This Keithley 2001 IS NOW saved! - Page 1
Forum section: electronics / repair

author: Zucca
author_rank: Unknown
timestamp: November 24, 2019, 09:13:36 pm
content: The previous owner did not care too much, he deserve a middle finger...I want to save this sick device!What I did:1) Replaces all leaking and not caps. Yeah they did leak but not soo much... board cleaned and it was not corroded.2) Fan replaced (just becaused it was cheap)3) the poor tortured U629 was replaced with a new one and put back in the original location.4) The missing R100 was installed with a similar model... the cement one was too expensive.5) Zip tied the big blue capacitor C611 15000µF closed to U629Now I got the following errors:404.1 – Absolute value (x1 gain); -full-scale DAC output404.2 – Absolute value (x1 gain); -half scale DAC output404.3 – Absolute value (x1 gain); zero DAC output404.4 – Absolute value (x1 gain); +half-scale DAC output404.5 – Absolute value (x1 gain); +full-scale DAC output405.2 – Absolute value x10 gain comparison; large +DAC output405.4 – Absolute value x10 gain comparison; small +DAC output406.6 – Voltage comparison407.1 – Front end; 2V range407.2 – Front end; 200V range407.3 – Front end; 750V range412.1 – AC amps switchThis is just the first post, now I will start the investigation.

author: Zucca
author_rank: Unknown
timestamp: November 24, 2019, 10:15:27 pm
content: Power supply check ok. The only thing somehow strange wasU103, pin 3: 22,3V (~+18V in the manual)U103, pin 2: 7,89V (+8V in the manual)but I will not consider it as a defect.Now with the unit warmed up I got these errors as well in addition to the others before:405.6 – Absolute value x10 gain comparison; small –DAC output405.8 – Absolute value x10 gain comparison; large –DAC output410.1 – True RMS converter411.1 – Filter; true RMS411.2 – Filter; true RMS

author: TiN
author_rank: Super Contributor
timestamp: November 24, 2019, 10:38:22 pm
content: Check booster power stage and stuff around dual JFETs U5** , if my memory still serve me well.

author: Kjelt
author_rank: Super Contributor
timestamp: November 25, 2019, 09:28:35 am
content: Did you recap all the electrolytics ?Better do it before you really get a mess.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 09:31:11 am
content: Quote from: Kjelt on November 25, 2019, 09:28:35 amoh yes read above point 1).Quote from: zucca on November 24, 2019, 09:13:36 pmI opened up the unit and fond some elco pee, it just started leacking.I did not power up the unit and replaced and cleaned everything like a good EE boy.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 09:41:07 am
content: https://xdevs.com/fix/kei2001/https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/Did some homework with the excellentTiNarticle and previous posts:Quotewill check it.QuoteMine were in contamination for about 12-14 hours, I cleaned them well and they look good... I pospone this.https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg727146/#msg727146Quotehttps://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg762210/#msg762210Quotewill checkPS: If you need the Service stuff, look here:https://cal.equipment/doc/Keithley/2001M/CDROM/Model%202001%20Repair%20Manuals/athttps://xdevs.com/the links do not work anymore.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 11:09:30 am
content: TO DO List after repair:1) New Front Panel (Assembly or not?)2) Missing Bolt at rear coax input, those are important to keep the analog board in place. where I can find them with washer?3) MEM2 update with DS1245Y or for the future:https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg956554/#msg9565544) FW UpgradeOPTIONAL1) µV Meter option

author: Kjelt
author_rank: Super Contributor
timestamp: November 25, 2019, 11:22:53 am
content: I got stuck with an ADC selftest error while the meter itself works flawlessly.The problem is probably somewhere a single corroded pcb trace perhaps inside layer that is high ohmish.The ADC draws current during selftest and then the voltage drops.Can not find the culprit, I like Keithley very much but the way they overcrowded this pcb with its tiny electrolytes stuffed against the very hot voltage regulators made me rethink if I like them really that much.So lessons learned, really spent time to see if the traces are clean and you don't have any corrosion inside the pcb.I do hope your patient on your table is in better condition than mine and you will get it to work 100%

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 11:28:30 am
content: Quote from: Kjelt on November 25, 2019, 11:22:53 amPut it on the bench again, we will fix it together.Yes the Keithely EE did some sloppy job somewhere in the K2001. That's why the EEVblog EE are here to help.

