop sharply; the +5 rail drops after about 1 amp load is applied, the +-15 volt rails drop with only 10ma on them (with or without the +5 volt load). I have tested Q1, Q2, Q3, Q5, PC1, IC1, IC3, IC4 and they all seem fine, the electrolytic Caps look fine, no signs of leakage or bulging. Could IC2 the voltage reference be the issue or one of the manTriton PSU.pdf(71.59 kB - downloaded 88 times.)y Zenner or smd caps?Kind regards,Graham

author: abdulbadii
author_rank: Frequent Contributor
timestamp: December 21, 2021, 11:39:09 pm
content: what max current rating stated?try cross-check MM capable of reading within the rate rangeslightly better is AMM (analog MM) than DMM if it has such capabilityif reading is less 79-85% than current rating stated, some caps have aged and borne ESRit demands quality ESR meter to read all on-PCB caps

author: Graham Tinkers
author_rank: Newbie
timestamp: December 22, 2021, 09:44:39 am
content: Hi abdulbadii,Thanks for the reply; I have the the service manual but it does not mention the current rating of the PSU, putting and LED and a resistor across the +-15 volt rails causes them to drop by 1 volt, if I put a 50ma load the voltage drops to about 7.5 volts. I will try replacing all the electrolytic caps on the output side to see if it make a difference.
KR-4010 and illuminating fuse (and STK-0040) - Page 1
Forum section: electronics / repair

author: m k
author_rank: Super Contributor
timestamp: December 08, 2020, 01:52:50 pm
content: After first fuse swap the thing has been aside for quite some time.Now, after second swap and stand alone, it's been behind a variac and with 80V it wants 1A, sharply increased after 60V.Then suddenly current dropped.Also stayed down with 100V.But still couldn't behave with full mains.Is that a usual thing for faulty STK-0040AT?Is that a possible capacitor reforming situation?Ripple was minimal.

author: mzacharias
author_rank: Frequent Contributor
timestamp: December 09, 2020, 01:22:07 pm
content: I presume you mean a Kenwood KR-4010.The STK packs in question can be checked for shorts between pins 1 and 2, and between pins 8 and 9.

author: m k
author_rank: Super Contributor
timestamp: December 11, 2020, 06:33:25 pm
content: Yes, Kenwood it is and a single channel stereo for now.Also, bottom is a removable plate and under it a circuit board is rounding the power pack and its pin holes are actually slots.Those were the days.

author: m k
author_rank: Super Contributor
timestamp: December 13, 2020, 05:10:30 pm
content: Replacement then.I read that replicas are pretty much a waste of time, if chip can stand the heat you can't stand the distorsion.Also that some have replaced them with discretes.If I continue with replicas anyway, some say they are just fine, I can upgrade both channels with STK-0050, the device is 220V and wall is 240V, but should I go to STK-1050?Small amplifier modules in general are also plenty.Is that the way?Authenticity is not a priority but all fine prints seems to be missing.BTW, now the current faulty power pack has both sides shorted.So at one point it released both sides and then shorted them again?
KRK Rokit 5 G3 no power to Tweeter, everything else works (No black glue) - Page 1
Forum section: electronics / repair

author: RikRepair01
author_rank: Newbie
timestamp: October 18, 2024, 06:53:42 pm
content: Pictures here:https://imgur.com/a/koTptmTProblem: I have a single KRK Rokit 5 G3 Studio Monitor that only plays music through the mid/bass speaker, the tweeter doesn't vibrate at all.I've tested the tweeter both with a multimeter set to Ohm and a 1.0 volt battery and it works.Power supply is delivering the correct voltages and the standby circuit works as intended, when an input is connected the relay clicks and the speaker starts to play music.PCB looks in good condition with no ossidation or burnt spots and the infamous black glue isn't used in this model.When playing music, there is around 2v going into the mid/bass speaker and 0v going into the tweeter.I've tested continuity between the positive wire of the mid bass speaker and the trs jack and I get continuity, if I do the same with the positive wire going to the tweeter I get nothing so there is definitely a break somewhere on the High Frequency side.I've tested continuity between the positive wire going to the tweeter and ground and I get nothing.My next move would be to start removing capacitors and test them with an ESR meter, would that be a good thing to try?I know my way with basic electronic repairs and have done stuff like console modding and swapping bios chips, but I'm new to board diagnostic.Thanks in advance for any helpful tip.

