hybridfree/eevblog-posts huggingface dataset:
Keithley 182-M NVM - offset with excessive noise - Page 1
Forum section: electronics / repair

author: MiDi
author_rank: Frequent Contributor
timestamp: June 20, 2022, 09:30:38 pm
content: By accident the front panel connector was hit and unit suddenly showed large offset in conjuction with excessive noise.Nothing can return instrument to normal behaviour (range change, turn off, long time waiting, w/ or w/o battery, etc.), except tapping the connector multiple times until offset is gone.I optically checked the guts for loose connectors, bad solder joints, suspicious parts, but could not find anything obvious (unit is already recapped).Any ideas what could cause the issue or where to look at?To give a better impression of the issue video and pictures attached:

author: Dr. Frank
author_rank: Super Contributor
timestamp: June 20, 2022, 10:25:24 pm
content: As the connector (with plug attached?) got a hit, the most probable defect would be a break inside this connector.. undetected so far, may be hard to detect at all.Check both input leads for continuityFrank

author: dietert1
author_rank: Super Contributor
timestamp: June 20, 2022, 10:32:27 pm
content: 20 uV could be thermal EMF. I would unplug and replug the input cable 10 or 20 times in an attempt to remove oxide from the contacts. Or use a chemical like vinagre to clean the copper surfaces. You can test your method on another copper part, to see whether it gets shiny.By the way these connectors exist in many variants (with different contact materials). Not all of them are low thermal EMF. Also there should be a rubber piece with two holes for the wires to fill air space inside the connector.Regards, Dieter

author: HighVoltage
author_rank: Super Contributor
timestamp: June 21, 2022, 09:00:51 am
content: Quote from: Dr. Frank on June 20, 2022, 10:25:24 pmVery likely so,I would short the input connectors at the PCB input to see if the offset and noise is gone, to quickly confirm that it is a problem with the connections in the connector.

author: MiDi
author_rank: Frequent Contributor
timestamp: June 26, 2022, 12:51:31 am
content: Guess what, both crimps on the input resistor are badResistance between both resistor legs and lugs varied a lot if touched and the lugs can be twisted slightly.Now specimen has to live without crimps 🦐After repair everything seems fine, no sensitivity to vibration spotted anymore, noise and values are as expected.21nVacrms/240nVpp @1PLC all filters off over 29h (1.4 Mio. datapoints)2.6nVacrms/20nVpp @100PLC equivalent (means of 100rdgs each w/o overlapping @1PLC - same dataset)

author: HighVoltage
author_rank: Super Contributor
timestamp: June 26, 2022, 07:57:53 am
content: Nice repair, what an interesting failure.One solution would have been to re-crimp the lugs.But you were really lucky that the legs were long enough to be mounted like this.
Keithley 182 VFD High Voltage Repair - Page 1
Forum section: electronics / repair

author: gamalot
author_rank: Super Contributor
timestamp: September 30, 2020, 04:34:06 am
content: About two years ago, I bought a damaged Keithley 182 on eBay (for $300 plus shipping). After inspection, I found that the high-voltage power module of the VFD was damaged. Since I couldn't find a suitable replacement, I decided to make one myself using the components I already had on hand.It is a typical application of 34063. The values of all the components in the schematic diagram are consistent with those actually used. The 8V input comes from the tantalum capacitor C544 before the regulator U514, and the 55V output is connected to another capacitor C554.I did not remove the original high voltage power module from the PCB, but cut off its output pins (see picture).A small aluminum enclosure is used to suppress EMI, and it is connected to the tab of the regulator U514. I used 3M Command strips to fix it in place.
Keithley 197 no oscillator ? - Page 1
Forum section: electronics / repair

author: MathWizard
author_rank: Super Contributor
timestamp: May 24, 2024, 04:53:54 pm
content: I had a problem with the LCD zebra strip for ages, and this winter I put a paper spacer in to help, and it did. And then over the past week or 2, the display would cut out, usually after a while, as if the DMM had a sleep mode. I didn't try pushing on the srceen, I just turned the DMM off/on, and sometimes only part of the screen would do anything, and then off/on again might make it work. Until a while later, it would go fully blank again.So I was planning to upgrade the LCD display anyways, to something with a backlight, and I have some dot-matrix type display, that is almost the same size and the LCD dis. So I soldered up a bunch of wires to see how all that will work.But I see the display problem is not just a bad zebra strip connection.The main DMM voltage rails are working, but for the LCD board, I have no 82kHz clock. It's supposed to come from another chip, and ultimately from the main Osc Y101, connected to the MC146805E2 microcontroller. Looking at the Osc in/out pins , there's no osc happening. Ages ago I replaced the 10Meg carbon resistor with a nice 1% one, so it's not the resistor.The MCU has Vdd, it's reset is high for normal running. But I guess without the osc, not much would be running.So besides reflowing the solder joints, or trying some 8-12MHz crystals, or I could feed a 10Mhz signal in from my signal gen, and see if that gets it's going.What else might this be ? The main rails are all nicely in spec, and I recapped it 2 winters ago.U124 is the MC146805, it and the crystal are on page 69https://www.tek.com/en/manual/keithley-model-197-autoranging-microvolt-dmm-instruction-manual-rev

author: coromonadalix
author_rank: Super Contributor
timestamp: May 24, 2024, 05:44:35 pm
content: small schematic from xdevsFind more on X'devs ... free registrationand you have display substitutes with oled or othershttps://www.eevblog.com/forum/testgear/modding-a-keithley-197/https://www.eevblog.com/forum/projects/keithley-197-led-display-hack/