author: Kjelt
author_rank: Super Contributor
timestamp: November 25, 2019, 11:31:17 am
content: Quote from: zucca on November 25, 2019, 11:28:30 amI have my patient put in another EE hospital with a doctor that has about 20 years more repair and faultfinding experience than I doHe has it as a pet project spending a few hours here and there.The nice thing about the Keithleys is that the service manuals and schematics are often available, perhaps not 100% complete but still thanks to TiN for a larger part.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 12:44:02 pm
content: Quotethis passes.This 404.1 fails:Quotethe circle is getting smaller.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 02:30:46 pm
content: U509 is mentioned in all the failing tests and only there.We have a high suspect component.Next move is to listen toTiNadvise andQuote

author: Kjelt
author_rank: Super Contributor
timestamp: November 25, 2019, 03:23:26 pm
content: But do you use acetone or IPA, I am afraid that acetone could remove the silkscreen ?

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 03:36:27 pm
content: IPA should be enough... silkscreen ist partially already gone.. do not care too much.

author: Zucca
author_rank: Unknown
timestamp: November 25, 2019, 08:40:44 pm
content: Under U507, U508, U509 there was some junk and I cleaned everything up.Unfortunately nothing changed.Time to dig more into the problem.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 25, 2019, 09:28:07 pm
content: Quote from: zucca on November 25, 2019, 03:36:27 pmFor cleaning things like leaking electrolyte water may be a better solvent than IPA. So it can be a good ideal to start with water or at least a water IPA mixture. Pure IPA or methanol would be than the last step.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 12:30:23 am
content: Thanks Kleinstein, I did wash the chips with IPA and water. On the boardI used IPA to remove the tacky flux and whatever was there. At the end it looked very clean.Anyway tonight one step back.... maybe.I powered off the unit to look for a good A ground with a 34461A so I could poke around for the signals...Guess what... I powered the unit back and got these new errors:400.1, 2, 4, 5and they stayed there no matter what I did.So back to the schematics and here what I found while running 400.1 (schematic 2001-902-06.pdf page 4)R560 is connected correctly and I measure 10KOhm betweem PRECOMP+ and U532 pin2.There is too much current flowing through R560 causing the big voltage drop.Are those DG411 and DG211 started to leak right now?Time to listed toplesa:https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg1064632/#msg1064632Quote

author: TiN
author_rank: Super Contributor
timestamp: November 26, 2019, 01:10:21 am
content: QuoteOnly if your meter has B-type firmware (2 ROMs) and you don't mind spending $1K+ for amplifier setup.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 08:25:03 am
content: Quote from: TiN on November 26, 2019, 01:10:21 amB-type 2 (ROMs) is there. That said I am very happy it's just an option for me, I do not really need a µV.Anyway much cheaper than many others µVmeters out there.Thanks you again TiN for all your effort to document your fixings.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 08:52:36 am
content: Coming next...IC, CMOS ANAL. SWITCH, DG411DY(SOIC)VISHAY DG-411DY-E3U317U5222 QtyIC,CMOS ANALOG SWITCH DG211DY(SOIC)VISHAY DG211BDY-E3U510,U515,532U318-320,3237 Qtyand if they are in stock and cheap:IC, CMOS ANAL SWITCH, DG444DY, (SOIC)VISHAY DG444DY-T1-E3U5261 QtyIC, 8 STAGE SHIFT/STORE,MC14094BD(SOIC)ON SEMI MC14094BDR2GU500,501,505,530U800,801U300,302,303,305,30711 QtyIC, MCHAN LAT DMOS QUAD FET, SD5400CY (SOIC)Unknow in ManualU5091 QtyIC, QUAD 2-INPUT NAND, 74HC00M (SOIC)Unknow in ManualU508,513,5363 Qty

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 11:24:37 am
content: DG411 can be upgraded to:https://www.mouser.de/datasheet/2/256/maxim%20integrated%20products_dg411-dg413-1178575.pdfsame with DG444https://datasheets.maximintegrated.com/en/ds/DG444-DG445.pdfBonus: same with DG408https://datasheets.maximintegrated.com/en/ds/DG408-DG409.pdf

