hybridfree/eevblog-posts huggingface dataset:
Keithley 2304A displays dashes instead of measurements - Page 1
Forum section: electronics / repair

author: jgorsk
author_rank: Regular Contributor
timestamp: February 03, 2025, 05:48:49 pm
content: I have a Keithley 2304A power supply that displays dashes instead of the measurements.The output works fine.I reset the settings to default, no difference.Is there a setting that can cause all the measurements including the DVM readingto display dashes instead of the actual measurements or is it a hardware fault?

author: macboy
author_rank: Super Contributor
timestamp: February 03, 2025, 11:39:02 pm
content: Based only on my experience with several other Keithley instruments, the "--------" display is the result of measurements not being triggered. Most people are accustomed to meters just measuring all the time, but all of my various Keithley meters require setting up a trigger. This can be set to "continuous" to get the usual behavior.

author: jgorsk
author_rank: Regular Contributor
timestamp: February 04, 2025, 06:57:48 am
content: I tried to change the trigger settings, but no change.What would be the settings to get the continuous triggering of the measurements?It's not only the current, the output voltage and the DVM readings are showing dashes.Applying a pulsed load also doesn't result in showing any measured value.

author: macboy
author_rank: Super Contributor
timestamp: February 04, 2025, 01:38:43 pm
content: If you are certain you have done everything right, but you still see no readings, then you may have a fault.I had a quick look and didn't find a service manual other than one for a 2303, which is in the same family. Unfortunately, that one has only a parts list, with no schematics, no troubleshooting information, no theory of operation or block diagrams. So basically, you are left to figure it out yourself.I am in a similar situation with a 2400 Source Meter. It has a fault which I don't think is serious but haven't yet identified. Its service manual has no schematics, but does have some block diagrams, theory, and limited troubleshooting information. It's not enough but it is something.

author: jgorsk
author_rank: Regular Contributor
timestamp: February 04, 2025, 02:34:46 pm
content: It looks like the unit is faulty and the measurements don't work.I tried calibrating the PSU and it just hangs when it tries to measure the output voltagein the first step of the calibration.Similar ADC is used on the 2000 multimeterhttps://doc.xdevs.com/doc/Keithley/2000/K2000.pdfSomeone did a great job drawing the schematic. Thank you.
Keithley 2304A_error limit current (LIM) - Page 1
Forum section: electronics / repair

author: anupong1983
author_rank: Contributor
timestamp: September 12, 2019, 05:09:25 pm
content: Does anyone can help or who has repaired the PSU KEITHLEY 2304A with an error limit current "LIM"?I set the any voltages and current then press operate to "on" or "off" the unit's display always stated 1.8-2.3V and 0.000A current and when I increase voltage more then 2V the LIM will showed on.The problem found on Analog board (top board), but I do not have circuit diagram to check which part have problems.Thank you so much.Anupong
Keithley 236s Repair - Page 1
Forum section: electronics / repair

author: MaxFrister
author_rank: Regular Contributor
timestamp: November 01, 2023, 05:34:20 am
content: I recently repaired a pair of Keithley 236s.The first was a challenge. The initial symptom was that the guard voltage was different than the output voltage and almost every setting was in compliance.A fragment of the analog schematic is attached. I found it challenging because so many things were making the voltages wrong on the main feedback path it was hard to locate the issues. I eventually used a 34401A 6-½ digit meter to trace problematic voltages back the source(s) [I always wonder how many people notice that that meter defaults to 5-½ digits on startup].It had a cascade failure on the main feedback loop of the analog board. In the end I found and replaced:Q29 NPN transistorVR2-5 ZenersU04 AD744KNU08 LT1055This machine is a latter serial number and differed in some ways from the only schematic I found for the machine. For example, a few resistors had been deleted, the K7 relay (only needed for the 237 option) was deleted, U8 and U13 were originally AD744KN but replaced with presumably cheaper LT1055. On the pcb there was an additional isolation slot and a few components had been moved around.Unfortunately, the second unit was not as interesting. Other than a noisy fan and some schmutz on the keypad it worked.

author: Hydron
author_rank: Super Contributor
timestamp: November 05, 2023, 12:09:13 am
content: Yeah I also found some differences to the schematic that's out there when I did a 236-237 conversion, yours looks very similar to mine. Reminds me that I have to write that conversion process up, it's been over a year now since I did it and others may be interested.
Keithley 237 Repair help needed. Offset Voltage? - Page 1
Forum section: electronics / repair

author: staticx57
author_rank: Newbie
timestamp: December 03, 2024, 04:57:50 pm
content: Hi,Recently diving into a new to me sold as repairs needed Keithley 237. Upon turning on it starts without errors and displays zero and reads zero volts on my multimeter. When I attempt to test the voltage sourcing it consistant has a 3.28V offset from what the front panel displays and what the multimeter reads. I trust the multimeter. When disabling the sourcing the 3.28V persists unlike when I turn the machine on and it correctly reads and outputs 0V.Troubleshooting performed:All power supply voltages are in spec.
Keithley 237 Voltage Source/Measuring problem - Page 1
Forum section: electronics / repair

author: JR.junior
author_rank: Newbie
timestamp: February 05, 2025, 08:47:11 pm
content: I"m repairing a Keithley 237 which has a voltage problem. It sourced +197V max and -280Max when select +/- 1000 Volt. I replaced all the electrolytic caps on the resonator and both AD549 on analog board and I get now +/-1000 Volts. Interesting is this: I can toggle to + 700 Volts and I get 700 immediately and from +750 to +1000 the voltage on the output increased slowly wenn toggle, but when I set the output to stby and press on again the 1000 Volts are immediately present on output, as it should be. On the negative sourcing there's absolutely no problems. At measuring Funktion giving +1000 Vdc to the input of the Keithley 237, it measures only +927 Volts. Has anybody an Idea what could causing this problem, got anybody similar problem?ThxRegards,JR.

