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Products => Test Equipment => Topic started by: TiN on September 28, 2013, 06:11:53 pm

Title: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 28, 2013, 06:11:53 pm
Time has come.  :-DMM
After seeing this new big-LCD DMMs like 34461A which Dave recently reviewed, and mm, new Keithley SMU with touch-screen..
Let's show some respect to good-old instruments, with bright nice VFD with 180°C viewing angles and simple interfaces which don't require
reading user manual to begin work.

Small intro - I work mostly with digital stuff, various microcontrollers projects and last few years PC components design. As with most of folks who started with electronics, first tool was some pos cheapo DMM. Then it become full-time stuff and I got decent Fluke 87V, which still working as first day, and covering 99% of needs for DMM usages. But I always wanted to get some more accuracy for analog circuit needs, and needed some real system/bench meter with nice display, good accuracy and interfacing to capture and process measurement data. But since there was no actual project-critical need, one could never justify spending hundreds on great meter. Till now.

But I do like messing with hardware, digging PCB design solutions and repairing stuff as hobby, so once I saw broken Keithley 2001 7.5 DMM on sale, I decided - now or never and pull a trigger. After couple weeks I got it in my hands, beast had some burnt components on PCB, but was able to power on. I loved it's screen, function set right a way. After this my DMM soul was sold to Keithey, as that was years ago.

After few weeks of digging thru service manual, messing with analog PCB I got it "working", it was able to take sort-a meaningful measurements but still failing some self-tests. Few years pass... I got somehow addicted to Keithley and bought total 7 (yes, seven) broken 2001's and even managed to get SMU 2400 with broken VFD (had to salvage one of 2001 screens to fix it). And because some of 2001's were missing small ADC board, i have now 3 complete meters and some parts. All meters had front-end failures due to leaky capacitors which corroded PCB traces.

(http://fotkidepo.ru/photo/115530/9515ZdJQKBoMHD/933522w.jpg)

Now my plan is to repair at least these 3 meters to fully functional state, to have self-test pass and to be able of running calibrating routine.
It's rather difficult for me, because i have minor experience in analog and precision stuff, but I'm eager to learn :)

(http://fotkidepo.ru/photo/115530/9515ZdJQKBoMHD/933339w.jpg)

Schematics reversing is in progress currently:
Schematics in PDF and DSN (http://dev.xdevs.com/hg/repair/kei2001/file/bf038f56a316/schematics)
I use Cadence Orcad for schematics, but export to Adobe to PDF as well.

---

Toolkit I have for aid this project:

HP 33120 15MHz ARB
TLA715 logic analyzer (I had plan to reverse how ADC board is interfaced so bought a TLA for it :D. Maybe can do DIY ADC board later with ALTERA FPGA's i have lying around)
CSA7404 scope (have TDS5034 with various probes at work lab too)
Keithley 2400 SMU (calibration state unknown, but assumed working in spec) (UPDATE: Completed calibration at January 2014)
Keithley 2002 (uncalibrated)
EDC MV106 (calibration unknown, but matches voltage cell within 140uV :))
Eppley 809684 Standard Voltage Cell 1.01909VDC @ 70F (history unknown, bought off ebay. It's resting already for couple month on table)

So second non-easy task will be to get resistance and voltage sources for calibrating K2001's. Per service manual, it needs 2VDC, 20VDC,20.75k,1.75Mohm for DC and Ohms calibration. I'm don't have access anything precise like 3458a, and because I currently work in Taiwan full-time, there are some language problems to get verification :D

I hope it's okay if I link my related keithley-repair redmine project here (http://dev.xdevs.com/projects/kei2001).
Also I have mercurial repository to keep all related files here (http://dev.xdevs.com/hg/repair/kei2001/).
Anyone is free to download everything, it's open project for fun.

Let's make it alive  :-DMM

EDIT 8.APR.2015

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/schematics.png) (http://doc.xdevs.com/article/keithley-instruments/#2001)

Model 2001 Multimeter, Calibration Manual, 2001-M-905-01 Rev. H / Mar 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-M-905-01.pdf)
Model 2001 Multimeter, Repair Manual Addendum Schematics part 2, 2001-902-07 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-07.pdf)
Model 2001 Multimeter, Operator's Manual, 2001-M-900-01 Rev. K / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-M-900-01.pdf)
Model 2001 Multimeter, Repair Manual Addendum Schematics part 1, 2001-902-06 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-06.pdf)
Model 2001 Multimeter, Repair Manual Addendum, 2001-902-05 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-05.pdf)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 28, 2013, 06:39:15 pm
UPDATED 30.12.2013 08.04.2015

Hardware (Digital board)

Main CPU: Motorola MC68302FC16C
RAM: 2x128K

Revision K is same as one used in Keithley 2002.

Hardware (Analog board)

Voltage reference: LM399 binned by Keithley (according to repair manual)

Hardware (ADC board)

3 modules, same PCB PN Keithley 2001-162-04G

Top:

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/933593w.jpg) (http://dev.xdevs.com/attachments/download/647/modules_top.jpg)

Bottom:

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/933594w.jpg) (http://dev.xdevs.com/attachments/download/648/modules_bot.jpg)

Integrating ADC implemented in U808 ALTERA/Cypress CPLD (MAX EPM5128JC (http://dev.xdevs.com/projects/kei2001/repository/revisions/f705223cdf34/entry/datasheets/m5000.pdf) or CY7C342B (http://dev.xdevs.com/projects/kei2001/repository/revisions/cbc699b0e5a3/entry/datasheets/CY7C342B.pdf)) and interfaced via SPI thru optocoupling to digital board.
Onboard power: Q812, 78L05AC in TO92 package
Clock: CMOS oscillator, 7.680 MHz
Output amplifier: BB OPA602AP, High-speed precision Difet OpAmp, 6.5MHz, +/-15V, 35V/us, +-1mV Vofs, +-15uV/°C Drift (http://dev.xdevs.com/projects/kei2001/repository/raw/datasheets/OPA602.pdf)
Onboard VREF Opamp? : 2 x LT1097CN8 (http://dev.xdevs.com/projects/kei2001/repository/raw/datasheets/LT1097.pdf)
Onboard VREF? : IN4579 Zener 6.4V
Timer: NE5534 (http://www.ti.com/lit/ds/symlink/ne5534.pdf)

Current schematics in PDF (not finished, work in progress) (http://dev.xdevs.com/projects/kei2001/repository/revisions/e6bec810c39e/entry/schematics/K2001-162-04G%20ADC.pdf).

Update for analog section of ADC: PDF Schematics of ADC analog parts (http://dev.xdevs.com/attachments/download/713/Keithley_2001J%20_ADC_Rev01.pdf).

Hardware (front panel board)

It's very similar to some other Keithley products as well.
Keithley 2002, 2400-series SMU, Keithley 7001, 7002 all use same VFD.

Hardware typical failures

First step should be replace leaky capacitors on front-end drive circuitry. All 7 meters which I had were made in 1992-1994 accoring to date codes on parts and had nasty corrosion from electrolyte leakage on capacitors C114,C115,C116,C117 (470uF 63V and 1000uF 35V) near mains transformer and LDO's.

Firmware (ROM)

Using standalone programmer I read EPROMs with firmwares from my units:
Firmware A05,A06,A08,B07,B08,B10,B15. (http://dev.xdevs.com/projects/kei2001/repository/show/firmware)

B07 had two EPROMs with even and odd bytes. So had to write small tool (http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/ROM_B07/merge.c) to merge two binaries into single ROM. Compiled by GCC in freebsd 7.2.

Funny to see, that there are names in open text (Firmware A06) of project engineers who probably worked on Keithley 2001 design.
Code: [Select]
Dave Skerkoski,Mike Marks,Robert Fitch,Mike Dahlhausen ,Andy Creque ,Roger Chaplin - The Software Team: Please report occurrance
 :clap:

And much more people in Firmware A08 from offset 0x741AA (probably whole team)

Code: [Select]
George Topola     Mike Szalkowski   Bob Spinks        Larry Spilar      Greg Sobolewsky   Dave Skerkoski    Dave Sherrets     Karl Sasgen      Paul Sally        Ken Reindel       Bill Pelster      Gerald Naujoks    Scott Oberlin     Steve Mihalick    Marla Mock        Michael Minneman Mike Marks       Peter Lui         Dave Lewis        Warren Kumley     Dave Kruszewski   John Kraizel      Larry Klubert     Meindert Kleefstra  Doug Kirsop       Fred Hume         Jim Horvath       Todd Hayes        Theresa Harlan    Jay Hardway       Kevin Hansen      Kevin Graham      Robert Fitch      John Ferman       Mike Dahlhausen   Mark D'Ambrosia   Jeff Cunningham   Andy Creque       Grant Coyle       Dale Cigoy        Roger Chaplin     Mark Brinich      Charles Bona      Robert Bennet     Gary Bish         John Banaska      Kevin Ballou      Mike Atwell   
The Project Team

Thumbs up to all these people for great meter!  :-+

Options (MEM1,MEM2,STD)

Hacking options on 2001 (http://xdevs.com/article/kei200x-mem/)

Secret goodies!

Secret menus in Keithley gear (http://xdevs.com/guide/keithley_secret/)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 28, 2013, 06:52:52 pm
Test setup

Components

PC software / GPIB Intefacing (LabView)

Scanner card

TBD later, sorry :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: cyr on September 28, 2013, 08:30:17 pm
I have upgraded my 2001 (firmware B06) from STD to MEM2 using a DS1245Y, works fine. Did you move the jumper to the correct position?

I think your firmware B07 dump is incomplete BTW, each EPROM should be 512kB of data and the merged image 1024kB, instead you have two 512kB files with half the bytes blank in each and a merged 512kB file.


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: free_electron on September 29, 2013, 12:00:53 am
I have adc modules for those things...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on September 30, 2013, 11:17:39 pm
I have upgraded my 2001 (firmware B06) from STD to MEM2 using a DS1245Y, works fine. Did you move the jumper to the correct position?
I tried doing this too, and it worked ... almost. The meter identifies the RAM and displays "MEM2" on power up, and lets me take over 30000 readings into memory, but they are lost at power-off. Also, it does not allow me to save settings other than slot "#0" (MEM2 should add #1 to #9). Can you save 10 sets of settings? If you save settings to memory are they retained after power-off? I think my firmware is A06.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: cyr on October 01, 2013, 01:44:03 am
Actually, you are correct. I never bothered testing anything beyond logging a lot of samples, and my unit behaves exactly the same. Interesting...

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 01, 2013, 02:29:39 am
My MEM2 with DS1245Y with A08/A01 firmware allows to store 6017 readings, and loses stored data when powered off as well (does not react on Recall button).
No issues with saving settings to #9 slot tho. Restores saved settings after power toogle from slot #9 too.

I'm hooking LA now to capture ADC module comms, to see what rates and data is used.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on October 01, 2013, 12:19:26 pm
My MEM2 with DS1245Y with A08/A01 firmware allows to store 6017 readings, and loses stored data when powered off as well (does not react on Recall button).
No issues with saving settings to #9 slot tho. Restores saved settings after power toogle from slot #9 too.

I'm hooking LA now to capture ADC module comms, to see what rates and data is used.
Is yours a "genuine" MEM2? Can you dump the NVSRAM contents with a device programmer and post them? I am guessing that Keithley initializes the chips with some special data, like some "empty" data structures to hold the extra 9 front panel settings.

I share your affliction; I have 4 2001's on my bench right now :-+  One of mine has B15 firmware, which is almost the newest (there is a B16). Are you interested in the B15 firmware? I need an excuse to finally buy a MiniPro programmer.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 01, 2013, 02:55:36 pm
It was genuine MEM1. And I need same excuse to buy standalone programmer, as I just borrowed one for a day from work to read my ROMs, lol.

On units i have digital boards have different revisions, some with two ROMs (even and odd), other seem simplified a little. How old are your meters? Analog board from two meters i have is different too, i assume Keithley had fix front end bias curcuitry which was failing on initial revision.

I got schematics for ADC module almost done, working on capturing transactions on digital bus. Will post it here when get some cleanup.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 06, 2013, 07:13:17 am
Almost finish ADC module schematics - PNG file (http://dev.xdevs.com/projects/kei2001/repository/entry/schematics/adc_board.png)
Added front panel schematics - PDF, ,need use black background, as i had black in CAD (http://dev.xdevs.com/projects/kei2001/repository/entry/schematics/K2001-112-01H_FRONT_PANEL.pdf)

Looks like front panel MCU which controls VFD and scans keypad is interfacing by simple UART.
This makes Keithley as neat chassis for own devices. For example Keithley 7001 switch units go quite cheap, and feature same front panel.

I already have idea to take one of those and assemble small ITX computer with Core i7,16GB DDR3,SSD in it. Add GPIB card and will be neat controller/storage unit for measurement devices in rack, with great VFD and keyboard on front.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: echen1024 on October 06, 2013, 02:37:20 pm
How much do you typically pay for a Keithley?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 06, 2013, 05:26:36 pm
That depends on patience and condition. I got most of them without ADC module as parts, for two hundred or so per unit. Still more than some decent handhelds might go for.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 07, 2013, 02:11:48 am
Project is going slow, but going :)

Got ADC modules for rest of 2001's. Now can bring all meters except one (lots of damages/missing parts on analog board, was used for parts anyway).
They also have now pin definition on silk :)

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/KADC/newadc_s.jpg)

Thanks, Vincent!

Interesting enough, old ADC modules I had were Revision G, with date codes on IC's 1992, while new ones are Revision H and Revision J, with datecodes 1992 and 1994. There are few layout differences and extra OPA177GS (http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sbos008&fileType=pdf) (U813) near to integrating amp U816 (OPA602AP). I will update schematics soon, to see what was changed.

I wish there could be some forum member which own fresh Keithley 2001 and don't mind to unsrew three screws and take a photo of internal boards of current 2001 hardware :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on November 07, 2013, 02:34:17 am
I have four 2001's. Three work fine (one of those has issues with AC current, but fine otherwise). The forth one had been working perfectly, no self test fails or strange behavior, but suddenly stopped working recently.

When turned on, it makes a few clicks after a few seconds, then stops. No display or other signs of life. I suspect the power supply of course. Nothing looks strange inside (no leaky/bulging caps). Do you have any suggestions as to where to look? Your reverse-engineered schematics will prove very helpful I think.

When all four were working, they all had read within +/- 3 ppm of the average at both 2 VDC and 20 VDC ranges (didn't cross-check them in other ranges/functions) even though none of them is recently calibrated, AFAIK.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: free_electron on November 07, 2013, 03:43:30 am
@macboy remove the powerr supply caps. you can bet your ass they have gone bad. these caps don;t bulge .. they leak at the bottom ,eating the traces !
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on November 07, 2013, 04:51:36 am
@macboy remove the powerr supply caps. you can bet your ass they have gone bad. these caps don;t bulge .. they leak at the bottom ,eating the traces !
Thanks, I will do that as soon as I can, certainly before I attempt to power it up again. No need to add electricity to an electrolyte spill, the traces would be gone it no time (if not already!). In your experience do the bad caps measure as low on a simple cap meter? I don't have a meter with ESR yet.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 07, 2013, 12:16:39 pm
What PCB revision of analog board? Its letter on top pcb label near rear input connectors.

 Early units often have issues with floating ground curcuitry. I would replace four big caps, four diodes and two zeners on analog board just near mains transformer output connector. As general precaution, I would replace electrolytes anyway, because even if they might look OK still can be faulty and start leaking from bottom, corroding PCB.

Also there are voltage check test pads near ADC board connector, with +/-15v, digital 5V and +/-8V voltages.

Worth checking your display board too, just hook working one to digital board, and check if anything changes :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on November 12, 2013, 01:46:18 am
What PCB revision of analog board? Its letter on top pcb label near rear input connectors.

 Early units often have issues with floating ground curcuitry. I would replace four big caps, four diodes and two zeners on analog board just near mains transformer output connector. As general precaution, I would replace electrolytes anyway, because even if they might look OK still can be faulty and start leaking from bottom, corroding PCB.

Also there are voltage check test pads near ADC board connector, with +/-15v, digital 5V and +/-8V voltages.

Worth checking your display board too, just hook working one to digital board, and check if anything changes :)
I had only a few minutes to look at it yesterday. All voltages are low, on analog board and digital board. No signs of leakage under capacitors. This meter was definitely built well before 2000, so it did not get a bad batch of capacitors from the early 2000's. Since all voltages are low, I think it is likely a failure on the pre-regulator and/or the voltage selector circuit on the primary side of the transformer. Too bad (for me) that you didn't reverse engineer the schematic for that section  :)
I'll check the analog board revision later tonight. Can you elaborate on the issues with "floating ground circuitry"?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 12, 2013, 04:32:57 am
All my units are 1992-94 year. Bad caps is not really batch issue, it's more just age with elevated temperature usage. I would replace old caps as general measure , when we talk about servicing highend test equipment which is 20 year old :)

As for schematics, i actually had input side reversed and posted before in this thread. There is electrolytic cap too. One of my units had faulty cap and dead 555 due to corrosion. After cleaning and replacements - come back to life at once :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on November 12, 2013, 02:56:44 pm
The analog board looks like revision N (labelled 2001-102-04N). Digital looks like revision K, and F/W is B10 on two 32-pin DIPs. Date codes on ICs and Caps indicate manufacture in late 1996 or early 1997. I have probed around and think that something is dragging down the power supply. Dried up caps wouldn't do that... leaking caps? Maybe, if something was shorted. No evidence of leaks. Maybe a bad tantalum, but none of the rails looks shorted out, they are all just low (3 V on 5 V rail, +/- 8V on 15 V rails). A bad shorted rectifier could cause the problem maybe. Which diodes did you recommend replacing? CR109-CR112? Or one of the bridge rectifiers? I don't see any zeners near the secondary connector of the transformer.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 12, 2013, 03:36:52 pm
Pretty sure problem is on primary side autorange detection curcuitry. Probably you have 110Vac on input but due to failure of selector mains xfrmr is commutated for 230Vac, so you get not enough voltage on secondary side.

Exactly what I was seeing on my unit. Check 555 (or replace it, its cost not worth bothering with test :)), relays, caps and mosfet. Schematics was posted earlier as well.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: turbo! on November 15, 2013, 01:54:11 am
Now my plan is to repair at least these 3 meters to fully functional state, to have self-test pass and to be able of running calibrating routine.
It's rather difficult for me, because i have minor experience in analog and precision stuff, but I'm eager to learn :)


If you work on any part of analog section or replace anything on it, it will need to go through a full calibration. As far as moving analog board between instruments, it depends on where calibration constants are stored. Replacement parts need to be the same or better tolerance. (not just 1% resistor. you need to look at ppm/°C, ppm/year which determines drift over time) Some instruments require an environmental chamber that can hold a stable temperature for quite a few hours, so you can test it at say 10C as well as 30C so it can learn the thermal characteristics to use for temperature compensation.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 15, 2013, 10:48:07 pm
Thanks, and yes, I'm aware of caveats with such sensetive designs, also do have access to temperature/humidity chamber (-40 to +80°C) at work.
I have those units with various problems, and it's about repair to get initial proper function first, then next step will be component testing/evaluation,
and only after all that work to be done - find local cal lab and perform full calibration. It's a long way to that point from now still.
Just because it's for-fun project, I decided go without rush and study it's design and construction methods.

I do have broken unit as a parts donor, so just swapping same specced parts when need to.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 16, 2013, 04:36:39 am
Still recovering schematics.

Fixed one of analog boards (datecode 1993), which had burnt PCB around negative terminal of C116 and wrong diodes soldered by previous owner.  :wtf:

As expected, aged caps leaked and set unit on fire. Replaced C114,C115,C116,C117,C106, avalanche diodes from another analog board donor (CR109,CR110,CR111,CR112), pair of zeners CR513,CR514.
Had to put two jumpwires too, as traces were burnt at connection from CR112.A to C110.K and at C117 from top layer to bottom.

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/956167w.jpg)

Luckly enough, this seem to be enough to get board to pass self-diagnostics test without errors, which surprised me. All rest analog boards have this or that errors, lol.  :-/O

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/956166w.jpg)

Measurement on various function seem to be nice too, except 1000VDC range.
It reads -1.1222...-1.1227 VDC with nothing connected on terminals.
If i supply 1V from EDC MV106 to it will read 0.1224V, so seem to have offset on 1000VDC range. Lower DC ranges are fine, so not sure if it's cal issue, or some internal component still faulty but not diagnosed by self-test.

Now have problem, where to calibrate unit in Taiwan, without knowledge of chineese language, haha.

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/956168w.jpg)

Also was curious if it's ok that meter on lower (200mV,2V,200V) VDC ranges have bouncing voltage readout, and 200mV usually shows overflow when nothing connected on terminals. Is it because of high input resistance of meter, and picking up charge? Do fully calibrated and functional 2001's or other 7.5/8.5 digit DMMs do this as well?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: wiss on December 16, 2013, 04:49:40 am
Fluke 8800a, Prema 5001/6001, Agilent 34461 and others do this, at least the fluke is a bipolar input with bias current compensation. You should worry if they don't behave like this.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 18, 2013, 01:27:58 am
Thanks, that's what I thought, but wanted to make sure :)

Started to recover schematics of analog board input protection area.
Not exactly clear function of everything there :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 24, 2013, 03:18:23 am
Was lurking around on the web, and found on bbs.38hot schematics of Keithey 2000 meter. Local forum guy went same way I'm going now with 2001 and
reversed whole schematics except front panel :)

I managed to register on that forum and download it (http://dev.xdevs.com/attachments/download/672/K2000.pdf) for history.

All credits for it go to jhzyou (http://bbs.38hot.net:8080/thread-59421-1-1.html)  :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 29, 2013, 07:45:47 am
Started cleaning-up schematics.

Here's PDF for checked parts:

ADC Board - ramp source? (http://dev.xdevs.com/attachments/download/707/Keithley_2001J%20_%2004a%20_%20SLOPE%20GE.pdf)
ADC Board - gain amp and zero cross comparator? (http://dev.xdevs.com/attachments/download/708/Keithley_2001J%20_%2004B%20_%20ZERO-CRO.pdf)
ADC Board - Integrator (http://dev.xdevs.com/attachments/download/712/Keithley_2001J%20_%2004C_%20INTEGRATO.pdf)

Can see how ramps are charging, and then discharge.
So if I'm correct - integrator charging cap switching VREF and ADC/IN and toggling bits by either positive or negative comparator into CPLD?

(http://dev.xdevs.com/attachments/709/zerocross_1.png)
(http://dev.xdevs.com/attachments/711/zerocross_3.png)
(http://dev.xdevs.com/attachments/710/zerocross_2.png)

Channel 1 (yellow) is ZCTL2 net, Channel 2 (cyan) - ZCTL1 net.
Sorry, my third active probe for Tek did not arrive yet, so cannot use third channel to capture actual integrator capacitor voltage yet :)

Here's quick view of measurement outputs of comparators U803 and U804:

Keithley 2001 zero-cross comparator check (http://www.youtube.com/watch?v=GJTcuw5d1VM#ws)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 30, 2013, 04:50:00 am
Finished redrawing analog ADC section.
Now need to get knowledge to understand it correctly :)

PDF Exported (http://dev.xdevs.com/attachments/download/713/Keithley_2001J%20_ADC_Rev01.pdf)

Seem this project not much interested to volt-nuts here?
Or need more suggestions/feedback to be posted? I know there are guys here with K2000/2001's  :bullshit: ;D

I also hooked self-test passing unit to EDC MV106 to check stability:

Keithley #5 2001 measurement, 7.5d, REL -6.770493e-06, Adv filter 100, 0.005% RNG, Line-sync and autozero - ON, range 200mV
Meter and EDC powered on constantly, 2-wired connection to rear inputs, 2 sec delay
EDC Setting: 100mV range, Positive polarity, 0-10-0-0-0-0

Date               Measurement minMeasurement maxAC tempDelta 
27.DEC.2013 1:34am 10.01116 mV    10.01153 mV    23 C  0.37 uV
27.DEC.2013 8:49am 10.00971 mV    10.01073 mV    22 C  1.02 uV
27.DEC.2013 23:43  10.00933 mV    10.01079 mV    22 C  1.46 uV
28.DEC.2013 4:15am 10.00904 mV    10.01184 mV    22 C  2.80 uV
28.DEC.2013 16:08  10.00904 mV    10.01206 mV    22 C  3.02 uV
29.DEC.2013 0:11am 10.00781 mV    10.01466 mV    23 C  6.85 uV
29.DEC.2013 17:31  10.00781 mV    10.01466 mV    22 C  6.85 uV
30.DEC.2013 1:45am 10.00781 mV    10.01466 mV    23 C  6.85 uV
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on December 30, 2013, 05:16:15 pm
Seem this project not much interested to volt-nuts here?
Or need more suggestions/feedback to be posted? I know there are guys here with K2000/2001's 
I've certainly been reading, anyway! 

I did manage to track down the comparator pins and such while trying to find the ADC noise on a k2k (I did not figure out the noise.)  Could watch the ADC input switch from ground, VRef, and VIn, watch the cap charging and comparator firing.  I don't remember where any of those pins were now, except the ADC test point.  I would loved to have had a pin out of the ADC!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: casinada on December 30, 2013, 05:56:56 pm
I follow your posts with great interest. Mine still works fine. I would be interested in the newest firmware........
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 30, 2013, 06:52:43 pm
I posted K2000 schematics few posts ago already :) Not done by me, i don't have K2000 :)

I'd be interested in latest firmware too, but all have is A05, A08 and B07 (which I don't like).

Good news - Tektronix replied today that they can calibrate my 2400 and 2001, so i'll try to prep at least these for cal,
and check how much that would cost. Also no need to send to USA, they can do it in Taiwan lab, which is relieving :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 31, 2013, 07:22:06 pm
Got a quote for 2001 and 2400 ISO9000 calibration with before/after data . It's around 600USD for 2001 DMM and 400USD for 2400 SMU.
I think I will do it after get all self-test and issues sorted out at least on two meters :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: neslekkim on January 01, 2014, 02:56:41 am
$600 for calibration???, is it very difficult to calibrate such units on your own?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on January 01, 2014, 03:11:30 am
$600 for calibration???, is it very difficult to calibrate such units on your own?

The procedure for this type of equipment is usually fairly easy. The difficult part is having the very expensive test equipment that has a recent $2000+ cals from the national standard.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Dave on January 01, 2014, 03:13:44 am
Got a quote for 2001 and 2400 ISO9000 calibration with before/after data . It's around 600USD for 2001 DMM and 400USD for 2400 SMU.
I think I will do it after get all self-test and issues sorted out at least on two meters :)
As far as I am aware, ISO 9000 (http://en.wikipedia.org/wiki/ISO_9000) has nothing to do with calibration. ISO 17025 (http://en.wikipedia.org/wiki/ISO/IEC_17025) is what you are looking.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 01, 2014, 03:16:58 am
$600 for calibration???, is it very difficult to calibrate such units on your own?

2002 calibration cost about 1k USD. It is impossible to calibrated it at home lab.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 02, 2014, 04:20:34 am
Time to bring some infrared voodoo to fixing one of analog boards (board #4).
Took one meter, two analog boards and got some IR pics with Fluke Ti32, swapping boards.

Board #4 have next self-test failures:

304.3, 304.4, 304.5, 304.6, 304.7, 306.1, 309.1, 407.1, 407.2, 407.3, 408.6, 409.6, 410.1, 411.1, 411.2

Board #1 have few items failing initially, but after 5 min warm-up, it can pass self-test cycling over and over. So used it as a "working" reference.

Here are results of 30 min poking around with IR cam:

Board #4

(http://dev.xdevs.com/attachments/716/a09891_top1.jpg)

Board #1

(http://dev.xdevs.com/attachments/715/k1_top2.jpg)

All seem similar here, so I looked over ohms/reference area, and spotted some higher temp parts

Board #4

R286 from CR335 near optocoupler U537

(http://dev.xdevs.com/attachments/718/a09891_R286.jpg)

Little bastard resistor heating up +65C, CR536 over 45C,  hmmm...

Passing board #1, same area

(http://dev.xdevs.com/attachments/719/k1_R286.jpg)

R286 little over ambient, +38C, CR536 dead cold +33c.

Another spot - Q540 under ADC board, near U324

(http://dev.xdevs.com/attachments/720/k1_right_a98_left_U324.jpg)

On left side - passing #1 board, right is faulty #4 board.

Correct Q540 temp - 35C, while on failed board it's over +53c..

Time to draw schematics of these boys above and find out what's wrong...

Bonus:

Money shot, LM199 VREF
(http://dev.xdevs.com/attachments/723/a09891_vref.jpg).
Taking into judgment that in Model 2001 whole analog section have thick plastic cover from both PCB sides with metalized internal surfaces to keep temperature constant on analog circuitry, probably VREF running over 70C.

More thermal images are on redmine related ticket (http://dev.xdevs.com/issues/885).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 02, 2014, 07:43:42 am
I made similar measurement on 2002 and the voltage reference seems to be quite cool (50 deg) but the 5V regulator 78L05 U108 has about 90deg.
I noticed that in your 2001 are four regulators and not only three
http://dev.xdevs.com/attachments/714/k1_top1.jpg (http://dev.xdevs.com/attachments/714/k1_top1.jpg)
On 2002 are only two with heatsing (+/15V) and tiny 78L05 instead four with proper heatsinks.
Could you please check the voltages on regulators? For which voltage is the last one?

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 02, 2014, 08:17:33 am
2001 have two regulators only in that area too. Those are +15 and -15 LDOs. Two heatsinks closer to board edge are TO220 darlington's for "BS- BS+" circuitry. I dont understand that section yet, but I guess its something to do with signal conditioning or ground offset. Check my schematics scetches, i have those on it. There are also test points BS+ BS- near AD637. They read +39.8 and -39.85V on current meter I debugging.

2002 prolly have other way to handle that, I would only dream to recover schematic for 2002 and see how its done. 2002 also uses LTZ reference, not LM199 like 2K1.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 03, 2014, 06:09:55 am
Okay, run some more comparsions regarding ohms issue.
There are two testpoints marked +8VF and -8VF near ADC header.

(http://fotkidepo.ru/photo/115530/51040E7LRaLOOqB/960766w.jpg)

There are some pulse trains when meter in resistance measurement mode, which depends on measurement speed and range.
On failing 304.x selftests board - those pulsetrains non-existant on ranges over 20kOhm.

200kohm range, high-accuracy speed, 7.5digit

-8VF PASS:
(http://dev.xdevs.com/attachments/757/compar-refok001.png)

+8VF PASS:
(http://dev.xdevs.com/attachments/758/compar-refok002.png)

-8VF FAIL:
(http://dev.xdevs.com/attachments/759/compar-refok003.png)

+8VF FAIL:
(http://dev.xdevs.com/attachments/760/compar-refok004.png)

I draw schematics of that part long ago, here it is in PDF (http://dev.xdevs.com/attachments/download/761/Keithley_2001J%20_%2003%20_%20FLOAT%20PSU.pdf).

BS- reads -39.8VDC, BS+ reads +39.8VDC on both failing and passing analog boards, disregarding of operation mode.
Anyone have clue what that +8VF, -8VF and NPN/PNP pair do?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 03, 2014, 08:55:51 am
I made some pictures of Analog board and ADC board as you requested, sorry for quality it has been taken by smartphone.
Thanks for tip about the current measurement. My unit ohm current source is totally out, instead 7.2mA it has 5.8 and on lower ranges the difference is much more bigger.
I was quite surprissed by the corrosion of the PCB trace under the sticker.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 03, 2014, 08:57:24 am
the rest
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 03, 2014, 02:40:28 pm
Any chance to get camera pics later in future? :)
Sorry for being picky, but 2002 deserves better photo treatment than phone webcam  :-X

Maybe 2002 use dual slope integrating, thus implement two ADCs in bigger CPLD MAX?

Also on photo of 2002 from bbs.38hot forums there are more resistors than on yours.
I cannot tell for sure, but maybe your analog board missing some components.

I'm refering to custom arrays near red reed relay this photo (http://dev.xdevs.com/projects/kei2001/repository/changes/photos/K2002/2_3_63189a349230b61.jpg), as there are four packages (R346, R339, R341?, R335?), while yours have only one (R341).
Service manual for 2002 also mentions about R335,R339,R341,R346, so that gives some hints too.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 04, 2014, 03:13:46 am
Any chance to get camera pics later in future? :)
Sorry for being picky, but 2002 deserves better photo treatment than phone webcam  :-X

Maybe 2002 use dual slope integrating, thus implement two ADCs in bigger CPLD MAX?

Also on photo of 2002 from bbs.38hot forums there are more resistors than on yours.
I cannot tell for sure, but maybe your analog board missing some components.

I'm refering to custom arrays near red reed relay this photo (http://dev.xdevs.com/projects/kei2001/repository/changes/photos/K2002/2_3_63189a349230b61.jpg), as there are four packages (R346, R339, R341?, R335?), while yours have only one (R341).
Service manual for 2002 also mentions about R335,R339,R341,R346, so that gives some hints too.

Yep, I will make better photos next week.
R341 are glued two Caddock resistors together TF050R 9,2MOhm and TF020R 100KOhm and overall type is TF-255, which seems to be custom.
It looks to that they were solving some resistor shortages or obsolescence, I do not know. The resistor pinout does not correspond to PCB layout.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 04, 2014, 03:28:02 am
Great, thanks.

Yes, those CADDOCK resistor networks are custom made for Keithley, and sandwich packaging on them is OK too.
If there are missing ones - replacing them possible, but not easy. As alternative will be get bunch of lowest tempco resistors with correct value,
assembly them together into thermally connected network, test tempco and stability - and install in place of original ones. Couple weeks of precision
voodoo :) That's of course if target is getting meter to fully comply with spec.

I was planing to try do so on one of 2001, to improve resistance accuracy. But that's plans for future.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 04, 2014, 03:42:14 am
Great, thanks.

Yes, those CADDOCK resistor networks are custom made for Keithley, and sandwich packaging on them is OK too.
If there are missing ones - replacing them possible, but not easy. As alternative will be get bunch of lowest tempco resistors with correct value,
assembly them together into thermally connected network, test tempco and stability - and install in place of original ones. Couple weeks of precision
voodoo :) That's of course if target is getting meter to fully comply with spec.

I was planing to try do so on one of 2001, to improve resistance accuracy. But that's plans for future.
I do not think there are any resistors missing in this area.
The PCB layout is prepared for parallel combination of R341 and R346
and next to them is another parallel combination preparation for R335 and R339.


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 05, 2014, 10:01:48 am
Seems K2000 use same CADDOCK assembly marked TF-255.

Ok, somebody was asking earlier what one should do for attempt repair 2001.
Here's starting point, as all seven units I got here had this issue more or less.
Due to age (my units were manufactured in 1992-1994), even good electrolytic
capacitors become bad and leak electrolyte on PCB. This can cause major destruction.
Problem is not always obvious, contrary to dodgy caps repairs like in PSU, as
these caps don't blow, but silently leak electrolyte under them.

Not a problem you say, PCB covered with protective soldering mask? Wrong!
Check it out (all photos clickable):

(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_fe_damage.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_fe_damage.jpg)-(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_555_damage.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_555_damage.jpg)

That's utter damage done to traces, as it got under mask and eated traces, vias and pads.
Older revision L analog board elevate this problem even more, as near C114,C115,C116,C117 there are diodes and two zeners,
which fail that curcuitry, causing PCB burns.

(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_mux_damage.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_mux_damage.jpg)-(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_pcb_damage.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_pcb_damage.jpg)

And electrolyte spreads around board, screwing everything around, which is really bad as analog board have all these high impedance signals around
which really sensetive to leakage and coupling. Cleaning this PCB is not an easy job. Not clean board often fails such self-tests like 304.6, 304.7 and 20MOhm,200MOhm,1GOhm ranges,
which require to source proper current levels in nanoAmp range.

(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_cap_damage.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_cap_damage.jpg)-(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_cap_damg.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_cap_damg.jpg) 

This is how bad it can be :) And notice, its not some cheesy Samwa/noname capacitor, it's well-respected Nichicon VZ cap.

(http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/small/K7_new_caps.jpg) (http://dev.xdevs.com/projects/kei2001/repository/raw/photos/K7/K7_new_caps.jpg) 

So as a story to learn, if you have 20-year old test equipment, not only Keithley 2001, take it apart and replace all electrolyte caps just to prevent such horrors happening. Capacitors, unlike voltage references, are not getting better with age.

As a bonus today:

Frequency test on passing 2001 #4 :)

Kei2001 Freq check (http://www.youtube.com/watch?v=l9GF8RHfC-o#ws)

Speedup 400% on video, to make it short :)
Was able to measure almost 25MHz, even while spec only states up to 15MHz.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 08, 2014, 09:26:48 pm
Redraw today digital section of ADC board. Much better now, can see what goes where :)

PDF (http://dev.xdevs.com/attachments/download/797/Keithley_2001J_ADC_Rev02.pdf),PNG, 1MB (http://dev.xdevs.com/attachments/download/798/Keithley_2001J_ADC_Rev02.png).

Sorry for colorful PDF, exporing from orcad replaces black background to white. I use colors to help defining signals in visual.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on January 09, 2014, 09:33:35 am
After watching all those horror images I tear down my K2001 dating to late 1996 to check caps. They are VZ(M) too :-(

They are not bulging now, wondering if is better to change it or leave everything like is now.

I found a circuit patch at q550 (watch next photo) anyone know why is there?

(http://img822.imageshack.us/img822/9848/plma.jpg)

For you all feticists of ADC I include some photos of my board. Don't know if it can help somewhere:

(http://img841.imageshack.us/img841/2654/o3lt.jpg)

(http://img841.imageshack.us/img841/1352/1ok6.jpg)


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 09, 2014, 10:45:34 am
Your unit prolly fixed that issue, but I would change then just in case. caps not getting better with age :]

Thanks for good pics. Your ADC have custom ASIC or factory remarked CPLD, that's interesting.

Can you make more photos of analog board parts and maybe one overall shot of digital board? Also if u have time and programmer , read firmware from ROM chip?

Ill check that signal bypass of yours tonight, be sure. That is control signal for one of mux gates. How its connected on Q550? Hard too see on photo.

UPDATE:

Added part of ohms source. Sorry, that's all i have so far.. That Q550 is NFET, according to 2001 repair manual, and none of my boards have it. It definately switches U323 and related to ohms function. Maybe just a fix for dead gate, dunno.
Would enjoy more photos like this, for sure, as your meter is newest from members over here, so far  O0

ADC schematics pretty much finished, unless some mistakes, so now my interest is analog board..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 11, 2014, 04:50:28 am
I'm still alive :)

Continue for some schematics reversing.

Redone mains input 110/230V selection circuitry and frequency detect. Based on Rev J, as Rev L have some little differences, will update later.

PDF (http://dev.xdevs.com/attachments/download/803/Keithley_2001_Mains_input.pdf)

Refreshed isolation components on analog board, added External trigger and DONE BNC outputs.

PDF (http://dev.xdevs.com/attachments/download/804/Keithley_2001_Isolation.pdf)

Little update for ohms/amps circuitry (hate this unit, hard to trace).

PDF (http://dev.xdevs.com/attachments/download/802/Keithley_2001_Ohms_Amps.pdf)

Added temporary block diagram into schematics, as opening repair manual PDF not convenient..:

PDF (http://dev.xdevs.com/attachments/download/805/Keithley_2001_Block_diag.pdf)

Total wasted today - 6 hours  :) (http://dev.xdevs.com/issues/859)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 11, 2014, 07:18:25 am
I followed this discussion for some time and I want to repair my 2001 to. Can somebody help me and give advice? My 2001 is working and I didn't notice anything strange. When I run the automatic self test I see some errors. Sometime there are only these errors:
407.1
407.2
407.3
408.6
409.6
410.1

but a few times it also showed error codes starting from 303.2.
The unit is not calibrated for ~ 10 years can this als cause self-test errors?

Any advice where to start?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on January 11, 2014, 07:25:25 am
I followed this discussion for some time and I want to repair my 2001 to. Can somebody help me and give advice? My 2001 is working and I didn't notice anything strange. When I run the automatic self test I see some errors. Sometime there are only these errors:
407.1
407.2
407.3
408.6
409.6
410.1

but a few times it also showed error codes starting from 303.2.
The unit is not calibrated for ~ 10 years can this als cause self-test errors?