author: Kleinstein
author_rank: Super Contributor
timestamp: November 26, 2019, 11:45:39 am
content: Those old CMOS switches somehow seem to be prone to failure.Not many of the switches are really critical and need very low leakage or resistance matching.The new chips are usually DG2xxB and thus already an upgrade to the old version without the B.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 12:29:16 pm
content: Quote from: Kleinstein on November 26, 2019, 11:45:39 amCorrect but I could not find the B version of DG411, DG444, DG408 and I went to Maxim.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 12:35:26 pm
content: if nobody has a better plan I will order tonight.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 26, 2019, 01:16:29 pm
content: For the switches in the AC part, I would be careful with an "upgrade", as for these switches the capacitance can be more important than leakage. So changing the switches would likely need a new low level Cal / adjustment for the AC part.Also many of the other switches are not with high impedance parts and not that critical. So no need for the more expensive Maxim parts. It looks like the really critical signals are switched with JFETs anyway.AFIAK most of the DG4xx are new chips and thus no separate old and B version.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 01:26:15 pm
content: Thanks Kleinstein to stay with me in this madness.I am planning to re-calibrate the unit at the end anyway also to have the certanty it works properly.Moreover this device with full schematics makes a lot of fun and I want play a little bit with it.. so it's more a learning experience than a proper fix it and forget it project. That's also the reason why I keept this 20 years old DMM and not turned in a DMM6500 or so.If someone have some idea to try it out just let me know.

author: Zucca
author_rank: Unknown
timestamp: November 26, 2019, 06:34:23 pm
content: Order placed.

author: Zucca
author_rank: Unknown
timestamp: November 30, 2019, 12:50:43 am
content: All right, Digikey delivered.One minor step forward tonight.Replaced U522, U532. Nothing changed.Well not so fast.Everytime after de- or soldering a chip, always power on the unit to check if and where something changed.I traced the problem at U526 (the next after U532 in the signal path).Replaced U526 and bingo the 400.x Problem went away.Now I got:402.1404.1-5405.2, 4 ,6 ,8406.6407.2-3412.1before was400.1, 2, 4, 5404.1-5405.2, 4, 6, 8406.6407.1-3410.1411.1-2412.1I could be more happy that I bough all the DGxxx chips.The plan is to get the unit error free again and then replace all the chips with new ones.It takes time but it is fun.

author: Zucca
author_rank: Unknown
timestamp: November 30, 2019, 01:09:04 am
content: oh oh..402.1Quotemy new fancy improved U522 has a Ron of 3Ω max....Tempted to replace R588 with a 75Ω to compensate

author: Zucca
author_rank: Unknown
timestamp: December 05, 2019, 02:01:01 am
content: 404.1 on hold, I start to suspect the U509 (IC, MCHAN LAT DMOS QUAD FET, SD5400CY (SOIC)) is gone...U508 and U515 were replaced with brand new ones....

author: Zucca
author_rank: Unknown
timestamp: December 05, 2019, 08:33:57 am
content: Two SD5400CY are on the way to me. I paid them 9€ incl. shipping

author: Kjelt
author_rank: Super Contributor
timestamp: December 05, 2019, 09:43:17 am
content: Darn looks like your 2001 was a zombie.

author: Zucca
author_rank: Unknown
timestamp: December 05, 2019, 10:35:28 am
content: This is a painful fun, the worse it is the more happy you will be at the end.

author: Kjelt
author_rank: Super Contributor
timestamp: December 05, 2019, 12:46:39 pm
content: Check and doublecheck internal pcb trace corrosion when the ics are removed with a bright led lamp below it.

author: Zucca
author_rank: Unknown
timestamp: December 05, 2019, 01:13:12 pm
content: Quote from: Kjelt on December 05, 2019, 12:46:39 pmGenerally yes, in my case the leacking damage was very little on the surface, so I don't think it will help.What is mandatory is to check if the same voltage is on the pins connected togheter, and if there is something not OK power down the unit and check the traces resistance with a DMM.

author: Zucca
author_rank: Unknown
timestamp: December 09, 2019, 06:48:58 pm
content: Desoldered Q501, between D and S 1,2KOhm with nothing on the gate.Maybe I did/do not need a new SD5400CY, oh well...

author: Kleinstein
author_rank: Super Contributor
timestamp: December 09, 2019, 06:56:07 pm
content: For testing the MOSFETs, one should use a defined signal at the gate, more like gate connected to source and substrate: should give high impedance.Testing with an open CMOS gate is like a random number generator.

author: Zucca
author_rank: Unknown
timestamp: December 10, 2019, 12:27:49 am
content: R gate to source = R gate to drain = 1,03 MOhmI don't like it.Moreover I tried to put a negative square wave at the gate and I did not get nothing on the drain out (yes with a 1K pull up resistor to 10V).Then I applied -10V=Vgs and the R between drain(+) and source was -2,1MOhm, between source(+) and drain was 30MOhm...With Vgs=0V (gate shorted to source), Rdrain-source 135Ohm.To me it's dead.And of course the SST4416 JFET is obsolete.https://eu.mouser.com/datasheet/2/427/910019-1211380.pdf

author: Zucca
author_rank: Unknown
timestamp: December 10, 2019, 12:40:36 am
content: MMBFJ112?https://www.onsemi.com/pub/Collateral/MMBFJ113-D.PDFI go in bed, see ya....