author: MathWizard
author_rank: Super Contributor
timestamp: May 24, 2024, 09:22:53 pm
content: Ok it was just the quartz crystal that failed. It was ~3.3MHz, and I had a 3.6MHz there, and it worked right away. Thank god it wasn't a rare chip.Yeah I've been looking at a few upgrade threads on these. I might have tried a VFD display I toyed with, but it uses too much current. I have some common display from an Arduino kit, for now that's what I'll try, but I want something bigger. I should load test the 5V rail, I wouldn't mind a big red LED display, like from old style alarm clocks, or some other Keithley meters., even if I make it myself with single LED's
keithley 197 reading stopped updating. (& ghost gpib signals?)  Suggestions? - Page 1
Forum section: electronics / repair

author: cnt
author_rank: Contributor
timestamp: December 06, 2021, 02:57:48 am
content: I recently got a very cheap 197 and i "fixed" the switches with some deoxit and replaced the cut off power cord and all was well. I left it on measuring 6v supply last night and after being powered up for 24-36 hours i noticed the display stopped updating. changing the mode to ohms yielded one update then it stopped, same changing it back to volts. A power cycle from the front panel switch seems to have fixed it, but I'm wondering what happened and how to troubleshoot if the problem comes back.I'm guessing it lost a clock somewhere, the manual mentions half a dozen clocks involved with the ADC.UPDATE: Now its regularly turning on "RMT" and going into cal mode with the "C" on. And occasionally flashing "out", or "out" gets stuck on. "out" is whats displayed when you try to save calibration without the switch in the back enabling cal mode. Seems like I've got a ghost in my GPIB board.

author: cnt
author_rank: Contributor
timestamp: December 07, 2021, 06:35:16 am
content: Well looks like I found the problem, or at least _A_ problem.the GPIB board's got its own transformer tap with a bridge rectifier, 2200uF cap, and a 7805. I was probing voltages and all looked good, but I thought I'd take a look with the scope on the 5V rail. I got this weird trace doubling about 100mv tall and near the cutoff frequency of my scope (100mhz), which I later traced to my probing and I think some EMF from my chinese florescent desk lamp light bulb. But, while probing I accidentally coughed and bumped something and got this on the 5v rail:I can't make it happen at will but it seems some combination of jiggling the filter cap and or breathing too heavily will trigger it.Probing it in circuit (its relay isolated when un powered) shows more than half the microfarads fell out at some point and I suspect there may be a crusty connection somewhere internal to the cap too. Figures the ONE Richey cap is bad and the rest are nichicon. I guess 35 years is a good run.16v 2200uF cap these days are almost all much smaller apparently. Searching by lead spacing and diameter and height and maximum expected life yielded a 25V 105C (up from 85) so hopefully this new cap will last another 35 years.

author: trobbins
author_rank: Frequent Contributor
timestamp: December 07, 2021, 10:13:03 pm
content: Yeh, I traced a noisy measurement value to the filter cap on the GPIB accessory board - easy to identify by disconnecting that board. Still got some last digit or two noise, but for the moment that's acceptable.
Keithley 197 slowly converging to Amps measurement - Page 1
Forum section: electronics / repair

author: AutomaticInvest_4
author_rank: Newbie
timestamp: January 25, 2025, 09:24:23 pm
content: Hello,I have a Keithley 197 that has good Volts, Ohms measurements in a few seconds but for Amps (including the 10 Amps unfused) is taking a few 2-3 minutes until it reaches correct measurementFor example if I have a circuit that has a current of 49.2 mAIt starts with about 48.2 mA, slowly converging..after about 1 minute it reaches 48.9 mA after another minute 49.1 and the final value after about 3 minutes is 49.2I have cleaned the switches with WD-40 Specialist cleaner,a similar issue is in the videoat 45:20Did anyone have similar issue ?regards

author: Kleinstein
author_rank: Super Contributor
timestamp: January 25, 2025, 10:47:46 pm
content: Drift in the high current ranges can be due to a thermal problem. With the high current the shunt heats up and this can change the gain.This effect can happen at the DMM, but also at the current source that provides the test current. How the the actual current measured or provided ?

author: AutomaticInvest_4
author_rank: Newbie
timestamp: January 26, 2025, 04:44:12 pm
content: A circuit on the breadboard, input of breadboard is 5Vwire from + of breadboard to - of breadboard, and there is a resistance of 100 Ohms in betweenThe circuit is disconnected after resistance and the test leads of the multimeter are placed in seriesSo standard measurement..Which component of the multimeter do you think is affected by thermal problem ?

author: Kleinstein
author_rank: Super Contributor
timestamp: January 26, 2025, 04:52:11 pm
content: From the description I would clearly blame heating of the 100 Ohm resistor. With 5 V and 50 mA this are 250 mW, which is quite a lot.For a test one could have the meter an resistor in series to measure the current, but forst for a while shorten out the meter. So the current could still heat the resistor, but initially not the meter. Removing the short across the meter will than tell if the drift is more with the meter or with the resistor.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 26, 2025, 05:15:49 pm
content: And a breadbord don't give an accurate precision connection.

author: tooki
author_rank: Super Contributor
timestamp: January 26, 2025, 05:36:44 pm
content: Quote from: Vovk_Z on January 26, 2025, 05:15:49 pmDoesn't matter for a current measurement.