author: beenai2018
author_rank: Contributor
timestamp: October 18, 2024, 08:06:38 pm
content: Since its a speaker ,please do the shake and tap test on wires/components ,before removing /checking esr etc.Connect your AC voltmeter to tweeter lines and check if anything changes when tapping the wires ,components etc.Whilst there is no nefarious black glue ,they have used some other translucent glue .. lol ..Also ,try to trace signal path for tweeter from source . This looks like Bi-Amped setup ,so there should be a HP filter opamp (possibly near the yellow rectangle looking caps ) which you can check the output .Check the frequency where the manufacture says they are High Passing between low and high driver . If your multimeter does not have bandwidth in the VAC mode , this test may not work correctly.
KRK rokit 5 speaker Part Identification - Page 1
Forum section: electronics / repair

author: Maxwell55
author_rank: Contributor
timestamp: September 06, 2024, 01:40:43 pm
content: Hi, I'm hoping someone could help me identify 2 components on a KRK RP5 G3 mainboard. These are labeled ES0 and ES1 and are on the RCA plug circuit.They blew up when I attached a hot RCA cable. Thank you

author: David_AVD
author_rank: Super Contributor
timestamp: September 06, 2024, 11:26:31 pm
content: How have you determined that they have failed?

author: Maxwell55
author_rank: Contributor
timestamp: September 07, 2024, 01:12:32 am
content: I've shown you a picture of the good speaker,I've determined they're blown from the following picture of the failed speaker.Have any idea what they are?

author: fzabkar
author_rank: Super Contributor
timestamp: September 07, 2024, 01:25:49 am
content: They appear to be bidirectional ESD protection diodes.

author: Maxwell55
author_rank: Contributor
timestamp: September 07, 2024, 01:33:18 am
content: Thank you for replying, I thought is was some kind of diode but wasn't sure. I don't have any specs of those 2 parts. I'll try to shine a light sideways to see if it shows anything, otherwise how could I find a replacement?

author: gamerpaddy
author_rank: Regular Contributor
timestamp: September 07, 2024, 01:53:44 am
content: unusual package for a diode, they are usually encased in plastic not ceramicES might stand for ESDi would have guessed a ferrite bead, but as its between signal and ground i think its more like a ESD protectionmight be a varistorhttps://www.meritekusa.com/product-category/esd-protection/esd-varistor/desolder a working one, apply a voltage with a very low current limit and see when it starts clamping at.

author: Maxwell55
author_rank: Contributor
timestamp: September 07, 2024, 03:03:12 am
content: Unfortunately I don't have a power supply to be able to do such a test with one of those components. I'll have to find the part number

author: David_AVD
author_rank: Super Contributor
timestamp: September 07, 2024, 06:32:25 am
content: How did you send such a significant voltage into the audio input to start with?

author: gamerpaddy
author_rank: Regular Contributor
timestamp: September 07, 2024, 03:03:59 pm
content: this might be itthe "ESDA" marking in the schematic got me this:https://www.tti.com/content/dam/ttiinc/manufacturers/eaton/doc/Eaton-Polymer-ESD-Suppressors-SurgX-Technology-ESDA-datasheet-specifications.pdf

author: Maxwell55
author_rank: Contributor
timestamp: September 07, 2024, 11:56:30 pm
content: HI, thanks for the info, I managed to get close for a shot in many angles, I am able to see some markings on one of them but unable to determine exactly what it says.I'll see if I can try to get a better shot, I'll include it, maybe you can detremine what it says?

author: Zioc
author_rank: Newbie
timestamp: March 04, 2025, 12:28:05 am
content: Hello, did this thread reach a conclusion to what ES0 and ES1 are? I ran into this as well.
KRK RP5 Rokit 5 G4 Bi-Amp 5" Powered Studio Monitor Pair - BOTH dead suddenly?? - Page 1
Forum section: electronics / repair

author: maffmatix
author_rank: Newbie
timestamp: March 16, 2024, 12:36:08 am
content: Hello all! New user here, I love this site! Lots of good stuff!Anyways, I have two of these Rokit 5 gen4 speakers in my tv room. They have worked fine for about 2 years (bought them new) but suddenly I came home from a short trip and BOTH of them don't work. You can tell there's some sort of power failure because there is no sound and little LCD screens on the back don't light up or work when they are plugged in and turned on.What I find strange is, BOTH stopped working simultaneously and I don't know why. The speakers attached to a KRK 10S sub bass, which still seems to power on and work fine. I researched online and found that these speakers have a fuse replacement that I could try, so I replaced the fuse under the power cable section, but that didn't help.I also tried new/different cables and different power sockets in the house. Nothing.Any ideas? Thanks! (pics attached)

author: coromonadalix
author_rank: Super Contributor
timestamp: March 17, 2024, 01:32:23 pm
content: blown fuse, ac voltage spikes, overvoltage ?