author: m k
author_rank: Super Contributor
timestamp: February 08, 2025, 07:14:56 am
content: Have you measured how U2 output and input compares?
Keithley 2400 Display not working - Page 1
Forum section: electronics / repair

author: Remdawg
author_rank: Newbie
timestamp: October 08, 2021, 11:56:00 pm
content: VFD display on my Keithley 2400 is not turning on, and there were no visible signs of damage.I get 5v on the display board supply header and IC's but there is nothing on the 37V supply header for the display, nor is there any high voltage supply going into the display driver IC's.The manual also mentions that the VFD is supplied with 60VDC and 5VAC directly from the digital board,which are supplied by U625 but this does not exist on either the digital board or the analog board(as far as I can tell, it is neither mentioned nor shown anywhere else in the service manual or on the physical board.)I read correct voltages on TP5 - TP9 on the digital board.

author: TiN
author_rank: Super Contributor
timestamp: October 09, 2021, 01:49:12 am
content: Photos of the screen? Is getter shiny?On 2400 and 2002 and few others DC-AC/DC module is on front panel pcb, not the digital board.

author: Remdawg
author_rank: Newbie
timestamp: October 09, 2021, 02:26:36 am
content: The getter looks fine, I can see the DC-AC/DC module you mention are you aware if it uses 5v and or 37v as the input voltage. As I did not find a 37v dc input to the display board I started trying to find the supply on the digital board.

author: TiN
author_rank: Super Contributor
timestamp: October 09, 2021, 04:49:09 am
content: Yep, glass looks good. It's using 5V input.

author: floobydust
author_rank: Super Contributor
timestamp: October 09, 2021, 05:20:43 am
content: Looking at Model 2001, U625 takes 5VDC in and generates 5VAC for the filament and 60VDC for the VFD drivers.The 37VDC rail seems to be for the HV output stage, the display does not appear to use it. P1005 pin 9 is 60V not 37V? is that a typo in the manual.I would look for signs of life with the DC-DC converter and display MCU.

author: openloop
author_rank: Regular Contributor
timestamp: October 09, 2021, 07:36:26 pm
content: +60V for the driver chip and AC for the filament are made on the display board by T901 from +5V.T901 primary's middle tap is connected to +5V. other ends of the primary are connected to collectors of Q901 and Q902.Those two guys pull it back and forth, controlled by a separate feedback winding.
Keithley 2400 Error Code: 601 Reading Buffer data lost - Page 1
Forum section: electronics / repair

author: JohnPi
author_rank: Regular Contributor
timestamp: January 13, 2018, 03:10:07 am
content: My 2400 sometimes indicates this error for a second or so on power on; I can't find any documentation about what causes it, or if it is a problem.Any ideas ?

author: Le_Bassiste
author_rank: Frequent Contributor
timestamp: January 13, 2018, 09:50:13 am
content: nothing serious. check the voltage of the 3V lithium battery that supplies the reading-buffer RAM. its probably dead.

author: JohnPi
author_rank: Regular Contributor
timestamp: January 13, 2018, 06:19:11 pm
content: Thanks. It's soldered in with tabs (manual implies it's socketed) -- it's hard to find a replacement nearby...

author: aronake
author_rank: Frequent Contributor
timestamp: November 02, 2022, 09:42:54 am
content: Did you get to replace the battery? Did that solve this problem?
Keithley 2400 Error: No Com Link - Page 1
Forum section: electronics / repair

author: cuongyd
author_rank: Newbie
timestamp: July 25, 2022, 04:00:54 pm
content: Dear all!I have a 2400 device, it display "No Comm Link" error, I checked according to Keithley's repair guide, U15 & U16 are smd types and solder joints are good. What should I do next to fix it.Thanks for supporting me!

author: TiN
author_rank: Super Contributor
timestamp: July 25, 2022, 10:45:13 pm
content: Start with checking all power per repair manual. Check that memory chips still have good firmware. No com link means that front panel cannot communicate with main CPU board.

author: cuongyd
author_rank: Newbie
timestamp: July 26, 2022, 01:09:01 am
content: Quote from: TiN on July 25, 2022, 10:45:13 pmThank you!I will re-check all power block.

author: inse
author_rank: Super Contributor
timestamp: July 26, 2022, 08:13:24 am
content: I also observed this behaviour on maybe two units.After power cycle, it starts up correctly, possibly a power supply issue.This is company property, so I won‘t investigate further.
Keithley 2400 - Page 1
Forum section: electronics / repair

author: AlexITC
author_rank: Newbie
timestamp: December 20, 2021, 01:45:01 pm
content: Hello to all.Maybe someone has encountered a problem with this device. After the next turn on, it stopped supporting the load. I set the mode to 1.89 Volts 100 miles Ampere. I connected a resistance store, the load I need is 20 ohms. But the source begins to reduce the voltage to 0.89999, the voltage is equalized only if the input resistance is increased to 19+ KΩ. I would be very grateful for any advice in this matter, since the high-precision device would like to return it to working condition.