author: AutomaticInvest_4
author_rank: Newbie
timestamp: January 26, 2025, 08:50:31 pm
content: It seems the breadboard is one of the reasons, since I measure now directly at the power supply's pins that are inserted into breadboard, with resistor between the + pin and red test lead and with black test lead to - pinSo without the breadboard.. and now it converges faster in just 20-30 seconds

author: tooki
author_rank: Super Contributor
timestamp: January 26, 2025, 10:15:17 pm
content: Quote from: AutomaticInvest_4 on January 26, 2025, 08:50:31 pmIf it is indeed a thermal effect, which is very plausible, then it’s possible the breadboard’s contact strips were simply acting as heatsinks.
Keithley 199 behaves strangely in resistance mode - Page 1
Forum section: electronics / repair

author: Hrvoje_CRO
author_rank: Regular Contributor
timestamp: April 12, 2019, 05:27:23 pm
content: Hello,Well i have the following issues with my 199.When in OHM mode i got under different ranges different readings. For example i've measured 10k resistor and sometimes it measures as it should, but if i measure it again it shows 23k. Also when i switch on autorange function under resistance mode, it does not works as it should. Display toggles between K and M letters when measuring 100k resistor. Lower resistance values are measured fine and accurate when autorange enabled, but if i manually change ranges it shows different values under different ranges...So what could be the cause of the problem? All other functions works fine and with good accuracy.Thank you in advance!Regards,Hrvoje

author: Kleinstein
author_rank: Super Contributor
timestamp: April 12, 2019, 08:12:09 pm
content: The wrong reading in some ranges suggest a defect that mainly effects some ranges. A service manual for this DMM is available. The different ranges use different paths. If it is know which ranges work and which don't should give a good idea where the defect is.Not working right in some ranges can also upset the auto-ranging.

author: srb1954
author_rank: Super Contributor
timestamp: April 20, 2020, 08:29:20 am
content: I also had a problem with erratic readings with my Keithley 199. Eventually it stopped giving any sort of sensible reading on some of the voltage ranges.I tracked the fault down to a bad COTO reed relay on the range switching. I had to search all over the world to find a replacement relay as it seemed to be a custom or obsolete version that wasn't listed in the current COTO catalog. Replacing the relay fixed the problems with erratic voltage readings although the meter still does go berserk sometimes when powering up.I don't know if a bad relay would affect the resistance ranges but I would check the contact resistance on all relays on the front end just to be sure.

author: kawal
author_rank: Frequent Contributor
timestamp: April 27, 2020, 01:08:11 pm
content: From what you describing the issue could be internal to meter or interference coming from noisy environment (switching power supplies, Leds...).Try turning off all LEDs around the area and repeat or use shielded cable to make measurement. I Have a 196 which uses inductors on input to filter out common mode interference. This is common and very efficient , making readings very stable as compared to 192 that did not have inductors on input.Same approach is used in many other meters like HP 3457A .......From the 199 schematichttps://doc.xdevs.com/docs/Keithley/199/199_901_01D.pdfit looks like the input has no inductor . The other issue is age of the meter , Check power supply for dried out caps. I had one 195 that had dried out caps and would make the meter unstable. The common mode inductor will not hurt.Also had one meter with dirty front/back switch which was causing errors on readings . Cleaning the switch helped that meter.
Keithley 2000, 2700, 2790 AC volts Noise - Page 1
Forum section: electronics / repair

author: TizianoHV
author_rank: Regular Contributor
timestamp: December 13, 2023, 04:12:53 pm
content: Hi,a few weeks ago, I was testing some current transducers and I needed to measure accurately (0.1%) low AC voltages (from 1mVrms up to 1Vrms @50Hz).As first thing I compared a few of my meters (Agilent 34970A, Keithley 2790, aneng AN8009) to find the best ones.To get precise low AC volts I feed stable 100mVrms@50Hz into my trafo decade (with 100ppm resolution).An8009 was spot-on down to 200uV (as Dave showed in the AN8008 review).As we know Ag34970A and K2790 use a TRMS chip so they can't measure accurately below 1% or 2% of range. Anyway, agilent performed better but I noticed (confirmed) an issue with K2790: in the 100mV and 10V ranges it was showing a low frequency oscillation (Img. 2) with a period of 1 - 2 minutes and an amplitude of 0.05% of range (regardless of the input voltage). When selecting the 10V range it clicks a relay, so it probably has the same gain (and noise) as the 100mV range.When a short is applied it shows the usual ofset (80uV) and no noise is detectable (+- a few microvolts).I've recently repaired the DCV and ohms of this meter (I killed it with inductive kickback) but I suspect it's not related to that since it showed the some noise even before.Can, someone with a Keithley 2000, 2700, 2790, log a few minutes while measuring a stable 100mV source with the meter in the 10V range (since 1mV in the 100mV range is a bit trickier to generate)?Thankyou!