author: Haenk
author_rank: Super Contributor
timestamp: March 17, 2024, 03:52:59 pm
content: Were the fuses blown?Were they left "on"?Anyway, it looks like both the power supplies blew - if left powered on, that might have been some line spike while being away. If left "off", that would be a seriously unlucky event, to fail at the same time.Maybe checking for visual clues on the power supply board will bring up more details (blown capacitor, maybe even another fuse). Be careful, high voltage might be present, don't touch the PCB (especially from the underside).

author: abeyer
author_rank: Frequent Contributor
timestamp: March 17, 2024, 11:16:44 pm
content: I've seen some of these small "powered" monitors that aren't truly independent... the "dumb" half relies on something in the "smart" half to function, and won't operate stand alone. Have you ever previously used/powered the one without the controls separately to confirm if the screen and/or input work that way?

author: maffmatix
author_rank: Newbie
timestamp: March 23, 2024, 02:37:57 am
content: So they each come with a new un-used fuse, and I tried replacing them to no avail. They were indeed left on while I was away so I assume it was a power spike situation that blew the power supplies.In regard to 'smart' and 'dumb' theory, actually both monitors are 'smart' so it can't be that.Oh well, I guess I gotta find someone who can fix power supplies of Rokit monitors in Phuket now !Thanks guys.
KRK RP8 Caps replacement - Page 1
Forum section: electronics / repair

author: Thermaltake
author_rank: Newbie
timestamp: April 02, 2019, 06:27:38 am
content: Hi I have RP8 model also with that black gunk stuff and rust problem. But I am also replacing all that Yiiiiiichon caps. I will tell me friend to replace all of them small ones and big ones with same V and uF. I will order from different sellers, what can I do. Here in my country they don't have Nichicon or Rubycon, only Samwha and some low quality caps like thatBut I am strugling to see because of that black gunk and position what values are those capacitors on the picture that I circled if someone can help me so I can order them too, and to tell me if they are normal caps or low esr. Picture in attachment.I mean when you do some maintenance it needs to be done properly by replacing all of themright ? what do you think ?

author: lpc32
author_rank: Frequent Contributor
timestamp: April 02, 2019, 04:31:51 pm
content: If you plan to remove them anyway can't you check then what their labels say?By the way, the green CH105 at the bottom looks charred. Maybe.

author: Thermaltake
author_rank: Newbie
timestamp: May 03, 2020, 07:07:07 am
content: Quote from: lpc32 on April 02, 2019, 04:31:51 pmIt wasn't charred, it was that black gunk on it.Just to say:All caps were replaced on both boards on both monitors. Monitors are working great for almost year now, no hiss, no buzzing from tweeter or woofer, silent in idle. And I must say that sound is kind of better now, healthier.
KSGER problem - Page 1
Forum section: electronics / repair

author: omtech1
author_rank: Newbie
timestamp: April 10, 2024, 05:05:17 pm
content: I bought a KSGER T12 about 4 years ago (has green circuit board) . It had worked fine but recently it started to make a very soft crackling noise inside and then the unit would turn off by itself and then turn back on. Inspection inside nothing obvious, no burned spots etc. I've already replaced it with a HAKKO FX888D based on the EEVblog video. Is the old unit even worth fixing?

author: smallfreak
author_rank: Contributor
timestamp: April 11, 2024, 11:21:46 am
content: Quote from: omtech1 on April 10, 2024, 05:05:17 pmAutomatic turn off might be because of voltage-sense problems. There is an option in the menu about alerting voltage problems. Depending on the SW you might have a different GUI. In any case, the "V1" GUI has an option to display the DC voltage in the lower left instead of the selected tip.Since the unit draws quite a noticable DC current, any soldering point is prone to get warm during use. They can oxidize, increase resistance and progressively make things worse. Soft crackling noise may be because of that, indication the final breakdown of the conduction.Re soldering the junctions on the DC path might help. But you have to use a spare iron for that, not poking the live T11 back into it's case.Quote from: omtech1 on April 10, 2024, 05:05:17 pmHey, this is a place to discuss electonics and repairs. Name it your new projectBtw, "old unit". My trusty Weller W61C from 1988 is still in use. I had to replace the burnt mains filter capacitor and the heating element in the meantime. Probably because the mains voltage went up from 220V to 230V in the last decades. Still in production and spares are available.