author: Zucca
author_rank: Unknown
timestamp: December 20, 2021, 03:17:30 pm
content: https://www.eevblog.com/forum/repair/help-with-repairs-keithley-2400/msg2862506/#msg2862506"read Forrest read!"
Keithley 2420 repair - Page 1
Forum section: electronics / repair

author: martinr33
author_rank: Frequent Contributor
timestamp: April 05, 2017, 04:31:01 am
content: Just finished fixing up a nice Keithley 2420 Sourcemeter.SymptomsOn this machine, the output was always on at about 23V, and a 0.5 ohm resistor on the main board was cooked.Replacing the resistor changed nothing.A 4-wire short with the output OFF caused the resistor to burn up.In circuit testing of transistors is not reliable on this machine.I removed the main bipolar output pair TIP142 / Q158 and TIP147 / Q521. Both tested as shorted.I also removed Q514 and Q516 (IRF240) because they also looked odd on on my meter.Galleryhttps://mrtn.smugmug.com/Other/Keithley-2420/n-VzNstbOnce I had done this, the meter started "working", delivering the correct voltages from just the driver amp, which is an AD847/U500Replacing the TIPs with the positive FETs mostly unpopulated also worked.I replaced the missing FETs with IRF540s as a temporary measure.The meter now works, and I am waiting for the correct substitute parts. IRF240 (p-channel is IRF9140)Pictures as I get around to it! I just wanted to get this in.Bottom line is, if he meter has a permanent output voltage - pull Q514 and Q516, to make sure that the analog driver is delivering the correct voltage. Then, you can work on fixing up the drive transistors.

author: HighVoltage
author_rank: Super Contributor
timestamp: April 05, 2017, 08:37:43 am
content: Nice of you to confirm this.It is also my experience.Usually if something goes wrong with these Keithley 24xx source meters it is the output stage and it is easily repaired.Pictures would be nice.

author: goaty
author_rank: Regular Contributor
timestamp: October 02, 2019, 10:33:08 am
content: I´m currently repairing a 2420 with several components blown up.From the service manual, I can get the component types, but they do not fully match the board I have.Does anyone know what Q415, Q416 are ? They list as MTP23P06, but have different Case.Thomas
Keithley 2420 - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: February 08, 2021, 02:38:49 pm
content: Hi AllKeithley model shows up -80 volts at the front hi lo terminal(without output on blue light enabled)as default even when the v source is 0 v.when the output on is enabled the residual voltage -80v offset disappears and unit works ok.However when the Output is programmed for High Impedance of state instead of Normal Off state unit works ok there is no offset of -80V at the output (without enabling output on button)strange problem, has anyone encountered this issue.I have checked all the ranges from mv to 60V , it is functioning ok.Thanks in advance
Keithley 2601 source meter errors - Page 1
Forum section: electronics / repair

author: macevergreen
author_rank: Newbie
timestamp: November 18, 2024, 01:18:25 pm
content: Dear all,I am glad that I got my hands on an inexpensive Keithley 2601 source meter. I cannot complain much since I bought it for 300 USD.However, when starting it up, the device displays two errors:1106 - Battery not present1402 - User transcripts lostThe device seems to be from around 2006 and so far everything seems to be working fine. I checked the other related blogs on the forum and by opening my device, I was able to locate the battery in the front of the device. The battery is connected with a relatively long cable to the digital board located at the rear of the device. Clearly not a CR2032 or some standard battery, not much useful information on the battery either. I also do not know whether the battery is rechargeable or not, but my first guess would be that it is not rechargeable.Does anybody have experience with replacing the battery? Can you only use an official spare part or is there some similar battery which I could use? Is it even worth the effort replacing the battery if I want for example not plan to use TSP-link?

author: Jetecnet
author_rank: Contributor
timestamp: November 19, 2024, 02:29:26 pm
content: The battery is a BA-52 Li-ion, not easily available. Similar batteries are on Ebay listed as LED bluetooth speaker batteries.These 260x will lose battery power and user settings if not used frequently so yours might just need to charge for a while.JC

author: macevergreen
author_rank: Newbie
timestamp: November 19, 2024, 03:43:14 pm
content: Thank you so much for the info. To be honest, I did not expect that it is rechargeable and since my battery seems to be completely discharged, I wonder if there is a chance to get it working again.But if not, you helped me a lot where to find a possible replacement, although it might be a bit more tricky. But since I don't need one immediately, it is not a problem.Thank you once again! I really appreciate your help!
Keithley 2602 repair need help! - Page 1
Forum section: electronics / repair

author: smaultre
author_rank: Regular Contributor
timestamp: July 29, 2024, 02:04:16 am
content: Hello i have two channel sourcemeter 2602 with one bad channel.Bad channel get full amplitude on output. That's cause one channel power supply to overload.On the bad channel:One of LM337 near the capacitors gets hot, and one LM317 have the room temperature, on working channel they both gets quite hotI thinks, that it's because one part of pre-amp eat more current.I try to trace and found one bad smd transistor Q32, marked as 2.(dot)A LLI 2.A LLILooks like 2n3906 or maybe some different type?It's connected with diode(zenner?) VR7When i de-solder bad transistor and check it with transistor tester. That shows that its BJT-PNP with hFe=0 Ic=0 Ube=0 (BAD).Then i check resistance to GND from solder pads on PCB and it's shows near the working-one channel resistivity.I try to put these transistor from a good channel and powering up my 2602 with one connected channel.Oscillations stops power supply doesn't goes to protect mode, but i have +2.48V on output.Ok, then i trying to put back Q32 to working channel, transistor tester shows that it's BJT-PNP with hFe=176 Ic=1,6mA Ube=658mV (Good ?)When i put it back on previously working channel it shows on output -2,68VNow two channels are bad.UPD, extracting another one same as 2.A LLI from non working channel, i'll bring previously working channel back..