author: TizianoHV
author_rank: Regular Contributor
timestamp: December 14, 2023, 07:49:22 am
content: *If you can't record data with a PC you can use the internal memory of the multimeter and its statistics. You set 10VAC SLOW, feed 100mVrms, store 150 readings in its internal memory (It will take 1 or 2 minutes) and then recall Standard deviation and Peak to Peak values.If it's as bad as mine you should get a std of 1.4mV and 5mVpkpk.(To verify if the 100mVac source is stable enough repeat the same measurement with the multimeter in the 100mV or 1V range, std should stay below 100uV)
Keithley 2000 400 and 600 error codes - Page 1
Forum section: electronics / repair

author: brokenslinky
author_rank: Newbie
timestamp: October 12, 2021, 03:00:06 pm
content: Have a 2000 that initially had a bunch of error codes in the 100s, 200s, 300s, 400s, 500s and 600s. Was able to eliminate all but 400.2, 401.2, 402.2, 403.2 and 601.2 by replacing all of the electrolytic capacitors and voltage regulators. The most likely culprits were the capacitors and traces around the -15V power side. They had leaked and were starting to cause some board damage.A lot of the remaining errors seem to involve C105. Wondering if there's any other components I should be looking at that seem to be the common causes for those errors?
Keithley 2000 Current Input Back Half - Page 1
Forum section: electronics / repair

author: brokenslinky
author_rank: Newbie
timestamp: September 22, 2021, 06:42:20 pm
content: Bought a sort of working Keithley 2000 and in the process of getting it 100% functional. It was missing the current input connector/fuse holder. Was able to source and buy what I thought would be the entire part (2001-312D). Turns out it is just the white front half of the fuse holder. Anyone know the part number for the back half of the fuse holder and/or where I might be able to source one?

author: chekhov
author_rank: Regular Contributor
timestamp: September 22, 2021, 07:21:34 pm
content: What do you mean by "back part" ? Back part is essentially the front panel. And if wire with spring is mentioned, there will be nothing you can buy IMO - only DIY / modify smth else.However, maybe I'm the only one who is confused by this question.

author: brokenslinky
author_rank: Newbie
timestamp: September 23, 2021, 12:22:59 pm
content: Quote from: chekhov on September 22, 2021, 07:21:34 pmThere must be something more than just a spring and wire? The white front portion has two 1/4 turn slots that mate with something on the backside. Whatever the mating portion is, is missing too.

author: chekhov
author_rank: Regular Contributor
timestamp: September 23, 2021, 01:13:53 pm
content: I think photo of the back of your front panel will tell more - I cannot imagine anything rather just it's broken (missing), comparing to how it should look like (there are plenty of photos of these front panels).

author: brokenslinky
author_rank: Newbie
timestamp: September 23, 2021, 02:25:55 pm
content: The back looks like others I have found online but haven't found a photo of what the inside looks like. I'm assuming there's supposed to be 2 little tabs molded into the front panel that have been snapped off by someone being overzealous.

author: Per Hansson
author_rank: Unknown
timestamp: September 23, 2021, 02:37:22 pm
content: Here is a picture of mine, yes there are tabs in the front panels plastic that the part you bought "screw into"

author: chekhov
author_rank: Regular Contributor
timestamp: September 23, 2021, 03:03:45 pm
content: Quote from: brokenslinky on September 23, 2021, 02:25:55 pmSuper, now we know that this is just a common design issue with this and newer Keithley DMMs - yep these two tabs are broken and that's why fuse holder was missing.'Just' need to restore them somehow. My option would be to cut place where they were supposed to be and put new ones (plate made maybe from FR4, or maybe smth metal). Plate - better to say circular ring with these tabs inside so you just put it on the back, maybe glue a bit, but it then really holds because of the spring tension.Don't remember seeing good solution on forum, but maybe it's already there.
Keithley 2000, preventive maintenance or don't touch it till it fails? - Page 1
Forum section: electronics / repair

author: Zorc
author_rank: Contributor
timestamp: October 26, 2020, 08:27:08 am
content: I've recently got a Keithley 2000 from the year 2000 with its last calibration 2 years ago and seems perfectly fine as far as I can check at the moment...Popped the hood, noticed nothing weird.However it has a few electrolytic capacitors from Nichicon (datecode also year 2000) which look perfectly fine visually (no bulging, leaking or whatsoever).What is recommended, leave everything as it is and use it till it fails or should I do some preventive maintenance on it?The outside could use some cleaning for sureIs it wise to replace those caps at this time or not? I've replaced failed caps before on other devices but never on a old test test equipment.Any other recommendations are welcome as well!

author: z01z
author_rank: Regular Contributor
timestamp: October 26, 2020, 09:18:08 am
content: There are a lot of topics about those caps leaking in Keithley 200x meters.It is your time and money, but once that goo is out, it'll eat PCB and components alike, and it'll be much more effort to repair the damage than a simple component swap.

author: coromonadalix
author_rank: Super Contributor
timestamp: October 26, 2020, 09:35:32 am
content: If you have good soldering skills do a preventive maintenance, but be careful its a precision instrument, antistatic counter measures should be applied, you have to use the right equipment for desoldering ... clean the board for solder residues when the new caps are in place etc ... you get the idea.

author: Zorc
author_rank: Contributor
timestamp: October 26, 2020, 11:53:14 am
content: Yeah, being it a precision instrument is kinda my dilemma.Not touching it seems the best if not needed even while I'm sure I could swap them out just fine...I've also heard bad things about leaking caps in Keithleys causing damage, no idea for which production years this happens though.However, most caps I've replaced in other electronics didn't really leak goo or maybe just a tiny drop not causing pcb damage.So I'm not sure if we are talking about a few isolated cases or that there is a significant risk for things to go bad.Would it be safe enough if I keep an eye on them to check for bulging/leaking signs?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 26, 2020, 05:29:56 pm
content: Sure

author: voltsandjolts
author_rank: Unknown
timestamp: October 26, 2020, 05:45:00 pm
content: Yeh, replace the caps. Take your time and you'll do fine.https://www.eevblog.com/forum/repair/2x-keithley-2000-repair-log/