author: omtech1
author_rank: Newbie
timestamp: April 13, 2024, 03:11:10 am
content: Thanks for your input. I may tinker with it. Resoldering will be a good place to start.
Ksger t12 fron panel display not on - Page 1
Forum section: electronics / repair

author: Nvmarv
author_rank: Newbie
timestamp: May 23, 2025, 01:33:00 am
content: I recently was soldering on a power switch with my kgser t12 and didn’t realize I had it still plugged to power and it zapped my gun and the front panel quit working.. the main board had a bad capacitor which I replaced and main board supplies 24v to display but no indication of any functioning. I’ve tested several components including the tpc8107 which seems to be ok.. curious on what powers or where the front panel gets it input/power from to do further testing..I’ve tested the capacitor there as well and it’s good..noticed a round cylinder with 2 wires coming out of it and was curious what it was as it appears to have continuity. Maybe another capacitor or fuse? Can’t find much info on front panel schematics..thanks in advance
Ksger t12 front display inop - Page 1
Forum section: electronics / repair

author: Nvmarv
author_rank: Newbie
timestamp: May 28, 2025, 08:57:33 pm
content: Was soldering on an 120v not realizing it was still plugged in and the soldering station went dead. I replaced the 400v 68 uf cap and get 24v to front panel but not display activity. Does anyone have a schematic on it? .. tested several components and don’t see any bad ones.. tks
KSGER T12 "INVER" Message - Page 1
Forum section: electronics / repair

author: Ricks_Radio
author_rank: Contributor
timestamp: September 30, 2025, 05:26:43 am
content: My trusty KSGER T12 solder station is giving me grief. It seemed to be reading high on most tips so I decided to recalibrate the various tips.All went well until the D16 tip. It suddenly threw a INVER error message? I have no idea what an INVER means?I removed the D16 and set the KSGER to receive a D24 tip. All was well with no error message and a reasonable temperature on the tip. I then reinserted the D16 and the INVER was gone. Eureka it's fixed!NOT SO FAST! I had neglected to change the tip type in the KSGER menu! Setting the menu back to D16 and INVER reappeared. My guess is the D16 tip is hooped? Is there a list of KSGER solder station error messages available?Thanks,Rick

author: thm_w
author_rank: Super Contributor
timestamp: October 02, 2025, 11:42:22 pm
content: Did you read this threadhttps://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/equipment-usage-soldering-techniques-and-reviews/3265985-quecoo-t12-958-soldering-station-inver-error

author: Ricks_Radio
author_rank: Contributor
timestamp: October 03, 2025, 01:29:43 am
content: *** SOLVED ***I still have no idea what INVER means, however, I have "fixed" the problem.I entered the tip calibration routine for tip D16. I did a INIT (intinialization) for the D16 tip and then I recalibrated using START. After the recalibration the error message was gone!Thanks for the bandwidth.Rick

author: Ricks_Radio
author_rank: Contributor
timestamp: October 03, 2025, 01:32:06 am
content: Thanks for the reply.Yes I checked out the link you posted. However, since my T12 functioned on all my other tips, I felt a power supply issue was unlikely.Rick
KSGER T12 soldering station  - Page 1
Forum section: electronics / repair

author: cwilliamsws6
author_rank: Newbie
timestamp: January 09, 2021, 01:25:56 am
content: I just bought one on eBay, I have seen a couple posts on here about them.I already know I need to ground the case, and there's a resistor I need to remove because mine has the lithium clock battery, but what else do I need to do to make this thing safe?

author: cwilliamsws6
author_rank: Newbie
timestamp: January 09, 2021, 01:49:23 am
content: Here's some pictures I took, it would not let me attach to the original post.https://imgur.com/gallery/qIUDUT5
Ksger t13 - Page 1
Forum section: electronics / repair

author: Nvmarv
author_rank: Newbie
timestamp: June 02, 2025, 11:14:54 pm
content: My soldering station quit working and replaced a cap on main board and got it wybut the display screen still isn’t. Did some basic testing of components and it seems the the r1 and resistor is open. I can’t read the value and was wondering if anyone has the value?.. tks in advance and will show pics

author: Nvmarv
author_rank: Newbie
timestamp: June 02, 2025, 11:16:19 pm
content: It’s a t12.. didn’t proof read before posting

author: Nvmarv
author_rank: Newbie
timestamp: June 02, 2025, 11:44:20 pm
content: The r1 smd resister value
Kunkin KL283 issues - Page 1
Forum section: electronics / repair