author: Zucca
author_rank: Unknown
timestamp: July 29, 2024, 04:06:46 am
content: I am sure you already looked here:https://xdevs.com/fix/kei2425/It is a K2425, but it could be a good source to narrow down your problem.

author: smaultre
author_rank: Regular Contributor
timestamp: July 29, 2024, 06:03:45 am
content: The product lines 24xx & 26xx have different schematics..

author: smaultre
author_rank: Regular Contributor
timestamp: August 03, 2024, 09:50:35 pm
content: What is the part type? 2n3906 ??

author: smaultre
author_rank: Regular Contributor
timestamp: August 05, 2024, 10:07:18 am
content: https://www.eevblog.com/forum/repair/keithley-2602-dual-smu-repair/DONE!
Keithley 2602a wrong Voltage after a couple of minutes - Page 1
Forum section: electronics / repair

author: Aheld
author_rank: Regular Contributor
timestamp: July 03, 2021, 06:36:24 pm
content: Hello,My Keithley 2602a seems to have an issue with output voltage and current measurement.After powering up, it works fine. But after a couple of minutes, the values are complete unrealistic.Tested with 4R7 resistor, with output voltage setting at 500mV, it messures a negativ current of a couple of hundret mA. The 5W resitor started with overheating. Does any one has any idea where to start with searching?Is there any source to download or buy schematics?Thanks a lot.Aheld

author: MathWizard
author_rank: Super Contributor
timestamp: July 06, 2021, 01:20:44 pm
content: here's the manual with lots of user interface help, funtions, etc. But no schematics is given, IDK, it's probably not given out if it's built in early 2000'shttps://download.tek.com/manual/2600AS-900-01_B-Sep2008_User.pdfcould be some bad part or solder joint heating up and not working, or some chip not happy and shutting down something

author: Aheld
author_rank: Regular Contributor
timestamp: July 06, 2021, 05:09:57 pm
content: Thank you for your reply, but the user manual can‘t help on this topic. I just opened the device and tried to find some test points to check the voltages. But t here are only a few testpoints visible and labeled with voltage levels.In my mind the defect needs to be located in power supply or other central position, because both channels are affected.If someone has information about the colour coding of the supply cables and the voltages in channel switched off and switched on mode? That would be helpful to find a solid starting point.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: July 07, 2021, 08:56:30 am
content: Photograph was found on this forum.

author: Aheld
author_rank: Regular Contributor
timestamp: July 08, 2021, 06:02:14 pm
content: Thank you very much. It seems that used wrong words for searching in this forum.

author: MegaVolt
author_rank: Frequent Contributor
timestamp: July 09, 2021, 07:24:16 am
content: There is one good person who has collected everything that can be found on the Internet: TiN.Here is its repository:https://xdevs.com/doc/Keithley/2601_2602_2604/Here is the file that I shared. And if you go a little higher in the catalog, there is more information about 26XX where XX differs from 02

author: Aheld
author_rank: Regular Contributor
timestamp: July 20, 2021, 03:23:32 pm
content: I had first success. The first device 2612 is up and running again.Some main voltages on the power connectors haven‘t been there. The effect was that the output voltage was wrong and only negative.I changes all Elkos to new one and found a couple of defect elkos.I‘ll post the voltages at the connectors soon. Maybe it helps for other repair trailsThanks MegaVolt for the tip on xdevs.com
Keithley 2602A repairs - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: October 24, 2023, 08:05:44 am
content: Hi AllTrying to troubleshoot the subject unit.unit powers up and doesnt boot left extreme two segments of display lighting up -- --problem appears to be with 5V supply showing 8.5Trying to locate the SMD cross ref of U136 marked as J96AB SSOP10 packageAlso Cr113 and Cr115 showing 20 ohms in cold check. both diodes connected to U136Any help is welcome. Attached picturesThanks in advance

author: hitecelec
author_rank: Regular Contributor
timestamp: October 24, 2023, 11:58:03 am
content: helloI found the Device . 5102Sd was written beneathLM5102SD half bridge driver

author: 晓看风云
author_rank: Contributor
timestamp: October 25, 2023, 02:35:50 am
content: If the short circuit points to u136, you can try using thermal imaging or simply removing it!
Keithley 2612A - Page 1
Forum section: electronics / repair

author: timbocgn
author_rank: Contributor
timestamp: April 06, 2025, 09:21:41 am
content: Hi guys,Has anyone come across a service manual or schematic for a Keithley 2612A?There are some affordable defective ones out there, but without any documentation it will be just luck. I already searched at xdevs and of course in this forum here.Thank you!Tim.
Keithley 2700 broken AMPS jack? - Page 1
Forum section: electronics / repair

