Keithley 2001M 7.5 digit multimeter repair (not a bad capacitor failure) - Page 1
Forum section: electronics / repair

author: neverendingstudent
author_rank: Regular Contributor
timestamp: March 11, 2025, 05:27:40 am
content: Ok, so this started off in the 'What did you buy today? Post your latest purchase!' thread, but it's more appropriate to create a dedicated repair post here.https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/13675/I recently purchased a Keithley 2001 on eBay. It was listed as functional, but turned out to be non-functional upon testing. Not a leaked capacitor failure.Starting off: I would like to be very humble here and say this is very much 'the deep end' for me in terms of the potential complexity of repair, and certainly will be the most important-to-me instrument I will have to-date attempted repair on. I humbly request any and all help, suggestions, and advice of my more learned colleges here.I am also interested in using this as an opportunity to get better / additional video and picture documentation (for at least my particular version of) the 2001 meter. It is both a nice 7.5 digit meter, and also ones that comes up needing repair off the secondary market. When looking through XDevs images and documentation on these meters (thank you so much for all you do XDevs!) I found that even with the high-res board images, I still couldn't make out things like individual component markings, and likewise haven't been able to find such elsewhere from my searches. I have good optics available to me, including a quality 4K camera on a microscope with a light polarizer, so I figure this is a good opportunity to add to the repair knowledge of this meter by documenting / imaging individual component markings for future reference by other's looking at repairs of this model.So: I'm looking for any advice relevant to this meter and this repair, but also any requests or suggestions on how to best use this to add to the available repair documentation for this meter.Thank you all.What I have so far: 3 videos (they say X of 4, but the 3rd of 4 is for the seller and shows their eBay username, it's only eBay stuff and not about the technical details of the meter) and a couple pictures of the 1 obviously blown component I have found so far.Video 1 - initial tests, not comprehensive:Video 2 - more comprehensive and systematic function tests with my DMMCheck Plus r8 and running the internal self-test, showing all errors: (link added 2025-Mar-22 / 23 midnight - sorry for taking so long, things have been busy)edit: removed again, I uploaded the wrong one, arg!!!!! Edit 2: ok, the correct one is uploading right now (12:44AM as I type this GMT -4)Video 3 - shows disassembly and initial Mk.1 Eyeball diagnostics: (link added 2025-Mar-23 T:0100 GMT -4)EDIT: apologies there was identifying information (for both me and the eBay seller) in at least the first video. I've removed links for now and will get public-friendly versions up.All those videos are unlisted links and have no quality processing like audio level normalization, you'll need to turn your volume up, sorry. I'll probably make better versions for public release on my YouTube channel later.Also the 2 pictures so far showing the blown component (U310) - attached.Additional links:XDevs K2001 page:https://xdevs.com/fix/kei2001/XDevs K2001 -M variant page:https://xdevs.com/review/kei2001m/Thank you already to users edavid and Zucca who have already been helping me with this on the 'what have you bought today' thread.

author: Zucca
author_rank: Unknown
timestamp: March 11, 2025, 01:03:13 pm
content: Even if you don't see acid traces below the caps there could be a hidden issue.This is what I suggest, better be safe than sorry especially with such rare and nice meter:1) some of us in the process of recapping, found out they started to leak but NO signs were visible prior to desolder them. Some were smelling acid odors but the eyes were happy.First step recap it and do not power it on.2) I propose replace shift registers 14094 and all analog switches (DG411/DG404/DG211). It is much faster than troubleshooting these failures.Those are again K2001 weak points.3) New U3104) Finally power it up and run a self test.If you feel lucky just replace U310 and run a selftest.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: March 12, 2025, 05:22:47 pm
content: Quote from: Zucca on March 11, 2025, 01:03:13 pmDon't worry, I will definitely be recapping it for preventative maintenance purposes if nothing else. I'll report back with findings - if there was any otherwise hidden leaks or damage.I'll gladly follow your advice on replacing the shift registers and the analog switches as well, and thank you for giving it.Currently I need to do some video editing to remove the identifying information from my original videos so I can share the potions that are relevant - showing the meter's behavior before any component replacement to maybe help others look up this thread if they come across a K2001 with similar symptoms. After that I have 2 boat-anchor size signal generators coming in that I need to do some basic functionality verification on so I can give feedback to their sellers, and then we're off to work on the Keithley. The second of the two signal generators should arrive later today.