author: jeffjmr
author_rank: Regular Contributor
timestamp: December 26, 2021, 03:41:20 am
content: I have a newly acquired used KL283.It was poorly packed and had a few connectors out of their receptacles. Once reconnected it appears to basically work OK with the exception of all four pots.Three of the four are appropriately at 0 when at their respective 0 stops, but increase the volts or amps as applicable rapidly with the slightest movement, then back to 0 as you increase them just 20 or 25% of the adjustment range, to their full stop. The remaining pot, I think it is the CC on Channel 1 won’t 0 at the stop, it calls for 30ma with a 6 volt battery, then goes to 0 rapidly with the slightest increase then increases to max as you reach full range.Anyone with a fair knowledge of the circuitry in these units who might be able to steer me in the right troubleshooting direction?Also, there is one connector with two blue wires coming from the transformer that has no open recepticle. There are a few 3-conductor recepticles but none for two. Normal?Thanks for any assistance.Jeff

author: jeffjmr
author_rank: Regular Contributor
timestamp: December 27, 2021, 10:23:32 pm
content: Surely someone has one of these or the similar 284 or 293 who can at least tell me about the homeless connector.And if no one can direct me for troubleshooting the strange reactions to pot adjustments, maybe someone has a schematic?Jeff
Kurzweil K2500S Keyboard Repair In Italy - Page 1
Forum section: electronics / repair

author: dexters_lab
author_rank: Unknown
timestamp: April 30, 2019, 07:07:41 am
content: I've been contacted by someone in Italy with a faulty Kurzweil K2500S sampling synth / keyboardthey asked me if i could repair it due to some of my early videos repairing one but it really isn't practical to ship and repair something that large from Italy so i suggested i would ask here if anyone in south Italy maybe able to help repair his keyboard?If you think you maybe able to help send me a PM and i'll put you in contact

author: StuUK
author_rank: Frequent Contributor
timestamp: April 30, 2019, 07:55:20 am
content: I used to have one of those. Fantastic Keyboard, I hope he gets it fixed...
KWeld Reversze polarised - Page 1
Forum section: electronics / repair

author: WaynesWorld
author_rank: Contributor
timestamp: July 11, 2022, 10:17:06 am
content: Got myself a KWeld spot welder last year and was working well till I connected the power cables to my source battery (100AH AGM) in reverse, and killed it... Well not completely. It blew a track off the back which I repaired. It still appears to weld but they do not hold, even when set to over 100 joules, using 0.2mm nickel. They just pull off.I suspected I killed the FETs, so I desoldered the 5 drain legs of each, and they all tested about 20.v forward and 2.8v reverse if memory serves. Is this right for these?I can see no other obvious damage. Anyone got schematics or know what i should be looking for next?

author: m k
author_rank: Super Contributor
timestamp: July 19, 2022, 01:55:57 pm
content: Maybe adding some pictures would help.https://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/25/

author: WaynesWorld
author_rank: Contributor
timestamp: July 20, 2022, 02:06:01 am
content: Not much to see. There is no obvious signs except the blown track I repaired. I just took the little strip off so you can see the damage caused by the polarity reverse. And I removed the display to expose the main board.Let me know if you need anything else?

author: static333
author_rank: Newbie
timestamp: July 20, 2022, 06:45:33 pm
content: Did you find the datasheet for these MOSFETS?Here is how to test MOSFETS:https://www.homemade-circuits.com/how-to-check-mosfet-using-digital/Still wrenching on the 720 SD?
Kyoritsu 1009 goes "OL" at each measurement - Page 1
Forum section: electronics / repair

author: +sync
author_rank: Contributor
timestamp: February 16, 2021, 07:35:05 pm
content: Didn't use my old Kyoritsu 1009 for a while.So, I put new batteries in it and it seemed to work, at least all of V, Ω, ][, Hz, µA, mA and A displayed the normal output when leads arenotconnected.And Ω, µA, mA and A seem OK when leads are connected.However for some reason,V,Hzand][(capacitance) do not work:- for whatever V measurement, AC or DC, like a 1.5V battery or from a power outlet, it shows after 1 second "OL", meaning Over Range.- same for ][ (tried from ~500 µF to ~2000 µF)- Hz simply remains at 0.000 and doesn't move at allThe last time I used it, all of that was working perfectly.Can the affected features give a hint on where the problem might be?

author: coromonadalix
author_rank: Super Contributor
timestamp: February 16, 2021, 08:09:41 pm
content: rotating dial ? crust, defective contact spring ? fuses ?

author: +sync
author_rank: Contributor
timestamp: February 17, 2021, 07:50:43 am
content: Bingo! Was the rotary switch, one of the contacts was misplaced.Not sure why that triggers the OL behavior, but anyway, working now!