author: Zucca
author_rank: Unknown
timestamp: December 11, 2019, 06:29:39 pm
content: New SD5400CY arrived today, replaced.Ah I resolder the q501 back.Now I get:402.1404.1 ,2405.6 ,8before it was:402.1404.1-5405.2, 4 ,6 ,8406.6407.2-3412.1

author: Zucca
author_rank: Unknown
timestamp: December 11, 2019, 06:36:27 pm
content: Power down and up again.Now I got:402.1404.4, 5405.2, 4407.1, 2, 3412.1ar the third time power up:402.1404.4, 5405.2, 4407.1, 2, 3412.1looks stable now.mmmm the temperature is playing a role here?

author: Kleinstein
author_rank: Super Contributor
timestamp: December 11, 2019, 07:08:56 pm
content: xxx4416 FETs of some kind should still be available, possibly in a SOT23 case.AFAIK J112/J113 are essentially the same as the usual 4391/4392 JFETs typical used as switches.Getting JFETs is becoming tricky if a TO92 / TO18 case is needed. The same chip in SOT23 is usually still available.There are quite a lot of similar FETs from the same process, but different testing sold under different numbers.A good reference for JFET data / replacements can be Fairchild AN6609.

author: Zucca
author_rank: Unknown
timestamp: December 11, 2019, 08:04:00 pm
content: KleinsteinThanks you so much, one day you need to tell me why you know everything about EE componets.

author: Zucca
author_rank: Unknown
timestamp: January 09, 2020, 10:42:31 pm
content: Well power it up today, here what I got:402.1404.1, 2405.6, 8I tried to let it warm it up, turn it off and on again but it did not moved from there.Is my bench slowly repairing the devices just by holding them against gravity?No sense, or I have an intermittent contact somewhere.

author: Zucca
author_rank: Unknown
timestamp: January 10, 2020, 05:17:39 pm
content: Today's errors:402.1404.4, 5405.2, 4407.1, 2, 3412.1

author: Kleinstein
author_rank: Super Contributor
timestamp: January 10, 2020, 08:36:24 pm
content: Different errors coming up could be a parameter that is just boarder-line. Something like a intermittent error (e.g. cold solder joint) is also possible.The 40x self tests are testing mainly the AC part.The service manual describes the test in quite some detail and AFAIK one can run them one at a time to bring the meter in a defined state.A point to check would be the DAC to generate test signals. Also have an eye on some of the CMOS switches - some of the old DG2xx tend to fail with age.Besides the build in tests one could also create a test case by hand: measure some AC voltage and follow the signal to the RMS converter.

author: Zucca
author_rank: Unknown
timestamp: January 10, 2020, 11:13:47 pm
content: Thanks Kleinstein, always a pleasure to read your comments.Now I know what is going on.The problem (thank God!) is the zero crossing amplifier, The input signal NETOUT is correct but the output signal COMP- goes bananas.For some reasons COMP- either is always >0V or <0 so U509 can not switch between the non inverting or the inverting path in the VGA amplifier.It is a very simple circuit and I am almost sure I will fix it easily.Stay tuned, I see the light at the end of this tunnel.

author: Zucca
author_rank: Unknown
timestamp: January 11, 2020, 08:55:37 pm
content: Do you see the bastard?

author: DuPe
author_rank: Regular Contributor
timestamp: January 13, 2020, 03:21:04 pm
content: U514?

author: RandallMcRee
author_rank: Frequent Contributor
timestamp: January 13, 2020, 04:05:39 pm
content: I'll bet on CR501.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 13, 2020, 04:34:29 pm
content: If the signals are all DC, U514 is not working normal.The current through R436 is rather high and there must be a way for it to go - looks like some path not intended: U514 is the main candidate, U515 is possible too. Q546 could be the culprit too though unlikely to be partially broken and the gate driver must be strong to still get 4.95 V.