author: bdunham7
author_rank: Super Contributor
timestamp: October 26, 2020, 06:04:41 pm
content: What series are the capacitors? Just post closeup photos if you can't decipher them.It looks like an easy job, just make sure you get top-quality replacements.
Keithley 2000 - TF-224 replacement - Page 1
Forum section: electronics / repair

author: a.pawlowski
author_rank: Newbie
timestamp: October 23, 2021, 02:29:08 am
content: Hi everyone! First post here.So long story short I've bought a K2000 on eBay for a nice price.It was listed "for parts only", an upon arriving I've discovered that C146 exploded, corroding a bunch of traces and the 7805.I've ordered a full set of 125℃ replacement caps from Mouser, and after fixing the traces and replacing the caps the unit sprung back to life.BUT!When I was assembling it back my dumb ass has broken off R117, Keithley part num TF-224.Description from the repair manual is RES NET, 100K, 9.9M, METAL FILM.I was unable to find an original replacement, but I have found HVD5-B10M-050-05.It has the same values, and seems to have decent accuracy and stability specs, so I ordered one from Mouser.The only issue is that it has a completely different footprint. Both TF-224 and HVD5-B10M-050-05 are 2.54mm pitch components, but HVD5 is 2x longer.Basically I need to create an adapter PCB. Designing one is straightforward, but I do worry about losing accuracy or stability, and because I have no expertise in these things, I'd really appreciate your help.So my question is, is your-run-of-the-mill PCBWay PCB will do? Or do I need some pure copper, gold plated thing?Also what kind of pin headers should I use? Also gold plated?And in general, I'd appreciate any tips you can give me on this journey.I do understand that the DMM will require recalibration after this surgery, but it was overdue for one anyway.Thanks in advance!

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2021, 07:49:37 am
content: The points to care about are leakage currents and possible high voltage discharge. There is no need to wory about thermal EMF. Gold plating would be mainly for better solderability, so not really needed as a board (or needed at all) would be used fresh.For a one of, i would consider some air wiring for the resistor network. Air is a reasonable good isolator and thus mainly need to find a place to fix the network mechanically. AFAIK the network is only used for the DC part and capacitance is thus not so critical.

author: a.pawlowski
author_rank: Newbie
timestamp: October 23, 2021, 02:43:08 pm
content: Thank you for the info!Well if thermal EMF is not a problem and I can use standard materials - I'll try to etch a tiny PCB on my CNC so I don't have to wait (and pay) for manufacturing.I'll update this thread if I'm successful in case anyone will face the same issue with their unit.
Keithley 2001 Calibration Failure Error #363 200uA Gain out of Spec - Page 1
Forum section: electronics / repair

author: mr.nicholaus
author_rank: Newbie
timestamp: April 29, 2019, 04:41:42 pm
content: Greetings,I am searching here in an attempt to remedy a failure I get when performing the comprehensive low level calibration.I have already replaced the Electrolytic Capacitors and the self test passes with no errors. I complete all of the steps of the calibrations once I enter the calibration due date. I get error +440 " Calibration not complete. Once I query the errors with SYST:ERR?I get 200uA gain OOT +363. I have about 10 of these unit is house. I have only gotten 2 to pass the low level calibration successfully.The one the passes has B17/A02. The two the fail so far have B16/A02. I think the issue is in the firmware.I had planned to purchase blank AT27C040-90PU-ND, copy the firmware from my working unit and install in the other unit. BUT I think this will not wWe have a DATA man M-pro that will allow for copying the firmware, will I still need to perform the calibration after updating the firmware?Any and all help would be appreciated

author: ddcc
author_rank: Regular Contributor
timestamp: May 02, 2019, 09:27:10 pm
content: Funny, I had the same problem with a 2001M:https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg2189003/#msg2189003Don't think the problem is in firmware, I upgraded from B16 to B17 and it made no difference. But I wasn't performing low-level calibration, only the regular comprehensive calibration. What worked for me was replacing some of the analog switches, and then making sure to recalibrate in 4W mode.

author: CM
author_rank: Contributor
timestamp: June 29, 2024, 12:00:27 pm
content: I have a Keithley 2001 firmware B06 that threw a 363 error on the open circuit section of the comprehensive calibration. Replacing the analog switches U317, U320 and U323 resolved that issue. Thank you ddcc for that great slouthing to figure out that one! Replacing the LM399 precision voltage reference also breathed new life into this unit! I am going to proceed with replacing the other 6 analog switches to see if I can drive down the ppm errors I am seeing on the resistance measurements.
Keithley 2001 - First Repair Attempt - Page 1
Forum section: electronics / repair

author: Tim51
author_rank: Contributor
timestamp: August 28, 2022, 01:20:22 am
content: Hi Guys,I have a first time Keithley 2001 repair. I'm following the repair process outlined here on xdevshttps://xdevs.com/fix/kei2001/.I have not powered on the board. Only visual inspection and continuity testing.The current primary fault suspect is C117 - This is an electrolytic capacitor on the secondary side of the main transformer and a part of the negative bootstrap rail. It has undergone a catastrophic failure which has resulted in a PCB charring and melted traces. See pictures below. I've continuity tested the entire area and am fairly confident I've identified the broken traces, see schematic mark up below.My question to you all:How should I handle this damage/repair?Here is what I am thinking:Clean all the electrolyte spill with IPA.Remove built up charring to smooth out the surface a little. (This is questionable, comments welcome)Repair the traces with jumper wires.Replace the components then verify the repair connections with a continuity test.Confirm all the power rails are not shorted to ground or low resistance.Attempt a power up.[ Attachment Invalid Or Does Not Exist ]

author: Tim51
author_rank: Contributor
timestamp: August 28, 2022, 01:33:07 am
content: Having issues loading more than 1 picture at a time.close_up.png(2752 kB. 1432x1058 - viewed 178 times.)