author: pso
author_rank: Newbie
timestamp: February 09, 2022, 01:04:30 pm
content: Hi,i hope that somebody can help me on this?maybe a picture of the AMPS jack inside and fuse holder would help already.I’m not sure if something is really broken, or maybe there is a part missing?I already was asking in the Tektronix Forum - but seems they are busy.This is the Plug and probably there is something broken - from the backside it looks like others found in the www - not sure now.this is the fuse holder, but there is no chance that this will workany advice? or a workaround?thanks in advancePeter Sevinc

author: chekhov
author_rank: Regular Contributor
timestamp: February 09, 2022, 03:51:52 pm
content: Look into similar topichttps://www.eevblog.com/forum/repair/keithley-2000-current-input-back-half/

author: pso
author_rank: Newbie
timestamp: February 09, 2022, 05:03:18 pm
content: Hi,many thanks for the link - now i can be sure that‘s broken.seems to be a poor construction.maybe a workaround will be saver, then trying to find a new front panel.
Keithley 2700 repair - Page 1
Forum section: electronics / repair

author: Adilpickles
author_rank: Newbie
timestamp: April 23, 2025, 04:15:32 pm
content: Hey all, first post here. I've recently picked up a broken keithley 2700 for pretty cheap with a broken dc/ohms range. Upon opening it up, u115 (lm339d) was completely charred. When I went ahead and removed it (as best I could) I still lifted a bunch of traces and pads. My next step was to figure out why this happened. But before that, I wanted to ask if this repair is even possible; I've repaired test equipment in the past, but nothing with this much char on the board. Does it make sense for me to even repair this meter? That being said, I could use this as a donor board since I plan to buy another keithley (a 2000) when I have enough saved.

author: Kleinstein
author_rank: Super Contributor
timestamp: April 23, 2025, 06:09:02 pm
content: The Keithley 2000/2700 use to a large part standard parts. So there is a chance for a success. Chances are there are more parts bad than just the LM339. The LM399 as mostly used to control JFETs (seem to be mostly mmbf4393 or similar) as switches. These would also be suspect. Another point is the supply, especially the negative supply, that could be on the high side.The chared PCB residue can be conductive. One the positive side the LM339 itself is not critical with leakage. It is more used as a level shifter, open collector driver.

author: Adilpickles
author_rank: Newbie
timestamp: April 23, 2025, 06:54:24 pm
content: Good place to start, thanks. Regardless if I fix it or not, I'll probably track down the problem
Keithley 580 GPIB option EEPROM needed - Page 1
Forum section: electronics / repair

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: February 12, 2020, 04:18:27 pm
content: Hi, wanted to ask if there is a copy of EEprom for the GPIB option in the 580 ohm meter maybe somewhere there.I have an option that came from 485 picoammeter wanted to use it in the 580.Can somebody make a copy and post it please. I would really appreciate.
Keithley 614 Electrometer repair - overvoltage on current measurement - Page 1
Forum section: electronics / repair

author: balage
author_rank: Regular Contributor
timestamp: July 09, 2021, 10:09:19 am
content: Hello,Shit happened today. I was measuring microamps in 20uA range when I disconnected the loop and connected it back again. The source was a current generator with a compliance voltage of 600 volts (max voltage for the 20uA range is 75V for the 614). So the input was fed with 600 volts.The 614 now measures exactly the half of the input current with opposite polarity. So when I fed 20uA in it measures -10uA. Resistance and voltage measurement is still fine.I was checking the schematic (full manual with schematic is attached) and trying to find what was damaged. So the input stage is almost the same for R, V & I measurements that includes the mighty Q104 and U102. So I think (hope) that if R and V measurements are okay than this stage is not damaged. The I measurement configuration is here:I don't really understand what does "Provides the inversion necessary for feedback current".Do you think it is possible that only this opamp is gone? It is still unobtainable and some replacement part must be found.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 09, 2021, 10:51:38 am
content: It is possible that only the OP U103 is bad. though there may be more things wrong, like some diodes. The input path to the JFETs is reasonably well protected with high resistors. The FB path has mainly the 10 K for surrent sensing to limit a current surge.It probably needs a few more readings to really tell that the OP is bad.There are still a few high voltage OPs available. At least the actual performance / parameters of this OP should not be that critical. So a substitute should be posssible.

author: balage
author_rank: Regular Contributor
timestamp: July 16, 2021, 06:06:45 am
content: Thanks for your ratification. The opamps are on their way to me. I will replace and will see.
Keithley 619 EPROMs - Page 1
Forum section: electronics / repair

author: alocam
author_rank: Regular Contributor
timestamp: July 05, 2023, 10:31:21 pm
content: Hello, I have a Keithley 619 that has been stored for quite a while, now it does not boot. Apart from investigating any other hw related failure, I found out that this unit has two 2732 eproms instead of the four that prior units came equipped with.I found no source to get the contents of the 2 eprom model. I wonder if anyone has or may dump the 2732 eproms content for me to verify the existing program.Thank you!

author: alocam
author_rank: Regular Contributor
timestamp: July 05, 2023, 10:34:14 pm
content: Additional comment: both chips are C1 version, marked PRO-114-C1 and PRO-115-C1.I have already checked the contents against the 4 eprom version, and none of the blocks seem to be the same, may be the versions differ, may be the eprom contents has been affected or has vanished after 40 years.Regards!