author: Zucca
author_rank: Unknown
timestamp: January 13, 2020, 05:10:47 pm
content: Yes all DC in Volts.U514 is already been shipped to me. U515 was replaced before.Funny thing it was the last AD847JR in stock at TME. After my order stock TME=0 Unit.Another gossip is that U514 started up either generating an always positive -COMP signal or a always negative one (maybe the nature of a sick unit in a positive feedback). That's why I was getting either one set of errors or the other one.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 13, 2020, 06:27:30 pm
content: For a fist test one could try a more normal, slower OP for U514 (e.g. LM318, maybe LF356 or similar). Chances are one would install a socket for the suspect OP anyway.A broken (conducting) Q542 could also cause the comparator to stay at it's state, as the hysteresis would than be quite large. However it can not explain the high current through R436 (unless R436 is broken). One could measure the other side of R279 and this way check if U515 is the culprit.With the positive voltage at the inverting input the AD847 should normally be all the way negative, so there is something wrong with the OP (unless the circuit is oscillating).

author: Zucca
author_rank: Unknown
timestamp: January 15, 2020, 08:58:24 pm
content: Well U514 was replaced,Now I got:404.1, 2405.6, 8there is another bastard on the board.EDIT: I forgot to point out that Q542 and Q546 are p-ch JFEThttp://www.learningaboutelectronics.com/Articles/P-channel-JFEThttp://pdf.datasheetcatalog.com/datasheet/calogic/J270.PDF

author: Zucca
author_rank: Unknown
timestamp: January 15, 2020, 10:34:30 pm
content: Unbelievable, check out U507 [everything in VDC]:TESTPin 2Pin 3 (-COMP)Pin 7Pin 8404.12,5m-0,294+0,29+4,49404.22,5m-0,257+0,29+4,49404.33,29m+0,42+0,29+4,55404.43,25m+0,59+0,29+4,57404.53,3m+0,628+0,29+4,57None of the circuits are oscillating. Because with the faulty U514 -COMP was always positive I could not detect that U507 was stuck and not switching.... FUUUUUUUU--> other 7€ to DHL for the next chip...

author: tagchen
author_rank: Contributor
timestamp: January 17, 2020, 08:54:27 am
content: hi, last weeks how i have some time, i begin repair two 2001.first defect spend parts for second repair.pcb blow up neer caps, repair pcb and caps, change relais and parts from power supply part, change all chips marked in blue!, change fan and pcb is running with many erros, but run. too many party needed so i do nothing more.defect now :transformer frontinterface, completed frontinterface (display+chips), thermalfuse (ceramic), transformer ...offer for new 2001 with many of discount is 2600euro, needed parts cost more!(offer for rebuild front transformer 580euro, offer transformer 960euro, offer frontinterface 1800euro)second repair same, blow up caps, change many of chips same other repair (blue marked), use transformer and thermalfuse from 1. (transformer positions needs new screwhole to mount, hole now left bevor in middle of transformer , change fan ...last error, Software 1991, A06, A01:200.1 A/D200.6 A/D200.7 A/D201.2 Testcal412.1 ACA Switchthe 200.x are errors from firmware??i reading herhttps://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/500/what can i do as next step??for test i calibrated the 2001 and runs without errors. voltage and current looks like good.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 17, 2020, 09:39:17 am
content: The 200.x Tests are supposed to be mainly for the ADC itself. So this may be the ADC board. With a 2nd K2001 bad at hand one could try swapping the ADC board - however only after checking the supplies, to make sure not to damage the ADC board.

author: tagchen
author_rank: Contributor
timestamp: January 17, 2020, 09:51:18 am
content: 2nd board has the same error 200.x.i read that the firmware A08 has not the problem with 200.x. it is?must change from A06 to A08?https://xdevs.com/fix/kei2001/https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/

author: Kjelt
author_rank: Super Contributor
timestamp: January 17, 2020, 01:44:49 pm
content: No the 200.x tests can be many things, causes. Often has nothing to do with the A/D board it self as with some of the needed signals , reference floating voltages.I am still trying to find my cause, even have a good friend who has 20 yr repair experience on it but it is hard when the cause is not continuous.His last thought about it is that due to the cap leakage some pcb trace inside the pcb has corroded might even make contact with other trace which influences the floating voltage reference.Hard to find.The meter it self is working and in calibration range on all inputs/settings, still get these weird ST errors.https://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg2303367/#msg2303367

author: tagchen
author_rank: Contributor
timestamp: January 17, 2020, 03:33:39 pm
content: thanks, idea in wich part of board is to search?