author: coromonadalix
author_rank: Super Contributor
timestamp: February 17, 2021, 11:47:36 am
content: you have a dial contact broken it seems ?

author: +sync
author_rank: Contributor
timestamp: February 17, 2021, 02:05:04 pm
content: Well, it's a picture taken from the Internet somewhere... as it's worth a thousand words, and I didn't know how to describe these things
L6598D SMPS For B&W Sub - Page 1
Forum section: electronics / repair

author: hazmoment
author_rank: Contributor
timestamp: April 05, 2023, 09:57:03 am
content: So I'm attempting a repair on a B&W Sub.I found the issue to be the SMPS is not generating the DC Rail the amplifier board requires. On closer inspection I found the switching Fets had shorted. So I replaced these along with the L6598D IC just in case.Short now gone, but still no DC Rail. I connected my scope probes up to High and Low Side switching pins of the L6598D but no switching going on. Just some noise.I replaced the IC again to eliminate the possibility of it being damaged/ faulty and Its still not switching.Pin 12 Vs - is 15v dc or so which seems standard. But dont know how to further check this circuit. had there got to be an enable signal present before the IC will start switchinf. If so, where would this likely be coming from?I happened to also find a 2.2R 5W ceramic resistor had open circuited. This is in a strange location in the circuit to me and I dont understand the purpose- It is inline with the AC Live conductor before the Full Bridge Rectifier and a SPST relay is in parallel with it. So when the relay is energised the 2.2 ohm resistor is shorted out. And when open the AC current goes through the resistor. This has been replaced too, but hasnt helped with the issue. Hope someone can shed some light on this!

author: Swake
author_rank: Frequent Contributor
timestamp: April 06, 2023, 07:21:18 pm
content: That 5W resistor and relay combo is likely an inrush current limiter. It keeps the resistor in the line for a second or so to avoid blowing fuses in the house when the big transformers/coils/caps take a charge at startup.Magic crystal balls are becoming scares these days. Without more info on the exact device or schematic we can't help much.Check for the datasheet of the L6598D, it might help out.
Lab power supply burnt NTC [Hanmatek HM310T] - Page 1
Forum section: electronics / repair

author: Guille
author_rank: Regular Contributor
timestamp: December 01, 2022, 07:15:37 pm
content: Hi everyone,Last year I bought a Hanmtek HM310T, used it 25 times max and sometimes upon switching on I would hear a loud pop coming from inside but the machine would work as intended so it didn't worry me too much (it should've). Now the machine won't turn on anymore because the NTC protecting form inrush current has exploded (which according to online reviews it's a common problem).I do remember last time I tried to switch it on I removed the casing to inspect the popping noise and saw a spark coming from an area between the diode bridge, filter caps and a small phase spade connector for a tinny 5V secondary power source (USB).The component is an [NTC-20D11][/https://datasheetspdf.com/pdf-file/815011/EXSENSE/NTC-20D11/1], I've visualy inspected both traces and components and they don't look shorted, what might be the cause of this type of failure common to this device? Should I expect it again in the future if I simply replace the NTC for a similar one? What parameters are particularly important when matching a replacement to the original NTC?EDIT: Sorry I'm a total noob at posting images and hyperlinks at this forum.

author: fzabkar
author_rank: Super Contributor
timestamp: December 02, 2022, 07:03:12 am
content: I expect that the NTC is bypassed by the relay (T78L-DC12V-C) after a short time delay. If so, then perhaps the relay isn't working, or maybe it isn't being activated quickly enough.I could be wrong, but I'm guessing this is the datasheet for a similar relay (HLS-T78-DC12V-C):https://www.radio18.ru/upload/radio/f88/f88a24317bd18569d09edbe48368ca81.pdf

author: wraper
author_rank: Unknown
timestamp: December 02, 2022, 07:20:41 am
content: There seem solder lacking from one of the solder joints of rectifier. If you experimented with rapidly switching power on/off, it may had caused NTC to blow up. It would not have time to cool down and would have low resistance on power on.