author: fzabkar
author_rank: Super Contributor
timestamp: July 06, 2023, 01:04:50 am
content: Can you upload your dumps? Perhaps someone may be able to identify a checksum.
Keithley DM6500 repair - error 1153 - Page 1
Forum section: electronics / repair

author: BeamDump
author_rank: Contributor
timestamp: November 15, 2024, 08:42:14 am
content: Was going over DCV measurements on a LED driver board, powered from AC source supply. Everything was what you'd expect, then DMM caused short on DUT and AC PSU went to OCP. Highest voltage on board is DC bus, 320V. Nothing the meter hasn't seen before. Both supply and DUT recovered no problem but DMM suffered error 1153. Looking inside, some analog power rails are down. Only 6VA = 10V.7V , 18VA = 22.8V and -18VA = -22.8V left, nothing on +5VA, -5VA, +15VA.If i try switching measurement types, it gives communication error...Anyone experienced this before?

author: gamerpaddy
author_rank: Regular Contributor
timestamp: November 15, 2024, 03:55:18 pm
content: very unusual fault.you still got warranty ?if not, try to check the basics firstthe regulators in and outputs. if outputs are down, you might have a short somewhere. if inputs are down, rectifier or transformer issues.when checking, look up the regulator part numbers if they require a enable pin.the missing +-5V and +15v are required for it to work obviously.the +-18v sitting at +-23v is a problem, its too much for most opamps.

author: BeamDump
author_rank: Contributor
timestamp: November 15, 2024, 06:08:56 pm
content: I found these notes from another user (attached), apparently he measured his +18/-18VA rails and it's the same reading as mine, so i assume no problem there...Unit bough in 2020, so no warranty i think.Transformer gives out all the voltages, rectification is present, caps are charged.Only 3 linear regulator: LM317D2, LM337BD2T, MC7805CD2TWill check them, so far haven't seen any Vout ot Vin from any of them.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 15, 2024, 07:22:53 pm
content: The +-18 V and 6 V are likely unregulated, raw voltage to be regulated to 5 V and +-15 V.The main suspect is a short somethere on the +15 V and some possibly odd problem on the +-5 V. The -5 V may need another voltage to work and may be rather low power. In the pictures there are only 3 somewhat power capable regulators and also not that many large filter capacitors. The -5 V may have a rather power max current.With a short the regulator for the +15 V should get rather hot. If not this would more point to an issue with the regulator.
keithley DMM2001 200ma  range not well ,how can i calibration the current - Page 1
Forum section: electronics / repair

author: leon1314
author_rank: Newbie
timestamp: February 09, 2023, 08:04:11 am
content: i have one keithely DMM2001 200ma not well , when i source +-100MA to 2001, the 2001 test value is about +100.8693ma/-100.8765ma ,when i calibrate the 2001 , i can't find the current calibration ,why ?Is the instrument version too low?? the version is B14 /A02 . thank you .
Keithley SCS 4200 software CD - Page 1
Forum section: electronics / repair

author: Johnny10
author_rank: Frequent Contributor
timestamp: November 03, 2020, 04:24:33 pm
content: Does anyone have the software for the SCS4200 ?I am working on one with no Harddrive.This is an older unit with Pentium 4 processor.Thanks

author: Johnny10
author_rank: Frequent Contributor
timestamp: November 11, 2020, 08:27:21 pm
content: OK, Contacted Keithley and seems this obsolete unit. And no Hard Drive available.Wondering if anyone here might have a unit with working hard drive I could clone?Seems you cannot simply load or reload OS except at factory. Some hardware specific magYou can reload Kite software though.This unit is older has 4 SMU cards and Pentium 4/Celeron CPUHard Drive is 100 ATA 250GB or more?Running XP Pro 1-2 CPU

author: Johnny10
author_rank: Frequent Contributor
timestamp: November 22, 2020, 07:27:33 pm
content: More pics for SCS 4200Left side is SMU units.Right Side is Robo CPU SBC

author: Johnny10
author_rank: Frequent Contributor
timestamp: November 24, 2020, 05:47:39 pm
content: Power Supply

author: jwenjun1970X
author_rank: Newbie
timestamp: July 13, 2025, 07:36:40 am
content: I have 4200 XP DISK image for system recovery if you need ! same time i am also searching for Keithley KTE 9.1 ,i need it to update to WIN7

author: Johnny10
author_rank: Frequent Contributor
timestamp: July 18, 2025, 01:26:19 am
content: I sold the unit a few years back. :-( I worked on finding and trying to buy Hard Drive clone for a long time but no luck.Thank you for your offer. Just too late.

author: squadchannel
author_rank: Frequent Contributor
timestamp: July 18, 2025, 03:52:54 am
content: If you don't mind, could you upload it?I don't have it, but I can help other people who are having trouble.
Keithley TF-245 Bodge - Page 1
Forum section: electronics / repair

author: ApertureScience
author_rank: Contributor
timestamp: July 14, 2024, 07:04:01 pm
content: I have another Keithley 2000 with a broken TF-245 resistor array (pin 4-14 30k). I wrote Tektronix Support, but I want to have a plan B. In my case only one path is broken, so im considering putting another low tempco resistor on top. Any recommendations? I was looking at WELWYN - PCF0805 5ppm surface mount or two NOS Alpha Electronics (20k+10k 5ppm) in series. Those seem to be readily available at 20 Euro for both options.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 14, 2024, 07:14:16 pm
content: Ideally one would like to have matching between the 3 x 30 K resistors. So 1 good external resistor may not be good enough. It is a bit unclear if the 3 resistors should have the same value of maybe a bit different.For 3 matched resistors I would consider 2 x NOMCT 10 K (or 20 K) using 6 + 3 of the resistors.