Any advice where to start?

The best place would be to look in the service manual and add the names of those error codes to your post.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 11, 2014, 08:25:35 am
Thanks KJDS,

I found the following errors:

Front End:
407.1   2V Range
407.2   200V Range
407.3   750V Range

/200 Correction Factor:
408.6   Signal Comparisons

/750 Correction Factor:
409.6   Signal Comparisons

Converter:
410.1   TRMS Converter


And after a new cold start I just got another long list of additional codes I did not all noted down but it started at:

Input Path:
303.2   Open Circuit Ohms and Ohms Protection
etc.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on January 11, 2014, 10:14:31 am
It sounds like there's so much wrong that I'll guess it's a power supply issue. Take the lid off and check all the rails.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on January 11, 2014, 11:04:57 am
Sorry I'd been busy ...

Here you the hi res photo of analog and digital board.

http://imageshack.com/a/img19/8351/3isw.jpg (http://imageshack.com/a/img19/8351/3isw.jpg)

http://imageshack.com/a/img18/222/1lnq.jpg (http://imageshack.com/a/img18/222/1lnq.jpg)

I'd prefer to add links because the images are very big.

Unfortunately the analog board is out of focus, I realized this when the meter was again on the shelf ... so in next days I will tear down again to take a new photo.

And this is how the patch on Q550 is done:

(http://imagizer.imageshack.us/v2/xq90/855/3avr.jpg)

I seems sort of AND port? Still have to check schematics posted here ...

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 11, 2014, 11:10:11 am
jan86, welcome, tear it down and make photos for us. Check electrolytes as first measure, you can see my post above. Those four near transformer are related to front end.

Make close visual inspection, if any borked components, or dirt on pcb anywhere.

Calibration is not cause of errors, as I have two units able to pass selftest over and over with cal date 1993 and 1994. :)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 12, 2014, 10:14:51 pm
Thanks for advice. I still need to get familiar to this instruments repair manual. I know there are different test points and ground. As a quick check I hooked up an oscilloscope to the ground bold of the plastic cover and the supply check points behind the display. I found the following voltages:

+5V = +4.88
+15V= +15.06
-15V= -14.99
-8VF= -7 and -8 (jumps very short to one voltage and back to the other approximately every second)
+8VF= +6.2 and +7.2 (jumps very short to one voltage and back to the other approximately every second)

Is this normal or is this caused by wrong reference ground?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 12, 2014, 11:09:55 pm
So far so good.

Can you take photos of your hardware? Overall shot of analog and digital boards, and closeup's of analog board top areas.

+8vf/-8vf jumping is okay, that's some dynamic signal i did not figure purpose out yet.
I show correct signals in this post (http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg358807/#msg358807).
Check if yours match. This is 2w ohms 200kohm range, normal speed, 6.5 digit.

Check Q543 (it's near TRMS AD637 area), is it getting hot?
Also make sure your C114,C115,C116,C117,C101,C104,C108 capacitors are okay and did not leak anything under them.

I attached PDF schematic part for BS-/BS+ and power curcuitry, you can measure those test points if you have them on PCB..

Make sure not short anything, these pesky circuits are sensetive.

Btw, if anyone get in touch regarding K2001 - i'm online on skype - tin_topmods :)
Working on schematics pretty much every day last few weeks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 13, 2014, 04:52:44 am
I can later make pictures when I have camera. I noticed that the +8vf/-8vf signals change depending on the mode the instrument is in  (I didn't check in detail). Q543 is not warm like all other components are low temperature and can easily be touched by hand. The BS voltages are 38V

No leaking capacitors and the instruments looks like it is brand new made in 2002. It seems to be working fine and if I didn't run the test mode I never new something is wrong. Sometimes many errors are gone. Is there really something wrong?

The cal seal is gone is this a problem or can the cal button be pushed?

PS: I must say I can hardly work on this project due to a lack of time so it can be that I will respond with a delay
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 13, 2014, 05:43:34 am
Seem you have newest meter, compared all stuff we have here. Would be really interesting to see which Rev is yours?

Quote
Sometimes many errors are gone.
Is it after warmup? I mean do you have selftest errors if just power-on cold meter, but they gone after it run 30 or so mins?
It can be dirt on PCB, which conducts current somewhere on analog board, but I'd hold off cleaning for now, as improper cleaning
can make it totally worse, as analog board is very sensitive for leakage. I have one PCB which have random errors, and plan to
debug it next week, so maybe then can help you for more specific diagnostics.

Quote
The cal seal is gone is this a problem or can the cal button be pushed?
No problem, cal button just unlocks calibration mode in main menu (Comprehensive calibration, manual PDF (http://dev.xdevs.com/projects/kei2001/repository/changes/service_manual/2001-905-01G%20calibrate.pdf)), in which meter will ask
you to provide precision voltages and resistances to it's input to perform self-cal.

I would not suggest doing so, unless your source is Fluke 5720A or similar grade calibration source.
If you send meter to calibration lab, they don't care if there is seal present or not :)

Tomorrow I'll send one of my K2001's (which i got pass self-test anytime everytime if powered on 110VAC mains) and K2400, will see
how it goes...

On chinese bbs some guy posted docprint corner of K2001 schematics, it's marked Rev R.

While mine analog boards are Rev L and Rev J.
You can find revision letter in analog board corner, near rear inputs fuse.

Mine: 2001-102-04L. 04 means layer, it's 4-layer PCB, so it's marked on every layer.

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=76357;image)

Quote
I must say I can hardly work on this project due to a lack of time so it can be that I will respond with a delay
No problems, take your time. Even while quick response is cool, we all here sharing just for fun, we still have stuff and work to do  8)

Interesting note:

I did some testing with variable input voltages (mains) using Chroma 61504 AC source (2KVA)

AC input settings: 90VAC, 132VAC, 180VAC, 250VAC - 50Hz - meter failed self-test with 200.1,200.6,200.7,201.2 (but still able to do measurements)
AC input settings: 90VAC, 132VAC, 180VAC, 250VAC - 60Hz - meter pass self-test without any errors, on all input voltages.
AC input settings: 90VAC, 132VAC, 180VAC - 400Hz - meter failed self-test with 200.1,200.2,200.6,200.7,201.2,401.1 (but still able to do measurements)
AC input settings: 250VAC - 400Hz - meter failed self-test with 200.1,200.6,200.7,201.2 (but still able to do measurements)

Something is screwy on that auto-selection input circuitry maybe...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 13, 2014, 07:15:05 am
the revision is p

I noticed it very often failed test after the click of the big white mechanical relay (k503?) near the big yellow capacitor. Maybe a coincidence. In cold condition it first failed earlier and now after warm-up with less errors.

I think it is still to early the draw a conclusion due to the low number of tests I did.

Is it possible some tuning in the instrument is not correct but just at the edge of pass/ fail?

I can also check what will happen if I hookup a variable transformer to change the mains voltage a little bit.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 13, 2014, 07:20:48 am
Cool, Rev P :D

I wonder, how many revisions they did in 20 years for 2001's PCB, if assuming one letter one revision is correct :D
Not like modern hardware development, revision 0 -> revision -> 1 -> EOL -> scrap :D

Different behavious on my unit was with change of mains frequency, not voltage. Except 250VAC level, all other voltage variances led to same result (I tried only 90,132,180 and 220,250VAC, as those are within meter specs).

When you perform self-test, you have nothing connected to meter inputs, correct?

Was meter used heavily since 2002, if you know? Maybe just faulty relay contacts.
Can you list errors in every conditions (worst case, and usual case after warmup) ?

Today's progress:

A/D buffer, gains, PDF (http://dev.xdevs.com/attachments/download/808/K2001J_AD_BUFFER.pdf)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 14, 2014, 05:40:45 am
Today I noticed something strange. When I set the instrument to 2w resistance measurement with manual range to 1GOhm and execute the test mode then I measure 0.1 GOhm. When I change range down and up it disappears. During this strange value that drifts slowly up I cannot measure resistance and it only starts to measure resistance when I toggle range.

bad relay?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 14, 2014, 01:10:48 pm
Hm, or solid-state switch (there are plently of DG211's there for ranges/function switches).
Let me check my meters later to see if they do similar :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jan86 on January 15, 2014, 08:06:39 am
I can confirm other 2001 instruments have the same issue/ bug.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 16, 2014, 05:53:47 pm
What about upgrade Model 2001 with new parts? :)

 >:D
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 17, 2014, 09:46:37 pm
In case anyone want jump in and join K2001 endavours, there is one with issues for sale on bay :)
eBay auction: #151210943549
Made in 1997

5 days to go.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 24, 2014, 12:00:14 am
Gone for $573 :) Hope it got into good hands.

Meanwhile, started design for new VREF to install in one of K2001's.

LTZ1000ACH with LT1112ACN8, +15V single-rail supply, VPG Z202 resistors (will try to order them).
Schematics attached.

Thinking maybe R3,R6 and R5,R4 could be better to try get VPG resistor network, as this is best way to have tempco same, thus keep ratio constant?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on January 24, 2014, 12:15:06 am
Does the K2991 use the same resistor network as the K2000? If so I may be able to find some spares.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 24, 2014, 12:37:57 am
No, not that I have on my revisions (maybe later one have it). Only K2002 shares TF255 with K2000.
But this is for another daughter board to replace LM199/399 to LTZ1000A , DIY stuff, so i'll try get VPG resistors (first will check cost)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 07, 2014, 02:05:22 pm
Well, time to bring some little life in this abandoned thread.

Got an update, first unit sent for Tek cal come back today, successfully adjusted.

(http://dev.xdevs.com/projects/kei2001/repository/revisions/0d89ad798460/entry/photos/K7/k7_cals.jpg)

This unit had cal last time in 90's, presumably by Keithley during manufacturing.

Had learn few things:

* Around 2V offset on 1000VDC range is due parts drift, compensated by calibration. I had this offset on most of my 2001's.
* Firmware A05 had issue with AC measurements on low freq (10 and 20Hz), it was fixed by firmware A08. Unless A08 installed unit was not able to pass calibration.

As received report (http://dev.xdevs.com/projects/kei2001/repository/revisions/2d120709098c/entry/cal/2001-0544257%20as%20received.pdf)
As returned report (http://dev.xdevs.com/projects/kei2001/repository/revisions/2d120709098c/entry/cal/2001-0544257%20as%20returned.pdf)

So prior to sending K2001's to callab - make sure you update ROM firmware chip to latest FW (A08 so far, not sure about "B" firmwares).

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 08, 2014, 04:35:00 am
Small update:

Checked K2001 current source in ohm's measurement mode, by using 2400 SMU in voltage source mode.

(http://dev.xdevs.com/projects/kei2001/repository/revisions/5bfa124d964b/entry/photos/K7/acal/ohms_check.jpg)

Also checked again self-test result on variable input mains:
AC Source - Chroma ATE 61505, local vsense

Now after calibration errors (200.2, 200.3 ? 401.1) only with low threshold voltage 90 VAC and 180 VAC with frequency 400Hz.
Before calibration and with firmware A05 it was failing all voltages with 50 and 400Hz, only 60Hz was passing.

Setup:

(http://dev.xdevs.com/projects/kei2001/repository/revisions/5bfa124d964b/entry/photos/K7/acal/ACK7-5.jpg)

Summary results (http://dev.xdevs.com/issues/869#change-1474).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 09, 2014, 06:34:33 am
Calibration constants from K2001 can be read using GPIB command.

Table C-2 of 2001-905-01G calibration manual (http://dev.xdevs.com/projects/kei2001/repository/raw/service_manual/2001-905-01G%20calibrate.pdf) lists the response to the :CAL:PROT:DATA? query. The response is an ASCII string of 99 numbers separated by commas, and is not affected by the FORMAT command.
Constants listed in Table C-2 are shown in the order they are sent.

Here values from cal'd unit #7 and from first 2001 (not calibrated) (http://dev.xdevs.com/issues/956)

Pretty sure all these stored in 24C16 I2C EEPROM located on digital board. Will read out it later on rest units.

EDIT:

And actually, seem like there is hidden 8.5 digit mode using remote control via GPIB on Model 2001 as well, like on HP's.

This query outputs 8.5 dig value as a readout
:FUNC 'VOLT:DC';:VOLT:DC:NPLC 1.000000E+1;:VOLT:DC:RANG 2.000000E+0;:VOLT:DC:DIG 9;:VOLT:DC:;REF:STAT OFF;:VOLT:DC:AVER:TCON REP;COUN 10;STAT ON;ADV:STAT OFF;
:FORM:ELEM READ;

DIG 9 means 8.5d, while DIG 8 is native 7.5 mode.

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=80504;image)

And yes, i tried DIG 10 too, it gave ERROR -222, value out of range, LOL  :-DD
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 09, 2014, 06:58:28 pm
As expected, calibration data stored in that I2C EEPROM as raw data.
I did not want to desolder IC, so borged a little I2C dongle to hook TL866 programmer (Thanks Dave, bought one for 60$ with bunch of adapters after EEVBlog video episode. Good tool).
There was a caveat - as I2C have open-collector lines, you don't want CPU to capture bus, in that case you will not be able to communicate with EEPROM by remote programmer.
Luckily - there is easy solution, tie RESET to ground, and there is a test post TP602, which easy to use to do so.
After keeping reset low, and power on - no problems to read/write EEPROM from TL866.

Whole setup, how i did it:

(http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/read_eeprom.jpg)

Binary image from digital board S/N A19956 ROM (http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/EEPROM_K1_A19956/X24C16P.BIN)

Quick look with hex-editor:

(http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/cal_data1.png)

Some values I was able to correlate to earlier read constant values from :CAL:PROT:DATA? query.
Need check what other formats are used for float-hex representation.

And there is some checksum algorithm to check ROM contents integrity, because if I try change calibration dates by hex editing - meter detects abuse and gives funny error :)

(http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/cal_corr2.jpg)+(http://dev.xdevs.com/projects/kei2001/repository/raw/firmware/cal_corr.jpg)

Amount of exclamation marks gives us feeling, that Keithley R&D were taking calibration serious enough  :-DMM
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 15, 2014, 03:28:45 am
Teaser:

(http://dev.xdevs.com/projects/kei2001/repository/entry/firmware/UV-ERASE/uv-c_2.jpg)

What I'm doing here? Any guess?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: sync on February 15, 2014, 03:35:24 am
Homemade weston cell? >:D
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 15, 2014, 03:52:34 am
Does it look like a cell, lol ?

Guess more.
It's something to do with photos above, but not directly related.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: sync on February 15, 2014, 04:01:14 am
Does it look like a cell, lol ?
The left fluorescent tube looks a bit like one.
(http://www.it-dlfh.de/b410.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 15, 2014, 04:02:54 am
No, i'm building LTZ1000 reference, no need any cells :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: sync on February 15, 2014, 04:07:32 am
And you destroyed all your CFLs so they can't disturb your measurements?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 16, 2014, 11:07:38 pm
(http://dev.xdevs.com/projects/kei2001/repository/entry/firmware/UV-ERASE/uv-c_1.jpg)

It was an mercury UV-C lamp for G23 socket, but I could not find any place to power it on normally , so just used CCFL inverter to create discharge in lamp :) Was desperate to erase UV EPROM 27C4096's for rest of my Keithley 2001's.

(http://dev.xdevs.com/projects/kei2001/repository/entry/firmware/UV-ERASE/uv-c_5.jpg)

Just disconnected starter bulb and capacitor, and provided high voltage to opposite cathodes to ignite discharge.

Around 3 min exposure above ROM was enough to erase it. TL866 programmed it well afterwards.
Now all boards have A08 firmware, which is good for cal. Not sure about "B"-version firmware's tho, how they
relate.

P.S. Meanwhile DC-DC convertor for front panel VFD which takes +5V and converts to AC filament voltage and +60VDC segments in calibrated unit ceased to work. Meter was just capturing log of LM399 breadboard overnight, and in morning next day i saw no display. GPIB worked fine, so no other damages. No smoke, no fireworks, just stopped working. Replaced digital board, reflashed calibration I2C EEPROM on new board, checked front panel board - all now working fine and measurements match. In such moments you appreciate modular construction, when can replace digital side without touching analog board. Will check pesky DC-DC convertor later, but initial check showed no 60VDC output, and current consumption over 1A (normally working digital board takes ~0.85-0.7 A on +5V).

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SeanB on February 16, 2014, 11:43:23 pm
That Phillips UV lamp will have a very short life with the way you are driving it. But with erasing for under an hour at a time you will have a lot of use before the cathodes go totally open. You should connect the unused wire on each side to the lead to reduce hot spots on the cathodes, it does work on IS lamps.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: casinada on February 17, 2014, 01:02:27 pm
If you need to erase an eprom, just expose it to natural light (sun) :) No need to play with broken glass unless is night time and you're in a hurry.
:)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 17, 2014, 03:19:26 pm
SeanB

Yes, I know, these lamps need hot plasma to recover their cathodes during operation, but current dirty way for couple minutes to erase UV ROM twice in year or so it will do fine.

casinada

Tried that, ROM was on balcony for 3 days, not worked, data still intact :) Maybe it was low UV days.

ALL

I managed to get Keithley 2002 into my hands, should I post about it here in thread too (as it's kinda similar to 2001) or create separate thread, as it's another league device (it is actually)?

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: chickenHeadKnob on February 17, 2014, 04:47:40 pm

ALL

I managed to get Keithley 2002 into my hands, should I post about it here in thread too (as it's kinda similar to 2001) or create separate thread, as it's another league device (it is actually)?

Please create a new thread, if only for search purpose/posterity. I love your photography and the teardown  and repair threads will be searched and refered to by others years in the future, particularly by non-forum members who get a google hit. Much personal self-interest in the 2002. Thanks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 23, 2014, 03:54:15 am
:-) Need find 24C16 in DIP package first to try more..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on February 23, 2014, 04:58:57 am
:-) Need find 24C16 in DIP package first to try more..

if there's one in a 2015THD then I can probably spare one.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 23, 2014, 05:03:20 am
Don't worry, I2C EEPROMs are popular as a dirt, i'll find one somewhere.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 02, 2014, 12:47:10 am
Based on TiN's recommendation, I am going to replace the electrolytics in my four 2001 meters. Do you have specific recommendations on what replacements to use (brand/series)? You mentioned also replacing diodes, which ones are you referring to, can you highlight them in a photo or give part numbers? I really appreciate all the hard work you've done with reverse-engineering the schematics.

You have at least one meter with a MEM1 or MEM2, correct? Can you read and post a copy of the NVSRAM contents here?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 02, 2014, 01:27:02 am
Congratulations, that's a correct questions you asked  :-+

Any meter can be modified MEM1/MEM2, make sure you have DS1245Y available on hand.

Can you help to please my eyes with your meters photos? :) Analog board, ADC boards and digital board?
I'll give you exact guideline what to do.

I used Chemicon KZE capacitors, but other first-tier vendor caps should be good too. Use same values, as original ones.
Be careful not to overheat pads, they are very easy to overheat and peel off, as no polygons there, just a thin trace.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 14, 2014, 10:37:32 pm
Little update.

One day I powered up one of my 2001's and was greeted by no display on VFD. Quicky suspected DC-AC inverter on digital board, and after quick check
that was a cause, there were no +55VDC to drive VFD segments.

Another 2001 have that inverter done as a custom module, while on other units it's just a ERG INC. E705 custom filled black block.

(http://dev.xdevs.com/projects/kei2001/repository/revisions/9dcad2b379ca/entry/schematics/u625_sch.png) (http://dev.xdevs.com/projects/kei2001/repository/entry/photos/U625/U625_top.jpg)

Module takes +5VDC input and outputs +55VDC and ~5.5VAC for filament.

(http://dev.xdevs.com/attachments/1000/dcacdc.png)

Here's recovered schematics:

(http://dev.xdevs.com/projects/kei2001/repository/entry/schematics/u625_sch.png)

Anybody knows similar DC-AC blocks to replace dead one?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jpb on July 15, 2014, 12:50:51 am
According to the repair manual it is a replaceable part :
(http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%202001%20Repair.pdf (http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%202001%20Repair.pdfU625))

U625

MOD,DC-AC/DC, 5DV-5VAC/60DC,E705-E905VF,MO-30

Keithley part number :182-170B

I would try Keithley/Tektronix first. For my 2015 they were quite happy to supply a new VFD display and it was quite reasonable (£53 + VAT).

Edit : Though I note the manual has the output as 60VDC rather than 55VDC.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: cyr on July 15, 2014, 01:08:05 am
One of mine has B15 firmware, which is almost the newest (there is a B16). Are you interested in the B15 firmware? I need an excuse to finally buy a MiniPro programmer.

Did you ever dump your B15 firmware? I would be very interested in a copy...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on July 26, 2014, 11:22:58 pm
Just got a (used) 2001. Working fine so far. Only issues are the fan sounding like being at the end of it's lifespan, some dirt around the fan and some dim pixels on the VFD.

In addition to replacing the fan I plan to replace the thick electrolytic caps as suggested here and order a DS1245Y for mem2.

Any interest in photos of the boards? Analog board is rev. P, ADC rev. J, digital rev. K. Firmware ist B10. From the datecodes the build date seems to be 1999 or shortly after.

What are my options about replacing the VFD? Can you get just the VFD as spare part from Keithley or is it always the whole front panel? I guess that getting the original from Keithley isn't cheap, so any other ideas?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 26, 2014, 11:35:49 pm
Congrats. Sure, please make photos of your hardware, ill add into 2001 revisions collection.
I dont have analog boards with rev.P

Also if you have tools its worth to get dump of firmware B10 and calibration data (stored in 24c16 i2c eeprom near cpu)

As of VFD, its tricky process. I was replacing VFD on Keithley 2400 before, it took an effort to carefully desolder it (i used solder wick to free every single pin from pcb). Be careful not to overheat pins as they are not very robust on glass.
Try to get VFD from Keithley or a front panel, I'd like to hear how much that would cost. Alternative option is to buy keithley 7001 from ebay with verified good VFD and replace VFD from there. Glass itself is same in 2001/2002/24xx/26xx Keithley's but front panel pcb is different.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 26, 2014, 11:38:42 pm
P.s. as of MEM2 upgrade, just replacing NVRAM chip is not 100% enough, i had plans to post article about proper procedure, but got other stuff to do and never finished it yet.

Could be a good reason to do so to help you :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on July 27, 2014, 12:01:28 am
Hi,

thanks for your quick answer. So I'll contact Keithley and see what they offer me about the VFD and front panel. I'm not afraid of a bit of soldering, so I'll compare the prices to 7001 scanners.

Will make proper photos of the board when I change the caps. Unfortunately I don't have a EPROM reader at hand to get a firmware dump.

About the MEM: currently there is sitting a LH5164A-10L SRAM in the socket, the jumper is in the STD position. Is that normal? I've seen several photos where the socket is completely unpopulated without the MEM option.

And a probably stupid question: whats the best way to unmount the analog board? I guess you remove the front panel and slide it out to the front. But what about the rear input sockets? Do you have to unsolder them or is there a trick to get them out intact?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 27, 2014, 12:32:00 am
I have email notifications on phone, ha-ha.

If you have GPIB connectivity, you can read calibration constants via GPIB.
It can be useful if your digital board fail, as once happened with one of my K2001's (VFD U625 PSU block failed).
I listed procedure and data result on my site - http://dev.xdevs.com/issues/956 (http://dev.xdevs.com/issues/956)

I had SRAM on all my STD K2001's too, it's normal to store all data till unit is powered. I never saw unpopulated KI2001 NVRAM socket yet.

Way to unmount APCB is next:

* Remove top black cover on analog PCB (APCB).
* Remove ferrite bead blocks on front and rear input cables, if your unit have them.
* Disconnect front and rear input cables from connector (they quite firm, so you will need to apply some force, but not too much). White cable from front AMPS input is soldered to APCB, so leave that alone for now.
* Disconnect power transformer connectors from APCB and digital PCB.
* Disconnect earth wires from transformer, unscrew one screw holding transformer bracket and carefully remove transformer
* Remove metal clip holding FET and resistor at chassis near mains input.
* Unfix BNC on rear back
* Release push button levers (Front/rear inputs switch to front panel and power switch)
* Disconnect ribbon interface cable from digital PCB
* Now, carefully slide analog board towards front panel.
* Take APCB and lift it starting from front panel side, it should go freely.
* Desolder AMPs input wire from APCB, and you are done.

Be careful with plastic align notches on bottom APCB cover, they are easy to break :) After some practice you will be able to do all this in 2 minutes.
Also avoid touching APCB surface with fingers around VREF area, contamination can easy cause nanoamp sources to fail due to leakage on PCB, and yours ohms on high ranges will fail.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on July 27, 2014, 01:28:54 am
Thank you for your detailed unmount description. Will try that once I got the caps.

I planned to dump (and post) the cal eeprom, that should be easy to do with my bus pirate as it is just I2C.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 27, 2014, 01:30:45 am
Keep CPU at reset then, like I described earlier pages in this thread :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on July 28, 2014, 11:13:37 pm
P.s. as of MEM2 upgrade, just replacing NVRAM chip is not 100% enough, i had plans to post article about proper procedure, but got other stuff to do and never finished it yet.

Could be a good reason to do so to help you :)
I am very interested in this information. Please tell! ;D
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on August 02, 2014, 01:04:49 am
Just got the offer from Keithley about the VFD:

When they got acquired by Tek they changed the part numbers. The VFD changed it's part number from "DD-51C" to "RPT-2001-110". This is a "Display board assembly", it includes the VFD and the board directly attached to it, but not the keyboard and so on.

They offered me the part for 375 EUR, with VAT that is 450 EUR. Wow, that is just a bit less than I payed for the whole 2001.   :wtf:

Will now reconsider changing the VFD, maybe I buy a cheap used 2700 scanner and transplant the VFD from there.

Or does somebody have a matching VFD lying around as spare and wants to sell it?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: jpb on August 02, 2014, 01:29:29 am
Just got the offer from Keithley about the VFD:

When they got acquired by Tek they changed the part numbers. The VFD changed it's part number from "DD-51C" to "RPT-2001-110". This is a "Display board assembly", it includes the VFD and the board directly attached to it, but not the keyboard and so on.

They offered me the part for 375 EUR, with VAT that is 450 EUR. Wow, that is just a bit less than I payed for the whole 2001.   :wtf:

Will now reconsider changing the VFD, maybe I buy a cheap used 2700 scanner and transplant the VFD from there.

Or does somebody have a matching VFD lying around as spare and wants to sell it?
I just bought (7th July) and replaced the VFD on a Keithley 2015, they wouldn't sell me a board (couldn't find a part number) but just the VFD (DD-52) was £53 + VAT. This is a simpler VFD than the one on the Keithley 2001 but I would think that if you can persuade Keithley to sell you a DD-51C it would be more like a 100 Euro (just a guess).

A word of warning, as I was trying to remove the old VFD in tact I managed to damage one of the tracks on the board when desoldering. Fortunately I could do a bodged solder fix, but if I was to do it again I'd sacrifice the old VFD and cut the pins and then desolder them separately.

EDIT : another word of warning, on the Keithley 2015 the VFD is held to the board by thin double sided sticky tape (a bit like electrical tape but with glue on both sides). Part of the reason I damaged the track was I was prizing the display away from the board and it wasn't quite desoldered. It would certainly be easier to just replace the board but I didn't have that option.

Keithley seem to charge widely different prices. I thought £53 for the VFD reasonable, but I also bought a tiny plastic bit that holds the board in place (mine had broken when I received it) and just one of these cost £9 + VAT!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 02, 2014, 01:39:32 am
Ouch, 450 is a lot. You can get another dead 2001 on bay for that, just like I did 2 years ago, ending up with 7 DMMs  :-DD

And beware, 27xx, 2000, 2010, 2015 series DMMs are using simpler segment VFD, while 2001,2002,700x,24xx,26xx use dot-matrix dual-line VFDs.
There are some 7001's on sale now with working VFD in 100-150usd range, plus few "for parts" for less, but could not power on/no proof that VFD ain't cracked.

I got 2400 SMU before with broken VFD, shown few photos on related thread: http://www.eevblog.com/forum/testgear/keithley-2400-sourcemeter-review-and-teardown (http://www.eevblog.com/forum/testgear/keithley-2400-sourcemeter-review-and-teardown)
There was caveat, pins formed in checker field on 2400 front panel PCB, while on mine 2001's and 7001 VFD is just single pin row. So had to do some bodging.

For sure, cut pins on broken display with sharp knife first, the remove remnants and solder from holes with copper wick.
As of removal good display - use solder wick to remove solder and free pin in it's hole. It will take some time, but this way you not risking of killing VFD contact bond to glass (which likely to happen if you try use heatgun to reflow PCB and apply force to release VFD from it).

P.S. I don't have spare VFD, sorry.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on August 02, 2014, 01:44:17 am
I just bought (7th July) and replaced the VFD on a Keithley 2015, they wouldn't sell me a board (couldn't find a part number) but just the VFD (DD-52) was £53 + VAT.
This price is similar to what Agilent is offering for a replacement of the 34401A VFDs.

This is a simpler VFD than the one on the Keithley 2001 but I would think that if you can persuade Keithley to sell you a DD-51C it would be more like a 100 Euro (just a guess).
I tried that but they said it isn't available anymore. Don't know if that is true, but I sent them an extra email reply asking for it.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on August 02, 2014, 01:49:52 am
And beware, 27xx, 2000, 2010, 2015 series DMMs are using simpler segment VFD, while 2001,2002,700x,24xx,26xx use dot-matrix dual-line VFDs.
Sorry, mixed that up. I meant 700x.

For sure, cut pins on broken display with sharp knife first, the remove remnants and solder from holes with copper wick. As of removal good display - use solder wick to remove solder and free pin in it's hole. It will take some time, but this way you not risking of killing VFD contact bond to glass (which likely to happen if you try use heatgun to reflow PCB and apply force to release VFD from it).
Thanks for the tips. But I got a true THT rework station from JBC. The special desolder tip can heat while the pump sucks the molten solder at the same time. So no more desolder wick or cut pins needed. Didn't have any desoldering problems anymore since I got that station.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: electronic_eel on August 14, 2014, 05:25:25 am
I bought one of the broken 7001 switch units on ebay and asked the seller to send me just the front panel to save shipping costs. Today I collected it from the customs office. Before I start soldering on my unit, I just hooked up the 7001 front panel to my 2001:

Meet the Frankenmeter   ;D

The defect in the 7001 must've been somewhere else (I guess leaked caps, mfg date of the ICs on the front panel was '92) - the vfd is working fine. It certainly isn't brand new, but readability is good and a big improvement from the vfd I have on my 2001.

As you can see the display portion is fully compatible between the 2001 and 7001. But the keys are completely different, so you can't navigate in the menu and so on.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 14, 2014, 09:09:27 am
If you look carefully, original 2001 front panel PCB, microcontoller on it is programmed to 7001-800-A01 firmware.
And front panel MCU talks to main CPU via simple UART protocol. And that's same with 2002,24xx,26xx units which share same display ;)

I have idea for long time already to have one of meters converted to mini-ITX PC, as motherboard fits nice inside instead of analog board. Would be neat little computer
to install in rack together with measurement gear, for datalogging/internet control for example :) Maybe I'll make that happen one day.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on September 10, 2014, 07:19:23 am
Hi, I am having trouble repairing Keithley 2001
Self test reported these error codes:

201.3   Test Cal Zero
300.2   1.75V Reference, x5 Gain
304.7   4.4nA and 770nA Ohms Sources
310.1   Amps Protection
412.1   AC Amps Switch

Sometimes it will blink „owerflow“ between readings and every other range will measure approximately 1/2 of estimated value.

Could somebody share the complete schematic for this analog board?
Thank you in advance for your help
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 10, 2014, 09:31:41 pm
Anyone opened meter before?
Check input circuits, 310.1 suggests there might be some issue.

Check voltage on ADC Input when running diagnostics item 2V div by 1 * 5.
Also check REFIN voltage. Should be around 7VDC stable, it's output from LM399 reference.

There is no complete schematic for 2001 in public, not that I aware about of any.
But you are welcome to join efforts of reversing one if you want (http://dev.xdevs.com/projects/kei2001/issues).
Even little help like taking detailed photos of your boards helpful ;)

Latest schematic pieces are posted here (http://dev.xdevs.com/issues/859)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on September 12, 2014, 07:52:35 am
I don't now if anyone opened the meter. It is possible, but boards looks untouched.

Circuit 310.1:
CR309 and Q314 seems to be OK
CR305 has internaly disconnected diode between pin 3(AC) and 4(-)
I measured 14ohm resistance between pins 2(AC) and 3(AC) on board (CR305 unmounted)
It that OK?
It's  hard to track signal lines.

ADC Input voltage, when running diagnostics item "2V div by 1 * 5", is cca +3.180V.
Also some voltage is on pins 2, 3 6, 7 of U318.

REFIN- on ADC board is -10.330V
LM399 seems to be OK

I replaced CR305 with KBU8, these errors remained:

201.3   1.75V Reference
300.2   1.75V Reference, x5 Gain
304.7   4.4nA and 770nA Ohms Sources
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 12, 2014, 02:43:41 pm
Quote
REFIN- on ADC board is -10.330V

I'm afraid that's not OK. It should be +7.xxx VDC.
Check U330, U328, U317, U322, U304

Quote
304.7   4.4nA and 770nA Ohms Sources

This is common error if there is any leakage on PCB near U322,U325,U333.
If board is really clean - check U333, Q317, U323, U325,U332.

If u had broken CR305, it's protection for AMPs input, check also Q310,Q305,Q309,Q307 (big transistors near CADDOCK network).

I can help you with reference measurements later, if you post photos of suspected areas with your results :)

--------

Meanwhile I got some addition to my broken Keithley's collection :D

It's borked Model 2000 this time. Why I bid on it? Well, I thought somebody else will win, haha.
Quote
This units powers up but not working it is mainly for part or repair, what you see in the pictures is exactly what you going to receive

It's pretty banged up, but display still intact, and units powers on, according to seller's photos.
So will be interesting to play with lesser brother to 200x's. Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.

Will post endeavors about it when I receive it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ElektroQuark on September 12, 2014, 04:37:26 pm
Quote from: TiN on Today at 03:43:41 PM (http://www.eevblog.com/forum/index.php?topic=21117.msg511553#msg511553)
Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.


Any link to it?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on September 13, 2014, 12:03:08 am
I checked reference circuit again
Voltage on U328 between pins 2 and 6 is 6.9..V and it's stable
Voltage between pins 2 and 3 (U328) is stable zero.
I think it's OK.
Voltage between pins 7 and 13 on U330 is 6.9..V
I don't sure for purpose U330B.

Voltage between -VREF and SCOM on ADC board is -10.330V (-VREF is negative)

Q310,Q305,Q309,Q307 seems to be OK

EdoNork: I don't found any schematic from chinese :(
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ElektroQuark on September 13, 2014, 12:14:03 am
Quote from: EdoNork on Yesterday at 05:37:26 PM (http://www.eevblog.com/forum/index.php?topic=21117.msg511585#msg511585)>Quote from: TiN on Today at 03:43:41 PM (http://www.eevblog.com/forum/index.php?topic=21117.msg511553#msg511553)
Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.


Any link to it?


Just found it. It's HERE (http://dev.xdevs.com/issues/874).

 Thank you.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 13, 2014, 12:52:03 am
Yea, i rehosted it on my site, but it's downed right now due to server internet issues.
Original author of 2000  schematics is from bbs.38hot.net forums.

SKE

U330 is precision multiplier/divider for reference voltages, using flying capacitors. Check LTC1043 datasheet for more details.
I'll do measurements tomorrow, i have exact same revision boards u have.

Also worth to check VF- VF+ voltages, should be around 38V. And if I would be you - i'd replace all electrolytic caps on analog board, your meter is old, and those caps are dying. You can see what could be a result few pages before in this thread...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on September 13, 2014, 02:05:17 am
Capacitor check was first think I do.
I was found small amount of electrolyte under the capacitors.
Even though orginal capacitors has good capacitance and ESR (measured at 100Hz and 1Khz)
I decided to replace capacitors with Panasonic EEUFR series.
Floating voltages seems to be OK.

In the pictures of analog board are new panasonic capacitors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jaap on September 23, 2014, 09:01:24 am
Hello All, I'm new to this list and this is my first activity on this forum.

Since one week I have a 2001.  I got it for free. At first it did not start up OK every time. Since then I took it completely apart. Changed the power supply caps (tip from this forum). Was necessary too - found some cap fluid. Cleaned some contacts and did some re-soldering on previous repairs and since then it starts up perfectly all the time. Build in test are all OK.

Now my question. I would like to upgrade to MEM 2 because of more setting storage. As I have read I need a DS1245Y for that. But is that all to it? Probably not.


TiN said before:
P.s. as of MEM2 upgrade, just replacing NVRAM chip is not 100% enough, i had plans to post article about proper procedure, but got other stuff to do and never finished it yet.

Could be a good reason to do so to help you :)



TiN, could you help me a bit more on this?

Thanks in advance.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 24, 2014, 10:52:55 am
Okay, let me finish guide today.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 24, 2014, 02:24:37 pm
Done :)

Article of memory option installation on Keithley 2001/2002 (http://xdevs.com/article/kei200x-mem/)

I don't have DS1244 or DS1248 yet, will update it after for K2002.

Hope this helps, let me know if any questions.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jaap on September 25, 2014, 01:27:44 am
Hello Illya

Thanks for the quick response and your work. I will start on this soon and will let you know my progress.

Jaap
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 25, 2014, 02:13:18 am
Hope it helps.

Should be no problems to get it working. I had only issue finding programming tool which can write those few bytes into DS1245/44/45/48Y

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/mem_start.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on September 25, 2014, 03:46:35 am
Hope it helps.

Should be no problems to get it working. I had only issue finding programming tool which can write those few bytes into DS1245/44/45/48Y

Which tool do you use? Software looks like TL866 but not exactly same as mine.

Nevermind.... I see that you are using TL866, and you selected DS1230 which appears as a R/W EEPROM, not DS1245, which shows up as SRAM, which can't be read or written to, just tested. I guess I'll need to rig up a socket adapter to convert the 28 pin to 32 pin properly.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 25, 2014, 10:30:31 am
Yes, TL866 cannot write 1245's :( I sent mail to vendor to add support for bigger DALLAS NVRAMs, but got no reply or progress :(.
To write DS1245's I used another programmer at work.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on September 26, 2014, 12:08:30 am
Yes, TL866 cannot write 1245's :( I sent mail to vendor to add support for bigger DALLAS NVRAMs, but got no reply or progress :(.
To write DS1245's I used another programmer at work.
I will write them an e-mail too. It should not be difficult for them to do since the DS1230 (32k) is already supported.

I took a DIP socket and connected the DS1245 Vcc to the DS1230 Vcc pin (N/C on DS1245), and I wired up a 2-position DIP switch to select 0/1 for Address bits 16,17. Then I can put the DS1245 into the socket, the socket into the TL866, and I can use the DS1230 device in TL866 software to read/write the DS1245, but only one 32 kB block at a time. I cleared the memory, programmed the serial number, and it works perfectly. Previously, the meter indicated MEM2 installed, but would not save setups, and would not restore the reading memory. Now I can save/restore 10 setups, and I have a 128 kB non-volatile readings memory. Fantastic. :-+

The only issue I noticed is that my DS1245 is likely counterfeit. I say this because the pin spacing is slightly too tight (<0.1000"). It will fit fine in a normal spring-contact IC socket, like the one in the K2001, but does not fit into a machine-pin socket; the pins at the ends of the IC bend and it just won't go in without damage. Oh well, that's what you get for buying from Chinese ebay sellers. It was cheap and it works, so  :-//
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on October 08, 2014, 01:07:11 pm
Hey guys, I just picked up a Keithley 2000 for a steal on eBay. Does anyone with a 2000 or 2001 parts unit have an “amps jack” from the front panel they could sell me? (You know, the one you twist out to get to the fuse.) Aside from applying some retr0bright to the front panel, that’s the only thing this little guy needs! (By the way, I think this is the part number: JACK, CURRENT INPUT; 2001-312D)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jf2014 on October 08, 2014, 07:41:37 pm
Hey guys, I just picked up a Keithley 2000 for a steal on eBay. Does anyone with a 2000 or 2001 parts unit have an “amps jack” from the front panel they could sell me? (You know, the one you twist out to get to the fuse.) Aside from applying some retr0bright to the front panel, that’s the only thing this little guy needs! (By the way, I think this is the part number: JACK, CURRENT INPUT; 2001-312D)

hi
I purchased direct from Keithley Service (Germany) - JACK, CURRENT INPUT ;2001-312 price 9,00 EUR
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: KJDS on October 09, 2014, 12:44:33 am
Hey guys, I just picked up a Keithley 2000 for a steal on eBay. Does anyone with a 2000 or 2001 parts unit have an “amps jack” from the front panel they could sell me? (You know, the one you twist out to get to the fuse.) Aside from applying some retr0bright to the front panel, that’s the only thing this little guy needs! (By the way, I think this is the part number: JACK, CURRENT INPUT; 2001-312D)

hi
I purchased direct from Keithley Service (Germany) - JACK, CURRENT INPUT ;2001-312 price 9,00 EUR

It's worth checking to see if the case is damaged,  there's a tiny lug in the plastic hole that holds the "amps jack" in place. If that is broken then you may need to improvise an alternative fixing. I'm assuming that it is the same as the 2015THD.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on October 09, 2014, 02:05:26 am
Yeah the molded portion of the front panel that holds it in place is alright. (It actually came with the jack, but all the plastic was torn to hell on the jack, like someone had used pliers to open it.)