author: wraper
author_rank: Unknown
timestamp: December 02, 2022, 07:28:52 am
content: As you say it's a common problem, NTC may be undersized. You could use 25D-15, 25D-20 or other similar sized with the same resistance instead.
Lab Technics D2012 Plus mini centrifuge board repair - Page 1
Forum section: electronics / repair

author: psysc0rpi0n
author_rank: Frequent Contributor
timestamp: January 16, 2025, 05:37:41 pm
content: Hi.I have the above mentioned equipment and when we turn it on, it stays one for like 2 seconds and then it shuts down the power supply / transformer.So I disassembled it and one of the control boards, next to the input plug, has a circuit composed by 6 IRF9540N (pictures attached).I am not sure how the 6 mosfets work together but the middle pin of each one is connected to the middle pin of the mosfet that is above/below it.Then, one of the rows of 3 mosfets have 3 diodes connected to one of the mosfet pins. The other end of the diode is connected (if I'm not mistaken) to a resistor and a led.So, I went measure all the 3 pins of all mosfets while the equipment was ON and I got the following results.Let's say 2 rows, each row with 3 mosfets.Row 1Mosfet 1Pin 1 - 24.4VPin 2 - 0VPin 3 - 24.4VMosfet 2Pin 1 - 24.4VPin 2 - 0VPin 3 - 24.4VMosfet 3Pin 1 - 24.4VPin 2 -24.4VPin 3 - 24.4VThen, Row 2Mosfet 4 (connected to Mosfet 3 by middle pin)Pin 1 - 0VPin 2 -24.4VPin 3 - 0VMosfet 5 (connected to Mosfet 2 by middle pin)Pin 1 - 0VPin 2 - 0VPin 3 - 0VMosfet 6 (connected to Mosfet 1 by middle pin)Pin 1 - 0VPin 2 - 0VPin 3 - 0VIs it likelly that the issue is on Mosfet 3 ?? It's the only one which voltage values are not the same as Mosfet 1 and Mosfet 2. Mosfet 4 middle pin is at 24.4V because is connected to Mosfet 3 middle pin, I guess, otherwise, it would also measure 0V just like Mosfet 5 and 6.Can you guys tell me anything about this with the provided information?PS:I also measure the 3 pins of all mosfets while the equipment was OFF in diode mode and all the mosfets read around 0.4V on 2 of their pins and around 1.5V on the other pin, except for Mosfet 3 that read very low values on its 3 pins! Like close to 0V.

author: Harry_22
author_rank: Frequent Contributor
timestamp: January 16, 2025, 07:45:12 pm
content: Hi!You are right.The Mosfet #3 is broken and should be changed.

author: psysc0rpi0n
author_rank: Frequent Contributor
timestamp: January 17, 2025, 08:54:24 am
content: Quote from: Harry_22 on January 16, 2025, 07:45:12 pmOk, thank you for your reply. You even figured out that 3 of them are N-channel and the other 3 are P-channel. I didn't even thought about that.I remember to have worked with a battery charger controller and they also have a similar circuitry where they use like 2 rows of 4 mosfets and they work together. When one row is ON the other is OFF and vice-versa. Probably in this case something similar should be the case, no?
LakeShore 330 temperature controller - Page 1
Forum section: electronics / repair

author: uwezi
author_rank: Unknown
timestamp: September 09, 2016, 06:58:50 am
content: Does anyone here have a schematic diagram over a vintage LakeShore 330 temperature controller, or could otherwise tell me what component Q6 used to be?I "fixed" the controller last week, where an OPA541 power opamp had blown out its magic smoke and it worked again for a couple of days, just to then burn up a TO-220 device on the same heatsink. Of the type number only the last two digits remain legible: ...15Since its right leg was connected to the positive rail of the power opamp and since all other TO-220 parts inside are voltage regulators (plenty of them) I falsely assumed it must have been a 7815 - in the hindsight quite clear that it could not have been...- but I was proven wrong by a small explosion...

author: tautech
author_rank: Super Contributor
timestamp: September 10, 2016, 07:49:39 pm
content: 7915, negative reg, not positive reg 7815 ?Grab the datasheet for both, check the pinouts and typical application schematics.Sometimes a pic of both sides of the PCB can help us......

author: uwezi
author_rank: Unknown
timestamp: September 12, 2016, 11:00:30 am
content: Quote from: tautech on September 10, 2016, 07:49:39 pmI thought of the 7915 as well, but it does not make sense either at this position. Also as I saw later all 78xx and 79xx are labeled as Uxx on the board (as they should), while the burned part was Q6. I suppose it might have been a MOSFET like an "...N15" or "...P15"

author: uwezi
author_rank: Unknown
timestamp: September 14, 2016, 03:51:36 pm
content: Let me rephrase my question:After a more detailed analysis of the traces and connections around the burned Q6:Is/Was there a power NPN transistor around in the mid-1990s:TO-220 package BCEpart number ending in 15VCEmax > 60VI am now quite sure that the transistor was part of a discrete voltage regulator with two zener diodes as references (1N5363 alone and 1N5363+1N5360 in series). The switching between the two ranges was done through a relay which also switched between two taps on the mains transformer.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 14, 2016, 04:25:04 pm
content: The BCE pinout it the normal one for TO220 transistors. So plenty of transistors to choose from.For the BD series, there are some types with subtypes of -40 / -25 and -15. There might also be 2Nxx15 or 2SCxx15.