author: ApertureScience
author_rank: Contributor
timestamp: July 15, 2024, 07:56:40 am
content: Thank you for the suggestion! I hope the spare part will be in stock, ill post once tektronix has replied back to me.

author: coromonadalix
author_rank: Super Contributor
timestamp: July 15, 2024, 11:20:33 am
content: there is a project to substitute it here on eevblog ....

author: ApertureScience
author_rank: Contributor
timestamp: August 20, 2024, 09:41:19 am
content: I got a quote from the german spare parts supplier, which is CALPLUS, for 48Euro not including tax and 3-4 weeks lead time. I will go that route.
Keithly 227 On the bench for repair.  - Page 1
Forum section: electronics / repair

author: Zenwizard
author_rank: Regular Contributor
timestamp: June 21, 2024, 01:13:37 am
content: I have a keithley 227 current source on the bench for repair. It seems to 1/2 way work but it will not output any voltage or current.I have verified the VS + and - 12 as well as the VD + and - 12 the high voltage is present as well. The odd part is when the meter is in current measure mode it is working and the meter will deflect. When it is in voltage measurement mode there is no meter deflection. Looking forward to adding this one to the lab if I can get it up and running.Anyone worked on these that might have a good starting point?Zen

author: Zenwizard
author_rank: Regular Contributor
timestamp: June 22, 2024, 01:39:04 pm
content: I think I have this one figured out. U205 is getting control and being told what to do but its output is stuck and will not move. Unfortunatly in the 227 U205 is a custom Keithley part and is just labeled IC -76. So there is not a lot that will be able to be done to fix the 227.Zen

author: tppc
author_rank: Regular Contributor
timestamp: June 22, 2024, 03:03:14 pm
content: As per the 227 service manual, U205-IC76 has the same pinout as LM318.The original Keithley part is probably a selected opamp with better carateristics, but at least for the repair, I believe you can try with a regular LM318.Regards.

author: ch_scr
author_rank: Frequent Contributor
timestamp: August 12, 2024, 05:22:26 pm
content: It's already broken, might as well desolder that OPA and try to find a replacement.
KEL103 Temp Control Issue - Looking for advice. - Page 1
Forum section: electronics / repair

author: rfdes
author_rank: Regular Contributor
timestamp: November 13, 2023, 07:45:04 pm
content: Hi -I own a Korad KEL103 electronic load that has served me well with no known issues. Until today.I've discovered an issue with the temperature control circuitry. I've been testing some 18650 batteries and running a low power capacity test where I never exceed a 2W dissipation. I would think that the fan would never come on but after about 5 hours of running the battery test at 2W the fan comes on. No big deal but then fan never shuts off even after an excessive cooling period.. At the conclusion of the test (another hour or so) I disable the load (ON/OFF) and only then does the fan turn off. Enabling the load to ON, the fan does NOT come back on. So, it seems that the thermistor properly kicks on the fan when needed, the fan does it's job but the fan is not disabled.I've heard other users claim that the fan would cycle every minute or so when cooling. I'm sure that if I was maxing out the load at 300W, I would expect the fan to stay on constantly but not at 2W.Anybody seen this issue before and know of the remedy?ThanksJim

author: Gediminas
author_rank: Regular Contributor
timestamp: November 14, 2023, 10:26:02 pm
content: I have Tenma (rebranded kel-103), it does same thing after long period of use. I think it is programmed to do that just to remove some heat from power supply.Otherwise it is cooling by switching on and off like you said.

author: t1d
author_rank: Super Contributor
timestamp: November 16, 2023, 12:54:25 am
content: Kind of sounds like a firmware issue? Maybe reflash the firmware, even if you have the current version. If that is not the cure, you are probably going to have to dig into the circuitry. Maybe the thermocoupler is held high, or low, and that resistor has failed? Maybe the thermocoupler is bad? Maybe the microcontroller is failing? HTH.
Kemppi Minarc Evo 180 welder IGBT module help/source/idea - Page 1
Forum section: electronics / repair

author: Gluteniz
author_rank: Newbie
timestamp: August 11, 2025, 06:20:34 pm
content: Repairing a Kemppi Minarc Evo 180, fault has been found and confirmed but the component that has the failed IGBT inside (MTP IGBT power module (VS-100MT060WSP)) seems to be impossible to buy as it has been marked as obsoleteWas able to confirm the fault by cutting the traces of the shorted parallel IGBT inside the power module.My idea now is if I can't find the module, is to cut the traces even on the working IGBT inside the power module that was parallel with the broken one and buy and install a external IGBT, wiring and modification is not a problem.Only thing that I am unsure of is that the original IGBT has something called "warp 2 IGBT" seems to be something with switching speeds, what happens if the replacement IGBT does not have this and is a slower one but with the same volt/amp rating and other ratings close enough?or is there someplace I can find this obsolete power module?Added a few pictures of the module.I appreciate all the help to save this from being a expensive paperweight.