Sent from my Smartphone
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on October 09, 2014, 04:05:50 am

Hey guys, I just picked up a Keithley 2000 for a steal on eBay. Does anyone with a 2000 or 2001 parts unit have an “amps jack” from the front panel they could sell me? (You know, the one you twist out to get to the fuse.) Aside from applying some retr0bright to the front panel, that’s the only thing this little guy needs! (By the way, I think this is the part number: JACK, CURRENT INPUT; 2001-312D)

hi
I purchased direct from Keithley Service (Germany) - JACK, CURRENT INPUT ;2001-312 price 9,00 EUR

Spot on man. I just got an email back from Keithley; $11 for a replacement, with a $30 minimum order. So maybe I'll go ahead and get those 2x4 Wire probes for my DMM4020.


Sent from my Smartphone
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: JayGee on October 18, 2014, 10:35:53 pm
Also struggling with  2001.
Here are my cct's.
Added layout of A/D as mine did not have all components marked.
Hope it helps.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 19, 2014, 03:18:44 pm
Good job, JayGee.

What are the issues with yours 2001?
Can I rehost your schematics on my site as well?

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on October 23, 2014, 08:36:05 am
@timb
do you still need this white jack?
It should cost me 2 eur to ship it (and hope it will arrive) to US from a K2000 donor ...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on October 24, 2014, 10:24:11 am

@timb
do you still need this white jack?
It should cost me 2 eur to ship it (and hope it will arrive) to US from a K2000 donor ...

I do! PM me your email and I'll PayPal you shipping and a few bucks for your time. (Tektronix has a $30 minimum order, so this will still be cheaper.)


Sent from my Smartphone
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 02, 2014, 07:26:17 pm
I do! PM me your email and I'll PayPal you shipping and a few bucks for your time. (Tektronix has a $30 minimum order, so this will still be cheaper.)

Hi Tim. I will be out for a travel up to the end of next week. As soon as back I will arrange the shipment. Just pm me if I forget :-P
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jaap on December 18, 2014, 12:16:20 am
"Error: ID code = 510     Reading buffer data lost" message after adding MEM 2

As I said in september (how times flies) I would like to upgrade my 2001 with the MEM 2 option as described by TiN on September 24. Yesterday I received my TL866A programmer from China, the DS1245Y was already waiting for that. The DS1245Y chip cannot be programmed yet, so I did it like macboy described on September 26th, thanks for the tip. I did not use DIP switches though, I connected pin 2 (A16) and pin 31 (A15) to pin 16 (GND) on a prepared socket. See pictures.

After insertion in the 2001 all is OK. I now have 10 settings I can store. I checked all ten.

But there is an extra message at startup. Just after the "Calibration due" message, I get a "Error: ID code = 510     Reading buffer data lost" message. It disappears in one second and the 2001 functions normal as far as I can see. I looked at the Error: ID code list in the Calibration Manual, but that does not go higher then +440 (the + is not in my message, neither a - ).
Question now is, what to do next. Someone who can help?

And TiN, just like you I added two zeroes at location 7 , just after the serial number. Is that the way to do it? I did not read anything about that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on December 18, 2014, 12:28:26 am
"Error: ID code = 510     Reading buffer data lost" message after adding MEM 2

As I said in september (how times flies) I would like to upgrade my 2001 with the MEM 2 option as described by TiN on September 24. Yesterday I received my TL866A programmer from China, the DS1245Y was already waiting for that. The DS1245Y chip cannot be programmed yet, so I did it like macboy described on September 26th, thanks for the tip. I did not use DIP switches though, I connected pin 2 (A16) and pin 31 (A15) to pin 16 (GND) on a prepared socket. See pictures.

After insertion in the 2001 all is OK. I now have 10 settings I can store. I checked all ten.

But there is an extra message at startup. Just after the "Calibration due" message, I get a "Error: ID code = 510     Reading buffer data lost" message. It disappears in one second and the 2001 functions normal as far as I can see. I looked at the Error: ID code list in the Calibration Manual, but that does not go higher then +440 (the + is not in my message, neither a - ).
Question now is, what to do next. Someone who can help?

And TiN, just like you I added two zeroes at location 7 , just after the serial number. Is that the way to do it? I did not read anything about that.

Glad to know that my tip helped.

To get rid of the Reading buffer data lost error, you need to initialize the reading buffer memory. You can either store some readings, or clear the buffer. To clear the buffer, press CONFIG, STORE, and select CLEAR-ALL in the menu. Or just press STORE and ENTER to store some readings.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on December 18, 2014, 12:43:11 am
Yes, macboy is the man. :) MEM2 for everyone. I tried writing Miniprog email to add support DS1245, 1243, 1248 and 1251 but they had no reply :(.

Meantime I am getting up my references to make 2V and 20V standards for calibration of my 2001s and 2002.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jaap on December 18, 2014, 06:10:04 am
macboy, you are perfect. Thanks again. Finally my DMM is ready for calibration. Don't know when or where, but I hope a colleague radio amateur I know, still works at the Navy Calibration Lab here in the Netherlands. Will keep this list updated. Happy hobby days,      Jaap
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 08, 2015, 03:48:45 pm
Just in case anybody want jump into this , there is a broken 2001 for sale on bay (http://pages.ebay.com/link/?nav=item.view&id=201258481835&alt=web). No power on, pretty old serial number, so lots of problems might be there. Or can be as simple as broken fuse or VFD screen.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on January 10, 2015, 02:23:48 am
@Tin nobody reply but everybody is going to bid on it :-)  :-DD
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 08, 2015, 04:50:36 am
Thanks to TiN and JayGee for the info I needed for restoring one of my 2001s.

I recently pulled out the meter from storage and found JayGee's diagrams from the previous page. Before storage, I replaced the leaking caps on the main board but I had several errors.
These were 407.1,410.1,411.1, and 411.2. They all had in common U505:Q8. I found a couple of problems with this circuit. U505 had already been swimming in electrolyte. There was damage to the pcb around this part. I replaced it and cleaned up the area. I was able to find R576 had a burnt area around the resistor. I replaced that resistor from a second board. Upon further t/s, I found that a hairline trace under R576 that lead to CR512 had burnt open. This was easily verified from U505:11 to CR512 on top of the board. I fixed the trace under R576 and retested the meter.

All tests pass fine now and I am looking forward to fixing the second unit. Hopefully I can fill in the dime sized hole and add bodge wires between traces. If not, I can keep it as a parts unit.
The A/D converter board also fails. It originally came from the working meter. It appears that there is excessive noise somewhere in the converter.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on February 09, 2015, 06:16:09 am
I am attempting a similar repair and seek some advice before doing anything too drastic.  Leaked electrolyte, like so many others.  Attached are pictures from right after I removed the parts and then after I removed a bunch of char.  On the CR513 picture, the right pad has been lifted up, revealing significant charring below.  I fear the same is true of the other pad, given how it looked before cleaning.  I don't feel confident that I've removed all the char from between the traces in the C117 area.  You can see an exposed inner layer trace there, too.

I'm wondering if I should drill out the affected board areas?  There's not too many traces in the C117 area, but there's a lot of stuff going on around CR513.  Or is there a better way to restore the integrity of the board?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 09, 2015, 07:43:05 am
I am also trying to repair under C117. The problem is that there are traces below the surface. I had at least two inner layer traces burnt in half. My board seemed to have as much damage as yours (if not more). When I started to cut out the burnt areas, it became apparent that the damage covered a bigger area.

When I removed the bad caps on the newly repaired meter, I took some pics in front of a bright light to get an idea where the traces connected. I drew some colored lines to map them out.

I started working on repairs yesterday and I am not sure if I can remove all the char. It is worth the effort now that I have one functional meter for comparison troubleshooting. I have worked with people that were skilled pcb repairers but I don't possess the experience. They typically used PACE repair stations with variable speed grinders. I think drilling out the char is probably your best bet, luckily there doesn't appear to be a lot going on below the surface. At least the burnt area appears to be far enough away from the via between the two solder pads.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 18, 2015, 09:47:56 pm
Some addition to firmware collection for Model 2001, thanks to Todd.

Now have:

Version A05
Version A06
Version A08 (I was told it's latest, when sent my 2001 to Tek calibration. Also without A08 they could not finish calibration due to AC ranges)
Version B07
Version B08
Version B10
Version B15

Download links (http://dev.xdevs.com/projects/kei2001/repository/show/firmware)

I don't know what is difference between "A"-versions and "B".
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on February 19, 2015, 01:49:16 am
Some addition to firmware collection for Model 2001, thanks to Todd.

Now have:

Version A05
Version A06
Version A08 (I was told it's latest, when sent my 2001 to Tek calibration. Also without A08 they could not finish calibration due to AC ranges)
Version B07
Version B08
Version B10
Version B15

Download links (http://dev.xdevs.com/projects/kei2001/repository/show/firmware)

I don't know what is difference between "A"-versions and "B".
Very nice. Have you ever tried to upgrade the firmware? I assume that this will cause loss of calibration, what do you think? I have two at B10 and one at B15, and a blank set of EPROMs but I am hesitant to upgrade the B10 to B15 in case I lose the calibration. I suppose I could just back up the I2C EEPROM in case of trouble.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 19, 2015, 02:52:56 am
Yes, I had upgraded few units to A08. As of calibration - you can always save EEPROM contents and revert it back, with no problems.
I actually had issue with calibrated 2001 with VFD DC converter, so just swapped digital boards and copied firmware and calibration ROM to other board without any issues.

Plan to change reference on second 2001 to LTZ1000 unit to compare for DCV noise performance, as it's easy to get 8.5 digits from 2001, but they are way noisier than from 2002.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 19, 2015, 04:05:12 am
I never received a reply from Keithley on their FW upgrade release notes. There is only one mention on the website which is for version B16

http://www.keithley.com/data?asset=13096 (http://www.keithley.com/data?asset=13096)

It refers to the addition of an average-responding RMS converter. It also states that it is for serial numbers < 0936521. I wonder if the later (A) fw versions were for a different hw configuration like flash memory or a single prom?

I see that TiN's K1 has the A version and K2 has the B version. Maybe the A08 includes the additional features of B16? Perhaps this is why the calibration failed?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: cyr on February 19, 2015, 05:32:56 am
I thought "B" was the later revision, and that late units have the larger flash memory needed.

Is A08 really the latest, or only the latest of the A series?

Anyway, time to upgrade my B06 unit to B15.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 19, 2015, 01:25:24 pm
Original FW on K2001 sent to cal was A05. They tried calibrate it, but could not do until updated FW to A08.
All my Keithley's are way below 09xxxxx S/N numbers, actually 054xxxx S/Ns

First unit: A06, Rev J digital board with single ROM chip, Rev L analog board
Second unit: B07, Rev K digital board with two ROM chips (Even and odd), Rev L analog board
Third unit: missing ROM chip :), Rev H digital board with single ROM socket
Forth unit: A08, Rev H digital board with single ROM socket, Rev J analog board
Fifth unit: A08, Rev G digital board, single ROM
6th unit: same as 5th.
7th unit: A05, Rev G digital board, single ROM socket, Rev L analog board
Keithley 2002: A09, Rev K digital board with two ROM chips (even and odd).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 20, 2015, 06:03:57 am
TiN,

I would love to see the results with a LTZ1000, especially after seeing your reference boards. I am guessing you will be looking at replacing the stock metal foil resistors with lower tempco versions if all goes well to improve your resistance measurements?

I also noticed that they could have used a better AD687 variant for the TRMS converter.

I have currently fixed the self-test errors on my #3 meter, but I have to track down the cause of a 6.9V offset on ACV. All other functions appear to work. Either I put in a bad part from meter #2 or something else near that part has died.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 20, 2015, 11:59:44 am
Did you try running AC calibration? (it does not need external gear).

What errors you had in 2001. I have unit on my desk now with 304.x, 306.1, 309.1, 407.x, 408.6, 410.1, 411.1, 411.2 errors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 20, 2015, 04:11:34 pm
The errors that I had were 406.6,407.1,407.2,407.3,408.6,410.1,411.1,411.2.

Fortunately the service manual pointed me in the right direction. I had to follow the SELFTEST and SELFTESTEN outputs from U505 pins 5 and 6. I ended drawing out a basic schematic of the signal flow and found that the levels from U513:9&10 were not going high enough (1.1v) to change U513:8 to low which failed to enable U522:8.

Q518 had failed with a low resistance path to ground.

Do you usually step through each failed test and measure the input at AD IN on the converter board? It would be interesting to see what you are measuring at each of the failing test steps considering some of the failing steps are nearly the same as the ones that pass like 301.1 and 304.2.

I have not tried running AC calibration, but I will look at the cal manual and see if it is possible. The offset is such a gross amount and so close to one of the failing tests I fixed (407.1 unable to measure 7V), that I believe there could be more issues. It is possible someone tried to calibrate the AC ranges and saved a bad offset.

I am currently trying to layout a better diagram of the few signals I traced so that it can be uploaded to xDevs.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 20, 2015, 08:34:55 pm
I was checking affected blocks by errors , trying to fix lowest number error first, but sometimes it's getting puzzling, as relation between different selfdiag steps not always straight forward.

Here's A/D input voltage with all error steps in manual mode

Passing tests:

201.2 - VREF check = +6.908974
304.1 - Ohm zero = -0.007313
304.2 - 0.98mA and 9.2mA = 0.745667 VDC (spec 0.7 to 0.86V)

Errors:

304.3 - 89uA and 0.98mA = 0.288570 VDC (spec 0.585 to 0.715V)
304.4 - 7uA and 89uA = -0.485134 VDC (spec 0.504 to 0.616V)
304.5 - 770nA and 7uA = raising from -0.2VDC (spec is 0.63 to 0.77 V)
304.6 - 70nA and 770nA = 6.0072++ VDC (spec is 0.63 to 0.77 V)
304.7 - 4.4nA and 770nA = 11.8315 VDC (spec is 1.6V to 2.8V)
306.1 - Ohm cal switch = -0.00975 VDC (spec is -0.001 to 0.001 V)
309.1 - Amps, 200uA = 0.03571 VDC (spec is 0.0801 to 0.0979 V)
407.1 - FE 2V = -0.00518 VDC (spec is 7V +-0.15)
407.2 - FE 200V = -0.00771 VDC (spec is 0.7+-0.2V)
407.3 - FE 750V = -0.00781 VDC (spec is 0.14+-0.04V)
408.6
409.6
410.1 - TRMS = 0.004572 VDC (spec is 7V +-0.18V)
411.1 - Filter TRMS = -0.0046 VDC (spec is 7V +-0.18V)
411.2 - same as 411.1

So obviously lots of stuff is wrong :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: cyr on February 20, 2015, 09:59:05 pm

Interesting enough, old ADC modules I had were Revision G, with date codes on IC's 1992, while new ones are Revision H and Revision J, with datecodes 1992 and 1994. There are few layout differences and extra OPA177GS (http://www.ti.com/general/docs/lit/getliterature.tsp?literatureNumber=sbos008&fileType=pdf) (U813) near to integrating amp U816 (OPA602AP). I will update schematics soon, to see what was changed.

Did you ever notice any difference in performance between these revisions?

I'm thinking of modding the OPA177 circuit into my older revision ADC board...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 20, 2015, 11:07:19 pm
Did not actually tested that point, as I did not had stable enough reference to test 2001-grade DMM till last few month.

I will do it as part of comparison with modified meter and stock calibrated 2001.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 21, 2015, 01:13:20 am
TiN,

Have you had to source any of the VN0605T Mosfets? I have borrowed a few from the one that I have been slowly repairing. I cannot find a reliable source for that part.

I have found the 2N7002E part that appears to have similar specs. I am not sure if it would make a suitable sub. Here is a link to the datasheets...

http://www.vishay.com/docs/70212/70212.pdf (http://www.vishay.com/docs/70212/70212.pdf)

http://www.vishay.com/docs/70860/70860.pdf (http://www.vishay.com/docs/70860/70860.pdf)

Do you think this will be a good fit? I am planning ahead to make sure I can attempt to fire up the board when I get the burnt areas fixed.

I did some quick checks on the TRMS circuit and found that the diagnostics work because the test signal on the TRMS input is always on in ACV mode. When the meter is switched back to normal use, the 0.69Vdc signal is still on the input to the rms converter. This is why it shows 6.9xxxx on the display. The input to the converter does change as I select the different manual tests.

I will have to step through the R1_STB and R2_STB registers and see if any of them are wrong.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 21, 2015, 04:39:12 am
Got some progress finally as of today.

Measured voltages on ohm current source resistor loads (common terminal of foil resistors R356,R358,R365,R366 and 100Meg R354) and control nodes
from registers (OHM_FA, OHM_FB, OHM FD, OHMCB, OHMCA, OHMCAL, /ACAL).
All these were OK. Mux U325,U332 work ok as well, also ~7VDC was present across resistors as per test points.

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/K4/304_errors.png)

Find out that switching JFETs Q320,Q312,Q324 were dodgy. After replacing these from another donor 2001 board (from same locations) - no problem with ohms 304.x tests now.
JFET are TO92 package, PN4392 I believe, selected and remarked by Keithley as TG128.

Measurements with reference to pin4 common on ADC board connector.

TestPASS unitFAIL unitAfter fix
304.1, U323.70.790 VDC0.744 VDC0.7854 VDC
304.2, U323.70.790 VDC0.744 VDC0.7854 VDC
304.3, U323.70.635 VDC0.291 VDC0.6301 VDC
304.4, U323.70.548 VDC-0.523 VDC0.5451 VDC
304.5, U323.70.736 VDC-0.523 VDC0.7331 VDC
304.6, U323.77.645 VDC6.12+ VDC7.6026 VDC
304.7, U323.70.482 VDC5.807 VDC0.4773 VDC

Now I have left 407.1, 407.2, 407.3, 408.6, 409.6 (sometimes this one pass), 410.1, 411.1, 411.2
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 21, 2015, 05:12:07 am
Great work. I had Q518 almost shorted to ground. I measured ~0.5 at AD IN. If you can measure the 7v there, I would look at Q519.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 21, 2015, 05:13:25 am
Also for your question, I think 2N7002E should do fine, as it's just bring common potential in schematics.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 21, 2015, 05:20:10 am
Great work. I had Q518 almost shorted to ground. I measured ~0.5 at AD IN instead of 7v. I believe R233 connected to Q518 through U531:18
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 21, 2015, 05:22:53 am
Sorry about the double post. My ipad is not cooperating (always blame the equipment). I don't think Q519 will apply and I tried to delete that info.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 21, 2015, 08:03:34 pm
Changed Q518, but nothing improved :)
Will debug in more depth later on.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 23, 2015, 05:41:14 am
I found the issue with my 2K1 #3 with the offset of 6.9V on the AC ranges. K503 had an open winding. I am not sure how it was caused but when I removed it, one of the pins tied to the coil came free from the body. The meter still passes self test and now the AC range seems to be functional.

I can now get back to repairing the burnt area on 2K1 #2.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 23, 2015, 11:50:41 am
Good job. As of mine, i found that problem is somewhere before function mux U511, as opamp U520 seeing wrong voltages on its inputs when running tests 407.x.
Its nice to have another 2001 for cross checks.

So far Q518, Q519, Q507, Q509, current source Q543 (2 leg metal can near dual JFET) are all ok, and not cause of problems.

I can make backlit hires photos of affected area , if you think it can help ur repair. :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 23, 2015, 12:38:25 pm
Thanks for the offer. I already have some pictures with both boards when I removed the caps. The best pictures I have are from my ipad.

If you already have some pics, I would be happy to see them.

Your description of components tested are the same ones I checked. The big difference is that my op-amps had good inputs. Nothing seemed bad until I probed around Q547 and found the open coil.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 24, 2015, 04:41:43 am
Here are some photos in case people use this as reference in future.

Fix for ohm 304.x failing on analog board #4

(http://xdevs.com/kei2001/.hglf/photos/K4/ohm_1_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/ohm_1.jpg)

Replace TG128 selected JFETs Q320,Q324 (near blue resistor network, on left side) and Q312 (near caddock network).
After doing so 304 errors are gone, resistance measurements fixed.

Now recap (remove old capacitors and replace with new ones). I used 1000uF 50V instead of 1000uF 35V for C116 and C117 positions. They are same diameter and pitch, just taller.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_1_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_1.jpg)

Remove analog board from chassis, prepare caps.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_2_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_2.jpg)

Remove all capacitors and clean board. Make sure no damaged traces or electrolyte corrosion anywhere.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_3_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_3.jpg)

Closeup on 4 caps which usually leak most on old 2001's.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_4_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_4.jpg)

Backlit photo to show traces in inner layers under capacitors area.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_5_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_5.jpg)

Backside backlit photo

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_6_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_6.jpg)

Clean holes with toothpick, so you can put new capacitors in place.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_7_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_7.jpg)

Soldered caps on analog PCB.

(http://xdevs.com/kei2001/.hglf/photos/K4/recap_8_s.jpg) (http://xdevs.com/kei2001/.hglf/photos/K4/recap_8.jpg)

1000uF 50V capacitor in mains switching circuit.

Also while trying fix 407.x errors and swapping components seems I got backwards and borked something else, as now selftest steps 402.1, 404.1 to 404.5, 405.2, 405.4, 405.6, 405.8, 406.6 are failing too!
Oh-oh, time to spend some time and recover schematics for all AC-measurement related circuit. :(
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on February 24, 2015, 05:15:28 am
TiN,
Photos are not showing on your most recent post.
Photos work now.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 24, 2015, 07:52:43 am
Thanks for posting the pics. I will try and get a basic schematic of what extra information I found in the AC section. I can send it in an email in eagle format. Hopefully you can add it to your existing drawings if possible.

I found a source for replacement COTO relays. They are not cheap but I should have a NOS relay in a week.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 24, 2015, 03:54:11 pm
Better in PDF format, I don't have eagle, sorry.

Here's what I got so far at schematic.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on February 26, 2015, 02:02:02 am
Hey there!

I've got one of these multimeters from an old lab which was working fine, but I noticed a klicking relay, so I took it apart, and looked for the klicking relay.
It was somewhere on the input voltage selector circuit, so I hooked up my Multimeter to the Capacitor on that circuit and noticed some ripple on the voltage.

To be sure that the ripple is related to the klicking relay i hooked up my oscilloscope to the bridge rectifier and the alligator clip to the negative side of the capacitor in the voltage selection circuit and ... yeah. I did watch Dave's Video about how to not blow up my oscilloscope, but I didn't do any measurements on that part. However, i did blew the voltage selection circuit. Luckily i didn't blew my oscilloscope (since i'm a sencondary school student, i can't really afford blowing up equipment), but i blew up the bridge rectifier and a trace to the capacitor.. I replaced it, and hooked it up to my bench power supply, and a mosfet started smoking.

However, i would declare the voltage selector as dead. I thought of connecting the transformer directly to the power switch, but I wanted to ask here if its safe to do it. I noticed that there is a optocoupler on the voltage selection circuit going into the multimeters circuit, what the reason for this? Also, what are the pins on the transformer cable for 230V mains?

I also don't really know how I shorted it out. Even if we talk about a mains earth referenced power supply, i hooked up my alligator clip to the negative side of the capacitor, so how could that happen?

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 26, 2015, 02:37:51 am
Which capacitor you talking about? C108?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on February 26, 2015, 02:39:35 am
Which capacitor you talking about? C108?

Thanks for your reply!

Yes, i'm talking about C108.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 26, 2015, 03:08:54 am
You shorted mains thru CR101 by direct scope connection (alligator is earth connected).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on February 26, 2015, 04:01:30 am
You shorted mains thru CR101 by direct scope connection (alligator is earth connected).

Yeah, i guessed that, but how could that happen? Since its an isolating transformer (i guess), and a full bridge rectifier?

Whats about my Idea to connect the transformer directly to the power switch?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 26, 2015, 06:14:54 am
I worked on the firmware for the 2001 including the front panel menu design.  Here's something to try:

Before turning on, hold down FREQ + MATH and then power it up while holding these keys down.
Now press Menu -> General and go all the way to right (2nd page).
If you did it right, you get the secret menu that lets you view the design team and set memory options as well as mess with some analog settings I can't remember now.

If FREQ + MATH doesn't work, try powering on with TEMP + (LEFT ARROW) held down.  The exact key combo that unlocks the secret menu depended on the revision of the front panel microprocessor FW, but it will be either FREQ+MATH or TEMP+ LEFT
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 26, 2015, 07:13:54 am
Rev A units were getting really tight on memory, so we only had enough space to list the software team.  Once we went to rev B ROMs, we could list everyone that had a hand in the project.  We also had an option to turn on a scrolling sales message intended for when the unit was sitting out at a trade show; that's why there's a plaintext list of features in there.

The MEM1 and MEM2 options used a Dallas Semiconductor RAM with a built-in battery; that's how they retained data with power off.  Even if you find the part, you have to initialize it with a secret menu command (see previous post) because marketing didn't want you buying a $50 part and plugging it in yourself when they could sell you the $500 option.  As I recall, you plug in the Dallas part, and then go into the secret menu and tell the 2001 what memory option you have.  It then writes the magic code into the Dallas part that lets the 2001 use it.
I wish I could recall the Dallas part numbers, but it has been too long.

This brought back some good memories of a good project team we had back then.

--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 26, 2015, 10:50:30 am
Thank you for the great info. I just received a couple Ds1245Y nvrams a few days ago for my two good meters. I will test your instructions tonight and give feedback. This will be with Rev B roms B15 and one other (B10?)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 26, 2015, 12:38:47 pm
I was able to confirm that the front panel init options does work and should be handy for people without access to a programmer.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 26, 2015, 03:40:01 pm
Welcome Mike! Very happy to see here someone who should take credit for this great DMM :)

Secret menu works on 2002 too, and have some fun in it!
But init BB RAM did not help my case for clock NVRAM. Maybe DS1251 is not right one for MEM2 on 2002.

Will post more details on weekend.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 26, 2015, 11:53:42 pm
The same key combination to get the secret menu will work on almost all Keithley products that have that same key layout, including the 2002, 7001, 7001, and 2400 family of products.  On those products with the 2-line VFD display, much of the front panel code and menu structure was able to be reused.

If you ever get ahold of a 7002 switch system, there is a shooting galley game hidden in there that uses the LED displays and the light pen.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on February 27, 2015, 12:45:19 am
The same key combination to get the secret menu will work on almost all Keithley products that have that same key layout, including the 2002, 7001, 7001, and 2400 family of products.  On those products with the 2-line VFD display, much of the front panel code and menu structure was able to be reused.

Do you know any useful easter eggs like that for Keithley 2000/2015 series?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 27, 2015, 01:12:23 am
The 2000/2015 series used the one-line VFD with "British flag" characters, so our menu options were much more limited.  If there is a secret menu in there, it would be accessed by those same two keys since they share front panel processors, but it has been too many years and I can't recall if the one-line display family has it or not.  If there is, then it would also be in the 2700 family as well.  I believe the 6517 and 2182 meters also have it since they share the two-line display.  The analog guys found that having some of these hidden options easily accessible without a magic SCPI command made their debugging a lot easier, and some options (like the design team) I put in just for fun.

The secret menu goes by key position, so if the key labels are different, then look at a 2001 front panel to see which 2000 keys would correspond to "FREQ+MATH" or "TEMP+LEFT" on the 2001.

The 2001 was my first project there when I started in 1991.  I worked on 2001/2, 2000, 2010, 2700, 7001/2, 2400 (& family), 6517, and 2182 during my 14-year tenure there.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 27, 2015, 02:12:28 am
Hm, Close+Card does not unlock anything on 7001..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 27, 2015, 02:28:16 am
My bad there.  I forgot about the keyboards with the number pad.  The unlock for 7001/2 is in the number pad.  Try 2+6 or 5+9.  I know it's two keys diagonal to each other.  Less likely but possible might be 3+5 or 6+8.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on February 27, 2015, 05:30:58 am
Whats about my Idea to connect the transformer directly to the power switch?

Hey there!

I've looked into the service manual, there is a section, which tells, that there is a power regulation for the transformer. So i think connecting the transformer directly to 230V mains is not working, am i right?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 27, 2015, 05:49:25 am
My bad there.  I forgot about the keyboards with the number pad.  The unlock for 7001/2 is in the number pad.  Try 2+6 or 5+9.  I know it's two keys diagonal to each other.  Less likely but possible might be 3+5 or 6+8.

Not working (Firmware A09 A02 on my 7001). Tried 1+5, 4+8, 7+0, 9+0, 5+7, no secret stuff in general menu.
Model 2510 secret key is (T)+CONFIG :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 27, 2015, 06:23:34 am
Weird, once I saw the number pad I thought for sure it was a diagonal combo of two buttons in the number pad for the 7001.  I emailed a couple software friends who also worked at KI during that time to see if their memory is better than mine.

It may be that the 7001 didn't have any back doors or need for the secret menu.  I know the 7002 does, because I put the light pen shooting game in there.

One of the products (2002 maybe or 6517?) includes a RAM editor and viewer in the secret menu.  That, along with a copy of the map file, would let you hand-edit any variables in the code :)
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 27, 2015, 06:59:38 am
@benvei,

Is there any reason not to diagnose and repair the AC selector circuit? Did you destroy any of the traces on the pcb?  Odds are that repairing the defective parts would be easier than rewiring the primary side of the meter.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 27, 2015, 07:33:07 am
I finally had a chance to skim some of the older messages in this forum.  The reverse-engineering you guys have done is quite impressive; you know more about the analog boards now than I did :)

To answer an old question about Rev A vs. Rev B firmware:
Rev A was done on the older digital board with a single x16 EPROM; square package and 4Mbit I believe.
Rev B requires the newer digital board with two 4 Mbit x8 EPROMS.  We ran out of space in rev A when marketing asked for more features, so we had to go to bigger ROMs and a new digital board.  The 2002 also uses the same board, I think.

I saw someone found the SCPI command for the secret 8-1/2 digit mode for 2001.  The last digit isn't very meaningful; it was more of a display exercise when we were using 2001 hardware to mock up 2002 software before we had real 2002 hardware.  Looks cool, though.  I think if you power up with the secret menu code, then go under the normal menu where you set the number of digits (CONFIG -> DCV), you'll see that 8.5 digit is an additional front panel selection.  Many times I snuck things like this into a secret menu because it was faster than rounding up the GPIB card and cable when I needed to show a quick demo to the marketing guys.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 27, 2015, 07:43:23 am
On the 7001 secret menu access, try STORE + 6.  If that doesn't work, then I'm at a loss.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 27, 2015, 12:49:52 pm
On the 7001 secret menu access, try STORE + 6.  If that doesn't work, then I'm at a loss.
--
Mike

Bingo. It shows "The Project Team:" thing on power on with 6+Store. No other goodies :)
Thanks for all valuable info!

I will post an article about secret menus in gear I have (2001 with A fw, 2001 with B fw, 2002, 2400, 2510, 7001, 2000)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 28, 2015, 12:16:03 am
The 2400 secret menu includes an option to set the product.  This allowed us to use one digital board and firmware rev for the entire family.  Of course, just because you say it's a 2420 or 2430 doesn't really give you those higher current or voltage ranges because they had different analog boards, but it's still pretty cool.  Again, we would use that for getting the display formatting right before the higher current and voltage models were available with real hardware.  That will probably apply to later revisions of 2400 firmware, but since the 2400 is flash-based, it should be upgradeable in the field.

On the 2001 rev A vs rev B, rev B will most likely have more hidden options because we had the ROM space to work with.  Not sure if the hidden 8.5 digit selection I mentioned earlier is available in both versions or just rev B.

The 7002 secret menu is probably the same as 7001 - my memory of diagonal keys on the number pad must be faulty.

I had a lot of fun with those secret menus.  Now that I'm doing medical device software, undocumented Easter eggs are strongly frowned on by the FDA, but those were the days :)
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Smith on February 28, 2015, 03:22:33 am
I would love to know about easter eggs in keithley 2000 and 2700 series. Some people just don't need cant afford the 7.5 /  8.5 digit goodness  :-//
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 28, 2015, 03:42:42 am
My memory on those isn't as good, since they were starting up while I was finishing on the 2-line display meters.  If there are any, then the key combination to get into it should be the same as the 2001, or at least those keys that map to the same positions of either FREQ+MATH or TEMP+LEFT.

The one-line segmented display didn't give us much room for creativity, so if there is a secret menu, it would most likely be for adjusting analog stuff or faking that certain options were installed.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on February 28, 2015, 04:54:07 am
For those with access to a 2002, I'm curious if my "HP Shooter" made it into the final firmware and is still there.  Accessible from the Secret Menu, this was a marketing-type display that showed the number 2002 shooting things at and obliterating the number 3458 (since the HP3458 was seen as our target competition).  The 2002 also had a 3548 emulation mode for the GPIB commands.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 28, 2015, 12:11:08 pm
Yes, HP shooter and HP Killer all there :). I recorded video of secret menus already, will post later. Not sure if my firmware final, its A09.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on March 01, 2015, 07:50:56 am
@benvei,

Is there any reason not to diagnose and repair the AC selector circuit? Did you destroy any of the traces on the pcb?  Odds are that repairing the defective parts would be easier than rewiring the primary side of the meter.
Yes, i did, but i think i should be able to fix it. I just wanted to know, if its even possible, to hook up the transformer directly to the 230V mains.

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 01, 2015, 11:34:59 am
It might be possible to hook it up straight to the power input connector. I just don't know if you will bypass anything important on the analog board. I believe the Freq Out signal may come from that section but I am not sure.

I am paranoid about modifying anything on the primary side of a transformer. I will do direct replacement of parts, but I would not bypass anything. I have read enough posts about input filters burning up and I am concerned my homeowners insurance will blame me if it happens and causes damage to my home.

Hopefully you can get it straightened out. I can get you some pictures of anything that may be missing or unreadable.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 01, 2015, 12:01:33 pm
I am one step closer to fixing 2K1 #2. I stole the A/D converter board from #2 to get #1 working.

The defective board from #1 had the following errors that were confirmed on both working meters...

200.1 No A/D communication and/or noisy A/D.
201.2 Cannot measure 7V at A/D IN

The 200.1 is a showstopper since some of the other individual tests run this first and will throw it as an error. The meter seemed to read fine and I was certain it would be difficult to track down.
I started probing the on-board voltages and everything seemed fine. All transistors "seemed" fine compared to another board using the diode test function.

I happened to notice that Vcc (+15V) had a low impedance to the GndA(S Com) signal path. After checking C828,C809, and C812 I started looking at resistance readings across component legs and eventually found Q806 had low resistance between the source and gate pins. I dropped in a replacement and now the board passes its self tests.

Unfortunately, I seem to have a new error 409.6 on #1. I am certain I had it before but it wasn't there earlier today. It throws the same error with two different converter boards.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 01, 2015, 04:03:36 pm
I have 409.6 come and go on one of analog boards too. It's unrelated to ADC board, just for note.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 01, 2015, 04:30:40 pm
I figured the same thing. I tested what I could so far with my handheld meter, but the circuit around C554 needs a higher impedance meter due to R557. I will check again tomorrow with a 8846A and hopefully find the part(s).

C554-C556 are available from Digikey, and it wouldn't be too much trouble to measure them. I confirmed that U526A (pins 2-3) measured within tolerance (33ohms) which matched my other meter.

Have you measured the input impedance on your meters that had the failed capacitors? I am wondering if the electrolyte has created any issues and I will have to measure it when I get these put back together.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on March 02, 2015, 12:58:17 am
Hopefully you can get it straightened out. I can get you some pictures of anything that may be missing or unreadable.

Hi!

Thanks for your advice. I wanted to connect the transformer directly, but yeah ... i thought about your post. And i went on searching for the problem. The Transistor that was smoking was Q103, which was switching the 110V relay. Since we have 230V I don't need it, so i just desoldered it. And? Oho - Its working fine! :)

I've attatched a picture of my test. Its just insane how accurate this thing is. It was built an calibrated in 1993!

I'm quite happy with it. Thanks to all of you, and thanks for reengineering and drawing the circuits, that was quite useful. And thanks to keithley for their great Repair manual! :)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 02, 2015, 01:59:07 am
It is nice to see it was a simple fix. I am sure it will be tempting to get a second.

I think Keithley did a great job with these meters. I would like to have TiN's setup but I think the eBay sellers are asking too much for non-functional units and I am happy with what I have. At least for today...

TiN and the other xDev's members have done a great job. They have certainly been a big help with their notes and schematics.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 02, 2015, 02:56:08 am
Probably most of them saw this thread and bumped prices up once to twice  >:D.

Anyway, be careful and get meter proper repair/treatment it worth. Accuracy of these machines is mostly on voltage/resistance ranges, not frequency  :-DMM.

Also if you have access to photocamera, photos of your 2001's internals would be good to add into collection.
What is firmware version in your meter?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on March 02, 2015, 04:01:03 am
Also if you have access to photocamera, photos of your 2001's internals would be good to add into collection.
What is firmware version in your meter?
Yes, i've got a photocamera, i'm going to take some pictures for you in the next few days. I just cleand up my workbench, and yeah ... if students start cleaning their desks without their parents shouting at them, it has to be a *real* mess. And ... it was. :P

Is the value displayed at the boot the hardware rev or the software rev? If its the software, its firmware "B06".
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 02, 2015, 04:31:50 am
It's software, thanks. I already have B06 :)
Hope to see photos of your digital and analog boards.

Meanwhile, here's draft article about secret menus in Keithley gear:
Keithley secret menu and settings (http://xdevs.com/guide/keithley_secret/)

Tried B-version 2001 with secret menu, it have little more stuff , and MESSAGES/GAME item, but it does nothing when I enter it  :-//
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: benvei on March 02, 2015, 05:56:57 am
Hope to see photos of your digital and analog boards.

http://cl.benvei.at/public.php?service=files&t=5975efac14949058f8775e8744de03c0 (http://cl.benvei.at/public.php?service=files&t=5975efac14949058f8775e8744de03c0)

Didn't upload them to the forum because of the large image size. Sorry for the bad light quality, should i do them again when i have some sunlight? Its 8pm here in Austria. :P
I've also got a Scanner Module, if you are interessted in it. I also replaced all the caps.

I know, cap 103 is a mess, didn't have one that fitted, going to change it as soon as i get one that fits. I could make photos of the other side of the PCB when i'm changing the cap (since it works now, i didn't really want to take it apart, sorry).

//edit:
Tried B-version 2001 with secret menu, it have little more stuff , and MESSAGES/GAME item, but it does nothing when I enter it  :-//

Same here. :(
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on March 03, 2015, 12:36:52 am
Nice article about the secret menus - brought back a few good memories.
The references and menus about a phase card are for a peripheral that we had considered making, but ultimately never was completed or sold. Not sure whether there wasn't enough market to justify it, we couldn't get the accuracy we wanted, or the designers got pulled off to other projects.
--
Mike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 03, 2015, 01:51:50 am
What is about TC-Ohms option?