author: little.tesla
author_rank: Regular Contributor
timestamp: June 28, 2022, 06:53:34 pm
content: Hi,sorry for resurrecting this thread.Did maybe somebody in the meantime find a schematic of this device or did dump it's firmware?

author: khach
author_rank: Contributor
timestamp: June 29, 2022, 07:45:51 pm
content: Schematic diagramm

author: zrq
author_rank: Frequent Contributor
timestamp: September 13, 2023, 01:45:36 pm
content: I got hands on a Lakeshore 330 in the exactly same condition. Q6 was cut and removed by the previous owner and the OPA541 exploded. If anyone needs a memory dump, drop a message and maybe I can help.
Lambda EMS 33-33-3 power supply - Page 1
Forum section: electronics / repair

author: big jooe
author_rank: Newbie
timestamp: September 30, 2024, 09:34:33 am
content: Hi all,Have obtained Lambda EMS 33-33-3 power supply but it does not have voltahe setting helipot, only current setting helipot. How to adjust voltage on this supply? ...or someone has a schematic of it?many thanksJoe

author: artag
author_rank: Super Contributor
timestamp: September 30, 2024, 11:16:45 am
content: It seems to be covered by the manual athttps://www.artisantg.com/info/TDK_Lambda_EMS_33_33_3_TP_LB_CE_1568_Manual_201981311314.pdfbut presumably in a version that has no or few front panel controls. However section 3.3.2 describes how to program it using the rear panel tag strip which might be appropriate.
Lambda Genesys GEN 60-25 Power Supply Calibration  - Page 1
Forum section: electronics / repair

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 11, 2024, 01:12:16 pm
content: Hi,I have a TDK Genesys GEN60-25 power supply. The current is accurate. The output voltage is about 5% high.This power supply is closed case calibration.There seems to be very little service information available for these power supplies.Does anybody know the commands to do the calibration?Regards,Jay_Diddy_B
Laminator Laminex Minitoke not sensing the heating temperature - Page 1
Forum section: electronics / repair

author: Diego_GM
author_rank: Newbie
timestamp: June 24, 2020, 02:04:19 am
content: Hi EEV community!I am currently working with the repair of a Laminex Minitoke laminator. As the title says this laminator its not sensing the temperature, overheating the resistance and finaly burning the thermal fuses.The lamiantor has 2 heating elements each one of them with 3 inside components; the heating resistance, one 216C thermal fuse and one more component that i think is the heat sensor (i think is a thermistor but not sure, picture attached).I started removing the "thermistor" from the heating element to measure it and see if it is working properly, the problem is that the "thermistor" has a weird behavior. I tried measuring the resistance with a multimeter, at room temperature this component has a resistance of 1.5 Ohm aprox, i started applying hot air with a heating gun to increase the component temperature and see if the resistance changes. The problem is when a measure the cables coming out of this component in one polarity the resistance increases as the component heats (normal of a PTC), but if a measure it in the opposite polarity the resistance decrease when the temperature increases but at one point it starts giving negative resistance.The previous described behavior confused me and i came to this forum to seek for assistance. Does someone know what this component could be or if this behavior is normal?Thank you in advance!Greetings Diego.

author: floobydust
author_rank: Super Contributor
timestamp: June 24, 2020, 02:37:18 am
content: It seems to be a type J thermocouple, not a thermistor. If it is not an open circuit and not shorted to the case/thermowell, you can measure the small DC voltage mV they generate. This is what is confusing your ohmmeter when you switch polarity. You could swap the top and bottom sensor (connectors) and see if the problem moves. The voltage is very tiny so the connections must be clean, check the connectors at the main board, if they are oxidized or not making contact.Does it give any temperature readings? I found this Minikote wiring, if it matches yours.

author: Diego_GM
author_rank: Newbie
timestamp: June 24, 2020, 08:16:55 am
content: Hi floobydust!First of all, thanks a lot for you reply, it is of great help.Indeed now that you say it, it must be a thermocouple and the negative resistance measured must be the small voltage generated.Im going to do some more test to the thermocouples to conclude if they are good or bad (I'm thinking they are in good state).The thermocouples (both of them) go to a control board, exactly to an op amp (LMC6462), maybe the op amp is the problem.Again, thank you for you reply.Greetings Diego.