author: Swake
author_rank: Frequent Contributor
timestamp: August 13, 2025, 11:22:32 am
content: Your plan is worth trying.You're probably right on the warp speed thing. Found this:A "warp 2 IGBT" refers to a Vishay Semiconductors technology that offers a significantly faster switching speed compared to traditional IGBTs, enabling higher operating frequencies and increased efficiency.There are some 'speed' specs in the datasheet. example for 100A collector current:Turn-on delay time td(on) - 137 nsRise time tr - 52 nsTurn-off delay time td(off) - 341 nsFall time tf - 52 nsYou might want to match that close enough.I'd replace both IGBT's.There is a temperature sensor in that thing. That is only going to monitor the diode junction temp. This means no more overheat protection in the machine.The seems to be some suspicious smudges of whatever on the diode on the left.PFC stands for power factor correction. Google found this in relation to that information:Specific design considerations for PFC IGBTs include their internal gate resistance and drift layer thickness, as highlighted by manufacturers like Renesas, Infineon, and Toshiba.
Kenwood 520SE 40 meters doesn’t work  - Page 1
Forum section: electronics / repair

author: KP4EV
author_rank: Newbie
timestamp: June 17, 2020, 04:00:22 am
content: I need to fix the 40 meters switch board wafer. I can transmit or receive in 40 meters. The rest of the bands word fine. Help!!

author: tkamiya
author_rank: Super Contributor
timestamp: June 18, 2020, 04:45:54 am
content: How can we of assistance? Looks like you've identified the problem to be a band switch wafer. What's wrong with it? Something lose? Something missing? Something broke?Is local xtal oscillator oscillating to spec for 40 meters band? It is quite possible, if you bought it used, someone tried to mess with it and it could be just out of alignment. Fortunately, user's manual has full circuit diagram and alignment procedures.Have you tried Deoxit? Just a little bit of it does wonders if it is otherwise physically intact.
Kenwood A-85 Amp fault help - Page 1
Forum section: electronics / repair

author: ronnie-dent
author_rank: Newbie
timestamp: May 03, 2025, 07:59:58 am
content: Hi all, I'm new here, was pointed here by a friend on another forum as he said there are lots of helpful users here, so thanks for letting me joinI'm trying to track down a problem on a Kenwood A-85 Hifi amp, the 41v rail has a short and is blowing both the fuses on the AC tap, The amp does come on and I'm getting DC volts on 3 of 4 speaker outputs, it slowly climbs to around 5v before the protect kicks in, I just wondered if anyone else may have had this issue with this amp and could offer any advice? I tried a few things like desoldering Q9 but it read ok and checked the caps etc. I did try injecting voltage to see what gets hot but my PSU could only inject around 3 volts with 3 amps but not sure I'm doing this right?I do have a pdf of the service manual I will try to attach it hereThanks for and adviceRonnie

author: ronnie-dent
author_rank: Newbie
timestamp: May 03, 2025, 09:34:26 am
content: Think I found the culprit! Q11 is introducing the short! It's a B1503
Kenwood CO-1305 service manual request - Page 1
Forum section: electronics / repair

author: yustech
author_rank: Newbie
timestamp: August 04, 2019, 09:44:33 am
content: Hello good people. Anyone has a copy of it? I bought a cute little scope. Couldn't help myself. Its so cute. Would like to prepare the documentation for future alignment/repairs. Did I mention its cute? Hehe.Thanks a million in advance people. Great forum and informative as always.
Kenwood CS-4125 horizontal position not working - Page 1
Forum section: electronics / repair

author: xbunnyraptorx
author_rank: Newbie
timestamp: April 22, 2022, 01:17:31 am
content: Hello all,I recently purchase a Kenwood CS-4125 analog scope because I am interested in getting into electronics. Preface the rest of this with the fact that I basically know nothing but the very basics of electronics, and ideally I do not want to destroy this thing by taking it apart into a million pieces. If I have to return it I will and will be out of the shipping costs. Oh well.All the knobs do what they are supposed to except the horizontal position. As you can see in the pictures below, the center is off to the left. The horizontal calibration knob works, but not the horizontal position.In addition, I sent in a signal that should have drawn a circle in X-Y mode. It doesn't appear as such, even when I mess with the calibrations for each. The CH1 and CH2 calibrations should be good as I did them both probing the calibration signal.I am more concerned with getting the horizontal position to work vs the error in X-Y mode, but it would be nice if that could be fixed too. I found this service manual online but honestly I have no idea what I'm looking for.I'd like to know if I have a prayer of fixing this (or at least centering the signal by some method). Thanks.Service manual:http://bee.mif.pg.gda.pl/ciasteczkowypotwor/Kenwood/Kenwood%20CS-4125.pdfThe 1 kHz 1 Vp-p calibration signalCenter with no input V in X-Y modeCircle signalInnards

author: xbunnyraptorx
author_rank: Newbie
timestamp: April 22, 2022, 01:51:08 pm
content: Update: I'm returning the item so no need to help. I'm new to the forum so I don't know how to remove a post.
kenwood  dcs-8200 clock issues - Page 1
Forum section: electronics / repair

author: m3vuv
author_rank: Super Contributor
timestamp: May 31, 2020, 11:34:41 am
content: hi all ive just got the above scope,when i got it the display said low batt,after stripping it down i found a tabbed lithium button cell soldered to a pcb,i didnt have a replacement so got 2x aaa nickel metal hydeide cells in a holder in series,so 2.4v as opposed to 3v,the leads from this are soldered where the original battery was,it no longer says low batt but the clock doesent keep the time date etc when the scope is power cycled,its not an issue as the scope still works fine,any ideas if 2.4v and not 3 will cause this?,cheers in advance,73 m3vuv.