author: Tim51
author_rank: Contributor
timestamp: August 28, 2022, 01:35:57 am
content: schematic_review.png(2487.82 kB. 1767x1170 - viewed 165 times.)

author: picburner
author_rank: Frequent Contributor
timestamp: August 28, 2022, 05:19:48 am
content: Don't just replace C117 only, all other electrolytic capacitors will probably be in the same condition, so you'll only do the board cleaning job once.Regarding washing the pcb, the ipa alone may not be enough, you should do a pre-wash with de-mineralized water.If you need an explanation of how the power supply section of the instrument works, you can find itherein a video by Ian Johnston, in the big brother k2002 repair tread.

author: Tim51
author_rank: Contributor
timestamp: August 28, 2022, 05:44:56 am
content: Absolutely, I've already removed all electrolytics and have replacements. Don't want to take any changes after this first repair. Hoping to have this unit running for years to come if this attempt is successful.Thanks for the pointer. I'll certainly watch it. Been really enjoying Ian Johnston's repairs.

author: IanJ
author_rank: Unknown
timestamp: August 28, 2022, 06:40:35 am
content: Keep us posted on your progress. Always great to follow along.Ian.

author: eurgenca
author_rank: Regular Contributor
timestamp: August 28, 2022, 08:56:16 pm
content: Isn't cr513 broken?

author: Tim51
author_rank: Contributor
timestamp: August 28, 2022, 11:46:04 pm
content: Yes, it is broken as well. I’ve already got a replacement. My intent was to go over the major issue which was the capacitor failure.
Keithley 2001 multimeter not completing boot up. - Page 1
Forum section: electronics / repair

author: dominitech
author_rank: Contributor
timestamp: May 11, 2020, 09:25:01 pm
content: I have a Keithley 2001 DMM that has been dropped during transit after getting it calibrated and now the unit will not complete the boot up cycle. There is fan spin on the rear of the unit so the power supply seems to work but nothing on the display. After a quick peak inside nothing seems out of place or even busted. Any tips on what components are susceptible to hard drops or where to check first would be appreciated(Already checked and reseated all cable connections).

author: coromonadalix
author_rank: Super Contributor
timestamp: May 12, 2020, 12:52:41 am
content: Any component whos physically big or massive could create problems, cracks in pcb ? connectors broken or have loosen up ?

author: TiN
author_rank: Super Contributor
timestamp: May 12, 2020, 01:04:54 am
content: 99.9% sure display glass is broken.

author: dominitech
author_rank: Contributor
timestamp: May 12, 2020, 03:20:24 am
content: Most of the damage appears to be on the rear. The aluminum frame is very warped on the back but thanks, I will check the display next.

author: dominitech
author_rank: Contributor
timestamp: May 12, 2020, 03:30:28 am
content: Quote from: TiN on May 12, 2020, 01:04:54 amThe display was indeed definitely damaged! Thanks again!

author: coromonadalix
author_rank: Super Contributor
timestamp: May 12, 2020, 10:41:50 am
content: Oh damn

author: dominitech
author_rank: Contributor
timestamp: June 05, 2020, 10:18:35 pm
content: Do you suppose I can use a display from a Keithley 2000? The part numbers slightly differ from each other and Keithley will not sell me a new one.

author: picburner
author_rank: Frequent Contributor
timestamp: June 06, 2020, 04:19:43 am
content: The Keithley 2000 vfd is completely different (1 row only). The Keithley 7001 vfd is the ideal donor candidate.

author: TiN
author_rank: Super Contributor
timestamp: June 06, 2020, 04:40:31 am
content: Beware two different types too...
Keithley 2001 repair and price for non working  - Page 1
Forum section: electronics / repair

author: Jester
author_rank: Frequent Contributor
timestamp: January 15, 2022, 04:20:49 pm
content: I see there is an extensive guide for the 2001.Are the usually repairable by someone with good troubleshooting skills, or are there too many unobtainable parts?What is a fair price for a non working unit that is cosmetically fair to good?Thanks J

author: vsmith
author_rank: Regular Contributor
timestamp: January 16, 2022, 10:56:17 am
content: Hi Jester, to answer your question, I am presently working on a damaged 2001. I bought it for about 250, as "Parts or Repair) based on photos that showed a decent display and signs that the Digital section was alive. I have a thread on this Forum describing my adventures so far, I am finding it pretty challenging, and I have years of experience with test equipment, but am mostly self taught. As you say, other Forum members have done an excellent job explaining and documenting how the various sections work, and there are several threads presenting repair cases that are good informational readings. At least there are a pretty good set of manuals (thanks to the US Govt buying these meters). Search out TiN's thread, from there you can explore what's available. As far as parts, as I say, mine has a working digital board so I cant speakn to that aspect, but the analog bboard has pretty common parts, although many are factory selected. There are some to-92 JFETs that are kind of hard to find. Good luck with the one you have your eye on, I think that theyt are worth some effort to repair, all in all.
Keithley 2001 with burned analog board. - Page 1
Forum section: electronics / repair