author: Cyclotron
author_rank: Unknown
timestamp: March 23, 2025, 03:43:00 am
content: @neverendingstudentI see we shop at the same ebay shop. I purchased 2 of the keithley 2001M meters from them and both have the exact same high voltage damage.These are the "Military" edition of the unit each are dated 2006 and 2007 which as with yours has the updated analog board.U310 (LM339DR2G) is blown exactly like yours and I've replaced that component on both. The amount of burning done there charred both units and I etched the carbonized PCB out and filled it with epoxy and recoated the board area with mask. The damage on one required bodging two wires for pads and on the second 3 wires were required to solve for blown out pads. This part of the repair, so far, is the most tedious and if you might say, advanced. You might get away without removing the carbon but I remove that on all repairs I do to avoid a low impedance path that causes "weirdness".The amount of current that went through these units is bound to fry more than one thing and so far that has been true with both of mine. I started at the lower numbers and work my way up as repair parts arrive. Unit A is waiting for a MC14094BDR2G to replace U300 as that appears to be gone on it and I can't move forward till its replaced. Unit B didn't suffer a problem with U300 but U323 (DG211BDY-E3) was fried. I replaced that and now have all the OHMs, VDC, and VAC errors cleared. The only errors that remain on that unit are 309.1, 309.2, 309.5, 309.6, 310.1, and 412.1.Per the repair docs U317 and a few resistors might be suspect. I have tested the caddock array and the other resistors listed and they are good so I suspect U317 and have placed and order for some DG411DY-E3 switches. I highly suspect 309.1, .2, .5, and .6 are failing for the same reason though u317 isn't listed for the last two it is common to the earlier ones and that likey impacts these. I have found that starting at the lower numbers and working up clears codes for higher numbers too. I believe 310.1 and 412.1 will clear once the 309 series are fixed.Unit A has more error codes after U310 replacement than before which is neat but expected sometimes as there can be things it can't do before. I will know more once u300 is replaced. In fact there's so many codes in Unit A it has overrun the error log buffer.I travel a lot and do not expect to get back to these with parts till next weekend. I hope you find my journey so far helpful on yours. I would note that the caps will be replaced in mine but, as far as I understand, the bad cap issues hasn't been seen in an 2001M. I say that and know that these caps were produced and installed in the band of "bad cap era" 1999-2006 were bad years for caps as formulas were being updated. There's lots of legends about why.

author: Cyclotron
author_rank: Unknown
timestamp: March 23, 2025, 03:50:33 am
content: I looked at your photos more closely. you may not have the charring that I had on both of mine. That would be fantastic as it may mean even less damage in other areas.Photos of one of mine attached. You can see the original chip and char. I don't seem to have a photo of just after chip removal.But then I got rid of the char across the board and filled with epoxy and covered back up with masking.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: March 23, 2025, 04:03:03 am
content: Quote from: Cyclotron on March 23, 2025, 03:43:00 amCyclotron: thank you so much for this level of detail. I've had a lot on my plate recently and haven't had time to continue the K2001 repair as fast as I would have liked - and I really want to add a functional 7.5 digit meter to my bench. I am extremely appreciative for the help and how specific you are being with your experience of what you have had to replace so far along with component identification associated with marked board identification - you're saving me an unknown, but presumably significant amount of now avoidable (thanks to you) duplication of effort. Thank you for those pictures as well.I need to be a better contributor here. I can at least get some of the videos up for others to have the information from my initial diagnostics.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: March 23, 2025, 04:30:56 am
content: Oh hey, Cyclotron, question for you. How did you derive the year of manufacture? I know HP/Agilent/Keysight codes that into the serial numbers, does Keithley do something similar or is it on a board somewhere?

author: Cyclotron
author_rank: Unknown
timestamp: March 23, 2025, 01:34:05 pm
content: Quote from: neverendingstudent on March 23, 2025, 04:30:56 amChip and component makers will often put a date code on the chips/parts. There are more than one date code method but a popular one is. YYWW or year and week. So you may find chips with codes like 0642 and that is the forty second of 2006. After looking around and finding several you can assume the board was built at some point after the chip. I believe you'll find such a code on your power inlet filter.

author: Cyclotron
author_rank: Unknown
timestamp: March 30, 2025, 01:49:21 am
content: Ok, I've got my "unit A" sorted and passing all internal tests. my replacement of U310 wasn't as proper as I had thought. I somehow shorted an -15v to a mid-board circuit to U300 pin 6. Also the damage to u310 seems to have popped U316 which seems logical given their relationship to each other.I also replaced U323 and U317 but in hindsight I'm not sure they were bad.This unit was 400 USD. With parts I probably have 410 in it. Bodge wires/repair photo of damaged area attached. I had gotten frustrated and this isn't my best work but I decided I'd leave it for now till I get the other one running. I also recapped Unit A and thoroughly cleaned the boards before reassembly.Unit B has issues with the 200ua and 20ma AMP range and several 40x issues. I think something in the power supply is impacting the 40xs. I may pursue some other repairs before going back to that unit.Cheers!