Also I am still puzzled about what is proper Dallas NVRAM for 2002, since it does not like DS1251 (say's no clock installed) even tho 1251 do have PhantomClock in it.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on March 03, 2015, 04:49:26 am
TC Ohms was a Temperature-compensated ohms card.  Not sure if it ever got sold or was just another feasibility/development project.

I don't recall the Dallas part number for the 2002 NVRAM, but it does have to have a real-time clock.  The 2001 does not have a real-time clock and the two parts are different, but that's all I remember.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on March 03, 2015, 06:27:13 am
What is about TC-Ohms option?

Also I am still puzzled about what is proper Dallas NVRAM for 2002, since it does not like DS1251 (say's no clock installed) even tho 1251 do have PhantomClock in it.
DS1251 is 512kB, but MEM2 option is 128kB, so it's unlikely to be right. DS1251 has 2 extra address pins over the 128k version. DS1646 is a Dallas 128kB with RTC. It's the right size at least, so it's more likely the correct part than the DS1251. Access to the clock portion of those two chips is completely different.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on March 15, 2015, 12:02:23 pm
I'm wondering if I should drill out the affected board areas?  There's not too many traces in the C117 area, but there's a lot of stuff going on around CR513.  Or is there a better way to restore the integrity of the board?
I couldn't convince myself that the isolation on that ground trace was still good, so I cut it and replaced it with an ugly bodge wire.  It seems that what actually finally stopped the catastrophe was the transformer secondary dying, so I bought a replacement transformer from Tek (only slightly more expensive than I expected, but not cheap)  And now the unit boots!

Should the fan start when the unit is powered up?  The next thing I did was let it sit there while watching it thermally, and the fan never came on.  Without anything to compare to, I don't know if this is because the case was open or is another fault.  It would make perfect sense if the fan died, causing the caps to overheat and die.

Do you remember what the hot spots were from your thermal analysis?  I've got several parts operating around 60C.  The two parts clipped to the chassis were also quite warm, with the power resistor at 65C.  Ambient was around 18C.

Before plugging in the new transformer, I compared winding resistances with the old transfer just to confirm that the old one was dead.  Here's the new resistances in case it might help someone else troubleshooting their unit: (Note I swapped the Orange/White pin from the connector order.)

Code: [Select]
BLK   -+                  PINK    -+
       |- 3                        |- 2.7
BLK/W -+                  ORNG/W  -+
       |- 14.3                     |- 2.6
WHT   -+                  PINK    -+
       |- 16.5
BRN/W -+                  PURP    -+
       |- 3.9                      |- 0.75
BRN   -+                  PURP    -+

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 15, 2015, 03:04:30 pm
You talk to yourself? :)
You could just shoot me PM, I had extra xfrmr from donor 2001.

Fan powers up instantly, it's running all the time. I got feeling that some of my 2001's died because of fan too, because it was locked on few units, while very noisy and near failure on others.
So just swap it out to standard 40x40mm 12V 0.3A fan and you will be ok.

(http://dev.xdevs.com/projects/kei2001/repository/entry/schematics/digital_power.png) (http://dev.xdevs.com/projects/kei2001/repository/entry/schematics/Keithley_2001J_PSU%20DIGITAL.pdf)

Unit does run quite warmish, that's normal to have linear regs and mains part around 60's. R100 and Q528 basically sit on rectified mains, as you can see from my schematics (posted before)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on March 15, 2015, 03:52:19 pm
Fan powers up instantly, it's running all the time. I got feeling that some of my 2001's died because of fan too, because it was locked on few units, while very noisy and near failure on others.
So just swap it out to standard 40x40mm 12V 0.3A fan and you will be ok.
...
Unit does run quite warmish, that's normal to have linear regs and mains part around 60's. R100 and Q528 basically sit on rectified mains, as you can see from my schematics (posted before)
Thanks! 

I had studied those parts of the schematics and the repair manual (section 2.10.2) before asking. I think I understand what's going on there, and I did expect Q528 was usually in the linear region (or it wouldn't be much of a pre-reg) but had no sense for the normal amount of current .  If mine were running hot, then I had another failure to go find. 

The schematics posted here are a part of why I undertook this repair and they've been very useful already.  I really appreciate all the information in this thread! 
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 15, 2015, 04:08:18 pm
How about your unit's selftest? Any error's? I have two units open on table now, waiting for more debug and schematics work for U5xx chips.

Also what is your analog board Rev? From thermal pics looks like it's older one with avalanche diodes on top near caps.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on March 16, 2015, 05:15:47 pm
How about your unit's selftest? Any error's?

I measured voltages, put the shield back on, hung a 50mm fan on the PSU section, let the unit stabilize for an hour, and ran the built-in tests.  No failures!  :-+

Adding airflow brought the top-side power components down into the 30-40C range, which was reassuring.  However, the bottom-side 5V supply (CR622 and U629) still runs 60-ish C.

I attached it to my 5xLM399 reference for awhile, and it has 15uV more noise in its measurements than my 2000s do (all using the default "slow" speed; 2Hz?)  I'm hoping that goes away when it's properly reassembled, but I'm not optimistic.

Quote
Also what is your analog board Rev? From thermal pics looks like it's older one with avalanche diodes on top near caps.
The board is marked:
2001-102-04L

On boot, it displays:
Rev. B06  A01

All the date codes on board components I've found so far are 92 or 93.  The old transformer's serial number ends in 9412, if that's not coincidence. So I think it's safe to say this is an older unit :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 16, 2015, 09:57:08 pm
Guys,

I am getting soon a 2001! I am so excited!!!!!

Question on the side, some EE brothers here:

http://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg583136/#msg583136 (http://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg583136/#msg583136)

managed to upgrade a DS1225Y NVRAM with FM18W08 FRAM:

(http://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/?action=dlattach;attach=128687;image)

Any idea if we can do the same here with the MEM2 chip Dallas DS1245Y? Sorry if it was a stupid question, I am not an expert here.

Can´t wait to post something here... thank you all for the hard work!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 16, 2015, 10:16:51 pm
Galaxyrise

Great job.
Can you send B06 as well for my collection, since I don't have it (http://doc.xdevs.com/article/keithley-instruments/)? :)
Try NPLC 10, auto-zero = synchronous (will auto zero before every new measurement), line-sync - enabled. You can enable 8.5 digit for fun too.

U629 mounts to chassis via screw for thermal transfer. Poor LDO powers whole digital board and front panel board including DC-AC converter.

Zucca,

Welcome, I can send you a 1245, have few extra. I thought you already had 2001 before?

Which unit you have got? All you people might bring some life again in this poor thread :) I wish could have some quality time to work on schematics too.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 17, 2015, 01:04:51 am
I can send you a 1245, have few extra.

Thanks for your offer TiN, I will consider that.

I thought you already had 2001 before?

Unfortunately no, I got only 6.5 DMMs on my bench never a 7.5 one.

Which unit you have got?

The Unit will be shipped to me, but there some pictures:
(http://i.imgur.com/HDXz8d3.jpg)
(http://i.imgur.com/sMXp0kE.jpg)

I don´t know if it has the B or A Firmware.... ah, it has the  2001-342c 10 ch Scanner card  :-+
Do you guys have an extra front handle for me?

PS: the owner was a wine producer in Canada, he was using the 2001 to control the wine temperatures  ???. I got it pretty cheap, but let´s see when it arrives in my hands.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 17, 2015, 01:35:35 am
I was watching that 2001. That was a good price with the included scanner card. It will probably be a rev B firmware. The serial number is between my B10 and B13 versions, but closer to B10.


TiN,

Will upgrading the FW blow out the calibration constants and/or serial number? I should have the adapter for my programmer in the next couple of days and I would like to back up the eeprom before I upgrade.

I also have to fix the serial number on my 2510 that was lost when I installed your uploaded version. BTW, I finally got time to upload ver A03 for the 2510 on xDevs.

I have been emailing Keithley for prices on new replacement parts to spruce up the external appearance. I will post an update when I can get my hands on some of them with updated part numbers from the service manual. A few parts have slightly different part numbers.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 17, 2015, 01:41:17 am
Very Interesting:

Replacing SRAM With FM1608B,FM16W08, FM1808B, or FM18W08
http://www.cypress.com/?docID=48118 (http://www.cypress.com/?docID=48118)

Does anyone know how the chip-enable transitions to LOW is managed in a Keithley 2001?

The serial number is between my B10 and B13 versions, but closer to B10.

Thanks for the Info!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 17, 2015, 03:43:22 am
Any idea if we can do the same here with the MEM2 chip Dallas DS1245Y? Sorry if it was a stupid question, I am not an expert here.

I did some homework and indeed it was not a clever question...

First of all we need to find a 32 pin parallel FRAM, like this one FM28V100:
http://www.cypress.com/?docID=50822 (http://www.cypress.com/?docID=50822)

Second it is not 1:1 pin compatible, so we need to build an adapter board.

Third that FRAM runs with 3.3V and not 5V like the DS1245Y, so a VREG should go on that adapter and pray the 3.3V FRAM will be interpreted from the 2001 as logic "1".
Fourth the FM28V100 has two chip enables pins CE1 and CE2... (not a show stopper but another difference)

It´s not looking to be that easy. Still it is a cool Week End project to work on.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 17, 2015, 04:02:55 am
ManateeMafia

Thanks. Can you drop your B13 as well? :)

I finally decided to make overall page with all files/data/firmwares for all Keithley gear in one place. (http://doc.xdevs.com/article/keithley-instruments/)
Will see how that goes.
You will likely to loose calibration, but I don't remember 100%. Just save 24C16 I2C ROM contents, all calibration of 2001 reside in there, as well as serial number.

I was wondering how much would be cost of front panel plastic for 2400 (part number 2400-313A), since mine 2400 have it quite busted up. Can you ask them about it as well? No need PCBA , just plastic with VFD panel plastic. It's  more topic for my 2400, which is somehow gone.  :o

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 17, 2015, 05:30:08 am
I made a mistake about fw rev. It should have been B15. I also have B08 but I believe you already have that.

The front panel is not cheap but it includes the front cover, lens, and banana jacks. I am pretty sure the overlay is also included. The price is around $150 US.
Are you missing the entire panel or just the lens?

I plan on replacing the missing cover for the scanner board and adding the missing feet.

The front panel is not in the parts list. It is part RPT-FP2001.

I don't have a price for the VFD but it is part RPT-2001-110 according to tech support.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 17, 2015, 05:39:46 am
I forgot to mention that I asked about the resistor R-289-1G and they told me the specs are.. 1.5W, 10kV, 2% accuracy, and a tempco of 200ppm. There are several suitable resistors that should meet those requirements. The 10000ppm characterization should be achievable with a 3458A or equivalent.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 19, 2015, 02:11:33 am
I always wanted a nanovoltmeter.....

Just found the 1801 Nanovolt preamp option Manual with Schematic of the board which goes inside the 2001.
https://public.magnet.fsu.edu/Graf/Manuals/Keithley/1801%20Nanovolt%20Preamp.pdf (https://public.magnet.fsu.edu/Graf/Manuals/Keithley/1801%20Nanovolt%20Preamp.pdf)

Here the datasheet:
www.keithley.com/data?asset=356 (http://www.keithley.com/data?asset=356)

We need now to understand what is in the box outside the Keithley 2001, oh dear another reverse engineering project in my list... anyone has this rare animal available?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 19, 2015, 02:43:07 am
I was going to post the same info the other day but forgot. When the secret menu option showed the 1801 I was hopeful that a plug-in board could be constructed using the schematics.
I have been keeping an eye open for that option for the last year but I have not seen it cheap. I believe it was listed once for around $2K US.

It is nice that it supports AC unlike the 2182/A and 34420A. I have picked up an Agilent 34420A (or two) in the last year but I have wondered if the AC function would be worth adding to my 2001. The additional milliohm ranges are nice too.

The plug-in board has an eeprom but it probably just has a serial number. The new secret front panel menu will probably set the serial number when the option is enabled.
A good place to start might be the 34420A schematics. They are available but pretty poor quality. I will make an effort to scan some if they are wanted.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on March 19, 2015, 02:54:27 am
ManateeMafia

I already contacted 2 companies (one in Germany and one in USA) to get a quote of this puppy. If it is below or equal €500 I will take it home (it will never happen, my guess is €1000 easy).
Maybe I can push them down because I know this used stuff is not going to sell quick, so I imagine those boards sitting on a shelf for years (waiting for me).

Anyway yes, this 2001 is becoming a (even more) wonderful project.

PS: Once I got the 10ch option boards I will upload nice pictures of it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 19, 2015, 05:17:52 am
Very great find.
I bet it something like described in this patent : US6069484 (https://www.google.com/patents/US6069484)

I have 2001-TCSCAN card, might post pics of it later.

And we might end up having own preamp (http://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/msg632023/#msg632023), ha :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on March 19, 2015, 06:11:12 am
I was thinking that it might be useful for a flicker noise amp or possibly a low noise preamp tied with some low thermal relays controlled by the digital io on the back of the meter.

Something similar to lymex's project http://www.eevblog.com/forum/projects/diy-low-thermal-emf-switchscanner-for-comparisons-of-voltage-and-resistor-stand/ (http://www.eevblog.com/forum/projects/diy-low-thermal-emf-switchscanner-for-comparisons-of-voltage-and-resistor-stand/)

I don't know how much space is available. A breakout board would be handy.
Does anyone know if a breakout board was made by Keithley?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mmarks3141 on March 20, 2015, 04:54:37 am
No breakout board was made that I can remember.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 06, 2015, 03:05:02 pm
Time to get back to drawing board...

Updated schematics of analog board parts, around U5xx parts.

As of switching board, there is existing 2001TC-SCAN, with spec Contact Potential: <±500nV typical per contact, 1uV max (except CH5 and CH10, which are 2uV).
I do have it, in case anyone interested. It also have AD590 thermal sensor coupled to copper bar on bottom side of PCB in terminals area to measure CJC.

Instruction manual (http://doc.xdevs.com/doc/Keithley/2001/2001-TCSC-901-01%20%28B%20-%20Jan%201997%29%28Instruction%29.pdf) for it does have full schematics as well.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 07, 2015, 04:45:25 am
Today is a good day.

Got unit #2 fixed, passes selftest now w/o issues.
It require full recalibration tho, since I got this unit with missing LM399, LTC1043, and other critical parts, so replaced these parts with new ones from Digikey.
With 1.00000V from my EDC it measures 0.986V  ::)

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/K2/fix/s/selftest_pass.jpg) (http://dev.xdevs.com/projects/kei2001/repository/entry/photos/K2/fix/selftest_pass.jpg)

Will post article with photos later.

P.S. Tomorrow I also post something which all of 2001 owners would be superhappy to see  :-+ :scared: :clap:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 07, 2015, 01:13:31 pm
Great job.  :-+

I also got my second one passing all tests (again). I had to repair some damaged traces under/around U505. Pin 8(Vss) was floating and was throwing 409.6 errors. It seems to be working now.

I have been looking at the preamp option like the Keithley 1801, but I cannot decide where to start. The plug in board seems straightforward but the preamp will be an interesting project by itself.
I know it is not trivial to build something that sensitive, but it would more of a learning experience. The most interesting article I have read so far is from Jim Williams . I was looking for a link to add here but I noticed you already have it on xDevs http://dev.xdevs.com/projects/rnd/repository/revisions/3a68a7e9a562/raw/Linear/Documentation/LTMag-V16N01-11-FETAmp-Williams.pdf (http://dev.xdevs.com/projects/rnd/repository/revisions/3a68a7e9a562/raw/Linear/Documentation/LTMag-V16N01-11-FETAmp-Williams.pdf)

I guess this may be related to the preamp design you recently mentioned?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 07, 2015, 02:27:26 pm
As for preamp I plan to have it as separate device. This will allow using it not just with K2001, but also with other gear, like scope and such.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 07, 2015, 11:07:03 pm
Today is a good day.
...
P.S. Tomorrow I also post something which all of 2001 owners would be superhappy to see  :-+ :scared: :clap:
I know what it is   8)
And it will be a game changer for those of us working to fix up these gems.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 08, 2015, 12:50:28 am
 LTZ1000(A)? MickleT or TiN rewrote the firmware to make it like a 2002?  :scared:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 03:12:06 am
Much better, full schematics from Keithley.  >:D

(http://dev.xdevs.com/projects/kei2001/repository/entry/photos/schematics.png) (http://doc.xdevs.com/article/keithley-instruments/#2001)

macboy did found military version Keithley 2001M up for sale yesterday with photos showing schematics addentum for repair manual, and guess what, entering that into google gave this (http://keithley.reprocenter.com/2001-M-R-950-01/keithley.html). Obviously US government did not like having 2001 without schematics, so those documents were disclosed for mil customers.  ^-^

(http://doc.xdevs.com/doc/Keithley/2001/2001M/intro_2001M_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/2001M/intro_2001M.JPG) (http://doc.xdevs.com/doc/Keithley/2001/2001M/2001M_full_manuals_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/2001M/2001M_full_manuals.JPG)

2001M also had B17 firmware version, which likely support 400Hz line frequency. Little birdie told me there is no RMS measurement different to usual 2001's.

Downloaded and rehosted documents on my machine, since we don't know if original URL survive for long. Google cache says there were some documents for 26xx SMU, but now they are gone.

Model 2001 Multimeter, Calibration Manual, 2001-M-905-01 Rev. H / Mar 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-M-905-01.pdf)
Model 2001 Multimeter, Repair Manual Addendum Schematics part 2, 2001-902-07 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-07.pdf)
Model 2001 Multimeter, Operator's Manual, 2001-M-900-01 Rev. K / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-M-900-01.pdf)
Model 2001 Multimeter, Repair Manual Addendum Schematics part 1, 2001-902-06 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-06.pdf)
Model 2001 Multimeter, Repair Manual Addendum, 2001-902-05 Rev. C / March 2011 (http://doc.xdevs.com/doc/Keithley/2001/2001-902-05.pdf)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 08, 2015, 03:24:23 am
I must be going blind. I looked at that auction several times but did not notice the schematics were included.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 08, 2015, 03:34:24 am
2001M also had B17 firmware version, which likely support 400Hz line frequency. Little birdie told me there is no RMS measurement different to usual 2001's.
Good point about  400 Hz line frequency as would be found on submarines, aircraft, etc.
2001M specifically supports RMS-calibrated average-responding AC measurements in addition to the 2001's true-RMS and average modes. The difference is a correction factor applied to the average mode so that when used with sine waves, it gives the equivalent RMS reading. This is needed since so many military technical procedures are written for this type of meter response. The reading mode is selectable in the config menu for ACV and ACI.

Firmwares B16 and B17 (and maybe newer?) are for 2001M. Model 2001 then apparently goes up to B15. I am guessing that there is no hardware difference for 2001M and that the only actual difference is for the addition of the new AC mode, and maybe for adjusting integration time to 50 Hz mode in order to support a 400 Hz line.

It is worthy to note that the digital board schematic is for the version B firmware type (two DIP ROMs) not the older A type (one PLCC ROM).

I must be going blind. I looked at that auction several times but did not notice the schematics were included.
I have an eye for details like that. I was prepared to drop big coin on that meter just for the documentation, but then two things happened nearly simultaneously: TiN, armed with new keywords from those photos, found the docs with his google-fu, and the auction was pulled.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 03:34:29 am
This one (http://www.ebay.com/itm/Keithley-Multimeter-High-Performance-7-5-Digit-DMM-2001-/111634541495?pt=LH_DefaultDomain_0&hash=item19fdefebb7&nma=true&si=7DFSDMlqbBawRE9%252FijNKfFWAqgI%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557). It was ~470USD with 14 bids and day before end yesterday, and was pulled promptly after I asked seller if there are full schematics in those documents on photo. I don't know if it's coincidence, but I googled proper keyword like on those paper covers, and gotcha what we all were looking for.  :-DMM  :phew:

I think that will still work on my schematic version, since their reproduction is far from clear and few parts are rather cryptic. Not easy to read, specially having far from ideal analog circuit topology understanding. Also it does not reflect newer changes from more recent units (which I still hoping to get more photos , since I have only Rev L and Rev J analog boards, but I do know there are Rev H and Rev P in existence).

But at least no need to probe every friggin pin on every part for dozen times to trace signal routing in 4-layers.  :palm:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 08, 2015, 03:41:14 am
That explains why I couldn't find the auction this morning.

I cannot imagine the time you spent tracing out each component. It sucked tracing out a couple of IC's across the board.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 03:46:17 am
B16 is still version for normal unit. I saw it on bay before (proof pic attached).
One more notice , S/N of that B16 unit is 1073931, 2001M from yesterday also starts with 1, 1411110.

Added calibration and operation manuals since they are different revision/more new than normal published ones from Keithley site. Don't know if any difference between, at first glance it's same.

macboy, where did you got information about RMS-function on -M?

Also I tested my primary 2001 with 400Hz (have Chroma 2000VA AC source at work lab), it was working even with usual firmware :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 08, 2015, 03:56:03 am
... was pulled promptly after I asked seller if there are full schematics in those documents on photo. I don't know if it's coincidence,...
Probably not coincidence. He maybe thought he could get more money by selling the docs separately or something. I had also inquired about them. But now they are out in the wild and are no longer as valuable as any of us, or he, thought.

Quote
I think that will still work on my schematic version, since their reproduction is far from clear and few parts are rather cryptic. Not easy to read, specially having far from ideal analog circuit topology understanding. Also it does not reflect newer changes from more recent units (which I still hoping to get more photos , since I have only Rev L and Rev J analog boards, but I do know there are Rev H and Rev P in existence).

But at least no need to probe every friggin pin on every part for dozen times to trace signal routing in 4-layers.  :palm:
It must be maddening work. I'll check the analog board versions of my four units later. Mine span A06 to B15 firmware versions IIRC so I probably have a wide range of analog boards too.
...
macboy, where did you got information about RMS-function on -M?

Also I tested my primary 2001 with 400Hz (have Chroma 2000VA AC source at work lab), it was working even with usual firmware :)
http://lmgtfy.com/?q=2001m+site%3Akeithley.com (http://lmgtfy.com/?q=2001m+site%3Akeithley.com)
specifically:
http://www.keithley.com/support/data?asset=13096 (http://www.keithley.com/support/data?asset=13096)
http://www.keithley.com/data?asset=14876 (http://www.keithley.com/data?asset=14876)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 04:11:23 am
I know about those documents, but I thought it's common for that firmware versions, not just 2001M. Just checked, my A08 and B15 units don't have that RMS-AVG.

Also since Keithley website require login/registration to download files, I got them all locally (http://doc.xdevs.com/doc/Keithley/) by DIY python robot. Every single "asset=N", with N from 0 to 100000.  ::) 5.5GB of files.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 08, 2015, 04:32:36 am
The version B16 firmware update document (http://dev.xdevs.com/attachments/download/287/2001_910_01A.pdf) that mentions the RMS-AVG mode also specifically refers to 2001-M, not just 2001. You might not have noticed that in the past.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 05:12:28 am
Published draft article for repair Keithley 2001 (http://xdevs.com/fix/kei2001/). Currently listed only items for unit #2 , will update with rest of info later this week.
Would like to consolidate all information we have about these instruments in one spot for easy newbie access!
Hires photos of newer units (manufactured later than 1994) are very welcome!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 08, 2015, 05:41:52 am
TiN,

I believe that I sent you some pics of my 2001 back in February. It was manufactured in 2001. Let me know if you need any additional pictures. I have it sitting in the corner waiting for the new front panel.
It looks like Keithley might be making them in batches because it only took them a week to send me the new 2400 display board and keypad. I have been waiting almost a month now...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: analogNewbie on April 08, 2015, 09:43:12 am
My 2001 seems much noiser than 34401 at 6.5 digits mode. Is it measuring the real noise or it's a noisy DMM?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 10:48:05 am
Did you set max NPLC, Line-sync, autozero to max? Measure short, or some signal?
Any data to reference? I can help to capture with same settings and post for you later on.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 08, 2015, 12:10:36 pm
TiN, my four units' analog boards have the following revisions: Rev H, K, N, and P.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on April 08, 2015, 12:17:16 pm
My 2001 seems much noiser than 34401 at 6.5 digits mode. Is it measuring the real noise or it's a noisy DMM?
Interesting to see this on someone else's.  I believe mine is a noisy DMM as it's almost 10x noisier than my K2K both with a 4-wire short and with a very stable 7V reference.  I don't have a gpib adapter though, so I'm not able to log it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 08, 2015, 01:20:26 pm
@Galaxyrise

Does it pass all self-tests?

I have yet to compare both my functioning 2K1's against my 8846A's, but maybe we can all agree on very specific settings like TiN suggested (NPLC, etc..) to try and compare results. I think all the ADC boards are probably running the same FW.

I am hoping Tektronix ships my last couple of parts so I can reassemble one of them. The other is ready for use once I do some performance tests.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 02:22:22 pm
Ok, here's idea (http://xdevs.com/zero_comp/). What if we have a page where performance data can be stored and updated?
I think I'm good enough with D3.js now to have charts for various meters displayed on page.
Participants can upload their CSV-files to FTP, and I'll add those data into page as well.
Would be nice to see what meter is quietest. Can add other measurements as well, such as zero ohm short test, own-reference measurement test, etc.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 08, 2015, 02:51:33 pm
TiN, my four units' analog boards have the following revisions: Rev H, K, N, and P.
Can you take some good photos of these puppies? I will add revision data into article. I saw later revisions have better input divider, using Caddock ceramic hybrid resistors instead of blue single substrate ones.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on April 08, 2015, 06:55:07 pm
Those are the days I think we can conquer the world guys! Still can't believe the FULL schematics are now in our hands  :-+.

Nice job TiN and macboy.

From my side I am still hunting the 1801 preamp, but I think it is official and extinct animal. Surely somewhere it is just sleeping in some dusty big company lab corners (:palm:).
Worth to try with the Keithley forum brothers (as it happen here (http://www.eevblog.com/forum/repair/teardown-keithley-2510-tec-smu-repair/msg562957/#msg562957)), and why not ask there for the B16 FW? I can do it if nobody already tried that.

My 2001 unit is still sailing the ocean finding his way from Canada to Germany....

Quote
'Grandpa, were you a hero in the war?' Grandpa said 'No... but I served in a company of heroes.'
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 11, 2015, 06:03:40 am
My 2001 seems much noiser than 34401 at 6.5 digits mode. Is it measuring the real noise or it's a noisy DMM?
Interesting to see this on someone else's.  I believe mine is a noisy DMM as it's almost 10x noisier than my K2K both with a 4-wire short and with a very stable 7V reference.  I don't have a gpib adapter though, so I'm not able to log it.

Cross-post to new thread (http://www.eevblog.com/forum/testgear/dmm-adc-noise-comparison-testing-project/msg649471/#msg649471), I think would be nice to compare other meters too, not just 2001.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 11, 2015, 08:43:41 pm
Someone forgot to replace capacitors in their Keithley 2001? Well, it's time to do so just now.
Everything was looking fine but analog board throwing lots of 4xx.x errors.. Remove all caps, and now look at this, ugh..  :palm:

(http://doc.xdevs.com/doc/Keithley/2001/K8/c101_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K8/c101.jpg)

Time to fix this bad boy..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Galaxyrise on April 12, 2015, 04:25:45 am
Cross-post to new thread (http://www.eevblog.com/forum/testgear/dmm-adc-noise-comparison-testing-project/msg649471/#msg649471), I think would be nice to compare other meters too, not just 2001.
Ooo, nice to see what a functioning 7.5 digit DMM should look like!  I'm going to run again with the SCPI commands you listed, but here's what I'm seeing after configuring it from the front panel.  You can see it's basically 10x as noisy as the k2k I posted in your DMM noise thread, and like 50x as noisy as yours! If your steps change the output, I'll update here.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 12, 2015, 07:27:44 am
Today's update..

Took very first unit I bought in 2011, to try fix it with new knowledge.
Run self-test: gotcha 309.1,401.1,402.1,403.1,405.2,405.4,405.6,405.8,406.6,407.1,407.2,407.3,409.6,410.1,411.1,411.2.

Sometimes there was 304.7, but that got fixed by cleaning area around ohms sources.

First step:

Recap analog board and repair damages:

(http://doc.xdevs.com/doc/Keithley/2001/K1/dmg1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/dmg1.jpg)

Fix:

(http://doc.xdevs.com/doc/Keithley/2001/K1/dmgfix_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/dmgfix.jpg)

(http://doc.xdevs.com/doc/Keithley/2001/K1/dmgfix2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/dmgfix2.jpg)

(http://doc.xdevs.com/doc/Keithley/2001/K1/recap_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/recap.jpg)

What is the outcome? :)

Anybody have extra plastic covers for analog board for sale? Two of my remaining 2001's lack plastic covers (top and bottom) for analog board.
Or I can trade to other 2001 parts maybe. Have extra digital board and analog donor board, case, transformer, front panel (no VFD).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Smith on April 13, 2015, 01:26:07 am
Do you mean the plastic standoffs?

I just noticed there is no metal cover as far as I can see around the ADC board? The 6517 electrometer  uses the same ADC board, but is has a metal cover covering the whole ADC board like the one in the upper left corner:
(http://imagizer.imageshack.us/v2/1024x768q90/673/KWrz17.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 13, 2015, 01:36:11 am
I think TiN means the plastic covers that sandwich most of the board. They are black and the interior is painted with a conductive coating.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 13, 2015, 02:05:39 am
Seems like everyone having nice weekend, and only weird voltnuts are messing with fixing some 25 year old instruments :)
So I will drop the suspense and show rest of progress on very first meter I got. It is a reason of all this Keithley madness, root of all evils.  :box:

(http://doc.xdevs.com/doc/Keithley/2001/K1/dmg2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/dmg2.jpg)

As above, this 2001 had analog board revision L, with avalance diodes on front side.
Obviously capacitors leaked after all those years and caused shorts in bootstrap regulator, allowing high current to do some PCB damage around C117.
Pad and connection to negative terminal of cap were completely burnt.

Lucky enough, no low-signal tracing on inner layers was affected. I had quick bodge with some noname fung-hwa-chi capacitors, and had this meter running for
few years in 2012-2013, as it was working for DCV,ohms,current ranges. After that it was collecting dust most of time, as I got other 2001's to play with which were in better shape.

Another issue - was open pin connection on U531 DAC, which was throwing lots of 4xx errors. Previous owner probably was not careful removing analog board, you can see DAC pins bent, like someone pushed poor IC off the PCB.
Fixed by reflowing pins with soldering iron. Easy enough.

(http://doc.xdevs.com/doc/Keithley/2001/K1/dac_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/dac.jpg)

As all Rev.L board I saw, this one have more stable Vishay R356,R358,R365 for current ranges, and ULT H5185A 1Meg 1% in little metal can (R360).
Cleaning around them fixed 304.7 issue for nA ohm current source.

(http://doc.xdevs.com/doc/Keithley/2001/K1/ohms2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/ohms2.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/ohms_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/ohms.jpg)

Had issue with 309.1, Amps. It was wrong Q305 on board. Replacement to IRFR020 from donor 2001 board fixed this problem.

(http://doc.xdevs.com/doc/Keithley/2001/K1/fan_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/fan.jpg)

Replaced fan to ADDA

(http://doc.xdevs.com/doc/Keithley/2001/K1/trms_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/trms.jpg)

No reworks for TRMS area.

(http://doc.xdevs.com/doc/Keithley/2001/K1/input_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/input.jpg)

No reworks on input side either. It's interesting to note, I had 6 units (2001) and none of them had any blown parts on input. Is this a case when sensitive electronics does job to protect 1 dollar protection circuit from failing well? :)

(http://doc.xdevs.com/doc/Keithley/2001/K1/vref_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/vref.jpg)

VREF is alright too, LMx99 with SL40057 IC-527 with datecode 22 week 1993. It have a crack on top cover, since I was curious to see what's inside 5 years ago when got this meter. :)

(http://doc.xdevs.com/doc/Keithley/2001/K1/power_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/power.jpg)

Here's recapped board with replaced avalance diodes, CR514,CR513 zeners.
I desoldered U505, U507, U508, U509, cleaned all PCB area, cleaned ICs themselves with KONTAKT60 (not best cleaner, but works OK and not aggressive as acetone)
Then soldered all except U508 back. U508 (74HC00) was replaced to new one 74F00 (just don't have HC ones in drawer). It's jellybean logic part, why not replace it to new? :)

Notice that I used 1000uF x 50V capacitors for C117,C116. Same diameter, just taller, but still fit nicely. This should reduce wear&tear forcaps, as they are near hot LDO.
I'm not sure why Keithley had 35V rated caps while output on bootstrap circut is +38..+44 and -38 to -44 VDC?

Also this time used general purpose Chemicon KMG 470uF x 63V instead of fattier Low-ESR KZE series Chemicon's.

Here replaced parts marked blue on schematics:

(http://doc.xdevs.com/doc/Keithley/2001/K1/bootstrap.png)

After you gave some capacitor love to analog board, don't forget digital too! There are three lonely 1000uF x 16V, I bet they want to leak and sneeze after all those decades too.
There are no high-power path there, so problem less evident, but it's worth to replace those too. Especially footprint is designed to fit wider 1000uF x 35V.
On my board C630 and C624 had some electrolyte escape already.

(http://doc.xdevs.com/doc/Keithley/2001/K1/digcap_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/digcap.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/digcap2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/digcap2.jpg)

Replaced to all three to 1000uF x 35V Chemicon KY's.

Overall photos of digital and analog boards:

(http://doc.xdevs.com/doc/Keithley/2001/K1/analog_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/analog.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/digital_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/digital.jpg)

How let's slap A/D board on and check this beast..
I used one of A/D boards bought few years ago from our fellow member, free_electron.

(http://doc.xdevs.com/doc/Keithley/2001/K1/adc_top_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/adc_top.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/adc_back_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/adc_back.jpg)

Meter power's on. -39 and +39 after bootstrap there, all voltages ok, no smoke or smell elsewhere. Time to run selftest.

(http://doc.xdevs.com/doc/Keithley/2001/K1/selftest_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/selftest.jpg)

And pass, no errors!

(http://doc.xdevs.com/doc/Keithley/2001/K1/diagpass_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/diagpass.jpg)

Run in continuous loops few dozen times, no problems.

(http://doc.xdevs.com/doc/Keithley/2001/K1/stest_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/stest.jpg)

Time to check voltages?

(http://doc.xdevs.com/doc/Keithley/2001/K1/1vdc_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/1vdc.jpg)

Sourced 1.00028VDC from 2400, measured 0.99029 VDC. No good.

(http://doc.xdevs.com/doc/Keithley/2001/K1/10vdc_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/10vdc.jpg)

Sourced 10V from EDC MV106, measured 9.89829 VDC. No good, definately need calibration, but should be no issues with that.

Bottom 2001 - one fixed last weekend, calibrated using VPG 19K and 1Meg resistors and 2V and 20V from EDC MV106 measured by reference 2001 (it's meter on top right, calibrated by Tektronix in February 2014)

Like always, enlarged photos on clicks ;)

Bonus

(http://doc.xdevs.com/doc/Keithley/2001/K1/test_adc_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/test_adc.jpg)

A/D board with probe port to Mictor (which in turn runs into Mictor-P6860 adapter and my TLA714. :) What's going on here?
Hope you enjoy reading..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 13, 2015, 02:10:21 am
Hi Smith,

No, i mean black cover which covers analog board from top and bottom.

(http://doc.xdevs.com/doc/Keithley/2001/K1/cover_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/cover.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/cable_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K1/cable.jpg)

It's unique to Keithley 2001 and 2002 units only.

I would LOVE to see more high-resolution photos of your 6517 internals. Information about electrometer insides are scarce. Maybe even A/D board if it's not same revision as one's I have (J and H).
You can upload you photos on my FTP (http://doc.xdevs.com/contact/) and I would rehost on website for people repairs. Size unlimited, everything is welcome :)
Also firmware would be nice to dump, if you have tool to read ROMs. We have (http://doc.xdevs.com/article/keithley-instruments/) only A10, A12 and A13 and it's only for 6517B.

Also maybe someone have front panel board with VFD? Since I had salvaged VFD to fix my 2400 long time ago, and now I need working front panel to one of 2001's.
If nobody have - then I will sacrifice my 7001 and desolder VFD from it's board and solder back on 2001 front panel PCB (still have it, just no glass).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Smith on April 13, 2015, 03:23:34 am
I will take a look tommorow, I just started calibrating and checking the 6517A. The main electrometer input circuit is pure electronics porn, so I will definetly take some pics. Too bad I don't have a EEPROM reader. I still have C03, C05 is newer but has to be flashed directly in the two EEPROMs.

The VFD is quite bad, it had been up and running for about 8 years, so some characters  can only be read from nearby. Maybe I'll try to get some donor, a new one is too expensive.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 14, 2015, 04:23:37 am
Here's a neat trick to increase the "resolution" when viewing signals much less than full scale, such as measuring a few microvolts or a null (like in the DMM Noise thread). Apply a mX+b math function with m=1000 (for example). Then the 200 mV full scale becomes 200 uV full scale... and you still get 7.5 digits on screen.  :-DMM  Enable a big long digital filter to tame some of those extra digits. Clearly one must understand what they are and are not achieving with such a trick, or just don't bother.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 14, 2015, 04:55:29 am
Yes, math flexibility is one reasons why I like 2001's.

Today no more meters get fixed, but got prepared frontpanel.
I have 2 units left to with, that's not counting donor unit, which is unrepairable.

One of units I bought had no front panel board. And VFD from donor front panel board was moved to my 2400 (http://www.eevblog.com/forum/testgear/keithley-2400-sourcemeter-review-and-teardown/), as original 2400's glass was broken. (http://xdevs.com/article/kei2400/). So I end up having 2001 front panel PCB, but no VFD glass.

Later few years I bought pair of 7001 for 100$. One had broken glass, second one fully functional. Since I don't have any scan cards, 7001 goes to destruction derby now. Already took DC-AC module from it before, so it's decided...

(http://doc.xdevs.com/doc/Keithley/2001/K4/before_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/before.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/before2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/before2.jpg)

Same glass, different PCBs.

This job is not for nervous people. It took me about an 1.5 hours and extensive use of censored language , together with solder wick and flux to "free" glass pins in thruhole pads.
I did not want to heat up whole board and glass, so did it this way, one by one. These glass mounted pins usually pretty gentle and easy to peel off if apply even little force.

(http://doc.xdevs.com/doc/Keithley/2001/K4/remove_vfd_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/remove_vfd.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/vfdpin_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/vfdpin.jpg)

I was gentle..

Then clean pin holes in 2001's board. To do so, just heat pad and push toothpick thru, to open hole.

(http://doc.xdevs.com/doc/Keithley/2001/K4/cleanvfd_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/cleanvfd.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/replacevfd_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/replacevfd.jpg)

After this everything is trivial. Pop glass in, it drops in like a charm with zero force, and solder it pin by pin with 1-1.5mm tip.

(http://doc.xdevs.com/doc/Keithley/2001/K4/vfdtest1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/vfdtest1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/vfdtest2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K4/vfdtest2.jpg)

End result - it works :) Front cover need some cleaning, that will do later.

Any one know how to make yellow plastic look like new?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 14, 2015, 05:13:56 am
Any one know how to make yellow plastic look like new?
Look up retr0bright.
It is a combination of very strong hydrogen peroxide (hair bleach) and a little bit of laundry oxygen booster. The other essential ingredient is strong UV light which is free in the form of sunshine. Now that spring has sprung here and the outdoor temperature is neither too cold nor hot I will be restoring a few bits of my own (one K2001 in particular is very yellow).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 14, 2015, 05:18:09 am
How about labels, could H2O2 destroy them? I remember strong one is pretty agressive.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 14, 2015, 05:30:36 am
How about labels, could H2O2 destroy them? I remember strong one is pretty agressive.
People use this stuff on old computers, gameboys, and other things made of ABS all the time, with little fear over painted / silkscreened labels. Paper labels and stickers are another story. This stuff is not a solvent; it is specifically reacting with bromine (fire retardant) in the plastic which is the cause of the yellowing.