author: Kjelt
author_rank: Super Contributor
timestamp: January 17, 2020, 10:15:32 pm
content: Iam concentrating on the traces near the powersupplies where the caps leaked.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 18, 2020, 11:56:21 am
content: Quote from: tagchen on January 17, 2020, 03:33:39 pmA first part could be looking for the signals that are measured in the self test. The general idea of the test is to generate a test voltage and measure than. AFAIK one can run the self tests in a kind of single step more and thus have a more static mode of operation.So one could than follow the path of the signal and do extra measurements with a scope or DMM, e.g. at the ADC inputs, DAC to generate the signal or amplifier input. This way one can often narrow down the area where the defect is.Different firmware version could be slightly different in the acceptable limits for the tests.

author: Zucca
author_rank: Unknown
timestamp: January 20, 2020, 09:29:47 am
content: Quote from: Kleinstein on January 18, 2020, 11:56:21 amThis, that's why I am investing time and energy in this old piece of equipment. The manuals (service + schematics) are awesome and the diagnostic test steps will make easy future fixes (I hope).

author: Zucca
author_rank: Unknown
timestamp: January 20, 2020, 09:44:42 am
content: Quote from: tagchen on January 17, 2020, 08:54:27 amSo R100 is a thermalfuse and not a power resistor? I am confused.EDIT:Original Part is:RES, 470, 5%, 10W, VERTICAL MOUNT Keithely Part Number R-401-470.Made by KRL/BANTRY code R-LF3476.I replaced it with:https://www.tme.eu/de/en/details/hs10-470rj/10w-resistors/arcol/

author: Zucca
author_rank: Unknown
timestamp: January 20, 2020, 06:33:44 pm
content: U507 replaced, no more errors!

author: bitseeker
author_rank: Super Contributor
timestamp: January 20, 2020, 10:47:13 pm
content: That was quite the adventure. Congrats, Zucca!

author: Specmaster
author_rank: Super Contributor
timestamp: January 20, 2020, 11:05:40 pm
content: Well done

author: Kjelt
author_rank: Super Contributor
timestamp: January 21, 2020, 06:09:03 am
content: great result.You tortured me a bit with the jodelahi video, but I'll survive.

author: Zucca
author_rank: Unknown
timestamp: January 21, 2020, 07:56:31 am
content: Quote from: Kjelt on January 17, 2020, 01:44:49 pmHow about let some current flow through the suspected traces and check with your Flir E4 if there are any hot spots? If a trace is corroded R goes up ---> heat will be generated there.

author: Zucca
author_rank: Unknown
timestamp: January 21, 2020, 08:06:14 am
content: Quote from: tagchen on January 17, 2020, 09:51:18 amTry to upgrade the firmware and see what happens (Not wasting time, I would do it anyway). Are both your K2001 old A-Units?

author: Zucca
author_rank: Unknown
timestamp: January 21, 2020, 08:30:59 am
content: Guys slowly is time to think about low prio little parts.I would like to buy:1) 2 Nuts and 2 washers for the rear coax2) If the rear writings are still good maybe I could upgrade the entire metal case3) GPIB connector screws4) Front Bezel with oder without display-key boardsee the pics below regarding 1), 2) and 3):If anyone has something for cheap please PM me.

author: tagchen
author_rank: Contributor
timestamp: January 23, 2020, 02:34:33 pm
content: Quote from: Zucca on January 20, 2020, 09:44:42 amoh no, it is a resistor with thermalfuse. You find it in many device from HP and Agilent. Its an producer in USA, you can order it by them or keithley.i open the ceramic resistor case and in this you find them in picture. i fixed it for testing device with new thermalfuse (red is original) and have order new in USA.

author: Zucca
author_rank: Unknown
timestamp: January 23, 2020, 02:57:07 pm
content: Thanks now everything is cristal clear, and finally I know why R100 goes open so often.I do not like thermalfuse, I think I will take the risk to live without it.

author: Zucca
author_rank: Unknown
timestamp: January 23, 2020, 05:05:11 pm
content: QuoteInteresting, now I understood how the Pre-regulator circuit works (service manual page 2-17).Since the previous owner moron put his dirty handy on R100, I need to check if this circuit is working since is it not tested in the self test.Moreover I have to be carefull around R100, it is main voltage territory.

author: Kjelt
author_rank: Super Contributor
timestamp: July 06, 2020, 09:49:10 pm
content: I am in despair, my second batch of 27C4096 eproms i ordered is also not good.They all fail on some bits , some can't be programmed at all.Is there a modern flash chip, pin equivalent for this chip that anyone knows or a trustworthy source ?I still would like to update the firmware to see if it solves my last error.