author: overvoltage
author_rank: Newbie
timestamp: October 23, 2021, 11:48:43 am
content: Hello everyone,I recently got this Keithley 2001 that would not power on.I checked the fuse and found it was blown so went inside to investigate.The fault was easy to spot as it had burned the PCB right below the power input jack.Two SMD resistors (R123 and R250) got so hot they charred through the board. (Shematics and Pictures attached)Obviously I want to save the analog board and thankfully this is the least densely populated area.R100 reads open so the thermal fuse in it probably got triggerd, was this heat transfered from R123 and R250 or is R100 involved in the fault?I suspect VR100 went short and overloaded these resistors, Q528, Q101, R102 and R103 seem fine so I doubt VR101 was directly involved.The transformer thankfully appears unaffected so it does not seem like the fault lays on the secondary side, that inspires some hope.How do I clean this board properly to check the traces?Any insight into the cause of this disaster?What is the appropriate cause of action? Desolder all components in the general area?PS: I know all Electrolytics in this meter need replacement but I dont want to invest into a new set of caps until I can power it on to check the precision analog section.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2021, 12:26:36 pm
content: This looks really burnt. The chard black part of the PCB may be no longer isolating. So it may may need something like a dril or dremel to "clean" / cut away the bad parts. So get to the area one would need to desolder a few parts, like the MOSFET, even if not brunt.For the cause of the desater I see 3 possible scenarios:1) the automatic 110/230 V dedection did not work and did not switch the relays right2) a relay of the 110/230 V switching got stuck3) supply voltage was too high or maybe frequently switching on off (e.g. bad cable) to cause the switch over to failI think the 110/220 V switching by relay deserves a few extra.

author: Gyro
author_rank: Super Contributor
timestamp: October 23, 2021, 01:05:41 pm
content: What ridiculous complexity!As you're in the EU, wouldn't be simpler just to depopulate the area and hardwire the transformer for 230V mains?... or am I missing something?

author: Kleinstein
author_rank: Super Contributor
timestamp: October 23, 2021, 01:29:04 pm
content: Removing K101 and hard wire to 220 V is likely a good idea to reduce the chance for future damage. The root cause may be on the control side, or maybe a stuck relay.K100 has 2 more settings for the voltage. Likely something like 220 and 240 V. Chances are the input circuit would survive if K100 is in the "wrong" setting. So I think it should be OK to keep K100.
Keithley 2010 VFD Display issue - Page 1
Forum section: electronics / repair

author: 705jas
author_rank: Contributor
timestamp: April 24, 2023, 05:15:58 am
content: Hi AllI have replaced the VFD in my 2010 which was working just very dim and now it is very bright BUT I have one row of segments (as per picture) that is on constantly. Anyone have an idea as to what might be wrong (or what I did wrong :-))It had the jumper from the VFD to U403 already and seems ok.ThanksAllan

author: picburner
author_rank: Frequent Contributor
timestamp: April 24, 2023, 06:24:37 am
content: The jumper is not factory original, someone probably did it before you.From the photo it would appear that the visible soldering of this jumper shorted two tracks together.But question of course is: Even with weak display before replacement was this problem there or not?Check carefully with a powerful lens that there are no small bits of tin shorting tracks/pads.I see a lot of them on the pcb.
Keithley 2015 THD Scehmatics - Page 1
Forum section: electronics / repair

author: Tony_G
author_rank: Super Contributor
timestamp: December 17, 2023, 02:42:40 am
content: Hey All,I'm looking for the schematics to a Keithley 2015 THD meter so that I can replace the input FETs (I'm suffering from the input bias current issue) - I know there are topics addressing this but I'd like to see where the component is in terms of the schematic instead of just replacing Qxxx if possible.Thanks,TonyG

author: Smokey
author_rank: Super Contributor
timestamp: December 17, 2023, 03:18:38 am
content: From what I understand, the 2015 is essentially a 2000 power/meter board with the THD module.

author: bingo600
author_rank: Super Contributor
timestamp: December 17, 2023, 07:32:46 am
content: I don't see any schematic , but there's a component list/Bingo

author: bingo600
author_rank: Super Contributor
timestamp: December 17, 2023, 07:34:30 am
content: For the K2000

author: Tony_G
author_rank: Super Contributor
timestamp: December 17, 2023, 03:50:52 pm
content: Thanks Bingo & Smoky - Appreciate it.
Keithley 2100 Project Revisited! –Display Data Sheet Available? - Page 1
Forum section: electronics / repair

author: Chris56000
author_rank: Frequent Contributor
timestamp: January 26, 2020, 12:51:17 pm
content: Hi!Was it REALLY two years ago I posted about my travails with the Keithley 2100 sans rubbers & handles?!Anyway I've just won and paid for another one, this time in much nicer condition and complete with both bumper rubbers AND the handle, so I will be keeping this one!In order to help with the circuit diagram I intend to draw for it, does anybody know if there's a datasheet for the VFD available, so I can design the circuit–symbol in my SPlan for it?Chris Williams
Keithley 2100 repair help - Page 1
Forum section: electronics / repair

author: Mav_2014
author_rank: Contributor
timestamp: July 20, 2019, 01:48:13 pm
content: Hi All, I'm out with my begging bowl. Keithley 2100, errors 612, 613, 617,618,619, which I believe are related to the current source.What have I replaced, well, u305, u401, q401, q402, q311.With q311 out of play the errors are the 500na source only with errors 612, 613 and the others gone. However q311 replaced did nothing, nor q401, q402 which I assume is the current source. The craddock divider is also ok. With q311 replaced ALL of the errors are back.All the errors above were there before and changing all of the above has made no difference to them.....Help much appreciated as it's driving me round the bend! Many thanks in advance!
Keithley 2110 back lit  - Page 1
Forum section: electronics / repair