I had to search for the right peroxide, I found what I wanted at a professional beauty supply store: 30 or 40 "vol" peroxide gel. The gel is convenient because you can just paint the mixture onto the plastic rather than needing to submerge the entire piece in a liquid. You can also add thickener xanthan gum (get that from a health food store; it is used as a binder in gluten-free baking).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on April 15, 2015, 09:35:49 pm
The first Retrobrite attempts involved buying and mixing lots of hard to get chemicals, but the guys from the retro computer scene have moved to using this product: http://www.amazon.co.uk/Jerome-Russell-Bblonde-Maximum-Peroxide/dp/B00DG8RTHK/ref=pd_cp_beauty_3/280-1602579-8962721 (http://www.amazon.co.uk/Jerome-Russell-Bblonde-Maximum-Peroxide/dp/B00DG8RTHK/ref=pd_cp_beauty_3/280-1602579-8962721)
Not sure if it's available where you are, but this can be used "as is" without having to add anything further. You just smear it on, cover the part in clear plastic and leave it out in the sun. Just rinse off afterwards to reveal a like new colour.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: wertyq on April 16, 2015, 01:31:29 am
I have adc modules for those things...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 17, 2015, 09:16:13 pm
wertyq
No, you do not have. You are some wierd spambot which copy other's messages  :-//

All
That military 2001M we talked about is back for sale (http://www.ebay.com/itm/111647302599?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT). I was thinking to watch it, but looking at heavy bidding 5 days before end ( :wtf: :blah:) it does not look good. So I'm out on this rare -M version with all paper documentation and schematics included :)
Just a heads up who want fresh 2001 desperately (serial number is 1xxxxxx and firmware is newest we ever know, B17), so if lucky winner of this unit happen to be EEVBlogger, please do post details :)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Smith on April 17, 2015, 09:22:11 pm
Hi Smith,

I would LOVE to see more high-resolution photos of your 6517 internals. Information about electrometer insides are scarce. Maybe even A/D board if it's not same revision as one's I have (J and H).
You can upload you photos on my FTP (http://doc.xdevs.com/contact/) and I would rehost on website for people repairs. Size unlimited, everything is welcome :)
Also firmware would be nice to dump, if you have tool to read ROMs. We have (http://doc.xdevs.com/article/keithley-instruments/) only A10, A12 and A13 and it's only for 6517B.

I have uploaded some pictures and 2 firmwares for the 6517A. I realized I hadn't took a picture of the ADC board itself. As far as I can remember it was one of the revisions you posted on the first page of this topic. BTW, in the overview of the Keithley documents there is a 6517, 6517A and 6516B. I think the last one was a typo.

BTW, do you know how to flash the name.x file on the two EPROMS?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 17, 2015, 09:33:30 pm
Yes, that's for sure typo, thanks.

As of .x files, these are motorola format. It's easy to convert into hex or binary, I use WinHEX for that for example.

But your firmware seem to be too small (in both 6517A_C03_ODD.bin and 6517C05.x files), should be same same as EVEN one.
Can you check?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Smith on April 17, 2015, 10:07:54 pm
You where right, something went wrong in the mail. I've uploaded them again and they should be OK.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 28, 2015, 10:40:56 pm
You still did not replace caps on your Keithley 2001?
Merphy's going to you...

Calibrated 2001 died, hangs often and "No Comm Link" ...

Here's what waiting inside, little 1000uF bastards did some peepee ...

(http://doc.xdevs.com/doc/Keithley/2001/K7/auch_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/auch.jpg)


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 28, 2015, 11:11:56 pm
I feel better now. I just placed an order yesterday for a bunch of those caps. I wasn't sure if it would be worth the extra effort.

I have also been replacing the power entry module. It is not made by Schaffner, but with all the other caps going bad I thought why take the chance? Mouser has them in single unit quantities.

My Tektronix order is coming in today so I should be reassembling the second 2001 awaiting the additional caps. I will let you know how that DS1248Y works out in the 2002. The front / rear switch in the 2002 will also have to be replaced since it won't lock. The order has some spare switches and at $11 they were relatively inexpensive.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 28, 2015, 11:27:50 pm
TiN,

Was that the meter that was 'singing' during the EZGPIB script? I hope I didn't add to the death of those caps. I have been testing a new script but still have a few tweaks to make.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 29, 2015, 12:21:28 am
TiN,

Was that the meter that was 'singing' during the EZGPIB script? I hope I didn't add to the death of those caps. I have been testing a new script but still have a few tweaks to make.
If it was related, then I would think that the "singing" was a side effect of the caps dieing, not the cause of their death.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on April 29, 2015, 01:25:18 am
I know, it just reminds me of the Apple II urban myth that it supposedly could be killed with a single POKE command. Not that I remember what an Apple II actually is...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 29, 2015, 01:56:11 am
Yes, it was a "singer".
Just sad that I spend evening yesterday replacing caps, cleaning board, desoldering VFD DC-DC (ERG E705-E905VF) , soldering it back, as it's still a dud.  :rant:
5VDC voltage is fine, reset is fine.

Here are some more photos during yesterday service:

(http://doc.xdevs.com/doc/Keithley/2001/K7/dcap1_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/dcap1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/dcap2_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/dcap2.jpg)

I removed all parts around caps, tried clean PCB with acetone, and I thought silkscreen mask got dissolved by acetone. That never happen before.
Then tried some other area's of PCB with acetone, nop, silkscreen mask intact. So that was not acetone, but aggressive electrolyte from caps, evil enough to dissolve silkscreens and solder mask!

(http://doc.xdevs.com/doc/Keithley/2001/K7/dcap3_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/dcap3.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/acetone_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/acetone.jpg)

After replacement :

(http://doc.xdevs.com/doc/Keithley/2001/K7/dcap5_s.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/dcap5.jpg)

Did that because donor board had missing U622 GPIB chip and U621,U623 buffers and firmware PLCC32 ROM chip. Well, now I have those chips, desoldered them from my poor 7001 (again), and will use firmware ROM from problem board now.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 29, 2015, 04:22:43 am
GPIB interface chip ready to solder on digital board. This one come from 7001 switch.

(http://doc.xdevs.com/doc/Keithley/2001/K7/gpib1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/gpib1.jpg)

GPIB transceivers ready to be soldered... This one come from 7001 switch too.

(http://doc.xdevs.com/doc/Keithley/2001/K7/gpib2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/gpib2.jpg)

Fixed board back in unit

(http://doc.xdevs.com/doc/Keithley/2001/K7/digbrd2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/digbrd2.jpg)

Working just fine after copy calibration ROM contents from old board. 19K000 0.005% VPG resistor measurement.

(http://doc.xdevs.com/doc/Keithley/2001/K7/digfix_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K7/digfix.jpg)

Funny note , it still have high-pitch noise, I guess it's from display DC-DC (as I moved it to new board) and noise frequency changes when display show different information.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on April 29, 2015, 05:28:19 am
In the photo of the repaired digital board, you have the memory jumper in "STD" position, but you have DS1245Y installed. I guess that you forgot to switch to "OPT" position.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 30, 2015, 01:50:36 am
I thought noone opens full resolution photos  ;D
Good catch.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 06, 2015, 04:53:14 am
How are our DMM restoration goes?
Anyone interested in calibration howto video? Recorded some footage during calibration of third repaired 2001.
End result (measuring 2V from EDC MV106):

(http://images.tapatalk-cdn.com/15/05/05/d540855430670c58352e3adf66dd7778.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 17, 2015, 07:27:55 am
Those are the days I think we can conquer the world guys! Still can't believe the FULL schematics are now in our hands  :-+.

Nice job TiN and macboy.

From my side I am still hunting the 1801 preamp, but I think it is official and extinct animal. Surely somewhere it is just sleeping in some dusty big company lab corners (:palm:).
Worth to try with the Keithley forum brothers (as it happen here (http://www.eevblog.com/forum/repair/teardown-keithley-2510-tec-smu-repair/msg562957/#msg562957)), and why not ask there for the B16 FW? I can do it if nobody already tried that.

My 2001 unit is still sailing the ocean finding his way from Canada to Germany....

Quote
'Grandpa, were you a hero in the war?' Grandpa said 'No... but I served in a company of heroes.'

I recently used an 1801 with a 2001. The stability/drift is less than 1nV. It is truly a gem of an instrument. It is obsolete but I believe that it was built in England by EM Electronics. Here is a link to a free-standing nV amplifier from EM http://www.emelectronics.co.uk/spec/A10.html (http://www.emelectronics.co.uk/spec/A10.html)

For the budget minded, I recommend finding a model 147. I have bought two model 147 and one model 148 from eBay. I have used a working 147 to measure a 5 nano-ohm resistance standard. Just source +1A and then -1A and calculate the slope R = (V1-V2)/(I1-I2). Using +/- 5A is easier but I don't have a 5A sourcemeter handy.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 17, 2015, 10:59:43 am
If you have possibility, some internal photo of 1801 would be really appreciated.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 17, 2015, 11:03:59 am
Sorry, no internal photos. The 1801 and 2001 belongs to my employer and I was not free to take the cover off.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on May 17, 2015, 01:12:32 pm
TiN,

I would be interested in any calibration videos you have made. The 2001 and 2400 would be helpful as I plan on doing mine (hopefully) by next weekend.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Theboel on May 17, 2015, 01:58:13 pm
Hi Tin,

Even I don't have any keithley yet the calibration video is interesting specially 2001

Thank You
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on May 20, 2015, 07:32:33 pm
Sorry, no internal photos. The 1801 and 2001 belongs to my employer and I was not free to take the cover off.

[fun] Just PM me the address and my Italian friends will do the job... [/fun]
What a pity! I definitely gave up with the hunt. In Europe and in USA the K 1801 is no more available, it is just an old ghost. Thanks a lot for the EM A10 hint, I think we are on  a very promising path.
EDIT:
Check this out:

EM Amplifier Utility Board UBc with Passive Filter (http://www.emelectronics.co.uk/Pages/UBc%20Board.html)
EM Amplifier Utility Board UBb with Active Filter (http://www.emelectronics.co.uk/Pages/UBb%20Board.html)

@Group: Sorry for not posting anything in the last month. I was busy. BTW my K 2001 is now here. It was owned by a Canadian winemaker and it was use to control the wine temperature!
I open it up and found some interesting (no sense?) stuff (according to my poor brain), I will post details soon. 
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 20, 2015, 09:56:21 pm
Welcome back :) Same story here, just mess with 2000 and 2002 a little last week. Busy upgrading my server lately.

Take some nice photos, we will clarify all non-sense stuff in it :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on May 21, 2015, 09:12:49 am
Hey guys, I mentioned on here sometime last fall about needing a replacement white amps/fuse jack for my 2000. Someone mentioned having one, but I can't find the post now. :-(

If anyone has one I'd be grateful!

If also be interested in an entire non-yellowed front panel (just the plastic, doesn't have to include the display, etc.) in good condition, as mine has turned "vintage PC plastic yellow". I guess Keithley must have used bromine as a flame retardant?


Sent from my Smartphone
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: eas on May 21, 2015, 03:12:03 pm
So, did one of you get the non-working 2001 on ebay for ~$205 today? I was planning to try and do a last minute bid on it in the 5 minutes between the end of an appointment and the end of the auction. My appointment ran long... :-[
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 03:57:45 am
So, did one of you get the non-working 2001 on ebay for ~$205 today? I was planning to try and do a last minute bid on it in the 5 minutes between the end of an appointment and the end of the auction. My appointment ran long... :-[

I bid on it at the end but was outbid. Not disappointed. I bought an as-is 2001 for $395 from a test equipment broker. It is supposed to arrive today. I will post pictures and results of the instrument's condition and behavior.

I did receive a 7001 today. Dim low display but it works. Paid $92.00 shipped. Inside looks pristine. Outside is scratched up but no dents or out-of-square bending. Cover comes off easily. Chips are dated 4299 so I guess this is year 2000 instrument.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 06:56:13 am
KI 2001 Last Calibration year 2000. Has the following errors

Testcal           201.3
A/D Mux  /Buff   300.2
Ohms Pretect   302.2
Input Protect   303.2
Ohms               304.2
Ohms           304.3
Ohms           304.4
Ohms           304.5
Ohms           304.6
Ohms           304.7
Input /100           305.2
Cal Divider           307.2
Cal Divider           307.3
4 Digit           308.1
Amps                   309.1
Amps                   309.2
Amps                   309.3
Amps                   309.5
Amps                   309.6
Amps Protect   310.1
S/H No. 2          406.6
Front End          407.1
Front End          407.2
Front End          407.3
Freq Cmp          409.6
TRMS          410.1
TRMS Filter       411.1
TRMS Filter   411.2
ACA Switch   412.1

Analog Daughter board 2001-162-04J

(http://i467.photobucket.com/albums/rr35/woofertester/KI2001/Daughter%20Board_zpsyp3pexdt.jpg) (http://s467.photobucket.com/user/woofertester/media/KI2001/Daughter%20Board_zpsyp3pexdt.jpg.html)

Digital Board 2001-142-06J

(http://i467.photobucket.com/albums/rr35/woofertester/KI2001/Digital%20Board_zpsxwomholw.jpg) (http://s467.photobucket.com/user/woofertester/media/KI2001/Digital%20Board_zpsxwomholw.jpg.html)

Analog Main Board 2001-102-04K

(http://i467.photobucket.com/albums/rr35/woofertester/KI2001/Analog%20Board_zpshlzvvw8b.jpg) (http://s467.photobucket.com/user/woofertester/media/KI2001/Analog%20Board_zpshlzvvw8b.jpg.html)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on May 22, 2015, 07:13:05 am
I see a capacitor soldered to R851. I don't remember seeing that 'mod' on another converter board. It looks like it connects to the DGND pin.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 07:33:45 am
Your are correct. Good eyes! It is definitely a white wire special.

None of the functions work even close to what you would expect.

All of the voltage regulators near the transformer get very warm. The large PLCC on the daughter board gets very warm.

I suppose its time to get out the DMM and start checking voltage rails.

Is it safe/wise to operate the instrument with the daughter board off?

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 22, 2015, 10:58:30 am
Yes, but your reference and bunch of other stuff would not work. Good enough for psu checks.

AD CPLD get little hot but not too much. It takes 5V rail.

Replace all electrolytics on both boards before you do anything.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 11:49:20 am
Yes, but your reference and bunch of other stuff would not work. Good enough for psu checks.

AD CPLD get little hot but not too much. It takes 5V rail.

Replace all electrolytics on both boards before you do anything.

Ok. I will have to make a list and order the capacitors all at once.
It looks like 8 electrolytics on the analog main board and 4 electrolytics on the digital board.

The 2001 passes all key press tests and passes the display tests.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 11:56:58 am
Closer inspection shows surface mount electrolytics on the converter daughter board and the analog main board.

Have you replaced those electrolytics as well?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 22, 2015, 12:08:01 pm
If you mean tantalums, no, you can leave those alone.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 22, 2015, 12:50:10 pm
If you mean tantalums, no, you can leave those alone.

Ok. Thanks.

Are the 4 regulators close to the power transformer running hot on your 2001s?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 22, 2015, 02:34:52 pm
I posted thermal photos before :

(https://dev.xdevs.com/projects/kei2001/repository/entry/ir/IR000075.jpg)

You can see them all in my K2001 repository (https://dev.xdevs.com/projects/kei2001/repository/show/ir).

Usually if someone buy old 2001, I would do next:

1. Take boards of meter, take photos (try not to use flash, to avoid glare on PCB :))
2. Upload photos (http://doc.xdevs.com/contact/) for my collection :)
3. Replace all thruhole electrolytic caps. You will need 470uF x 63V 2pcs, 2200uF x 35V big ones, 1000uF 50V x 3pcs, 2200uF x 16V - 1pc, 1000uF 35V x 3pcs (for digital board), 47uF x 63V for digital board.
4. If there is electolyte gunk from old caps - you must desolder stuff around affected area, clean area very well, solder parts back. Believe me, this will save you DAYS of troubleshooting...
5. If any traces damaged/black - repair them. Pay attention to little vias around, to make sure they are not eaten/open.
6. Assembly stuff back, power on, check voltages (5V digital, 5V analog, +15V, -15V, +8VF, -8VF (there are test pads near A/D board connector), +38V, -38V (test pads near AD637)).
6b. Replace fan, usually they are bad in all old units (You need 40x40mm 12V 0.1A DC Fan).
7. CR11x avalance diodes near transformer must be cold, if they heating up - something around them and caps is messed up.
8. If all voltages within few % tolerance, run self-test and report what errors occur :)
9. Dump firmware and 24C16 calibration ROM contents, upload them for our collection :)

304.6,304.7 errors on ohms are usually contamination/dirt around ohm source ranges (Area around U325). If lower 304.x errors present - check Q320,Q311,Q312.
Correct voltage reference on pin 1 of A/D connector is -10.xx VDC.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 22, 2015, 09:56:28 pm
Quote
So, did one of you get the non-working 2001 on ebay for ~$205 today?
I know who got it  ;) (Not me  :-DD)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 23, 2015, 03:12:58 am
I posted thermal photos before :

(https://dev.xdevs.com/projects/kei2001/repository/entry/ir/IR000075.jpg)

You can see them all in my K2001 repository (https://dev.xdevs.com/projects/kei2001/repository/show/ir).

Usually if someone buy old 2001, I would do next:

1. Take boards of meter, take photos (try not to use flash, to avoid glare on PCB :))
2. Upload photos (http://doc.xdevs.com/contact/) for my collection :)
3. Replace all thruhole electrolytic caps. You will need 470uF x 63V 2pcs, 2200uF x 35V big ones, 1000uF 50V x 3pcs, 2200uF x 16V - 1pc, 1000uF 35V x 3pcs (for digital board), 47uF x 63V for digital board.
4. If there is electolyte gunk from old caps - you must desolder stuff around affected area, clean area very well, solder parts back. Believe me, this will save you DAYS of troubleshooting...
5. If any traces damaged/black - repair them. Pay attention to little vias around, to make sure they are not eaten/open.
6. Assembly stuff back, power on, check voltages (5V digital, 5V analog, +15V, -15V, +8VF, -8VF (there are test pads near A/D board connector), +38V, -38V (test pads near AD637)).
6b. Replace fan, usually they are bad in all old units (You need 40x40mm 12V 0.1A DC Fan).
7. CR11x avalance diodes near transformer must be cold, if they heating up - something around them and caps is messed up.
8. If all voltages within few % tolerance, run self-test and report what errors occur :)
9. Dump firmware and 24C16 calibration ROM contents, upload them for our collection :)

304.6,304.7 errors on ohms are usually contamination/dirt around ohm source ranges (Area around U325). If lower 304.x errors present - check Q320,Q311,Q312.
Correct voltage reference on pin 1 of A/D connector is -10.xx VDC.

Thanks. I will do all of that.

I wonder if the high heat of the regulators is a cause of the nearby electrolytic capacitors failure. I also wonder if installing some massive heatsink to the regulators , getting the heat out of the regulators, may improve the reliability of the capacitors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 23, 2015, 03:45:53 am
Its usually combo of factors, like fan failure (on two 2001 i have fans were dead), high temps, and old age of caps. I would keep stock heatsinks, in case you may want sell meter in future, just use proper high quality 105 degree rated caps from respected vendor.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: VintageNut on May 23, 2015, 06:27:36 am
Its usually combo of factors, like fan failure (on two 2001 i have fans were dead), high temps, and old age of caps. I would keep stock heatsinks, in case you may want sell meter in future, just use proper high quality 105 degree rated caps from respected vendor.

For sure I would keep stock heatsinks.

Here is my reasoning. The internal temperature of a 2002 I am using is above 110 F. If the regulators are much hotter than the air temp, the capacitors close to the regulators may be much closer to 105 C than to 110F. If the regulators can be kept much cooler, that may help the reliability of the capacitors nearby.



Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on June 17, 2015, 07:38:10 am
VintageNut passed his 2001 on to me; now I'm looking at it.

I'll put together a cap order, but I'm looking at that 201.3 fail.  That has the same symptoms and V measurements that SKE reported way back at the beginning of this thread.  Unfortunately, he disappeared without reporting a resolution. 

I see 6.98V referenced to COM at pin 6 of U330, 7.4V at pins 2 and 3 and 7.22 at pin 7 of U318 (the output of U327, which should be 1.75V)  Obviously the last is wrong, the first looks reasonable but what about the other two measurements?

The power supply voltages all looked good.

edit: OK, this looks like a bad U330.  The leading edge of REFCLOCK is bleeding through and the output is a fuzzy squarewave on top of a DC level.  If I'm reading the schematic right, I should be seeing a 0-7V squarewave that's integrated by U327.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on June 23, 2015, 01:55:26 pm
Hi Group,

I can report a successful repair of a 2001.
I bought the meter for $30.00 CDN ($24 USD or 21.60 Euro.

It was missing the bridge rectifier on the Digital Board, the NAT488 chip.

It is also missing the outer cover, rear bezel and needs a replacement keypad because of one of the buttons is damaged.


After I installed the rectifier, the meter powered up and I was able to make measurements and get reasonably good results.

I ran the self-test and got a whole pile of errors. Having read this thread I decided I should start by replacing all the electrolytic capacitors. Here is the capacitors that I pulled out:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157784;image)

I did not find any damaged tracks, there was little electrolyte on the board. I scrubbed the board with alcohol (IPA) and then fitted replacement capacitors. Here is the list of capacitors I bought:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157786;image)

I have also attached a pdf with the capacitor list.

Here is a picture showing the new caps installed:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157788;image)

The unit now passes all the self-tests except two:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157790;image)

This one will probably go away if I install a NAT488:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157792;image)

The other error I believe is also related to the missing NAT488 chip:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157794;image)

I am looking for some case parts:

Cover
Handle
Rear Bezel
Rubber Keypad

Can anybody help?

Regards,

Jay_Diddy_B




Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 23, 2015, 02:53:06 pm
Great, thanks for photos.
You sure they are UCC caps are original? All KZE's I had are brown plastic color, not black like on your photo.  :-//

Where did optocouplers near input selection switch go? You need those back :)
I have spare digital board, which have some issues (often does not boot), but have all the parts on it.
I can send it for you and optocouplers, if you don't mind pay shipping (~30-40USD or so).

Btw, for a general note - GPIB chipset (NAT488 or compatible part) can be found on many similar instruments.
One of my boards was missing GPIB chip too, and I salvaged it from Keithley 7001 (bought for 50$).


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on June 23, 2015, 10:21:28 pm
Great, thanks for photos.
You sure they are UCC caps are original? All KZE's I had are brown plastic color, not black like on your photo.  :-//

Where did optocouplers near input selection switch go? You need those back :)
I have spare digital board, which have some issues (often does not boot), but have all the parts on it.
I can send it for you and optocouplers, if you don't mind pay shipping (~30-40USD or so).

Btw, for a general note - GPIB chipset (NAT488 or compatible part) can be found on many similar instruments.
One of my boards was missing GPIB chip too, and I salvaged it from Keithley 7001 (bought for 50$).


I hope the UCC caps are original, they are dark brown, I bought fresh ones from Digikey. I did not want to do the repair with New Old Stock (NOS). I have lots of NOS caps, but it is such a pain to change them. I went with fresh caps from a official distributor.

Thank you for the kind offer to send me a spare digital board. The opto-couplers are in the board, for some reason they are mounted on the solder side with a jumper on the component side to correct the wiring. I suspect that they may have been changed at some point. The meter seems to work properly.

Do you know the function of the opto-couplers?

I may have the NAT9914BPL on an old GPIB board for a PC. I haven't had a good look. I wanted to make that the analog section was working properly before I fixed the missing part. The part was used on NI GPIB PC-II/IIa ISA bus cards:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=157868;image)

Regards,

Jay_Diddy_B



Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 23, 2015, 11:01:22 pm
That chip is bigger PLCC on GPIB-PCII photo, will not fit.

Optocouplers are part of input protection and input buffer circuitry.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on June 24, 2015, 12:16:24 am
...

I may have the NAT9914BPL on an old GPIB board for a PC. I haven't had a good look. I wanted to make that the analog section was working properly before I fixed the missing part. The part was used on NI GPIB PC-II/IIa ISA bus cards:

Regards,

Jay_Diddy_B
9144 != 9914
I have a few 7001 switching systems, and I may be willing to part one out for a nominal cost. That will provide you with the cover, rear bezel, 9914 IC, and maybe the switch membrane. Sadly, they were rack mounted so I don't have handles. You can buy a "2000 Benchkit" from places like Mouser, etc., for around $25 or so. This includes the feet and handle. They used to sell the pieces of that kit separately for a total cost of around $12 but I think they have wised up since then.
Where in Canada are you? I'm in Ottawa.

p.s. Keithley has parts distributors in Canada as well, but generally they have a $250 or so minimum. I had wanted to replace the front panel of one of my 2001's, but that came to only about half of that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 24, 2015, 12:32:22 am
Cover from 7001 is not compatible with 2001, if we talking outside chassis thing.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on June 24, 2015, 12:38:46 am
Cover from 7001 is not compatible with 2001, if we talking outside chassis thing.
Too bad. I hadn't checked. Is it a length difference?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on June 24, 2015, 12:59:15 am
The 7001 is missing the vent holes. I accidently put a 7001 cover on my 2001 and realized the vent holes were missing. I think with the right measurements, some holes could be made to fix that issue.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on June 24, 2015, 01:48:19 am
Mouser doesn't stock the benchkit, but Test Equipment Depot does.  They have it through Amazon, but it's cheaper to go direct.  Base price on that is now $31 + s/h, so figure $40+ for the handle and feet.

That takes care of the handle, anyone got a rear bezel they would sell?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dadler on June 24, 2015, 05:56:32 am
The 7001 is missing the vent holes. I accidently put a 7001 cover on my 2001 and realized the vent holes were missing. I think with the right measurements, some holes could be made to fix that issue.

On this topic, anyone know if the 7001 cover is compatible with the 2015 series? I don't think either of them have "vent holes"?

The 2015-P I just bought on eBay is missing the feet and handle, so I was hoping to swap those over from a 7001 to my 2015.

My 2015 case is a bit gouged up as well, so if the cover swaps as well that would be great.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on June 24, 2015, 06:47:20 am
Mouser doesn't stock the benchkit, but Test Equipment Depot does.  They have it through Amazon, but it's cheaper to go direct.  Base price on that is now $31 + s/h, so figure $40+ for the handle and feet.

That takes care of the handle, anyone got a rear bezel they would sell?
If you are ordering parts, the Keithley part number for the rear bezel is 428-303.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on June 25, 2015, 01:09:38 pm
Hi,

Does anybody have a picture that shows the mechanical parts of the Keithley 2001 DMM?

I found a list in the repair manual:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=158100;image)


But, I would like know the difference between 'Front Panel Assembly 2001-061' and 'Front Panel '2001-302'

I am considering doing my restoration with new parts from Keithley instead of buying another meter for parts. If I buy parts meter, I might be tempted to fix it  :D

Thanks!!

Jay_Diddy_B

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on June 25, 2015, 10:49:28 pm
I looked into this at one time since the front panel of one of mine is very dinged up and yellowed. The Front Panel Assembly includes the lens and the input jacks. You would still need to swap the electronics over, and you will need the "conductive rubber switch" as well. Then your meter will look brand new, from the front anyway. The quote I had received was $134 USD for the front panel assembly, through Testforce (Pickering, ON).

You are exceedingly unlikely to find another parts machine for $70. How did you find that? If you find any more, let me know!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on June 25, 2015, 11:16:35 pm
Mine is like this:

(http://i.imgur.com/HDXz8d3.jpg)

As you can see it there is a nasty electric tape covering the front panel border all round. It looks like mine was used as a rugby ball and the front panel was damaged.
I can buy a brown/yellow front panel from someone who is upgrading to a shiny one (I like the "good old" style) as long it is one piece with no cracks, and I am also interested on a handle bar + feet.

PS: Lord have mercy I am a sinner, my lab bench DIY build project is stopping everything else. Shame on me for posting nothing here for a long time...  |O
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 26, 2015, 03:50:37 am
Seems activity in this thread, yey.

To keep things rolling, here's a teaser:

(http://doc.xdevs.com/doc/Keithley/2001M/photo/3_ADC_1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001M/photo/3_ADC_1.jpg)
(http://doc.xdevs.com/doc/Keithley/2001M/photo/3_ADC_2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001M/photo/3_ADC_2.jpg)

This is from that 2001M. It was manufactured in early 2012, which is by far the newest meter in this whole thread.
Unit finally arrived to fellow member, which shared photos and data about it in other EE forum.
Firmware B17 uploaded (https://doc.xdevs.com/article/keithley-instruments/#2001M) as usual.

Article in progress, stay tuned...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dadler on June 27, 2015, 07:29:15 am
I am tempted to offer on this one, but the number of inquiries (and the lack of explanation on what is broken) has got me suspect:

http://www.ebay.com/itm/Keithley-2001-7-5-Digit-Benchtop-Multimeter-Note-Needs-Repair-/380950606692?pt=LH_DefaultDomain_0&hash=item58b26cf364 (http://www.ebay.com/itm/Keithley-2001-7-5-Digit-Benchtop-Multimeter-Note-Needs-Repair-/380950606692?pt=LH_DefaultDomain_0&hash=item58b26cf364)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on June 27, 2015, 07:44:58 am
I made a couple of offers on that one.  I think he'll take $725 :)  Would be nice to get the results of the self test.

I've already got $100 in parts and pieces into the one I'm working on.  Since it could use a new display window and rubber switches, I'm not done yet.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on June 27, 2015, 07:51:25 am
I also made a couple of offers. It seems they are easily offended or don't bother with best offers as I never got a response.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dadler on June 27, 2015, 12:01:00 pm
Hmm, I think he is asking for too much, especially without the results of the self test.

I was going to offer much less than that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Sailor on June 27, 2015, 01:42:14 pm
International Customers:
Payment must be made via Bank Wire Transfer only. "NO EXCEPTIONS" ???
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 27, 2015, 02:03:15 pm
2001's going like hot cakes now.
I might consider selling few myself soon (fully functional and calibrated (not official service center, just myself to my standards))
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dadler on July 04, 2015, 10:19:44 am
So, just in case anyone is interested:

The 2001/7001 outer metal enclosure is ~33cm long.
The 2015 outer metal enclosure is ~32cm long, and doesn't wrap all the way around. So you can't even come close to interchanging these.

Also, the enclosure that came with my 7001 is stamped "2001-327   F" on the inside. Makes me think that for at least some years, the outer enclosure is identical between the 2001/700 models? Might just be a coincidence, due to the lack of a fan/fan holes in the 7001.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on July 19, 2015, 10:57:49 am
Can somebody measure the +15 to common resistance?  I'm seeing around 70 ohms on mine and that doesn't seem quite right, -15 to ground is around 1.2K.

Tracked things down to an LM339 that was running around 180F.  After tracking through the schematic to find out why a line was low, I could have saved myself a lot of trouble just by poking my finger around.  After pulling that out, I'm still seeing 70 ohms from +15 to ground.

thanks
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 19, 2015, 03:05:57 pm
+15V to analog GND (Lo terminal) : ~75.2 Ohm
-15V to analog GND (Lo terminal) : ~1283 Ohm
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on July 19, 2015, 09:43:41 pm
thanks!

Now to replace that lm399 and see if any self tests clear.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 20, 2015, 11:31:06 pm
Unlikely, I did not yet remember seeing failed LM399 in any Keithley so far. :)
What are error codes exactly? 4xx series are often to do with flaky bootstrap circuitry..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on July 21, 2015, 12:46:43 am
I',m tracking down a 302.2 fail.  I've followed it down to a missing OHM signal due to a stuck low CLR preset on U301 pin 1 (OHM never goes low, K300 never pulls in and OHMS is not available).  U316 was the very hot lm399 lm339.  The new lm399 lm339 no longer gets hot, but I still have the 302.2 fail.  I"m about to look into that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Andreas on July 21, 2015, 05:02:15 am
The new lm399 no longer gets hot

A lm399 has 85 deg C as operating temperature -> the new lm399 is defective.

With best regards

Andreas
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PaulAm on July 21, 2015, 05:07:19 am
Gah, that's a typo.  It's a lm339.

The lm399 is fine.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on July 21, 2015, 05:15:27 am
LOOL, nice typo ;-) This comparator failure has been already discussed. I needs to replace many of them in the range switching on different Keithley instruments.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 21, 2015, 09:25:22 am
Worth to check Q311,Q312,Q320,Q324 (TO92 packages) around ohms circuitry. I had these throwing 30x errors before, fixed after replacement from donor board.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on July 23, 2015, 05:43:28 am
Hi All,

this is my first post in the forum (although I have been following it for a couple of years)...

I acquired KEI2001 and found out it had noisy readings. Last digit (6-1/2 resolution, 1 NPLC, 20V range, no filter) is not stable, even if a stable signal (LM399 7V reference or short) is connected to the multimeter's input. This is confirmed by the internal self-test: error 200.2 (A/D noise) is reported...

I think the error is somewhere in A/D converter circuit (the error is reported even if the input buffer is disconnected and the input of A/D converter is shorted). I measured some signals in A/D converter circuit and found that CB and /CB signals were not clear (there was a ringing, see attached picture). Signals are generated by U812 (74HC74 - dual D-type flip-flop), so I suspect it could be defective.

Since there is a lof of knowledgeable and enthusiastic people in the forum, I would like to ask if someone could measure these signals and provide me a feedback - do they contain a ringing or not? I also attached a photo of my A/D converted board with signals locations.

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: robert_ on July 23, 2015, 06:24:23 am
I cant compare the signal, but the ringing looks like it could well be caused by poor probe grounding. Do you use a long ground lead, and where is it connected to? Keep the lead below 5cm for a bandwidth of 100Mhz, and even shorter (ie use no ground lead but probe sockets) for higher BW.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on July 23, 2015, 07:21:38 am
Thank you for your feedback. Yes, you are right - I had difficulty connecting probe to gnd, so I use an extension. With the shortest ground lead possible, the signals are perfect...

Well, I will try to do more measurements...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 28, 2015, 02:57:37 am
Tried change LM399 to LTZ1000 module in one of my 2001, so far epic fail.

(http://xdevs.com/doc/Keithley/2001/LTZ/ltz_test1.jpg)

125 samples of 10V DC signal (from MV106), measured same time with three meters:

Usual K2001 with LM399, min -3.96uV, max +6.15uV, SDEV 1.86uV
K2002, min -4.4uV, max 0.65uV, SDEV 0.848uV
K2001 with LTZ1000, min -50.32uV, +40.35uV, SDEV 23.24uV   :-\

Will probe with scope..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on July 28, 2015, 06:26:50 am
@TiN

What about shorting the inputs? Do you think that the connecting wires are picking up any nearby noise? I would guess the VFD itself could be causing some issues.
How stable is the reference board as measured with the K2002?

Keep up the good work  :-+

@saturnin

I had similar issues with one of my K2001's failing self-test 200.1 . Q806 was causing the problem. you can make some measurements and if anything looks off, I can compare it to a known good board.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on July 28, 2015, 06:57:16 am
Wow pimped K2001, good start!! What about putting the ADC board on andle connector and soldering LTZ1000 board directly to analog board and isolate it from outside world.
Based on my experience with LM399 it is too sensitive to outside world. Only the metal case and insulation reduced it to acceptable level.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on July 28, 2015, 08:56:07 am
@ManateeMafia

Actually, during further investigation I found out that I get 200.1 and 200.3 errors too (but not always - they are rarer than 200.2 error). Moreover, it is much more probable that I get these errors when I run test in "step" mode than in "continuous" mode. Strange...

I also made a comparison of my KEI2001 and KEI2000. I measured a stable 10V reference output:

-> KEI2000 (10V, MEDIUM speed = 1NPLC, no filter, 1000 samples)
average value: 10.04788 V
std dev.: 2.08 uV
min. / max. reading: 10.04787 V / 10.04788 V

-> KEI2001 (20V, 1NPLC, line sync, synchronous autozero, no filter, 404 samples)
average value: 10.048091 V
std. dev.: 7.86 uV
min. / max. reading: 10.04807 V / 10.04811 V

I also measured all supply voltages. They are in tolerance and without any unusual noise. The main +7V reference is stable too. Then, I checked reference signals in A/D converter circuit:

DC measurements with my KEI2000, same config as above:
Vref 6.4V : 6.22416 V, std. dev.: 2.28 uV
+Vref +10.25V : 10.26373 V, std. dev.: 9.59 uV
-Vref -10.25V: -10.26004 V, std. dev.: 25.92 uV (quite high noise, IMO)

When A/D converter is disabled, i.e. it is not measuring, local reference voltages are much more stable:
+Vref +10.25V : 10.26370 V, std. dev. 2.56 uV
-Vref -10.25V : -10.25980 V, std. dev. 1.00 uV

With my scope, I measured several signals in A/D converter. They seem to be ok, except one suspicious - a control signal at gate of Q807. It is a square signal with levels 0V / -15V. I zoomed at its 0V level and I can see there is a overshoot to positive values (as high as ~300 mV, see attached pictures), which could be quite enough to inject some noise current to integrator's input (because a diode in the jfet would be forward biased). My reference ground for this measurement was "signal common" (1). I wonder if this could be an error or not...?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on July 28, 2015, 02:21:09 pm
@saturnin

I have looked at the gate of Q807, and zoomed in to the signal with a Fluke 199C. I do not see the overshoot that you have posted.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 29, 2015, 02:58:32 am
Q807 is nice and clean here too, measured with CSA7404 + P6245 probe.

(http://xdevs.com/doc/Keithley/2001/LTZ/r859_adc_meas.png)

Back to LTZ-mod. Separated heater supply from LTZ module to take power directly from analog board +15V node near LDO.
Will run longer term test next days.

(http://xdevs.com/doc/Keithley/2001/LTZ/ltz_test2_1.jpg) (http://xdevs.com/doc/Keithley/2001/LTZ/ltz_test2.jpg)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on July 29, 2015, 07:58:28 am
ManateeMafia, TiN,

thanks for your measurements and confirmation the signal is clean in your cases. I will continue with debugging...

Btw. TiN, I noticed your scope showed 10.47V p-p, but it should be 15V p-p, since Q807 gate is connected to U807, which is a comparator with open collector. Therefore its high state should be 0V and low state -15V, since its gnd (terminal 12) is connected to -15V. Did you really measure signal across R859?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 29, 2015, 02:19:16 pm
Dynamic range of P6245 probe is +/- 8V only, so it's capped by probe, that's why 10.47V.
I forgot my TCA-1MEG buffer at work, so that's why it was not measured properly.  :-BROKE
I don't have any other "easier" scope. :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: bson on July 29, 2015, 03:16:43 pm
Hi guys.  My Keithley 2001 has B13 firmware and I'm looking to upgrade it.  Correct me if I'm wrong, but to upgrade it I download the odd/even banks (thanks TIN!!!), program a pair of 27C040s (I got Winbond W27E040 EEPROMs, -12 while the stock EPROMs appear to be -15) and replace the stock ROMs?  Or I might use ATMEL '040 OTPs, which I assume are just EPROMs without a window. :)  Will the instrument require recalibration (i.e. is the calibration data firmware specific)?  It's due for a calibration anyway, so no big deal.

Looking at the 68302 freescale data sheet for the bus timing combined with the 7.68MHz clock, it seems to me ROM speed is completely irrelevant, and even a 250ns read time should work just fine...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 29, 2015, 10:29:36 pm
Hi bson,

Welcome. Do you mind to upload your B13 firmware and EEPROM dumps perhaps to my collection (https://doc.xdevs.com/article/keithley-instruments/#2001)? You can use my FTP (https://doc.xdevs.com/contact/) for that.
You can use latest B17 2001-M firmware with your dual-ROM 2001.

Also if you can take few photos of internals both analog, ADC and digital boards, would be great addition as well, seems your units is recent is you have EEPROMs there.

Regarding your questions, yes, it does not matter which ROM speedgrade you use, it's all slow and nice. And for recalibration, so far I'm not aware of any 2001 version changes which would need recalibration (except perhaps going from B-version to A-version firmware, but that's not your case anyway). I upgraded my original B08 to B15 and now B17 2001-M, calibration still no change, based on measurements with 2V, 10VDC, 1Meg, 10K, 19K, 190R resistors, etc.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on July 31, 2015, 04:55:49 pm
This is a great thread - and probably extremely useful as I received a 2001 today. It has B09 firmware and needs a little TLC.
It has the following errors in diagnostics:

407.1 Front end
407.2 Front end
407.3 Front end
409.6 /500 Freq Comp
410.1 TRMS
411.1 TRMS
411.2 TRMS

I haven't opened it up but am told it has had the common bad capacitors replaced already.