author: Cyclotron
author_rank: Unknown
timestamp: April 10, 2025, 06:09:13 pm
content: Ok, the last part on unit B was a U441 for Q512 that my dumbass shorted. Luckily I found a replacement. The short also took out a couple OpAmps on the AMP IN Rail as well as Q507-509.Anyway, all sorted and the twins are up and running. I posted over in the TEA thread an image of them both reading 1 Volt solid from my Valhalla 2701C.It really was through the amazing posts I've read through on this forum and xDevs that I was able to understand some of the workings. It was also nice that I had gotten one working when I needed to sort the one I busted.If you get back to your efforts, I look forward to your results and anything I can do to help you get through it. If you're not interested in pursuing it, I'd be interested in the unit.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: April 10, 2025, 06:32:11 pm
content: Though I've had a bunch of stuff come up and delay the Keithley repair since I made this post, I did actually get parts ordered last night, both for this and for a 34401a I've had in the queue. It will be a bit before they arrive but I'm looking forward to finally getting components replaced and finding out if I have a working unit or if I'll be tracing down other component failures for a rinse-and-repeat.Your posts here have been just as invaluable to me as the referenced other posts and XDevs have been to you, so thank you again, especially since we got the same -M model with the same failure from the same source!

author: Cyclotron
author_rank: Unknown
timestamp: April 10, 2025, 06:35:22 pm
content: Take it easy on it, I ham fisted one and suffered the consequences. The one blown chip is likely 99% of the problems. There may be one or two others but yours appears to be lightly damaged compared to both of mine so I'm optimistic yours will be easier. I've been plenty wrong, plenty of other times though.

author: neverendingstudent
author_rank: Regular Contributor
timestamp: April 18, 2025, 05:33:57 pm
content: Ok, some of my parts arrived. Kind of unhappy with Newark about this. I had ordered 30 Vishay DG411DY-E3 switches (I figure there are more broken K2001 units always on the market and if I'm getting a part once may as well keep some stock of it) and they sent me 17. I called them, they assured me it was just an issue of what was in stock at the time (even though they showed it as more than that many in stock when I ordered) and that they would absolutely ship out the remainder of my order as soon as more came in. So far no problem, right?A few days later I get an email from them saying they've canceled the rest of my order. The part is now listed for 6x the price (from 37 cents to $2) and went from a minimum order of 1 to a minimum order of... 2K. I call them up, explain how they had assured me they absolutely would get the rest of my order out, that it was just delayed, and in polite customer service language they told me to screw off and if I wanted more I could order a reel for $8K USD. Not happy with them.I do get that they are being squeezed under external pressures from the tariff chaos, so I can't be *as* upset at them compared to if this were in normal times, but still, not cool.

author: 晓看风云
author_rank: Contributor
timestamp: April 19, 2025, 04:07:28 pm
content: If someone is watching, I think I also need to seek help. I have a Keithley 2000 with a 6.5, which has no errors. Yes, I have tested it and everything passed. However, when I tested the two-wire and four wire resistors, there was no response in automatic mode and it displayed 'over'. When manually switching the gear range between 100 ohms and 1M ohms, the resistance value can be recognized normally, but it cannot be measured at 10M and 100M. I have tested the current source and all other gears are normal, except for the 10M and 100M gears where the output current is 71ua and the output voltage is 6.9V. I think this should be normal. I followed the circuit diagram downloaded from 38hot to exclude the 10M and 100M lines, but it had no effect and I did not find any suspicious areas. I need everyone's advice! c'mon!

author: neverendingstudent
author_rank: Regular Contributor
timestamp: April 19, 2025, 04:27:11 pm
content: Quote from: 晓看风云 on April 19, 2025, 04:07:28 pmJust to make sure your 'which has no errors' statement is fully understood - do you mean it shows no errors when initially powered on, or have you done the manual full self-test option and that passes with no errors? I ask just to make sure there is no misunderstanding.

author: 晓看风云
author_rank: Contributor
timestamp: April 19, 2025, 07:13:24 pm
content: Just to make sure your 'which has no errors' statement is fully understood - do you mean it shows no errors when initially powered on, or have you done the manual full self-test option and that passes with no errors? I ask just to make sure there is no misunderstanding.Yes, I ran the automated test without any errors. Do you know the difference between this and manual testing? Perhaps I should try more tests, such as 100V DC voltage, such as manual testing... I will keep updating later and provide as much information as possible