author: hitecelec
author_rank: Regular Contributor
timestamp: April 02, 2019, 10:30:06 am
content: HiI have a unit functioning perfectly except for the white back lit. suspect the rectangular back lit module beneath the display. the number written on the back lit RFWO69322G2 V1. any clues?thanks in advance

author: rtekal
author_rank: Contributor
timestamp: July 07, 2021, 05:50:23 am
content: I also have the same problem. Instrument is good, but no display on LCD as the backlight is not working. The back light is a separate module that is mounted behind the LCD.Is anyone having schematics or solved this problem?

author: tooki
author_rank: Super Contributor
timestamp: July 07, 2021, 04:35:47 pm
content: Not having any specific knowledge of that meter model, the first thing I'd check is the backlight LED itself:1. is it getting power? That's easy enough to measure.2. Remove the backlight and test it on its own. Does it light?If the LED itself has gone bad, just dremel it out of the backlight panel and then epoxy in a new LED.If the LED is fine, then start looking at whatever is driving it.

author: voltsandjolts
author_rank: Unknown
timestamp: October 30, 2022, 10:00:54 am
content: So, failing backlight LEDs seems to be common issue with these Keithley 2110. I've seen it on a couple of units, but they've been on permanently for >5 years, so it's wear-and-tear rather than a fault IMO.The light comes from two small PCBs mounted at each end of the plastic block "backlight diffuser". See attached photo. One of these PCBs is 'surface mounted' on the display PCB. The other is through hole and is trickier to remove - I just snipped the legs going into the display PCB. There are some clear plastic tabs that need snipped out too.Anyway, replace the three SM0603 LEDs on each backlight PCB, refit and its job done. Quite easy.Make sure the PCBs go back on at their original location, i.e. putting them back on the wrong side of the LCD will reverse polarity, won't work.
Keithley 2182 transformer tr 299 - Page 1
Forum section: electronics / repair

author: spinup
author_rank: Newbie
timestamp: August 18, 2024, 08:30:05 pm
content: Hi all,I have a Keithley 2182 that was plugged in 220v ( instead of 120v) and as a result the transformer is busted. It looks it is an old model and I can't find the replacement. I found that similar ( at least name) transformer is used on Keithley 2000 but when I looked at the manuals they are very different. Any suggestion is helpful. Can i send the transformer for repair ( any place you guys know can do a high end job ?).

author: m k
author_rank: Super Contributor
timestamp: August 30, 2024, 05:19:26 am
content: Are there really that many windings?Maybe 2000 model picture is drawn differently.

author: derZockerMP
author_rank: Regular Contributor
timestamp: August 30, 2024, 06:08:07 am
content: You can show us a picture of the transformer. I think if it's the same as in the K2000, a replacement part should be easier to get as for your meter.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 30, 2024, 06:16:04 am
content: There is a picture on xdevs.TR-299. Looks like the same transformer as K2000.https://xdevs.com/doc/Keithley/2182/img/nv_psu.jpg
Keithley 225 - Transformer wanted (or replacement advice) - Page 1
Forum section: electronics / repair

author: 705jas
author_rank: Contributor
timestamp: May 25, 2022, 12:19:37 am
content: Hi AllI have a Keithley 225 that I think is otherwise in good condition but unfortunately, I get no voltages out of the transformer at all. Looks to have been butchered at some time in the past?? I am looking for a replacement either new or second-hand. If someone can advise on a suitable substitute that would be great. Any help appreciated.cheers...Allan

author: james_s
author_rank: Super Contributor
timestamp: May 25, 2022, 12:33:27 am
content: Do you know the specs of the transformer? I assume from what you've said that the primary is open? Have you looked to see if there's a thermal fuse? I've repaired several transformers that had the thermal fuse blown by a power surge.

author: alm
author_rank: Super Contributor
timestamp: May 25, 2022, 11:24:51 am
content: The transformer will very likely have a grounded shield between primary and secondary to reduce capacitance to ground (check the schematics). In that case replacing it with a generic transformer would probably degrade performance. I'd try to fix the existing transformer first.

author: wishboneash
author_rank: Contributor
timestamp: September 24, 2022, 11:38:34 pm
content: I had removed the transformer from my 225 when I thought I had destroyed it. It turned out to be fine. I measured the voltages on the windings while it was out. Attached a picture with some voltage details. I am not sure about the currents, but conservatively I would think it should be around 200mA on the high voltage windings and less than 100mA on the low voltage windings. I put up a video on Youtube (https://youtu.be/UovNGGD8vFE) on the work I did to make it functional again. Most of the problems were created by me due to carelessness or overstressing the instrument. Anyhow, it's working again although quite heavily modified from the original! I have a few more tweaks to do bring it up to original specs.

author: 705jas
author_rank: Contributor
timestamp: October 22, 2022, 03:17:42 am
content: HI guysthanks for the replies. i have donated the unit to Ian Johnston so he may end up posting a video about it. All a bit beyond me, unfortunately. Know your limits and stay well under them i say

author: IanJ
author_rank: Unknown
timestamp: October 29, 2022, 10:18:52 am
content: Quote from: 705jas on October 22, 2022, 03:17:42 amPart 1:-Ian