Another fun project for the bench.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dadler on July 31, 2015, 05:04:37 pm
Do the caps in the 2000/2015 models similarly die and eat pcb traces, or is this a problem that occurs more frequently in the 2001 models?

The caps in my 2015 (I think it was manufactured in 2002/2003?) look ok to me, but I'll swap them if this is just a headache waiting to happen.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on July 31, 2015, 05:30:51 pm
Do the caps in the 2000/2015 models similarly die and eat pcb traces, or is this a problem that occurs more frequently in the 2001 models?

The caps in my 2015 (I think it was manufactured in 2002/2003?) look ok to me, but I'll swap them if this is just a headache waiting to happen.

It's not just common to 2000/2015 and 2001 models, it's common to anything that has electrolytic capacitors in it. Although obviously a device from Keithley will have used better quality caps than some cjheap Chinese device, so they should last longer. The question with caps is never "if" but "when".

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 31, 2015, 09:18:14 pm
This is a great thread - and probably extremely useful as I received a 2001 today. It has B09 firmware and needs a little TLC.
It has the following errors in diagnostics:

I haven't opened it up but am told it has had the common bad capacitors replaced already.

Welcome.

Don't forget to upload your B09 (http://doc.xdevs.com/article/keithley-instruments/#2001) firmware into our humble collection. Also pics would be nice addition as well.
Replace caps asap unless your unit is 2010+ year (can tell from date codes on ICs). Caps are prone to leak and cause disasters because on 2001/2002 they are located in worst spot possible, just near hot regulators, transformer and getting cooked with temps over 60°C 24/7, still being under high voltage applied.
Most of 4xx series errors are due issues with bootstrap circuitry as well. In case you missed, i have this little summary (http://xdevs.com/fix/kei2001/) of issues in few of my 2001's.

Replace caps on digital board too.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on July 31, 2015, 09:29:55 pm
2010+ ? Is that not being a bit over cautious? My Keithley 2000 is from 2005, but looks like it was rarely used. I opened it up and the caps look like new. Pulled one and checked capacitance and ESR which were also both well within tolerance.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 31, 2015, 09:47:20 pm
Better be safe than sorry. Also 2001 is very different beast, compared to 2000 (which does not have bootstrap block with leaking capacitors).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 02, 2015, 06:33:15 am
This is a great thread - and probably extremely useful as I received a 2001 today. It has B09 firmware and needs a little TLC.
It has the following errors in diagnostics:

I haven't opened it up but am told it has had the common bad capacitors replaced already.

Welcome.

Don't forget to upload your B09 (http://doc.xdevs.com/article/keithley-instruments/#2001) firmware into our humble collection. Also pics would be nice addition as well.
Replace caps asap unless your unit is 2010+ year (can tell from date codes on ICs). Caps are prone to leak and cause disasters because on 2001/2002 they are located in worst spot possible, just near hot regulators, transformer and getting cooked with temps over 60°C 24/7, still being under high voltage applied.
Most of 4xx series errors are due issues with bootstrap circuitry as well. In case you missed, i have this little summary (http://xdevs.com/fix/kei2001/) of issues in few of my 2001's.

Replace caps on digital board too.

Thank you for the advice.

I was going to read the eproms but my reader/writer is just too vintage for a 27c4001, lol. I will visit a friend or buy something newer in the near future to get a dump for the group.
I see many of the caps of have been replaced in my unit and there was clearly some damage from the previous bad caps. I have attaching two pics of how I received it. One shows the area near the bad caps, the second shows Q339 and Q340(is this normal?). I checked and BS+ and BS- actually look fine on the scope and show the proper voltage. However +8VF varies between 5.8 and 6.2 volts. All of the other voltages look fine. I think I will order all new caps even if some have been replaced and I will replace the missing diode(s). Any thoughts on other parts I might want to order at the same time?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 02, 2015, 06:49:14 am
Ouch... Get all electrolytes (both digital board and analog) for replacement (your unit made in 1994).
CR513,CR514 are BAV103 in SOD80.
Bodgery around Q340 is NOT normal. I'd buy bunch of LM339, cheap digital logic, MC14094s, DG211's, 74HC00A and just replace those guys as well.
Highly suggest desolder U507,U508,U509, clean everything around there with clean alcohol very well, solder unobtanium U509 back, replace rest.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 08, 2015, 06:20:42 am
Ouch... Get all electrolytes (both digital board and analog) for replacement (your unit made in 1994).
CR513,CR514 are BAV103 in SOD80.
Bodgery around Q340 is NOT normal. I'd buy bunch of LM339, cheap digital logic, MC14094s, DG211's, 74HC00A and just replace those guys as well.
Highly suggest desolder U507,U508,U509, clean everything around there with clean alcohol very well, solder unobtanium U509 back, replace rest.

I replaced all of the caps on both analog and digital boards last night. I also installed the proper missing diodes and gave the board a good cleaning. This didn't change any of the faults but at least it has the correct parts everywhere now. The weird bodges around Q340 seem to match up with the schematic and the solder connections look original. I'll have another look this weekend but perhaps it was a short run with a bad PCB design.
I didn't replace any of the chips near U507/508/509 as the board was very clean in that area and doesn't show any indication of having had capacitor leakage on it. I will dig into the diagnostics this weekend and hopefully track down the bad component that is causing my faults - if anyone has any guesses let me know and I'll start the trouble shooting there.

My faults are:
407.1 Front end
407.2 Front end
407.3 Front end
409.6 /500 Freq Comp(this one may not occur 100% of the time)
410.1 TRMS
411.1 TRMS
411.2 TRMS
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 08, 2015, 03:05:10 pm
Well, bear in mind, that on two units with same faults I spent days finding fault but could not isolate any. After desoldering those chips, cleaning and putting them back - all errors were gone.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 09, 2015, 01:27:31 pm
I am pleased to report my Keithley 2001 is now error free and working great!

The failed component was Q547 - it wasn't totally open but but didn't turn on properly so relay K503 never closed.
I didn't remove any of the other IC's  as they all looked very clean and didn't appear to have suffered any contamination.
Just to have it all in the same post the faults I was seeing were:
407.1 Front end
407.2 Front end
407.3 Front end
409.6 /500 Freq Comp(this one may not occur 100% of the time)
410.1 TRMS
411.1 TRMS
411.2 TRMS

When I swapped the caps C116 and C117 they were changed to 50 volts(as previously mentioned in this thread they should never have been spec'd at 35 volts).

Having the schematics made all the difference - I can't believe you guys slogged through this thing without them originally, especially being the PCB layout is not very refined.

I still plan to dump my firmware and calibration eeprom next time I visit a buddy with a programmer and will upload them. I guess I may as well convert it to a MEMS version at the same time.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on August 09, 2015, 05:17:22 pm
Great work. These are wonderful meters and it should give you many years of use. It will be tempting to throw it in 8.5 digit mode now.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 09, 2015, 05:26:56 pm
Indeed, I went into the special menu and then enabled 8.5 digit mode just to see all those numbers!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: bson on August 11, 2015, 04:51:41 pm
FINALLY received my EEPROMs from China!  I'm now the happy owner of a B17 2001M!  :-DMM
Uploaded the B13 firmware.  That was a little tricky - one EPROM was a national semidestructor and was easy enough to read, but the other was an ST device I couldn't get to the part number on; too much hardened sticker residue.  Instead of destroying the sticker with something nasty I tried all the various ST EPROMs, turns out it was a 27C4001.  Go figure.  The TL866A wouldn't read it unless I got it right, which is a bit silly...  Oh, and I couldn't use use my trusty old Xeltek programmer either... no more parports!!!  :palm:

Now I'm just waiting for my DS1245YK NVRAM (MEM2) to arrive so I can initialize it with my S/N, pop it into the socket and close this bugger back up!    ;D
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 11, 2015, 05:22:32 pm
I will be doing the same when the programmer and DS1245Y I ordered arrives(probably a month from china). I will upgrade to B17 2001M MEMS2. I also noticed a 2001 with B17 firmware on ebay(no M) - item # 161779473828 for pics.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: bson on August 12, 2015, 04:00:58 am
Ooh, it'll be interesting to see how much the ROM dumps differ between the B17 2001/2001M...

It seems the 2001M has an extra ACV mode (average-responding ACV with calculated RMS) to make it an upgrade path from the 175-AV, for automated test systems.  Basically it's an averaging mode reported as RMS.  I bet this is all firmware.  Not much use for it with true RMS, other than for readout compatibility with older pre-TRMS setups.
http://www.keithley.com/data?asset=14876 (http://www.keithley.com/data?asset=14876)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 12, 2015, 04:44:48 am
Thanks for firmware, added to collection and document page (https://doc.xdevs.com/article/keithley-instruments/).

I have teardown article almost ready about 2001M, just need translate it and readproof it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 3roomlab on August 12, 2015, 02:20:15 pm
out of a itching curiosity to get a better DMM ...

i went bonkers and scored a used (est 9yr old) 2015 THD for slightly under USD350 with shipping to my tiny island (i was deliberating very very long to buy a BRYMEN 8xx ... i dont think ima part with USD250 for that anymore  :P)

on initial power up, it appears to show some symtoms of this http://www.eevblog.com/forum/testgear/keithley-2015-problems/msg606924/#msg606924 (http://www.eevblog.com/forum/testgear/keithley-2015-problems/msg606924/#msg606924)  ... so im not sure if he got to solve his problem  :-//
1 of the interesting "traits" of my set, whenever you press any button, the display flickers ... it seems like there is some problem in the supply feed to the front panel, the change in logic+beep is like causing the entire display board to have a tiny brown out and cause the VFD to flick around abit.

on uncovering the unit, the insides appear to be lightly dusted with muck ... and there appears to be some bits of rust. the unit must have been sitting in storage for a very long time. last cal was in 2007, build date appears to be in 2006 (Vref 0641), number of times cal = 2  :o  ... so other than being stored for a long time, it seems this unit seems to be used for only about 2 years (the front panel is clean). and this little guy is a rev B17.

so i think i will be rummaging around this restoration thread for a while (since 20xx seems to share some common PCB). when i have some time to further pick apart and clean up this used 2015... i should be able to share my "journey" (wish me luck  O0)

(n tyvm 2 all contributors for this thread)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 12, 2015, 02:29:31 pm
Btw, there is another thread about 2000 series meters (2000,2015, 2010) - http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/ (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/) , perhaps you can take few photos of rust and muck, and we can take it from there if it needs repair.

2000/2015 are very different meters to 2001/2002, PCB and topology wise.
You can compare both 2001 (https://xdevs.com/fix/kei2001/) and 2000 (https://xdevs.com/fix/kei2000/) from my notes & photos.

DCV readings jumping all over the place on 0.2,2,20V range (or 0.1,1,10V in your case) are completely normal, as on this ranges meter have high impedance and just picking up change from air/statics. You can short input with 10meg resistor and readout should be around zero.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: eas on August 12, 2015, 02:33:26 pm
I'm not sure if the 2015 has the same built in self-test as the 2000 (the 2700 doesn't), but if it does, run it. You'll need some way of shorting all 4 inputs together for some of the tests.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 3roomlab on August 12, 2015, 02:38:40 pm
Btw, there is another thread about 2000 series meters (2000,2015, 2010) - http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/ (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/) , perhaps you can take few photos of rust and muck, and we can take it from there if it needs repair.

2000/2015 are very different meters to 2001/2002, PCB and topology wise.
You can compare both 2001 (https://xdevs.com/fix/kei2001/) and 2000 (https://xdevs.com/fix/kei2000/) from my notes & photos.

DCV readings jumping all over the place on 0.2,2,20V range (or 0.1,1,10V in your case) are completely normal, as on this ranges meter have high impedance and just picking up change from air/statics. You can short input with 10meg resistor and readout should be around zero.

thanks for the other thread info
well being new to 6.5 digits, im not sure if what im seeing is what it should be.
with a 100R shorting the input -->  000.0xxx mV (the x dances, fast mode)
with a 100R shorting the input -->  0.0000xx V (the x dances, fast mode)
*edit* 2wire mode 100R --> 100.0xxx (the x dances, fast mode)
in ACV, with a 100R shorting the input -->  000.115x mV (the x dances, fast mode) i think ACV is working normally. even the dancing so much much slower by what appears to be a factor of 10.
im suspecting the very dirty PCB for now :P until i have more time
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 12, 2015, 02:44:24 pm
That is normal, nothing wrong in this perspective.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 3roomlab on August 12, 2015, 02:49:24 pm
That is normal, nothing wrong in this perspective.

really? ok, then ima have to get used to the "dancing"  :P ... or shall i say ... "NPLC" modes ... experiencing this term in real time is pretty new to me even after reading so much about it ...  (sorry, im real noob at 6.5digits)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: bson on August 14, 2015, 09:21:39 am
DS1245YK installed.   The TL866A doesn't support this chip and using the 1230 profile to initialize it didn't work for me, perhaps because the extra address lines weren't grounded but left floating and in my case floated high.  So I used the secret menu to initialize it instead, which worked great.  I assume the secret menu is the actual procedure used by Keithley themselves...  Nice to finally have the instrument back in use!


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 17, 2015, 02:54:57 pm
Review of 2001M internals is public now, sorry all for delay, took a while to get it all posted:

(http://doc.xdevs.com/doc/Keithley/2001M/photo/1_Ext_1_1.jpg) (https://xdevs.com/review/kei2001m/)

Article on photo click ;)

Hope you enjoy the efforts  ::)

P.S. I don't own unit, photos are shared to me by it's owner to be used in article for our reference.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on August 24, 2015, 05:21:06 pm
Sorry I was on vacation cruising with my GS1200 in Europe. Meanwhile you guys were having fun here...

Review of 2001M internals is public now, sorry all for delay, took a while to get it all posted:

and here the bomb...

Quote
For those who want upgrade their 2001 to 2001M, I tried to flash usual Model 2001 with digital board revision K (two ROM chips) with this firmware 2001M B17, and everything went well. Meter was detected as 2001M and all functions were operation correctly. No recalibration was required.

What a bless your article... I enjoyed it so much! Thanks TiN  >:D :-+ O0 ^-^
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dkozel on September 10, 2015, 01:21:21 am
There are two on Ebay at the moment for just under $400 US, listed as for parts.
http://www.ebay.com/itm/Keithley-2001-Parts-unit-/400988421081 (http://www.ebay.com/itm/Keithley-2001-Parts-unit-/400988421081)

I asked for photos and they sent these:
https://drive.google.com/folderview?id=0B5SWO8HGjYzSU2gwRG54MEx0Ylk&usp=sharing (https://drive.google.com/folderview?id=0B5SWO8HGjYzSU2gwRG54MEx0Ylk&usp=sharing)

Looks like one is missing a case and both were knocked around a bit. So sad. They didn't send any interior photos so I'm hesitant to go with them when I know that there are other deals out there.

Thanks for all the resources! I think I'm going to go with a Keithley 2000 instead as those come up more often in good condition under $300.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: eas on September 10, 2015, 02:35:07 am
Given how much that place asks for working equipment, I'd guess that those parts units have been stripped to the bone.

There have been some working (but not necessarily well) 2701s that have gone for ~$750 or so in the last few months. You should have no trouble getting a working 2000 for under $300. Actually, check the for-sale forum here. Timb had one he was selling.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dkozel on September 10, 2015, 04:19:35 am
Given how they've only supplied the bare minimum of what I've asked for in each email I'm guessing you're right as well. They know the value of it in parts and have probably kitted it out, or at least verified that it isn't easily fixable.

I'll put a post up in the wanted forum, see what comes up. I'm looking for my first bench meter, having been using a Fluke 189 for the past four years. Computer control is a must which limits the options somewhat but thankfully all these high end meters come with RS232 and one day I'll get into the GPIB game.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: timb on September 10, 2015, 04:50:57 am
Yeah, I've still got my 2000 for sale. I just got a best offer on eBay for $250, so if anyone wants it here for that price contact me within 24 hours. I'd rather sell it off eBay and save the fees.


Sent from my Smartphone
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on September 10, 2015, 04:55:18 am
Given how they've only supplied the bare minimum of what I've asked for in each email I'm guessing you're right as well. They know the value of it in parts and have probably kitted it out, or at least verified that it isn't easily fixable.

I'll put a post up in the wanted forum, see what comes up. I'm looking for my first bench meter, having been using a Fluke 189 for the past four years. Computer control is a must which limits the options somewhat but thankfully all these high end meters come with RS232 and one day I'll get into the GPIB game.
The Keithley 2001 has what appears to be an RS-232 port (a DB-9 connector) but it is definitely not an RS-232 port. That is a digital I/O port, with one input and four outputs. They can be read or controlled by GPIB commands and can be tied into some functions (high/low tests). The 2001 can be controlled remotely by GPIB only.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Vgkid on September 10, 2015, 06:53:34 am
One of those k2001 looks hollow...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: dkozel on September 10, 2015, 07:57:36 am
macboy: That would have been a surprise if I bought one! The 2000 does have RS232, so another reason it's probably a better match at this point I suppose.

Vgkid: It's not hollow, but it's missing it's case so you can see straight through the bottom because it doesn't have the optional add-in card.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Vgkid on September 10, 2015, 09:53:39 am
Makes sense, must be a full sized card.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on September 10, 2015, 10:50:34 am
macboy: That would have been a surprise if I bought one! The 2000 does have RS232, so another reason it's probably a better match at this point I suppose.
Yes, I have a 2000 and a 2015 and both work perfectly using the RS232 port with a cheap USB serial cable. All SCPI commands are available directly through a terminal, or using VISA drivers.

Even better, Keithley actually have an IVI-COM driver for download (most IVI drivers I find are IVI-C which are not user friendly unless you have LabView or something). IVI-COM and IVI.NET you can very easily use in VB, Excel, C#, etc.  :-+ (Mind you, just using SCPI with the VISA library is no big deal either)  ;)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: eas on September 10, 2015, 04:14:10 pm
There is a hardware and software flaw that lead to annoying drop-outs in RS-232 communication in many Keithley 2000s (http://techobsessed.net/2015/05/keithley-2000-rs-232-serial-wtf/). The solution is to use a cable or adapter that leaves the RTS pin unconnected.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on September 15, 2015, 02:36:34 pm
Received my TL866CS (now converted to a TL866A) today, read the 2001 B09 firmware and uploaded to the FTP site.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 15, 2015, 02:44:05 pm
Added to collection (https://doc.xdevs.com/article/keithley-instruments/#2001).
Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on September 15, 2015, 03:03:40 pm
Hah, installed 2001M B17, ran the self test which has never failed since the last repair and I now have faults again.

309.1 - Amps 200 uA range (this one isn't constant)
310.1 - Amps protect - Amps protection
412.1 ACA switch - AC amps switching error

Service manual gives good detail on them, I am now off to check CR305 and CR309 before anything else.

Edit - sure enough CR305 has an open diode in it. Now to find a replacement...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jaap on September 16, 2015, 04:08:34 am
Had 310.1 Amps Protect and 412.1 ACA Switch - AC Amp Switching Error errors too one year ago.
Also open diode in CR305. Original one here was a PE05 from EDI (Electronic Devices Inc.)  -  50V 5A
Replaced it with KBL04  -  400V 4A. Leg distance is slightly different though. Then all was ok again. Success
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Magnum on September 16, 2015, 04:20:41 am
First time 2001 user here. Bought one on ebay for a good price.
Received the unit, self test ok. Opened it up to check the production date, closed it and made some measurements.
Then I had approx 7V on ACV measurements with nothing connected. With AC coupling the 7V stayed even with shorting plug inserted. With AC+DC coupling it read 0V. Self test gave one error (forgot which one). Opened it up again and found relay K503 stuck closed. Took it out and AC measurements are ok, but self test throws 407.1 Front end, 407.2 Front end, 407.3 Front end, 410.1 TRMS, 411.1 TRMS, 411.2 TRMS as TheSteve had before.
I don't have the original relay available, so I used another reed relay. Error messages are gone except 408.6 /100 Freq Comp. But this error is not always there. I hope it will be gone when I receive the original relay.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on September 17, 2015, 02:59:40 pm
I replaced CR305 today - all self tests are passing just fine again.

I did find one area in which the 2001 still has an issue though - measuring resistances over 20 meg ohms it varies a lot and is sometimes in the ball park but not enough to really trust it. This occurs in both the 200 Meg and 1 G ohm range. My test is a 22 meg ohm resistor which I know is fine. I am not the first person to work on this 2001 but the board looks very clean and it has been carefully cleaned in areas with IPA. Before and after cleaning there was no difference. I did notice with the cover removed and the analog shield removed if I blow gently under the A/D board I can consistently make the resistance drop down. I don't believe there is any problem with the A/D board itself, if I measure the voltage on pin 3 (A/D in) it varies when I see the incorrect values.

Any thoughts on how to futher troubleshoot this? It is something I can live with but it will always be in the back of my mind.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on September 21, 2015, 06:38:30 am
I replaced CR305 today - all self tests are passing just fine again.

I did find one area in which the 2001 still has an issue though - measuring resistances over 20 meg ohms it varies a lot and is sometimes in the ball park but not enough to really trust it. This occurs in both the 200 Meg and 1 G ohm range. My test is a 22 meg ohm resistor which I know is fine. I am not the first person to work on this 2001 but the board looks very clean and it has been carefully cleaned in areas with IPA. Before and after cleaning there was no difference. I did notice with the cover removed and the analog shield removed if I blow gently under the A/D board I can consistently make the resistance drop down. I don't believe there is any problem with the A/D board itself, if I measure the voltage on pin 3 (A/D in) it varies when I see the incorrect values.

Any thoughts on how to further troubleshoot this? It is something I can live with but it will always be in the back of my mind.

Well after messing around I suspect the problem is leakage/contamination in the front/rear switch - part S300. Has anyone removed one to clean it before or can I get a replacement easily from Digikey/Mouser?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Magnum on September 24, 2015, 05:11:24 am
First time 2001 user here. Bought one on ebay for a good price.
Received the unit, self test ok. Opened it up to check the production date, closed it and made some measurements.
Then I had approx 7V on ACV measurements with nothing connected. With AC coupling the 7V stayed even with shorting plug inserted. With AC+DC coupling it read 0V. Self test gave one error (forgot which one). Opened it up again and found relay K503 stuck closed. Took it out and AC measurements are ok, but self test throws 407.1 Front end, 407.2 Front end, 407.3 Front end, 410.1 TRMS, 411.1 TRMS, 411.2 TRMS as TheSteve had before.
I don't have the original relay available, so I used another reed relay. Error messages are gone except 408.6 /100 Freq Comp. But this error is not always there. I hope it will be gone when I receive the original relay.

Unit is fixed. Received the original relay (thanks TiN), but that didn't cure the problem. Q518 was shot, IMHO because K503 was stuck closed before.
What I didn't understand was that test 409.6 /750 Freq Comp. made no problems at all, as this is the same test procedure (except U526 switched on) which needs Q518, too.
Don't care why as it is error free now.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on September 30, 2015, 01:45:38 pm
Finally received my Dallas DS1245Y from a seller in china, it took 2 months but it arrived and is working. It had data stored in it so I assume it is a used pull. I blanked it using my TL866A and then used the secret menu in the 2001 to enable it. Once enabled I read it it out again and see it stored the serial # and another 65 bytes after that with what looks like a two byte checksum at the end.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ez24 on September 30, 2015, 02:50:53 pm
Tin
Can I ask what city your are in?  Every time you mention Taiwan it brings up memories of the years I lived in Taipei (Sungsan).
This post is like a history lesson.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 30, 2015, 02:55:40 pm
Taipei it is. :-) But my first piece of Keithley gear, 2001 was bought back when I was in Kiev, Ukraine.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: neslekkim on September 30, 2015, 07:00:39 pm
I was asking in the other keithley thread for some time ago, but no answer, so I try to pollute this one instead :)

The two screws to hold the enclosure for the 2015 meter, can anyone verify the threading on those?
It looks like M3, but I'm not sure, and don't want to destroy the threading if it is something else.
I managed to drill out the screws on mine, and want to replace them. (guess I need to use grease or something so they don't rust again)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ez24 on October 01, 2015, 06:01:35 am
Taipei it is. :-) But my first piece of Keithley gear, 2001 was bought back when I was in Kiev, Ukraine.
Thanks and even though your work is way over my head, I enjoy reading your posts.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 01, 2015, 06:15:59 am
The two screws to hold the enclosure for the 2015 meter, can anyone verify the threading on those?

Bottom screws, or rear plastic bezel screws? I don't have 2015, but I think 2000 using same frame. The only hard thing is to find which screws were there  :scared:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: neslekkim on October 01, 2015, 06:22:59 am
Bottom, there are only two screws there, countersunk one, very close to m3 in size. But I'm not sure if it is m3, so I don't want to force m3 in there, incase it's some imperial size.

I have tried to read the service manual, hoping that things like that was specified, but couldn't find it

I bought mine from that UK seller that was selling huge amounts of these for some time ago. After trying to open it that time, and the screw was rusted, so I didn't dare to try again.
But I got this lefthand drill bits, and drilled the screw out, and I was suprised of how nice the unit was inside, superclean, no dust at all, no sign at all of caps leaking, or anything, so It seems I was lucky with my unit.

I tried to screw a m3 nut on the screw, but it feels like it's not quite there, so I thought it could be an imperial size, but I'm not so know of those sizes, so I didn't want to force it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on October 01, 2015, 07:29:42 am
Take a look at the Keithley 2000 Repair Manual. The 2015 Service Manual doesn't list these mechanical items for some reason. From my brief perusal all the fasteners are imperial. TiN's xdevs will have it, or I think I got mine from tequipment.com. Keithley should have it too but you may have to sign up for it.

ETA: I had heard bad things about the UK seller, particularly his lack of attention to packaging and stuff arriving a bit bashed. I got mine from the Korean seller who has loads going for a fair bit cheaper. No rust at all on mine, and spotless inside. VFD is only really worn on the REAR and GPIB annunciators. This thing has been in a rack all its life. My guess is Samsung.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: neslekkim on October 01, 2015, 05:27:22 pm
Aha!, on page 3-5, they are named Grounding Screws
On page 4-10, table 4-4, there are references to screws, but I cannot find any that matches the size, but all sizes given are in imperial units, damn..

I took a picture of the screws I'm inquiring about, attached.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Performa01 on October 01, 2015, 05:56:20 pm
Yeah, this is imperial for sure...
Whenever I have to replace imperial screws, sometimes I get lucky finding a reasonable match in my collection of PC screws. Countersunk ones aren't that common in a PC though. So if I can't find anything, I just cut a M4 thread into the mounting holes and use appropriate metric screws.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on October 01, 2015, 05:57:52 pm
www.boltdepot.com (http://www.boltdepot.com) has some really good stuff, in particular the Printable Fastener Tools (https://www.boltdepot.com/Fastener-Information/Printable-Tools/Default.aspx)

As you have them to hand you should be able to measure them up against the printout  :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: neslekkim on October 01, 2015, 08:21:32 pm
Wait now, is 4-40 the way to say the with of the screws?, maybe this is the one I need:

4-40X1/4 PHIL FLAT HD UNDERCUT SR WRAP TO CHASSIS

I though 1/4 was the dimentions, but that is maybe the length?, I looked at this chart:
http://www.trfastenings.com/pages/Thread+Conversion+Tables (http://www.trfastenings.com/pages/Thread+Conversion+Tables) 
And there i find M3, and under UNC and UNF it's written 4-40 and 4-48?

If so I guess screws like this should fit: http://www.ebay.com/itm/131178564711 (http://www.ebay.com/itm/131178564711)
(need to look for another head though, or attach feets on the unit to not scratch what's under it.)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on October 03, 2015, 03:14:44 am
@TheSteve

Somehow I have missed your post. I have replaced a switch on a K2001. The original was difficult to actuate and the switch was not that expensive from Tektronix.

I don't like the design. It is open from the rear and does not seem to protect it from contamination. Not good if you are measuring high ohms or volts.

Contact Tek and get a price quote. I think it cost me around $15-20 US. Shipping will probably cost more than that. I had a big order and could justify the cost.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 07:53:02 am
Hello there, I am having trouble repairing Keithley 2001 #2

All electrolytic caps have leaked out and some corrosion appeared next to U506, U507 and U110.
I have replaced elyts and test diodes in power supply, cleaned the board and tried to switch it back on but with no success.

Self test reported these error codes:
200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference

ADC board in other, working Keithley 2000 (#1) works well and meter does not report errors.
During 200.x tests the voltage in faulty Keithley 2001  #2 on "AD IN" to "S COM" on ADC board header was approximately 0.8mV.
Thinking that might be the cause I replaced U318 and U319. Offset was then 0.0x mV.
Voltages in tests comparing to Keithley #1 were similar but errors remained.

There is a similar situation described on this website: https://dev.xdevs.com/issues/869 but it did not help me to get to the source of the problem.
Can anyone help?


(Photos attached were taken before repair)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 06:10:02 pm
Welcome :)
Are all your voltages OK?

Do you have relays clicking when you power up meter?

Is you reference voltage 7V present (-VREF pin one)? It can be ~10V too, depends on mode.

Do you have any other error, or just those?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 09:31:32 pm
Thank you for the answer.

Are all your voltages OK?
Line voltage 240VAC 50Hz

Voltages to "S COM"
+5V    4.9485
+15V   15.028
-15V  -15.050
-8VF  -7.5..7.7V jumping
+8VF   6.8..7.1V jumping
-VREF -10.318
7VM    6.917  (very stable)

Voltages to "COM"
+BS   38.78
-BS  -38.66
HTP   19.46
KTP  -19.52

Do you have relays clicking when you power up meter?
Yes, with little delay after power on. (One relay)

Is you reference voltage 7V present (-VREF pin one)? It can be ~10V too, depends on mode.
Yes

Do you have any other error, or just those?
Just those
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 09:56:20 pm
Alright, sounds like your optical interface working good and ADC is ok, that's good start. Let's do next:

* Select DCV mode, 20VDC range. Enter menu, diagnostics (not self-test!), and have it in 7V div by 1*1 mode. Measure AD_IN, it should be 6.917V. If it's not check U300,U303,U317,U330,U329,U328,Q328,Q525. Check input on buffer and output on buffer (DIP opamp near AD_IN on analog board).

7V div by 1*1.5 should give you 10.5V on AD_IN pin.

Let us know the results. I personally never had just these 200.x errors, only everything together when optical isolation was not working right. Make sure boards are clean and nice.

What happens if you use good ADC board from meter #1 in meter #2? Same errors?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 10:19:28 pm
* Select DCV mode, 20VDC range. Enter menu, diagnostics (not self-test!), and have it in 7V div by 1*1 mode. Measure AD_IN, it should be 6.917V. If it's not check U300,U303,U317,U330,U329,U328,Q328,Q525. Check input on buffer and output on buffer (DIP opamp near AD_IN on analog board).
7V div by 1*1.5 should give you 10.5V on AD_IN pin.
I did it before I asked here. No problem found.

What happens if you use good ADC board from meter #1 in meter #2? Same errors?
Yes, same errors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 10:36:10 pm
OK, let's go other side.
Did you replaced 1000uF 50V on mains side cap too (if other caps leaked, that one gone boo too, I bet). Replace that cap and clean all around there too.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 10:53:50 pm
I replaced all electrolytic caps except C611 (15mF/16V), but it has cca 14mF at 100Hz.
1000uF/16V on CPU board has been leaked out too.
Capacitor check and replace was first think I do.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 10:56:08 pm
Ok, so you had checked all those chips and transistors I mentioned? What is actual AC_IN voltages on failed tests ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 11:23:21 pm
What is actual AC_IN voltages on failed tests ?
I'm not sure what voltage you mean. It's line voltage AC1-AC2?

Bit pattern on the shift registers is same as described in repair manual.
Voltage outputs on U330 looks OK
Voltages on Q328 and Q525 are cca. 0V (in halted test 200.1)
-Vref and 7VM are good, then I think U328 is good too

I try test Q328 and Q525 more detailed.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 11:24:55 pm
AD_IN input on A/D board, during manual steps for 200 series tests.
You can step them one by one manually, and measure AD_IN vs S_COM.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 18, 2015, 11:37:41 pm
In all 200.x tests AD_IN to S_COM measured with fluke289 is 0.032mV (In min-max mode fluke catch minimum 0.020mV when test running. maximum is 0.033mV)
Test also failed with connected fluke with same errors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 18, 2015, 11:45:49 pm
Can you measure U317 pin 15, pin 14 and pin 16 when your meter halted in 201.2 test?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 19, 2015, 12:01:20 am
U317 after 200.1 test (200.1 on display)
14  -0.020mC
15   6.917V
16   4.9136V

U317 after 200.2 test (200.2 on display)
14  -0.019mV
15   6.917V
16   4.4963V
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 19, 2015, 12:05:00 am
Sorry, my bad 201.2 test. I measure it again...

U317 after 201.1 test (201.1 on display)
14 -0.018mV
15 6.917V
16 4.9423V

U317 after 201.2 test (201.2 on display)
14 6.917V
15 6.917V
16 0.0253V
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 19, 2015, 12:30:58 am
OK, mux working fine.
Your output from U322 (which goes to AD_IN thru 1K resistor R284 on bottom of analog board) with 201.2 on display should be same 6.917V.
If it's not then gain switching made up with U318,U319 and resistors around them might be sick, or U322 itself could be sick.

(http://xdevs.com/doc/Keithley/2001/photo/SKE/ske_kei.png)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 19, 2015, 01:20:20 am
Thank you for the advice.

Output voltage on the U332 pin 6 seems to be wrong.
U318 and U319 has been replaced before. New parts are DG211DY from mouser.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 19, 2015, 01:30:06 am
Mm, if you have reference voltage on 201 test, then result should be pass. Let me measure voltages for you, seems not 100% right.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 19, 2015, 03:59:20 am
OK, here are results for your reference:

200.1 - AD_IN = 0.044 mV, Pin.2 of U322 = -0.012mV, REF (pin.1 AD board) = -10.2893V
all othe 200.x tests about same voltages, so it's mostly internal test on A/D board using U80x registers and CPLD.
Check you voltage supplies (+15,-15,+5) to make sure they are not noisy. If I artifically cause shift on VREF even 0.1mV - test will fail.

201.1 =  0.137mV, SCOM = 3.491mV, pin2 u322 = -0.020mV, REF = -10.28967V, pin.6 U322 = -8.467mV
201.2 = 6.88303V, SCOM = 3.484mV, pin2 = 6.88364V, REF = -10.2897V, pin.6 U322 = +7.994V
201.3 = 1.72111V, SCOM = 3.489mV, 1.72094V, -10.2897V, pin.6 U322 = +1.9922V

All measurements taken relative to black wire LO terminal. I have about 8mV pk-pk noise on +15V, 3mV pk-pk on -15V, 12mV pk-pk on +5V going to A/D board, measured by other 2001 using VAC PEAK mode.


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 19, 2015, 06:54:36 am
Measured with keithley #1 7.5d high-accuracy, no filter
x - mean unstable digits

201.1
SCOM  from -0.2 to 0.3uV (slowly change, it's difficult to measure)
U322-2   -0.034xx mV
U322-6   -8.550xx mV
-VREF     -10.316239 V

201.2
SCOM     0.012xx mV
U322-2   6.91693x V
U322-3   6.91693x V
U322-6   9.03565x V
AD_IN    6.91701x V
-VREF    -10.31625x V

201.3
SCOM      0.006xx mV
U322-2   1.729238x V
U322-3   1.729205x V
U322-6    2.002529x V
AD_IN     1.729306x V
-VREF     -10.31625x V

200.1
SCOM     0.005xx mV
U322-2   0.06xx mV
U322-3   0.06xx mV
U322-6   -8.548xx mV
AD_IN     0.036xx mV
-VREF   -10.31627x V

Oscilloscope in peak detect mode, passive probe 1:1

200.1 measure with keithley 2001 #1 VAC in peak-peak, speed-normal, no filter
I don't think this reading is giving me any usable data

+15V 11.1mV p-p
-15V 6.3mV p-p
+5V 12.6mV 9-p

Oscilloscope in peak-detect mode
Noise floor mean short end of ground pigtail to probe tip.
Length of ground pigtail is cca. 15cm (I now, it's too much)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SKE on October 26, 2015, 09:26:16 am
After my last post, I started thinking that it was the ripple in +15 and -15V which was causing of the problem.
Therefore I measured the ripple on pins +-15V voltage regulators and I was surprised with what I found.
With no signs of 100Hz ripple in power rails I tried to connect GND pins on C101 and C104 together (see photo).
The ripple on ADC and +-15V testpoints looked the same as in working kei2001 #1.

In the previous measurement I had to use the long GDN wire as I had nothing else to use at that time. Sorry I forgot to mention it in my last post.

Then I disconnected  AD_IN pin from buffer and connected it to S_GND. When I ran 200.x test, the test failed, showing the same errors as before (200.1, 200.6, 200.7) whereas on the working kei2001 #1 the test passed with no errors.
In that case the problem should not be in the voltage offset on AD_IN from buffer.
Is it possible that these errors could be caused by wrong calibration data except power supply for ADC?

(The analog board is revision K, firmware version of digital board is A5.)
Would it be possible to connect digital board from working kei2001 #1 with FW version B07 to this analog board?

Which is the latest FW version  I could use for this analog board revision?

Do you think I should update FW in faulty kei #2 and in working #1 too?

Many thanks for your help
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on November 01, 2015, 10:01:29 pm
I recently acquired a used 2001 that was previously restored by TiN.  It is now spuriously throwing 201.x errors, starting at 201.1, when cold started, with voltage display drifting up to OVERVOLTAGE message. After about 10 mins of warm-up, a power-cycle somtimes brings it into error-free status and it then functions normally (that's at least what i guess, as voltage readings against a known good voltmeter are matching pretty well, with a tad of offset in the 200V range).
somewhere else in this thread, a similar fault was described, which was cured by swapping out the ADC board.
So, my question here: could it be the CPLD gone wild with corrupted config memory? a quick check with scope on pin 23 of the module shows signal stuck at either low or high, when fault occurs. did anybody manage to read out the cpld (i know, probably read protected, don't have programmer to look into it)? And, if all else fails, is somebody willing to sell me a spare working ADC module? any help very much appreciated!
 the VCD is pretty close to leaving the building, although all pixels still give some light. I'm planning to do a VCD replacement board with either TLCD or GLCD and an FPGA on it. Any interest in such a replacement board?
(reason for this project is keithley asking 430 EUR in germany for front panel assembly. Insert bomb emoticon here)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 02, 2015, 02:02:30 am
Magnum unit travels around, I see. You may want check your mains (I know it sounds wierd), and primary earth-reference circuits and optocouplers. I saw these errors one other unit when running 50Hz mains. here some test results (https://dev.xdevs.com/issues/869) with AC source. Even with those errors I was not able to see any difference in operation.

I believe SKE tried another A/D and it was still failing, while one from failed unit work fine in another unit.

As of VFD I recall Magnum's unit had bright screen, so not sure now if we talking same meter then. You can always grab 7001 for cheap (http://www.ebay.com/itm/Keithley-7001-80-Ch-2-Slot-Half-Rack-Switch-Mainframe-/151851102168?hash=item235b07efd8:g:DuQAAOSwo6lWIUfr) and swap the glass, if you have steady hand on soldering :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on November 02, 2015, 03:25:29 am
Thanks 1e6 for the quick reply. Yep, it's the one from magnum. good to have a starting point for further investigations now! will be posting results here when i have time to dig into it, as i'm also travelling atm. i had suspected the AC mains side first, but couldn't find any evidence for malfunction there, didn't check the optos, though. These are quite prone to ageing of their LEDs, so there is  indeed a probability that their current gain has dropped below specs. Avago has a white paper about opto ageing, but i don't have the name from top of my hat. otoh, i'm also suspecting the 5V supply rail on the ADC, because its at 4.8V, which is just 50mV above VDDmin for the CPLD.
will keep you posted!
as for the 7001 display, that paricular unit you are mentioning looks like a taker, but customs into germany is simply forbidding. Thus,  i'd prefer to stay with the bad VFD and save the bucks for a nice ISO calibration, rather than sinking more bucks into parts of unknown condition.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Magnum on November 02, 2015, 06:18:04 am
Sorry to hear that you are having problems with the unit. I had it running without any problems, I sent you a PM.
I swaped the screen with my other 2001, but that shouldn't cause the problem.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on November 09, 2015, 05:55:31 am
error 201.1 on cold start seem to be gone, could trace it back to ribbon cable on P1027:3 not always making contact, so DTA_IN on A/D board was missing.
the reading on 200 mVDC with HI-LO shorted (HI ACCURACY, SYNC AUTOZERO) has some offset, something around +2.0 µV after 2 hrs. warm-up, with extremes going between 1.8...2.2 µV.
can somebody please confirm as to whether this is normal behavior due to thermal emf on the inputs?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Magnum on November 09, 2015, 08:45:24 am
I checked with my 2001, same settings:
Min/Max: -1,404uV / -0,868uV
Avg: -1,166uV
StdDeviation: 0,11uV (0,556PPM)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Magnum on November 09, 2015, 09:05:07 am
When playing around with a small tool I wrote to get the values for Le_Bassiste, I found a problem with my 2001:
When measuring the voltage in 20V range and only with 10PLC the voltage first drops and then rises again. Other ranges don't have this problem.
I attached a screenshot. The graph on top is the measured voltage, first 200 samples with 0.1 PLC, then 1 PLC and after that 10PLC. The graph below shows the difference between Min and Max and the standard deviation, both in PPM.
Someone having an idea what might be wrong?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 3roomlab on January 06, 2016, 01:30:21 am
ebay alert

http://www.ebay.com/itm/Keithley-2001-Digital-Multimeter-7-5-Digit-Parts-Repair-/231797719292?hash=item35f83880fc:g:C-EAAOSw3KFWgtw9#shpCntId (http://www.ebay.com/itm/Keithley-2001-Digital-Multimeter-7-5-Digit-Parts-Repair-/231797719292?hash=item35f83880fc:g:C-EAAOSw3KFWgtw9#shpCntId)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on January 06, 2016, 02:10:07 am
@Magnum: the drop in measured voltage looks strange. Is it reproducable or just a singel event.

It could be a problem with the auto zero function. The AZ reading may not use just one zero reading for each measurement, but could use the average of several past zero readings too.  This somewhat makes sense, as the zero is not changing very fast.

So switching just the NPLC setting could upset the meter und mixing readings for different settings or get one poor conversion to upset more than just one value. So it might be a good idea not to change NPLC setting one the fly, but stop / restart after that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 06, 2016, 06:48:39 am
ebay alert

http://www.ebay.com/itm/Keithley-2001-Digital-Multimeter-7-5-Digit-Parts-Repair-/231797719292?hash=item35f83880fc:g:C-EAAOSw3KFWgtw9#shpCntId (http://www.ebay.com/itm/Keithley-2001-Digital-Multimeter-7-5-Digit-Parts-Repair-/231797719292?hash=item35f83880fc:g:C-EAAOSw3KFWgtw9#shpCntId)

Too late, $500 seems to be fair, repair based on picture will be piece of cake (find 7001 as VFD donor and solder new VFD).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 3roomlab on January 06, 2016, 07:03:34 am
i would love to participate in the bidding war but they do not ship out of USA, but then again, it went somewhat out of my budget @ over 450 :P ... it could be a nice "season 2" of keithley frankenstein modding :P
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on January 06, 2016, 12:27:20 pm
The unit in auction was not the best for your type of modding, it looks like new. So I will put there new VFD and resell it.
BTW check the http://www.go-dove.com/en/index (http://www.go-dove.com/en/index)
About month ago there were huge auction where was about 20x K2001 ($100-$150 not working and $300 operational).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on January 06, 2016, 01:43:17 pm
Hopefully there is nothing else wrong with it - changing the caps should be done no matter what of course.
Values on the 2001 seem good, probably a good time to sell mine.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on January 22, 2016, 03:25:23 am
Hi

I recently acquired a broken 2001 that won't power up at all.
After a bit of testing I think the transformer is blown, specifically the red windings on the secondary.
Would someone be able to please confirm going by the resistances ? (Also note the exact model / revision of your transformer ).
I've looked around but can't seem to find where to buy a replacement one.
Would it be possible to replace it with a different generic one if I match the output voltages ( assuming someone can post the AC out voltages ).

I've looked through this thread but can't find the schematic for the mains input circuit ( The one with the relays K101 / K100, Q528, CR100 .. ). Has that not been documented so far or have I missed something ?
One other glaring issue is that R123 & R250 (bottom side, close to power resistor & MOSFET heatsinked to the case) reach 130C within 1 minute of connecting power. I'm assuming this is not normal ?

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on January 22, 2016, 04:00:05 am
The transformer was measured here...

http://www.eevblog.com/forum/testgear/anyone-got-a-keithley-2001-and-want-to-check-something-for-me/ (http://www.eevblog.com/forum/testgear/anyone-got-a-keithley-2001-and-want-to-check-something-for-me/)

The schematics are listed on page 1 and TiN has a webpage documentating the same repair here...

https://xdevs.com/fix/kei2001/ (https://xdevs.com/fix/kei2001/)

The part still might be available through Tektronix parts ordering. I have ordered Keithley parts from them over the last 12 months. Shipping is a little high but you know the part will work out of the box.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on January 22, 2016, 04:00:06 am
The resistance values look resonable. So the transformer is likely not blown. There is a small chance to have a shorted turn - but this can not be measured from the ohms readings. Here a test with the secondery not connected can help. In case of a shortet turn, the no load consumption would be way to high.

The transformer has a PE connected shield winding, to reduce capacitive coupled current leakage. So a normal transformer would not give the same performance. Also there are 3 secondary winding so it would be rather hard to find a suitabel transformer.

Getting a MOSFET run so hot, there is likely something very wrong like a short or blown chip to draw way to much current.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on January 22, 2016, 04:01:56 am
Hi,

Here is the partial schematic of the power supply:


(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=195464;image)

I would expect the resistance red to red/wht and the other red to red/white to be similar. It is a centre tapped winding.

Regards,

Jay_Diddy_B
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on January 22, 2016, 04:14:06 am
The resistance values look resonable. So the transformer is likely not blown. There is a small chance to have a shorted turn - but this can not be measured from the ohms readings. Here a test with the secondery not connected can help. In case of a shortet turn, the no load consumption would be way to high.

The transformer has a PE connected shield winding, to reduce capacitive coupled current leakage. So a normal transformer would not give the same performance. Also there are 3 secondary winding so it would be rather hard to find a suitabel transformer.

Getting a MOSFET run so hot, there is likely something very wrong like a short or blown chip to draw way to much current.
Actually it looks like the red wired center-tapped secondary is shorted, his measures 0.75 ohms or less, and the example in the other thread measures about 3 ohms from CT to either side or 6 ohms across.

I 100% agree that a normal transformer will not work here, it must be the special shielded type. Otherwise there will be much too high capacitance to the primary and/or ground, compromising the "floating" nature of the instrument.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on January 22, 2016, 04:42:02 am
The transformer was measured here...

http://www.eevblog.com/forum/testgear/anyone-got-a-keithley-2001-and-want-to-check-something-for-me/ (http://www.eevblog.com/forum/testgear/anyone-got-a-keithley-2001-and-want-to-check-something-for-me/)
The exact model of the transformer was not posted there so I was still holding out some hope :).

The schematics are listed on page 1 and TiN has a webpage documentating the same repair here...

https://xdevs.com/fix/kei2001/ (https://xdevs.com/fix/kei2001/)

The part still might be available through Tektronix parts ordering. I have ordered Keithley parts from them over the last 12 months. Shipping is a little high but you know the part will work out of the box.
Found the input schematic thanks. In the URL you provided I can't find anything relating to troubleshooting the power supply (wrong link ?)

Getting a MOSFET run so hot, there is likely something very wrong like a short or blown chip to draw way to much current.
It is not the MOSFET that is getting hot, it is 2xSMD resistors that are placed in parallel ( 2x20k for a total of 10k ). See attached.

Actually it looks like the red wired center-tapped secondary is shorted, his measures 0.75 ohms or less, and the example in the other thread measures about 3 ohms from CT to either side or 6 ohms across.
That's what I'm afraid of ... I think I'll connect 120V mains to the transformer directly (1-3 / BLK-WHT / 20VAC + 90VAC) and see what happens on the secondary .. would this be a bad idea ?

I 100% agree that a normal transformer will not work here, it must be the special shielded type. Otherwise there will be much too high capacitance to the primary and/or ground, compromising the "floating" nature of the instrument.
So I'll get a noisy meter or something more sinister ? Is there a cheaper device that shares the same transformer with the 2001 ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on January 22, 2016, 05:15:34 am
The manual with part numbers is here ...
https://xdevs.com/doc/Keithley/2001/2001-902-01.pdf (https://xdevs.com/doc/Keithley/2001/2001-902-01.pdf)

The transformer part number in the manual matches what is printed on the side (TR-280). I have had a few issues tracking down new part numbers with Tektronix as some have changed. For example a letter (A,B,C,etc.) has been added to the part.
The manual also lists test voltages. I don't think any real t/s procedure has been written. The current method of repair is to remove all the electrolytic caps around the supplies and inspect for leakage. I have done this for three 2001 and one 2002. At least two had pcb damage to traces.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on January 22, 2016, 05:30:27 am
The manual with part numbers is here ...
https://xdevs.com/doc/Keithley/2001/2001-902-01.pdf (https://xdevs.com/doc/Keithley/2001/2001-902-01.pdf)

The transformer part number in the manual matches what is printed on the side (TR-280). I have had a few issues tracking down new part numbers with Tektronix as some have changed. For example a letter (A,B,C,etc.) has been added to the part.
The manual also lists test voltages. I don't think any real t/s procedure has been written. The current method of repair is to remove all the electrolytic caps around the supplies and inspect for leakage. I have done this for three 2001 and one 2002. At least two had pcb damage to traces.

Mine look fine to me :(.


(http://i.imgur.com/LGOTv24.jpg)


It even melted away CR513. Seems I was too concerned with the pre-regulator not working to notice the bigger issue. I'll do a restoration and see what can be done.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on January 22, 2016, 05:42:53 am
I have one 2001 that needs similar repair. It is sitting there waiting for me to test it. I had C117 burn through the board. I have scraped and cut out most of it and filled the hole with epoxy but I will not be surprised if it is BER.  The A/D board was also defective but was repaired so at least I have some spare parts.

Good luck with the fix.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 22, 2016, 03:31:47 pm
ManateeMafia

2001? BER?  :-DD It's nothing after 3458A, believe or not.  ;D
There are just few nodes going on inner layers under C117,C116, so it's reasonably easy fix even if there is a hole in PCB. Actually my calibrated "golden" 2001 is with hole on C117 and bodge-wire running other side of PCB :D Still works a charm after 2 years (I think, lol, did not sent it for official cal second time. Will know for sure after volt transfer ;) ).

I did not know you had that many 2001's too.

michaeliv

I think i need to work on my 2001 repair article a bit, but here's summary for first steps for you (https://xdevs.com/fix/kei2001/#fix_2001).
Keithley transformer was tested in here, with VAC data presented (https://xdevs.com/fix/hp3458a/#a4rep). It's 3458's repair log, but just scroll down a little, you will see K2001's xfmr used for power supply tests. I have extra transformer, but not sure how viable it would be shipping to you.

Quote
see what happens on the secondary .. would this be a bad idea ?
That's a good idea, it's just 50Hz xfrmr with good shielding/low noise construction, but no magic there. If your transformer heats up, or voltages are not as on mine, than it's likely shorted internally.

Your board does not look too bad to me, should be fixable with some cleaning and care. Make sure to remove all black burnt FR4, as carbonized board is conductive! You don't want that there. Don't be afraid to scrap thru layers a bit, you can fix broken connections later with bodgewires.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on January 22, 2016, 04:48:06 pm
michaeliv

I think i need to work on my 2001 repair article a bit, but here's summary for first steps for you (https://xdevs.com/fix/kei2001/#fix_2001).
Keithley transformer was tested in here, with VAC data presented (https://xdevs.com/fix/hp3458a/#a4rep). It's 3458's repair log, but just scroll down a little, you will see K2001's xfmr used for power supply tests. I have extra transformer, but not sure how viable it would be shipping to you.

Quote
see what happens on the secondary .. would this be a bad idea ?
That's a good idea, it's just 50Hz xfrmr with good shielding/low noise construction, but no magic there. If your transformer heats up, or voltages are not as on mine, than it's likely shorted internally.

Your board does not look too bad to me, should be fixable with some cleaning and care. Make sure to remove all black burnt FR4, as carbonized board is conductive! You don't want that there. Don't be afraid to scrap thru layers a bit, you can fix broken connections later with bodgewires.

Special thanks to you TiN for all your work on this - I would be lost without it.
I did connect the White-Black to 120VAc and the transformer started drawing 150W from the mains (with no load on it) and I quickly pulled the plug. It heated up by 15C in just 2-3 seconds.
I will inquire with tek if it is possible to get a replacement transformer.

According to https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_keitr_1.jpg
Red-Red/White-Red is 0-16VAC-32VAC and Violet-Violet is 0-7.1VAC.
I haven't managed to find what voltage is in between BLUE-BLUE.

Would it be possible to feed in DC voltages to the header where the transformer secondary connects in order to test the meter ? Looking at the schematics there are no obvious problems. I don't think I even need the caps to do it(though the voltage regs may require the output caps to be happy). Thoughts ?
Also I understand that CR513 is a BAV103 (missing, blown off, from my board) - Could I just put in a 1N4007 instead until replacement parts arrive ?

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on January 22, 2016, 09:07:32 pm
Yeah I have a little Keithley fan club going on here too.  ;D

The 2001 is a good bench meter once all self tests are passing. Unless a graphic lcd is needed, it is one of the best used bench meters available. Having the full service manuals is also a plus.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 01, 2016, 06:45:25 am
While I was waiting for parts to fix my 2001 I decided to try and bleach the front face of the instrument with I think good results.
The procedure is simple : Apply hydrogen peroxide + UV to the yellow plastic.
For UV I think the sun works best - It should be done in a few hours with 12% peroxide, but there's no sun here at this time of year. Best I had was 100x5mm UV leds(395nm) that I used.
For peroxide - I used hair developer cream 40 volume (12% peroxide) - easiest to obtain.
Other options for peroxide:
- 3% liquid peroxide ~50c/L - found at any supermarket --- this however might take a LONG time and results might not be optimal
- 12%(40Vol) or 15%(50Vol) Hair developer cream (recommended) - You can find it at beauty salon shops for around $3-$5 -- You will probably need 4oz -- 16oz to be safe. The advantage of the cream is that you can apply only where needed so you don't have to remove the metal input jacks to dip the entire face in peroxide.  http://www.ebay.com/itm/-/161694949754 (http://www.ebay.com/itm/-/161694949754)
- 35% hydrogen peroxide teeth whitening gel (make sure it's not carbamide peroxide) - http://www.aliexpress.com/item/-/32393540490.html (http://www.aliexpress.com/item/-/32393540490.html)
- 35% hydrogen peroxide liquid - http://www.ebay.com/itm/-/311387951479 (http://www.ebay.com/itm/-/311387951479)

I also found a YouTube video describing the procedure: youtube.com/watch?v=9hRI6b-49Pw
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on February 01, 2016, 08:41:22 am
Nice results.

In the retro computer scene there's a huge community of people that are regularly doing this on old Amigas, Commodores and other beige / white computers. They call it "Retrobrite" (Retrobriting). You'll find loads of tips / do's / don't from them. Checkout the site Amibay.com.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on February 01, 2016, 09:53:08 am
@michaeliv

One of my Keithley DMM has yellow front panel too, so I am thinking of renew it. I would also use UV leds. Please, what was exposition time in your case? Thanks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 01, 2016, 10:07:10 am
One of my Keithley DMM has yellow front panel too, so I am thinking of renew it. I would also use UV leds. Please, what was exposition time in your case? Thanks.
In my case (100 UV LED's @ 30ma each + 12% gel peroxide) I exposed basically each side(5 sides total) for about one night (12 hours). I did each side at a time because the LED's are directional and because the gel is not dense enough to stick if not supported directly against gravity.
One thing I would like to mention is that UV seems very important - I did spot tests without UV and the bleaching was 10 times less intense.
Also don't scrub the instrument face with anything -- bleaching won't affect the painted text (Power/Range/Display ... etc.) but scrubbing will.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Muxr on February 01, 2016, 10:23:36 am
Nice results.

In the retro computer scene there's a huge community of people that regularly doing this on old Amigas, Commodores and other beige / white computers. They call it "Retrobrite" (Retrobriting). You'll find loads of tips / do's / don't from them. Checkout the site Amibay.com.

McBryce.
Yup, I was looking at doing this to some of my gear. But I was sad to learn though that the plastic goes back to its original form after a short while.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 01, 2016, 10:39:03 am
Yup, I was looking at doing this to some of my gear. But I was sad to learn though that the plastic goes back to its original form after a short while.
Yes, I've also seen some info that the yellowing will be accelerated now. Not sure how true / universal the info is. But still even if what took originally 20 years to happen will now happen in 2-5 years, that's pretty good considering that if I had sunlight I think I could have done this in 10 min + a few hours wait, without even taking the instrument apart.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: pelule on February 01, 2016, 11:05:09 am
It may help to use ARMOR ALL as fnish and protection.

PeLUle
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on February 01, 2016, 08:03:52 pm
Yup, I was looking at doing this to some of my gear. But I was sad to learn though that the plastic goes back to its original form after a short while.

Yes, my experience is that it lasts about 4 years before it's back to yellow. Some people claim that coating it with a UV blocking laquer slows this down, but that's not my experience and the people in the know (my sister is a doctor of chemistry) says that the UV blocker would have absolutely no effect on the process.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on February 02, 2016, 10:00:38 am
Well, if it lasts ~4 years until it gets back to yellow, it is not so bad (at least for me).

@ michaeliv: thank you for your very informative feedback!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 03, 2016, 06:31:15 pm
After installing a new transformer donated by the very generous TiN, replacing the caps and replacing the burnt 470R input resistor, my 2001 booted right up with only 6 self-test errors which I'll try to fix.
105.2 - System trigger bus -- Probably burnt MOSFET or hopefully not 5064 ASIC.
302.2 - Ohms Protect
304.6 - Ohms sources; 70nA and 770nA - Probably contaminated PCB
304.7 - Ohms sources; 4.4nA and 770nA - Probably contaminated PCB
305.2 - Test 305.2 – Input divider; divide by 100
307.3 -  Cal divider; A/D mux/buffer (x-0.5)

I also try to increase the brightness of the VFD with not so good results - the display got even dimmer.
I probably got over-zealous with the heating -- I heated up the filaments to low-medium red hot for about 30 sec then medium-high red hot for another 30-40 sec.
The filaments were not visibly physically damaged, their cold impedance is the same as before (6.8R) and the signal applied to them is the same (5v AC, waveform attached).
Any idea what happened to them and maybe of a way to undo it ?

The display is actually dimmer than it appears in the photos -- if looking at the before shot you would think the display is totally OK, however, while it was usable, it was certainly dim.


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 04, 2016, 03:33:11 am
Glad that package arrived ok.
I see cap on mains side in not replaced? Replace them all :)

304.6 and 304.7 are likely due to dirty PCB or front/rear switch. We talking nanoamps there, so area around ohms muxes (two DIPs near LTC1043) must be cleaned very well for that.

105.2 - probably some resistor knocked off on digital board.

VFD - wow, that's bad. Unexpected. Perhaps you can share which currents did you run thru for more details? Also did you check your high voltage DC-DC output, to make sure you getting +55V or so?
In worst case you looking for 50-150$ for Keithley 7001 to donor VFD....

Also don't run it for too long without chassis, as big MOSFET at mains circuit, LDO on digital board are using chassis as heatsink. Without chassis, with boards laying around those will get very hot within minute.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on February 04, 2016, 06:00:48 am
Damage of VFD is strange. On single line instruments I saw big differences between the filaments. On some instruments are filaments orange and shining ( in dark room and with DISP:OFF) and on other are almost invisible. The VFD brightness seems to be same.

For 7001 I paid 35 USD and it was brand new with protective foil still in place:)
Try to ask Keithley/Tektronix for replacement part only ( DD-51C ). Smith mentioned that Keithley/Tekronix response time, so be patient.
We were discussing the displays in Electrometer thread
http://www.eevblog.com/forum/repair/electrometer-output-stage-keithley-6517 (http://www.eevblog.com/forum/repair/electrometer-output-stage-keithley-6517)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 04, 2016, 02:54:24 pm
From what I recall the "high" current that I applied for 30-40 sec was 550ma @ 22.5v. See picture for how the filament looked at that load.
From what I read online the filament is coated with a film of good oxides which I might have evaporated away. It's these oxides that have the property of emitting electrons when heated up.
Also the DC-DC output is 56.3, same as before the "rejuvenation".
Funny enough for me it's not the power MOSFET that's getting hot when running without the heatsink -- it's getting to around 64C. But the voltage regulator on the digital board is getting to around 107-117C.
The capacitor near the preregulator has also been replaced -- It's just a different color than the rest.

"[...] The filament consists of a very thin tungsten wire coated with barium, strontium and calcium oxides [...]"
"[...] the lifetime of a VFD is dictated by the extent of evaporation of oxide materials coated onto the tungsten filament wires [...]"

I'll be getting a unit from which I can transplant the VFD. plesa where did you get yours -- was it eBay or somewhere else they can be found for cheap ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 04, 2016, 06:22:20 pm
That's likely way too strong you had it there.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on February 05, 2016, 05:53:07 am
I'll be getting a unit from which I can transplant the VFD. plesa where did you get yours -- was it eBay or somewhere else they can be found for cheap ?

My unit is from ebay, I found it and send offer which was accepted.
The damage of the VFD you have can be explained by evaporating thin layer on tungsteen wire. By this you needs higher energy to generate electron (work function).
Maybe you can try to heat filament for longer time to make brightness consistent and after that increase  bias voltage ( acceleration voltage ).
But I'm not sure how long it will last. Try to contact Keithley and ask for new VFD.

The problem of overheating voltage regulators is the same on 2002  ( 5V stabilizator has without airflow and cover 90°C 0.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 07, 2016, 12:28:59 pm
105.2 - probably some resistor knocked off on digital board.
This is exactly what this was. Took me a while to realize that it was knocked off of the bottom side of the board.
My front/rear switch does not latch all the time -- I remember you mentioning that it is possible to disassemble & clean -- any tips on this ?

VFD - I have a Keithley 7002 heading my way that I will use as a donor. Tektronix gave me a quote of $417 for the display board( display by itself is not available ). Add shipping and perhaps tax. I haven't done anything to the damaged VFD because I wanted to avoid destroying it completely so I would be able to continue troubleshooting. I will try to re-heat it after I receive the 7002.

All other errors(105.2 302.2 304.6 304.7 305.2 307.3) - These were caused by a faulty R394. R394 is a 100k / 9.9M divider resistor. The 9.9M was reading infinite. I replaced that leg with a 10M that reads 9.9M. With this fix I get no errors - all tests pass. The 10M resistor has a ppm of about 1500. If I heat it up even 5C I start getting 304.7 errors (Ohms sources; 4.4nA and 770nA).

Anyone know what is the exact purpose of this divider(what measurements/ranges does it come into effect) ? I'm guessing high voltage measurements ?
It seems to be a Keithley custom part(Anyone know more ? Pic attached) . I will ask if they have it available.  Perhaps someone has a for-parts analog board and want to sell the resistor ?
Found a similar one on DigiKey but not sure if the performance matches -- http://www.digikey.com/product-detail/en/HVD5-B10M-050-05/HVD5-B10M-050-05-ND/2929140 (http://www.digikey.com/product-detail/en/HVD5-B10M-050-05/HVD5-B10M-050-05-ND/2929140)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 07, 2016, 12:41:10 pm
Yes, that Caddock will be fine replacement. It's high voltage divider for DCV/ACV 200V and KV ranges, and probably high ohms (used as current divider). On newer units this HV divider is already formed with two Caddock's glued together for matching tempco.

Happy to hear overall progress, now should be easy to get all sorted out.

7002 is a big beast, do you plan on it's teardown? Will be interesting, as I never saw one inside. It can make a good chassis for other DIY projects :)

With switch it's all straightforward. Desolder it from board, remove front lock spring, slider switch rod out. Make note on direction of metal contact elements. Do NOT put them opposite side, or they will stuck inside! If its not loking it may be lost springy things at front. Then you may want new switch. They should be available from Tek.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 07, 2016, 03:53:26 pm
Do you happen to know the manufacturer part numbers for the new Caddock resistors used for HV divider ? I'm interested if they're the same resistance (100k/9.9M) or just the same ratio 1:100.
Sure, I'll do a teardown and upload pics to your ftp.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 07, 2016, 04:27:27 pm
You can see photos of them in Model 2001M review (https://xdevs.com/review/kei2001m/) and Model 2002 (https://xdevs.com/review/kei2002/). I'm 99.9% sure they are same 100k/9.9M, but did not measure.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 11, 2016, 11:23:52 pm
Let's fix another 2001...

(http://xdevs.com/doc/Keithley/2001/photo/keilab_1.jpg) (http://xdevs.com/doc/Keithley/2001/photo/keilab.jpg)

This one have 4xx self-test issues after capacitor replacement and PCB cleanup...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 12, 2016, 03:30:04 am
Meter reports errors 401.1, 402.1, 404.1,2,3,4,5, 405.2,4,6,8, 406.6, 407.1,2,3 , 409.6, 410.1, 411.1,2.
If switch to ACV or ACI mode it just shows 470VAC or overflow, and DCI current on 200mA,20mA,2mA,200uA is overflow too.

If I remove Q516 transistor which routes ACV stuff thru U526 mux into measurement front end - I can see some right-ish readings on DCI, so something is going on on AC-side.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 12, 2016, 02:34:26 pm
I'm trying to swap the VFD of the Keithley 2001 with a compatible one from a different board. I'm having quite a bit of difficulty removing the VFD from the board. Anyone who has done this successfully -- any tips on how to go about it ? The problem is that there are lots of pins which are soldered all the way through the 1.6mm PCB. The pins are about the same diameter as the hole they plug into -- so not much wiggle room. Any tips on desoldering the VFD ? I basically only have access to one side of the PCB so it doesn't look like I can use solder wick.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 12, 2016, 03:51:44 pm
Solder wick and lots of patience is the way I went with my 2400 repair. Add lots of flux, remove solder with wick, and then wiggle pin till it's free. If you have large enough solder bath (http://www.hakko.com/english/products/hakko_96.html) large enough you can reflow whole row as well, but I don't have such things, so I went with wick and wiggle.

It took me about an 1.5 hours to get display free from PCB, so patience is a key.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: JoeO on February 12, 2016, 11:45:22 pm
I'm trying to swap the VFD of the Keithley 2001 with a compatible one from a different board. I'm having quite a bit of difficulty removing the VFD from the board. Anyone who has done this successfully -- any tips on how to go about it ? The problem is that there are lots of pins which are soldered all the way through the 1.6mm PCB. The pins are about the same diameter as the hole they plug into -- so not much wiggle room. Any tips on desoldering the VFD ? I basically only have access to one side of the PCB so it doesn't look like I can use solder wick.
ISJ has a video about how he did it.

http://www.youtube.com/watch?v=wXQdo42C6pE (http://www.youtube.com/watch?v=wXQdo42C6pE)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on February 13, 2016, 05:44:23 am
Use solder extract tool (vacuum one) and make rotation movement during sucking solder. This should free almost all pins.If not, repeat it. After that use heat gun to heat up the double side tape and peel the display carefully.

Or ask nearest repair center, for them it is piece of cake.
What did you use as VFD donor? 7001?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 13, 2016, 06:59:23 am
ISJ has a video about how he did it.
The 2015 in the Youtube video is not nearly as hard enough to desolder as the 2001. Mainly because the pins are spaced much farther apart and they have lots of wiggle room in the through-holes -- compared to the 2001 which are a very snug fit.

What did you use as VFD donor? 7001?
I used a 7002 as a donor -- the one from here: http://www.eevblog.com/forum/testgear/keithley-7002-switch-system-teardown/ (http://www.eevblog.com/forum/testgear/keithley-7002-switch-system-teardown/)
I actually tried with 2 solder extract vacuum guns but the pins are so close together that I couldn't generate a good contact so I couldn't easily melt the solder or if I did manage to I couldn't create a seal in order to suck out the solder. I imagine it should be doable with the adequate tip for the solder sucker - but I don't have one and I think they don't make tips that narrow.
BTW no need to heat the board to detach. It's very easy to cut / detach the tape with a box cutter. Took me 5 seconds with a sharp cutter.

In my attempts I manage to over-heat the pins and they're not making consistent contact with the VFD glass-printed metal any more :) ... so I'll be trying it again with a new VFD board. I also bent up the VFD from the board which turns out is a big no-no and may have added / caused some pins to not make contact.
The good news is that I was able to experiment some more with reviving the VFD(that's how my original VFD got damaged, by applying too much voltage/current in trying to revive it).
From new experiments 15V for 2-3 seconds would be ideal for this type of VFD. I did get a decent bump in brightness by doing so.
VFD damage(it actually got dimmer) started to occur once I got to 22-23 V, even for only 2 seconds.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 13, 2016, 07:03:25 am
Meanwhile I got some progress on redrawing schematics of 2001, as I cannot follow what goes where on vendors schematic.
Draft as of today:

(http://xdevs.com/doc/Keithley/2001/sch/FEB_13_2015_1.png) (http://xdevs.com/doc/Keithley/2001/sch/FEB_13_2015.png)

I need another lifetime to understand everything in there completely though.  :scared:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: pelule on February 13, 2016, 07:44:29 am
If you don't need the old VFD anymore, the secures method is, to cut the leads to remove the old gals first.
Reduces the thermal capacity of the leads und allows easier unsolding.
We did it in that ways when I was working for a Japanese VFD company...
BR
PeLuLe
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on February 13, 2016, 11:04:54 am
I don't see what the problem is with these VFDs. Every VCR back in the '90s had a similar display and I replaced plenty with nothing more than a handheld solder sucker (ORYX was the best IMHO) and a regular Iron (Weller it has to be said, but a good old mains power Antex was no problem)

Of course the unleaded crap wasn't around then, but you can always just pre-solder with leaded, Chip-Quik or flux. Really though, two layer is nothing to deal with. It's the multi layer boards are kryptonite!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 14, 2016, 11:10:23 am
Fixed my third 2001. Problem was bad chopper LTC1050 with 145 ohm from -V to +V, which caused floating supply from +38/-38V booster to get screwed.
VR502,VR504 and Q543 were checked and found OK. VR504 was bit off, so i replaced it with new 4.4V zener.
After replacement of LTC1050 meter passed all self-test steps and both ACV,DCI,ACI working like a charm now.

(http://xdevs.com/doc/Keithley/2001/K1/FEB_14_2015.png)

Now one more 2001 left to fix, on which issue is already likely narrowed down to LT1223, but I need get replacement part next week to continue troubleshooting.
I'll post my redrawn schematics once all checked and cleaned up.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 14, 2016, 11:18:00 am
One more thing, I was always curious how Keithley able to deliver those ACV specs using just a AD637JR. Answer is here in this US patent (https://dev.xdevs.com/attachments/download/1289/US5220276.pdf). They use standalone full-wave rectifier with crest factor detector and lot of balancing around R530 to improve accuracy ~20 times and extend frequency range of TrueRMS converter, using some smart analog voodoo.

Obviously, Keithley 2002 is exactly same in this respect as ACV/ACI is 100% copy of 2001's circuit for it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 14, 2016, 11:28:54 am
You are running out of broken meters! What's next?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 14, 2016, 11:30:41 am
Perhaps K2000. I stolen few DG211's from there today..
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on February 14, 2016, 11:38:13 am
Great job on repair. Hopefully broken ones don't go up in price now. The empty 3458A's are selling too high already....
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on February 14, 2016, 12:07:53 pm
One more thing, I was always curious how Keithley able to deliver those ACV specs using just a AD637JR. Answer is here in this US patent (https://dev.xdevs.com/attachments/download/1289/US5220276.pdf). They use standalone full-wave rectifier with crest factor detector and lot of balancing around R530 to improve accuracy ~20 times and extend frequency range of TrueRMS converter, using some smart analog voodoo.

Obviously, Keithley 2002 is exactly same in this respect as ACV/ACI is 100% copy of 2001's circuit for it.
Fascinating.

Good job on another repair, another top notch meter saved from scrap and ready to get to work.  I am really looking forward to your redrawn schematics as I too have a hard time following the seemingly randomly chopped up multi page schematics from Keithley. (Not that we can complain about just having factory schematics at all!).

As for my own, I did repair my one faulty 2001 by simply replacing all the electrolytic caps. None of the originals had leaked, and all measured at a sensible capacitance but had maybe 3 to 5 times the ESR of the new ones. Maybe that was the issue? I also touched up dodgy looking soldering on a bridge rectifier. Maybe that did it. In any case it is back on duty now alongside its three friends.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 14, 2016, 10:48:16 pm
Assembled unit, now it's ready for some tests :).

Here are some photos for you, precision gear fanboys.

(http://doc.xdevs.com/doc/Keithley/2001/K3/an_dcv_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_dcv.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_parts_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_parts.jpg)

Boards in place:

(http://doc.xdevs.com/doc/Keithley/2001/K3/an_top_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_top.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_dig_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/an_dig.jpg)

Digital board is the only one I have with dual ROMs. I pimped it up with fresh capacitors, latest firmware 2001-M B17 and MEM2 option with knockoff Dallas (not dead yet). Note on photo incorrect dallas position, should be rotated 180° :).

(http://doc.xdevs.com/doc/Keithley/2001/K3/serno_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/serno.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/stest1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/stest1.jpg)

First self-test after assembly.

(http://doc.xdevs.com/doc/Keithley/2001/K3/stest2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/stest2.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/10v_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/10v.jpg)

All pass with flying colors. Calibrated it quickly with 2V,20V,20KOhm,1MOhm, measured 10V off my 3245A.

One thing I found interesting in 2001M B17 f/w is presence of extra config option for DCV : Analog filter.
url]
(http://doc.xdevs.com/doc/Keithley/2001/K3/filt1_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/filt1.jpg)(http://doc.xdevs.com/doc/Keithley/2001/K3/filt2_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/filt2.jpg)(http://doc.xdevs.com/doc/Keithley/2001/K3/filt3_1.jpg) (http://doc.xdevs.com/doc/Keithley/2001/K3/filt3.jpg)

2001M's user menu says:

Quote
The Model 2001 has an analog filter for use with the DCV function. This filter reduces the number of overflow errors caused by noise seen on the input signal. The analog filter is most effective when measuring voltages greater than 2 Vp-p frequencies ranging from 10kHz to 1MHz.

The analog filter is a single stage, single-pole, low-pass RC network that rolls off the signal at an approximate rate of 20dB per decade above the cutoff frequency of 10kHz. The analog filter has a zero at 600kHz. Figure 3-41, part B shows the general frequency response for the analog filter.

The analog filter is most effective on the 2V or 20V range with line synchronization enabled. On the 200mV range, a noisy input signal may cause overflow readings even though the analog filter is enabled.

I wonder if it should be somewhere on analog board, as my analog board is Rev.J, definately not real 2001M's Rev.R (https://xdevs.com/review/kei2001m/). Perhaps I should take my googles and look on photos for extra resistor and capacitor, compared to my analog PCB.

Since these last units were bought as scrap long ago, I don't have black shield cover. Anyone have 2 for sale? Also need bottom part. I bodged paper "air tunnel wall" around power parts to direct most of airflow to exhaust on side, just like stock K2001 does. Seems some of air still go elsewhere, as with DCV measuring 10V even with filter readings jump ~75uV (other 2001, with native cover stays ~10uV stable).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on February 15, 2016, 12:02:05 am
Interesting that you haven't seen the analog filter before. All four of mine have the analog filter, they range from firmware A06 to B15. I think I had posted the analog board revisions in this thread long ago.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 15, 2016, 12:07:18 am
I think A06 dont have that, as mine A08 does not have it either too.
I'm sure It's only B-version feature, and B10 don't have it (no text strings in firmware binary), but B15 does have. If it's analog, then there should be hardware somewhere for it.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on February 15, 2016, 02:13:46 am
I think A06 dont have that, as mine A08 does not have it either too.
I'm sure It's only B-version feature, and B10 don't have it (no text strings in firmware binary), but B15 does have. If it's analog, then there should be hardware somewhere for it.
I stand corrected. My A06 version does not have the analog filter.
My B10 had been upgraded to B17, so I downgraded it again (with original ROMs) and checked... it does have the analog filter with B10. The analog board is 2001-012-04N. I checked the firmware dumps of those B10 ROMs and I do see the strings "AAO ITR" in one and "NLGFLE" in the other, which combine to make "ANALOG FILTER". As a sanity check, I downloaded the B10 firmware from your server (http://dev.xdevs.com/projects/kei2001/repository/show/firmware/ROM_B10) and the files are identical to my own.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 25, 2016, 07:21:40 pm
Got myself a new 7001 to pull the display from and put it in my 2001. As expected the display is not like new and could use some brightening up. I was thinking to increase the runtime current through the filament. However, the filament seems to be driven directly by a winding on the DC-DC converter that also generates the 55V for the VFD.
Any bright ideas on how to get a 6-7V peek-to-peek to apply to the VFD filament?

Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 25, 2016, 09:06:14 pm
Is your DC-DC open board, or molded epoxied box?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 26, 2016, 02:14:24 am
Is your DC-DC open board, or molded epoxied box?
It is the open board type, identical to the one in the 7002: http://i.imgur.com/tAd07fT.jpg (http://i.imgur.com/tAd07fT.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 26, 2016, 08:22:01 am
Here's schematics of it which I reversed a year ago.

(https://xdevs.com/doc/Keithley/2001/xDevs/u625_sch.png)

Perhaps try on bad VFD first and reduce R102/R101 a bit, to see if higher current can be delivered. Check output voltages during this.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: michaeliv on February 26, 2016, 05:01:43 pm
Here's schematics of it which I reversed a year ago.

(https://xdevs.com/doc/Keithley/2001/xDevs/u625_sch.png)

Perhaps try on bad VFD first and reduce R102/R101 a bit, to see if higher current can be delivered. Check output voltages during this.
Thanks for the suggestion, but I had no luck with this, unfortunately.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: kada on February 29, 2016, 03:18:57 am
Hello Keithley fans!  :)

I got my first 2001 (actually 2001M) #1 a one year ago. It mentioned in this thread. It is working properly and regarding to calibration date string it was calibrated in 2012.

I also got another one 2001 #2 not working from eBay without cover and board shield.
Analog board revision K. Digital board revision J. ADC board revision G. Firmware version A06.

(http://s7.postimg.org/ru7104kmf/image.jpg) (http://postimg.org/image/ru7104kmf/) (http://s22.postimg.org/prubiteql/image.jpg) (http://postimg.org/image/prubiteql/) (http://s15.postimg.org/jawu66urb/image.jpg) (http://postimg.org/image/jawu66urb/) (http://s13.postimg.org/viubtd95f/image.jpg) (http://postimg.org/image/viubtd95f/)

Desolder caps and see familiar picture:

(http://s13.postimg.org/tej5jrmab/image.jpg) (http://postimg.org/image/tej5jrmab/)

Board washing/cleaning:

(http://s23.postimg.org/yq4uqmmhz/image.jpg) (http://postimg.org/image/yq4uqmmhz/) (http://s23.postimg.org/3us9d84fb/image.jpg) (http://postimg.org/image/3us9d84fb/)

New caps soldered (thanks to TiN  :-+):

(http://s17.postimg.org/bqft4wk3v/image.jpg) (http://postimg.org/image/bqft4wk3v/)

Replaced leaked 1000 uF caps on the digital board with new 2200 uF as well.

Also some retrobright experiments:

(http://s17.postimg.org/foc9lslor/image.jpg) (http://postimg.org/image/foc9lslor/)

...and result:
(http://s22.postimg.org/yz8ruahnh/image.jpg) (http://postimg.org/image/yz8ruahnh/)

After power on the VFD does not display anything. The problem was in burned DC/DC converter on the digital board.
After replacing (taken from 7001) the VFD start working. Multimeter operates good except some errors:

200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference

SKE encountered with the same errors:
Self test reported these error codes:
200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference
Did you find a solution?

What I tried to do to localize the problem:
1. Insert ADC board from my working 2001M #1 to #2 - same errors 200.1, 200.6, 200.7, 201.2
2. Insert ADC board from #2 to 2001M #1 - no errors
3. Insert digital board from 2001M #1 to #2 - no errors!
4. Insert digital board from #2 to 2001M #1 - same errors 200.1, 200.6, 200.7, 201.2

Looks like the problem is defective digital board. In the meanwhile I can do all measurements with unit #2 without problems. So the analog <-> digital board communication works properly.
I also expected damaged EEPROM and tried to load various images to EEPROM which TiN posted without luck.

Are there any thoughts?
Thanks,
Andrey.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 29, 2016, 03:42:27 am
Privet :) This is the owner of infamous 2001M thanks to whom I got hint and found original Keithley's schematics for 2001.

Update your firmware ROM to A08. When I had my meter sent to Tektronix Cal 2 years ago, they were not able to calibrate it with older fw. After update to A08, everything went well.

Check frequency line, perhaps CPU cannot read mains frequency correctly, causing issues.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 05, 2016, 10:16:37 am
After whole night of debugging on latest Model 2001, and replacement all parts except rare U441 dual JFET, I finally unit fixed by replacing pesky Q512 with NXP PMBFJ620 in tiny SOT363 package.
Quick calibration show no errors and meter show nice readings.

(http://xdevs.com/doc/Keithley/2001/KQ/sick_fet.png)

It's not pretty, let me tell you, but works as proof of concept...

(http://xdevs.com/doc/Keithley/2001/KQ/mosfet_1.jpg) (http://xdevs.com/doc/Keithley/2001/KQ/mosfet.jpg)

Already ordered U441 from UTSource on ebay store for final fix.  :blah:
DMM passes Self-test without any problems (before was almost every 4xx error).

Time to go sleep, 7:23 AM here...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on March 05, 2016, 04:29:22 pm
TiN, what I would do is decap pesky Q512 and replace the die with PMBFJ620  :-DD

Lots of old antique electronics restorers use similar tricks with ancient capacitors, batteries, etc.  ;)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on March 05, 2016, 06:47:18 pm
U441 is still manufactured by Micross www.micross.com (http://www.micross.com), price £6.96.
https://www.micross.com/pdf/LSM_U441_TO-71.pdf (https://www.micross.com/pdf/LSM_U441_TO-71.pdf)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 05, 2016, 11:01:27 pm
Manufacturer is Linear Systems, and Vishay Siliconix, but I think it would be longer and more expensive to buy one piece from them with shipping to TW, so I'd try luck with UTSource guys :) Bought some parts from them before, was okay.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on March 22, 2016, 02:07:19 am
2001 arrived and it is in good conditions. ( small damage on front cover and metal enclosure). New cover quoted from Keithley $168, display lens $38.
After power up Error 514 ( DC calibration data lost) this will requite full DC calibration at least. For initial testing I will upload the dump from other instrument).
I have no idea how the data can be lost, unit seems to be intact calibrated in 2009 ( manufactured in 2005/2006).
followed by
304.3 Ohms Source - 89uA and 0.98mA Sources
304.4 Ohms Source - 7uA and 89uA Ohms Source
309.1 Amps - 200uA Range
These errors seems to be familiar and I expect some of DG411/DG404/DG211 switch, Q320/Q324 JFET or 4052 shift registers is not working properly.
Lowest current range is working properly, so faulty is Ohm current source.
And the fain is loosen which resulted in lot of vibration and noise.

Firmware is B16, uploaded to TiN site and already upgraded to B17 (K2001M) - used ST27C4001 UV EPROM chips instead original  Atmel OTP 27C040.
Analog board is revision P, digital board revision K.
Memory upgrade to MEM2 -parts ordered:)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on March 24, 2016, 09:42:01 am
DC calibration data lost error during startup has been solved. The problem is corrupted memory U634 (24C164) after uploading data from one of TiN 2001 unit there is no error message during startup.
I'm not sure how data corruption can occur, probably swithing off unit off during saving calibration data. Plan is to decode and fix error with original data.

Ohm current source errors - current measurement is working properly and 20k, 200M and 1G Ohm ranges are not working. Unfortunately both suspected IC are thru hole.
I have no idea why they used THT instead of SMD like is used in 2002. Parts ordered.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on March 24, 2016, 10:34:44 am
plesa, did you upgrade the firmware? OK, not at all the same meter, but the K2000 has a famous DC calibration lost when upgrading from any firmware to latest A20. Even when getting this alarming DC cal data lost message (and proving it by measuring stuff) rolling back to an earlier firmware seems to restore good working order. Of course I made sure I saved my little 24C' EEPROM anyway, but there doesn't seem to be any need if you just roll back firmware.

Using someone elses backed up calibration is clearly not going to do you good.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on March 25, 2016, 10:41:35 pm
plesa, did you upgrade the firmware? OK, not at all the same meter, but the K2000 has a famous DC calibration lost when upgrading from any firmware to latest A20. Even when getting this alarming DC cal data lost message (and proving it by measuring stuff) rolling back to an earlier firmware seems to restore good working order. Of course I made sure I saved my little 24C' EEPROM anyway, but there doesn't seem to be any need if you just roll back firmware.

Using someone elses backed up calibration is clearly not going to do you good.

Yes, I upgraded from B16 to B17 and error during startup was the same. I checked the backup of U634 and it looks like OK. So I tried to upload it back instead of TiN backup and error is gone.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on March 27, 2016, 03:21:33 am
Failed test 304.3 and 304.4 has been solved. It was component which I was not suspecting.
R365 78.7k 0.5% Vishay VSA100 foil resistor is open. I replaced it by two Vishay UXB series resistors in series and errors are gone :-DMM
The best replacement I found is VSA101 series http://www.vishaypg.com/docs/63143/vsa101.pdf (http://www.vishaypg.com/docs/63143/vsa101.pdf)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on April 23, 2016, 08:30:57 pm
I was curios what is inside VSA100 resistor and also I wanted to identify failure mechanism of foil resistor.
So I remove epoxy potting from all foud sides and expose the resistor chip. Chip was coated by orange slicone.
The biggest surprise was that when measure the resistor is working and has 78k7. So it is contact or broken chip....
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: SeanB on April 23, 2016, 09:56:36 pm
You will probably find it was a lead broken off at the glass substrate. Either took the pad with it, or cracked the glass off in that area.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: klaus11 on May 03, 2016, 10:34:06 pm
K2001 has in secret menu 3458A simulator? As K2002
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 03, 2016, 10:53:38 pm
No, no 3458A mode nor 3458A game in 2001.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 08, 2016, 09:51:52 pm
Gave some hydrogen peroxide + sunlight love to one of my 2001's..
Photo before:

(https://xdevs.com/doc/Keithley/2001/photo/kei2001_uv1_1.jpg)

Photo after:

(https://xdevs.com/doc/Keithley/2001/photo/kei2001_uv2_1.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: klaus11 on May 09, 2016, 09:03:25 am
Nice!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on May 09, 2016, 10:01:10 am
Hmm... nice, but I think I will go to the effort of removing the plastics that are not affected by the yellow peril, like the display panel and input jacks because they seem to have come off a bit worse :(

Also allows for safer 150C hot air treatment to reform the ABS to factory on all those edge dings. Something I learned of recently ;)

What would be a good way of removing the scratches from the display panel? I've heard polishing with toothpaste and the like but in my experience it's been ineffectual or made matters worse on other stuff (notably scratched eyeglasses).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on May 09, 2016, 11:31:07 am
For polishing display windows I recommend the Novus line of scratch removing products. I have used them with great success. The cloth you use to apply the product and buff the display window must be very soft or you'll never get anywhere. Obviously protect silk screen labels, stickers, or paint with masking tape before hand. Ideally you should also remove the display window from the chassis beforehand.
The last display window I did was on a Agilent frequency counter, you may not get it 100% but you can get in the high 90's.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: AF6LJ on May 09, 2016, 12:25:32 pm
You beat me to it TheSteve.
A friend turned me on to that stuff, works like a Bomb.  :-+ :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on May 10, 2016, 01:16:01 am
Gave some hydrogen peroxide + sunlight love to one of my 2001's..
Photo before:

(https://xdevs.com/doc/Keithley/2001/photo/kei2001_uv1_1.jpg)

Photo after:

(https://xdevs.com/doc/Keithley/2001/photo/kei2001_uv2_1.jpg)

It looks that it also remove Keithley marking on top left corner. But it seems to be only one alternative ( new plastic price is ridicilous).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 10, 2016, 02:26:37 am
That was mechanical damage from my careless tossing panel around in the jar.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 10, 2016, 11:01:21 pm
...Also allows for safer 150C hot air treatment to reform the ABS to factory on all those edge dings. Something I learned of recently ;)
...
How about credit where credit is due? I mentioned this technique in TiN's K2000 thread here (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/msg934047/#msg934047). I came up with this crazy idea one day, decided to try it on a Keithley 199, and it worked like a charm. I am certain that I am not the first to do this but I hadn't heard of anyone doing it.

Here is an example. I fixed up a Keithley 7001 panel yesterday, including de-yellowing and fixing minor dings. These are very minor dings but I wanted to post up some pictures. I have fixed far worse.

1. Panel with lens removed, yellowing of the ABS plastic is quite evident.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223816;image)
2. Panel after ~2 hours in the sun with "40 volume" strength gel Hydrogen Peroxide hair bleach, brushed on straight from the bottle.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223818;image)
3. Small ding in a corner.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223820;image)
4. Ding removed with hot air, set to 170oC and high fan.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223822;image]http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223822;image)
5. Two small dings in side
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223824;image)
6. Removed.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223826;image)
7. Side-by-side comparison with a unit awaiting restoration.
(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=223828;image)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: AF6LJ on May 11, 2016, 12:51:16 am
That looks really good and almost like new.  :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 11, 2016, 01:00:20 am
Better than new - proven by time!

Thanks for great details and photos. I'll try and report back the progress once done. I have three 2001s, both 2002 and 2304 panels in line.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on May 18, 2016, 04:42:01 pm
To prove hydrogen peroxide whitening I submerged covers from K2002,K2001,K6517 and K2410 in 15% hydrogen peroxide. After 2h there was small change, but after one day they are like new. Thanks for hint :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 18, 2016, 09:18:49 pm
Process depends a lot on UV light intensity, so best would be to have it for few hours under direct sunshine, swapping sides/rotating the thing each hour or so to get even white surfaces.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: nidlaX on May 18, 2016, 09:50:12 pm
Whoa, nice ding restoration trick! I've gotta try that sometime. :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 18, 2016, 10:58:34 pm
Whoa, nice ding restoration trick! I've gotta try that sometime. :-+
It depends on the peculiar properties of ABS plastic. Most other types of plastic won't do this. Practice on LEGO bricks, they are ABS too. A couple of ordinary LEGO, a hammer, and your heat gun can provide an oddly satisfying half hour of fun. Destroy, fix, destroy, fix, ...  >:D  But actually the point of practicing is to fine tune the temperature and technique. If the temp is too low, then you need to heat for too long to make the plastic become "plastic", and you risk heating the part right through, and then it might deform, losing the original shape forever. You want to heat the surface high enough to soften, but keep the structure underneath solid. Alternately, if the temperature is too high, then the surface will melt (not just soften) and will become glossy or worse. The ABS will also tend to lose its "shape memory" when heated too high, then it won't return to its original shape.

I wish I had taken pictures of the really bad ones before fixing. The difference is astonishing.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on May 19, 2016, 02:09:34 am
Process depends a lot on UV light intensity, so best would be to have it for few hours under direct sunshine, swapping sides/rotating the thing each hour or so to get even white surfaces.

I forgot to mention that it was whole day on direct sunshine ( I leave on garden in big transparent container with 4l of hydrogen peroxide) The circulation has been made by lot of bubbles made by peroxide decomposition.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 19, 2016, 04:12:17 am
Process depends a lot on UV light intensity, so best would be to have it for few hours under direct sunshine, swapping sides/rotating the thing each hour or so to get even white surfaces.

I forgot to mention that it was whole day on direct sunshine ( I leave on garden in big transparent container with 4l of hydrogen peroxide) The circulation has been made by lot of bubbles made by peroxide decomposition.
That method obviously isn't ideal.
Last week I did 5 panels at the same time (2 x K2001, 3 x K7001). Start to finish < 1 hour in the sun. I used 40 vol (very strong, 12%) hydrogen peroxide gel. I placed the panels in a shallow plastic container, I brushed on a thin layer, covered the container with plastic food wrap ("Glad Cling Wrap") to prevent evaportaion, and put it in the sun. The sun was at an angle, so I rotated the container a few times over the hour. I re-applied fresh HP after 30 minutes to help combat evaporation. Last time (2 weeks ago) it took 2 hours but it was partly cloudy. This time, 1 hour and done. The UV light is essential and you must be careful about what you cover the item with, or it will block UV. Maybe your panel, submerged deep in liquid HP, didn't get enough UV light.

I was happy to be done in only 1 or 2 hours. Too much time in HP and the dye in the plastic can bleach, leaving it with light patches. We want only to convert the brown/yellow Bromine back into colorless Bromide or Bromate.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on May 19, 2016, 05:14:03 am
Process depends a lot on UV light intensity, so best would be to have it for few hours under direct sunshine, swapping sides/rotating the thing each hour or so to get even white surfaces.

I forgot to mention that it was whole day on direct sunshine ( I leave on garden in big transparent container with 4l of hydrogen peroxide) The circulation has been made by lot of bubbles made by peroxide decomposition.
That method obviously isn't ideal.
Last week I did 5 panels at the same time (2 x K2001, 3 x K7001). Start to finish < 1 hour in the sun. I used 40 vol (very strong, 12%) hydrogen peroxide gel. I placed the panels in a shallow plastic container, I brushed on a thin layer, covered the container with plastic food wrap ("Glad Cling Wrap") to prevent evaportaion, and put it in the sun. The sun was at an angle, so I rotated the container a few times over the hour. I re-applied fresh HP after 30 minutes to help combat evaporation. Last time (2 weeks ago) it took 2 hours but it was partly cloudy. This time, 1 hour and done. The UV light is essential and you must be careful about what you cover the item with, or it will block UV. Maybe your panel, submerged deep in liquid HP, didn't get enough UV light.

I was happy to be done in only 1 or 2 hours. Too much time in HP and the dye in the plastic can bleach, leaving it with light patches. We want only to convert the brown/yellow Bromine back into colorless Bromide or Bromate.
Maybe not, but it works. The container is made from PP so it is UV transparent. I do not think evaporation is issue, hydrogen peroxide will sooner degrade to water and oxygen.
I'm also going to test it o keyboard plastic from other equipment.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on May 22, 2016, 05:02:04 pm
Tried to leave the front panel plastic in hydrogen peroxide for 5 days. After this extra long time exposed to sunlight the plastic ( not Keithley, but HP/Agilent) became light blue.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 23, 2016, 03:10:36 am
Yep, light-blue :)

Here I've got K2304 and 2001 with whitened panels assembled. Had this time rear bezel from 2001 before too + TAED and it stay in solution for way too long, 4 days, 2 of which were raining. Its now sorta bluish white. :) I'll snap few photos later to show. 1L Bottle of peroxide already gone, so need buy few more to continue other units.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on May 23, 2016, 10:23:51 am
Are we advancing the previous research that led to retr0bright (http://www.retr0bright.com/)? It seemed clear that a deep soaking in lots of peroxide was not needed, just a soapy suds (mixed with washing powder) application. It seems even 6% peroxide is good enough, never mind the "salon professionals only" 12% (or 40 vol as I have now learned it is known). A few hours in the sun and Bob's your uncle!

The blue thing is worrying. Glad I leave it to you pioneers in Keithley plastics rather than me  :-DD

Also, macboy's great hot plastic revival trick - before or after?  ???
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on May 23, 2016, 05:45:18 pm
Process depends a lot on UV light intensity, so best would be to have it for few hours under direct sunshine, swapping sides/rotating the thing each hour or so to get even white surfaces.


I forgot to mention that it was whole day on direct sunshine ( I leave on garden in big transparent container with 4l of hydrogen peroxide) The circulation has been made by lot of bubbles made by peroxide decomposition.
That method obviously isn't ideal.
Last week I did 5 panels at the same time (2 x K2001, 3 x K7001). Start to finish < 1 hour in the sun. I used 40 vol (very strong, 12%) hydrogen peroxide gel. I placed the panels in a shallow plastic container, I brushed on a thin layer, covered the container with plastic food wrap ("Glad Cling Wrap") to prevent evaportaion, and put it in the sun. The sun was at an angle, so I rotated the container a few times over the hour. I re-applied fresh HP after 30 minutes to help combat evaporation. Last time (2 weeks ago) it took 2 hours but it was partly cloudy. This time, 1 hour and done. The UV light is essential and you must be careful about what you cover the item with, or it will block UV. Maybe your panel, submerged deep in liquid HP, didn't get enough UV light.

I was happy to be done in only 1 or 2 hours. Too much time in HP and the dye in the plastic can bleach, leaving it with light patches. We want only to convert the brown/yellow Bromine back into colorless Bromide or Bromate.


Cling-Film (or whatever that transparent food covering film is called in your neck of the woods) works very well for covering the parts while they enjoy the sun. Just make sure there are no creases in the film on the sunny side or it can cause un-even bleaching.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Richard Head on May 23, 2016, 06:40:47 pm
I've learned something! I'm going to try the hydrogen peroxide trick on my Avdantest spectrum analyser screen bezel. They are renowned for turning yellow with time/sunlight.
I hope it doesn't make the plastic brittle.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 23, 2016, 10:58:41 pm
Are we advancing the previous research that led to retr0bright (http://www.retr0bright.com/)? It seemed clear that a deep soaking in lots of peroxide was not needed, just a soapy suds (mixed with washing powder) application. It seems even 6% peroxide is good enough, never mind the "salon professionals only" 12% (or 40 vol as I have now learned it is known). A few hours in the sun and Bob's your uncle!

The blue thing is worrying. Glad I leave it to you pioneers in Keithley plastics rather than me  :-DD

Also, macboy's great hot plastic revival trick - before or after?  ???
Some magic sauce is missing from TiN's and plesa'a attempts to have force a multi-day attempt. I have in the past added "Oxy Clean" (the concentrated stain remover powder, not the one marketed specifically as laundry detergent/booster). I found that it caused the HP to foam, and I didn't care for that. So my latest attempts did not use any Oxy booster at all, and it still worked like magic. As I said earlier, I used just a thin layer of 40 Vol (12%) HP gel brushed on, put into direct sunlight under cling wrap, and one hour later, done.

The heat reshaping can be done before or after color restoration. I have tried both ways and observe no difference to the result. I usually choose to do it after.

Here is one more weapon in the ABS panel restoration arsenal: Tamiya Extra Thin Cement.
(http://www.hobbylinc.com/gr/tam/tam87038.jpg)
It is a model cement with extremely thin consistency. It is perfect for fixing cracks in ABS. If you have a crack, just apply a small amount of this to the crack, it will instantly disappear into the crack by capillary action. The solvents then melt the plastic, and as they evaporate away, the crack is literally welded shut. If the crack has a little bit of a gap between sides, repeated application may be necessary. Each time, the solvent will dissolve a little plastic, filling in a little bit of the gap. (as with the heat reforming, practice with LEGO can be useful!).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on May 23, 2016, 11:11:01 pm
Lego master give us another gem. I can see you tried many things on many legos to find out these tricks.
Thanks for sharing, really. I have cracks in 2400's panel "ears" which made it barely holding as a whole.
And it's bit different than 200x one, so I can't replace it directly. So I'll try to buy that cement to give it a whirl.  :-/O
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on May 23, 2016, 11:14:49 pm
Yup, thumbs up for that solvent. I used it to repair the bezel on my HP3478A and the crack is almost invisible now. One further tip however: Clean the surface inside the crack with Isopropanol first, especially if the crack is old, otherwise you weld a (visible) line of dirt into the crack too.

Regarding the bleaching. There's a product in the UK known as BBlonde http://www.superdrug.com/B-Blonde/Jerome-Russell-B-Blonde-Cream-Peroxide-40-Vol-12%25-Lightner/p/42293 (http://www.superdrug.com/B-Blonde/Jerome-Russell-B-Blonde-Cream-Peroxide-40-Vol-12%25-Lightner/p/42293) which already contains the exact mixture needed for "bezel blonding" without the need to mix your own solution with Oxy or whatever. Possibly there's some similar product over there you could try?

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 24, 2016, 08:54:21 am
Yup, thumbs up for that solvent. I used it to repair the bezel on my HP3478A and the crack is almost invisible now. One further tip however: Clean the surface inside the crack with Isopropanol first, especially if the crack is old, otherwise you weld a (visible) line of dirt into the crack too.

Regarding the bleaching. There's a product in the UK known as BBlonde http://www.superdrug.com/B-Blonde/Jerome-Russell-B-Blonde-Cream-Peroxide-40-Vol-12%25-Lightner/p/42293 (http://www.superdrug.com/B-Blonde/Jerome-Russell-B-Blonde-Cream-Peroxide-40-Vol-12%25-Lightner/p/42293) which already contains the exact mixture needed for "bezel blonding" without the need to mix your own solution with Oxy or whatever. Possibly there's some similar product over there you could try?

McBryce.
Good tip about cleaning the plastic before welding.

Interesting about the "BBlonde". Maybe the cream peroxide I have here also has some of the other active ingredient in it already, which is why it works so well. In any case, since it is very effective compared to what some of you guys are trying, I'd be willing to ship a bottle to forum members at cost.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Macbeth on May 24, 2016, 09:02:15 am
I've got a Superdrug round the corner. For less than £2 for a bottle of BBlonde it seems a no brainer to give this a try. Now finding Lego bricks is another matter...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on May 24, 2016, 10:37:05 am
I've got a Superdrug round the corner. For less than £2 for a bottle of BBlonde it seems a no brainer to give this a try. Now finding Lego bricks is another matter...

Lego costs more then Keithley gear...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 24, 2016, 10:44:05 am
I've got a Superdrug round the corner. For less than £2 for a bottle of BBlonde it seems a no brainer to give this a try. Now finding Lego bricks is another matter...
I have  5 and 7 year old boys. I'm lucky if can not find Lego everywhere I look.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on May 24, 2016, 05:58:43 pm
I have a 5 year old son = If I need Lego I just choose one of the pieces embedded in my foot!

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: xrunner on May 30, 2016, 09:03:08 am
How about credit where credit is due? I mentioned this technique in TiN's K2000 thread here (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/msg934047/#msg934047). I came up with this crazy idea one day, decided to try it on a Keithley 199, and it worked like a charm. I am certain that I am not the first to do this but I hadn't heard of anyone doing it.

Wow - I tried this for the first time today. I tried it on an old GE camera controller case. I used the cream peroxide that is sold in beauty supply stores. I just brushed it on and covered it with plastic wrap, and left it in the sun for about 4 hours. I only did the top to see the difference. It worked that fast. Great tip and method.  :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 30, 2016, 11:35:50 pm
How about credit where credit is due? I mentioned this technique in TiN's K2000 thread here (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/msg934047/#msg934047). I came up with this crazy idea one day, decided to try it on a Keithley 199, and it worked like a charm. I am certain that I am not the first to do this but I hadn't heard of anyone doing it.

Wow - I tried this for the first time today. I tried it on an old GE camera controller case. I used the cream peroxide that is sold in beauty supply stores. I just brushed it on and covered it with plastic wrap, and left it in the sun for about 4 hours. I only did the top to see the difference. It worked that fast. Great tip and method.  :-+
It really is amazing to see isn't it?

Let's be clear, I don't claim any credit for the whitening process. This was pioneered by folks at Retr0Bright (http://www.retr0bright.com/) who wanted a way to de-yellow vintage computers and game consoles. There is some additional history on their site.

I was claiming some credit for the process of removing small dents and dings in the plastic by heating it to a specific temperature with a hot air gun. This seems to "relax" the plastic and allows the damaged surface to return to its original shape. As above, I'm sure I'm not the first to do it, but I haven't heard of anyone doing this.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: xrunner on May 31, 2016, 08:44:27 am
I was claiming some credit for the process of removing small dents and dings in the plastic by heating it to a specific temperature with a hot air gun. This seems to "relax" the plastic and allows the damaged surface to return to its original shape. As above, I'm sure I'm not the first to do it, but I haven't heard of anyone doing this.

I'll review that process: Do you think the unit shown in the attachments is a good candidate for that?

Thanks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on May 31, 2016, 08:53:06 am
I was claiming some credit for the process of removing small dents and dings in the plastic by heating it to a specific temperature with a hot air gun. This seems to "relax" the plastic and allows the damaged surface to return to its original shape. As above, I'm sure I'm not the first to do it, but I haven't heard of anyone doing this.

I'll review that process: Do you think the unit shown in the attachments is a good candidate for that?

Thanks.
No, it looks like that isn't simply dented but has chunks of material missing. There is no simple fix for that.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: xrunner on May 31, 2016, 08:58:55 am
No, it looks like that isn't simply dented but has chunks of material missing. There is no simple fix for that.

Well ... I got it. What about the next best thing - would the process make it look any better, given that material is gone? Would it smooth it out?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on June 07, 2016, 04:22:55 am
recently got the chance to acquire a KEI2001 in beautiful condition (alas, a very faint display), with no pcb damages whatsoever. after giving it the full capacitor exchange, i decided to give it a shot with a home-brew MEM2 option. SRAM is an HY628100B that i salvaged from an HP-40G calculator. works like a charm after initializing it via the secret menu.
piggy-backed battery is not the most elegant solution, but don't know a better one.  the whole shebang just so fits under the hood with some clearance.
(http://)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 25, 2016, 07:16:59 pm
Hi all,
Happy owner of 2 Keithley multimeters which I bought recently. 1 is a 2000 which is 100% functional, no self test errors. The second one is a 2001 which has substantial damage done by leaky caps. Somebody already did a repair attempt to it, but its definitely not 100%.

After some investigation this is where its at at this moment:
It does power on, let me take measurements, seems on the low voltages ranges its pretty accurate. Not really possible for me to check its accuracy anyway. It does jump up in voltage for no apparent reason once every few seconds for a very short time. Ohms range is not working well. Shorting the probes gives good readings, but anything above a few ohms sometimes give me an ok reading, but most of the time its al over the place.
Its missing its mains transformer. Probably it got a shorted turn, and got tossed away at some point in the past. Now it is running from an external transformer which is putting out the following voltages:
9.3v and 35.0v to analog board, and 9.5v to digital board.

I noticed that J1025 is not used atm. This is for the voltage selection. Do you guys think that this can give issues? Maybe the circuit is trying to sense and switch all the time causing issues?
I started to take some measurements but when I saw that the voltage at one of the avalanche diodes was at around 48v I stopped and thought it would be better to clean and replace all obvious problems first.

Failing self tests:
200.1  No A/D communication, noisy A/D
200.6  U808 Malfunctioning
200.7  U808 Malfunctioning
201.2  Cannot measure 7v at A/D
201.3  Cannot measure 1.75v at A/D
300.2   A/D Mux 1.75V Ref,  x5 gain
304.6  70nA Ohms source
304.7   5nA source

What I found inside:

Analog board:




A/D converter board, running rev A06




Power supply caps replaced (not by me). Notice the bodge wire running under it. If you look closely you can already see the horror that happened between those 2 caps.




Burnt hole in PCB, and some surgery already done (not by me)

(http://)


Bodgewire running from U510 all the way to U320





Corrosion around c108




Wierd pin on U626, original or not?

(http://)


Half eaten away resistors near C633




C623 and c624 leaky

(http://)

So lots of rework needs to be done. First of al I'm planning to change all caps, also the ones that already have been replaced. Just so all caps are fresh, and the same brand/type (I ordered Panasonic 105c ). I also want to put in the original transformer. Quoted Tek via parts request on the website, but no response so far (about a week now). Called them, and they said it is available for 220 euro shipped to the Netherlands (where I live). If somebody is willing to sell one for less than that, I'm happy to hear.
Lastly, I want to thank TiN, and definitely all the other who contributed to this magnificent work!!!

Thanks,

Tom

***Having trouble getting the pics online, will fix that tonight***
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 25, 2016, 10:36:31 pm
You can upload pics on my ftp, i'll mirror them for you.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 25, 2016, 11:03:13 pm
I actually already uploaded them to your site this morning. Its in the folder with my username in it. Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 26, 2016, 03:37:06 am
Wow, pretty nasty :)
Remove all caps, all damaged components and let's see what we dealing with.

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_FULL_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_FULL.jpg)

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BODGE_WIRE_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BODGE_WIRE.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BODGE_WIRE2_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BODGE_WIRE2.jpg)

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ADBOARD_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ADBOARD.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BOTTOM_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/ANALOG_BOARD_BOTTOM.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/BURNT_HOLE_IN_PCB_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/BURNT_HOLE_IN_PCB.jpg)

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/C630_LEAKING_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/C630_LEAKING.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/DIGITAL_BOARD_1_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/DIGITAL_BOARD_1.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/POWER_SUPPLY_CAPS_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/POWER_SUPPLY_CAPS.jpg)

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/R606_R607_CORROSION_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/R606_R607_CORROSION.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U103_CORROSION_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U103_CORROSION.jpg)

(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U503_CORROSION_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U503_CORROSION.jpg)(https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U626_STRANGE_PIN_1.jpg) (https://doc.xdevs.com/doc/Keithley/2001/photo/TomThaMan/U626_STRANGE_PIN.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on June 26, 2016, 05:38:09 am
Wow, that one is going to need some serious TLC. It must have spent many hours powered on with the caps leaking away.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 26, 2016, 05:51:30 am
Thanks TiN!!

Does anybody has a spare transformer and willing to sell it?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ManateeMafia on June 26, 2016, 06:44:23 am
There is also a bracket that fits over the transformer. Don't forget to get one of those, it is used to mount the transformer to the case.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 26, 2016, 06:53:38 am
thanks for the info, that one I already have.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: PedroDaGr8 on June 26, 2016, 02:52:33 pm
Lego master give us another gem. I can see you tried many things on many legos to find out these tricks.
Thanks for sharing, really. I have cracks in 2400's panel "ears" which made it barely holding as a whole.
And it's bit different than 200x one, so I can't replace it directly. So I'll try to buy that cement to give it a whirl.  :-/O
Finally, something I, as a chemist, can contribute instead of just reading in interest and awe. For plastic welding the three most common solvents are acetone, chloroform/methylene chloride or methyl ethyl ketone. Chloroform and methylene chloride are 100% interchangeable and perform the exact same, I will refer to them as methylene chloride from here on out.

Methylene chloride, also called dichloromethane, is commonly used for pvc welding and works on many rigid plastics. MEK is commonly used in certain other plastics that chloroform doesn't work on (such as ABS). I have used methylene chloride to plastic weld a stop pin back on the sliding door of an instrument. It maintained perfect rigidity. In fact, about a year later, someone broke the pin off again, and it broke in a different location indicating the strength of the weld. These are all VERY low viscosity liquids which will seep into any crack. They also evaporate really quickly. To weld the plastic together, coat both surfaces in the solvent and press together firmly for about 30sec. Be careful to not apply too much because you can actually substantially melt the plastic when they press together. Just a thin coat is all it takes. Then let sit and dry for a few hours to ensure complete evaporation of the solvent. You can increase evaporation by heating (methylene chloride is not at all flammable, MEK on the other hand is so heat accordingly).

Link of interest:
A list of common plastics and the solvents that can be used to weld them: http://nerfhaven.com/forums/topic/18527-intro-to-solvent-welding-plastic/ (http://nerfhaven.com/forums/topic/18527-intro-to-solvent-welding-plastic/)

There is a pdf I am looking for similar to above but I cna't find it.

This will allow you to find the solvents much cheaper than the previously linked cement. As previously note: Acetone, Dichloromethane and MEK are the big ones to use. Personally, I haven't had much luck with acetone (not sure if I am doing it wrong) but the other two work AMAZING.

Sent from my LGLS992 using Tapatalk
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 26, 2016, 07:57:27 pm
Nice info on plastic welding! I run my own independent car garage in the Netherlands, and what I usually do with thermoplastics (not thermosets, check that first!!) is weld them on the non visible side by melting the parts together with a nice fat soldering iron.  You can also add material, as long as its the same type. Maybe not the best solution for small stuff like this, but it works very well and the only thing you need basically is a soldering iron. Could help you out in some situations where the correct plastic welding solution is not available atm.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on June 26, 2016, 08:18:52 pm
I started out with a bunch of 400 series errors. After replacing all the caps and the chips around the capacitors I am down to just one error now.
412.1 ACA switch - AC amps switching error

I changed CR 305 and CR 309 but the error still won't go away. Before I changed the diodes it would pass all tests from a cold start, but now even that doesn't happen.

Any clues?

PS: Thanks Tin for the great post and the wealth of info on this multimeter. I am becoming a Keithley fan!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on June 27, 2016, 09:13:36 pm
Update: my 412.1 ACA switch error went away for while. I ran several tests after meter warmup and it was still passing all test. But after a few more hours the error is back. I am pulling my hair out. |O Someone please help!!  I am thinking its temperature related but I don't know how to troubleshoot without a thermal camera.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 28, 2016, 03:18:15 am
Perhaps you have leakage for current somewhere in U5xx area on board.
Also check voltage rails on LT1050 near TrueRMS. Make sure they are balanced against DMM LO.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on June 28, 2016, 10:14:00 am
Perhaps you have leakage for current somewhere in U5xx area on board.
Also check voltage rails on LT1050 near TrueRMS. Make sure they are balanced against DMM LO.

I will give that section an alcohol bath and see if that helps. Otherwise, I just need to start replacing chips in that section. Or perhaps it could be a damaged track that acts up when the temperature increases? I  am wondering if I need to do the yellow bodge wire that Tom's meter has (Bodgewire running from U510 all the way to U320). Those chips are part of the Amps switching test circuit.

I'll check the LT1050 again. I replaced this earlier too so I doubt its busted. But for some reason the 4.3 zener near it shows 3.99V. I changed that too but the new one shows the same behavior.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on June 28, 2016, 10:16:16 am
Bodgewire running from U510 all the way to U320

Hi Tom, what pin on U320 does the bodge wire go? pin #6?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 28, 2016, 02:27:45 pm
I'd hold off bodging wires if no clear understanding of related circuitry purpose is achieved. Also try with clean IPA swipe first around. Putting whole board into bath likely cause more issues than currently you have. Such things are not something you usually do on 26+ bit analog instrument.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on June 28, 2016, 03:47:14 pm
I'd hold off bodging wires if no clear understanding of related circuitry purpose is achieved. Also try with clean IPA swipe first around. Putting whole board into bath likely cause more issues than currently you have. Such things are not something you usually do on 26+ bit analog instrument.

I agree. I was exaggerating when I said alcohol bath.  :) I have swiped the front and back of the PCB with 99.9% IPA without luck.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 28, 2016, 04:20:32 pm
I would probably do what TiN suggests, but to answer the question, yes, its connected to pin 6.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 29, 2016, 05:40:20 am
U320.6 is ADBUF+ node, common input of A/D buffer.
It's side of switch which routes 1.75V Reference voltage to ADBUF.
It shouldn't run to U510 which is switching in AC block.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on June 30, 2016, 04:46:43 pm
I have multiple 1.75v related errors, may be that's why... Or maybe someone tried to correct these errors with this bodge. I just ordered the transformer at Keithley, and new caps and diodes are in. Will remove all caps and chips around them which have oxidation on them and clean thoroughly. The transformer will take 3 weeks to arrive.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 01, 2016, 11:38:23 pm
How much was for transformer. You got from official Tektronix support?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TomThaMan on July 02, 2016, 01:03:37 am
The transformer costs 320(!!) euro shipped. awful lot of money for a simple transformer. Its from Tek. If somebody got a good one for less I'm still happy to hear!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 02, 2016, 01:38:30 am
Yah, that's inline what I heard from others. Yikes. Been there before with HP 3458A transformer (http://www.eevblog.com/forum/repair/repair-old-rusty-hp-3458a/)...  :rant:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on July 03, 2016, 04:03:13 pm
U320.6 is ADBUF+ node, common input of A/D buffer.
It's side of switch which routes 1.75V Reference voltage to ADBUF.
It shouldn't run to U510 which is switching in AC block.


So, I traced the ~1.8V (3 diode drop) 412.1 test signal according to the repair manual to pin 6 of U510 and it should show up on pin 7 through the switch. When my 412.1 test fails pin 7 is always at 0V.
 I cleaned with ISO again around the U5xx chips, re-soldered  U510 and the error went away for a whole day. I ran the automatic test for 24 hrs continuously and it kept passing. Its a little warm here today (room temperature is at 27.56 C and the air coming out of the DMM vent is around 50 C) and guess what the error is back. Wondering if U510 is faulty or some other part after that is pulling the switch output to low.

Excerpt from the repair manual


Test 412.1 – AC amps switch
Cannot measure 1.7V ±0.3V at A/D IN.
The 9.2mA ohms source is turned on to dump current through switch U323 (ACAL
pulled low) to the amps protection diodes (CR305 and CR309). The three diode voltage
drop is routed through U317 (/200uA pulled low), U320 (/ACA pulled low), U510
(REL3 pulled low), U526 and Q516 to the input buffer (Q512 and U520). The buffered
signal is tied to AMP IN.
The signal at AMP IN is then routed to the variable gain amplifier (VGA) and, being
positive, follows the non-inverting x1 path that consists of R530, Q509, Q507, U519,
R531, U509, Q501, and U516 to pin 12 of multiplexer U511.
The output (OUT) of the multiplexer is routed through buffer U342 to ACV/A. The signal
at ACV/A is routed through U320 (/AC pulled low) and applied to the A/D buffer
(U322), which is configured for x1 gain. Measure 1.7V at A/D IN.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 03, 2016, 04:21:13 pm
Try replacing LM339 which drive those switches. I had bad 339's in two out of 6 units before. Also could be your U510 is leaky/flaky.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on July 03, 2016, 05:12:07 pm
Try replacing LM339 which drive those switches. I had bad 339's in two out of 6 units before. Also could be your U510 is leaky/flaky.

Thanks!
Yes, I am about to order some DG211Y s, 411s, and 339s. Its definitely temperature related since the test passes at cold startup.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: pelule on July 03, 2016, 08:22:42 pm
If there is a temperature depending issue, you may search the critical part using coolant spray.
PeLuLe
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on July 09, 2016, 01:34:08 pm
Replaced U510(DG211Y) today. Self-test have been running for 4 hours and passing. I'll keep it running overnight, but looks like a flaky analog switch which was acting up at elevated temperatures was the issue here.
Thanks!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: girish on July 10, 2016, 11:10:00 am
Automatic tests have been passing for 2 :(4+ hrs now. I think the unit is fixed. Now calibration $$$... :(
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Signal32 on July 10, 2016, 04:59:42 pm
Now calibration $$$... :(
What have people been quoted for calibrating a 2001 ?
Also any recommendations for a quiet fan replacement ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on July 28, 2016, 05:04:06 am
for my KEI2001, it was (done by TEKTRONIX / KEITHLEY in Germering, Germany)
Cal & Adjust: 340 EUR
Cal Report: 70 EUR
Pick-up and Bring Sevice via UPS 50 EUR
so, that totals to 460 EUR plus 19% VAT = 547.40 EUR. (insert ring of cash register here).
cal docs consist of two reports: as-received and calibrated, with used assets listed.

for my KEI2002, they quoted cal & adjust 700 EUR (sans VAT)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 28, 2016, 02:27:41 pm
I'd suggest to keep same CFM/speed fan, to keep capacitor life. It also could affect calibration, as temperature condition is important with respect of all parts.
K2002's manual even state that unit need to keep same condition of rear scan-option opening as was during calibration (either covered or open).

Le_Bassiste

Congratz on your cal :) Is yours A08 firmware or B-series?.
Btw, that funny 20 uV range you saw on K2002 during power on, before trigger is not fake, it's lowest range meter can go with K1801 option. ;)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on July 28, 2016, 07:34:11 pm
it's actually this one (http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg650132/#msg650132)   :-DD
so, it's an A08
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 28, 2016, 09:17:45 pm
I was wondering where did the unit end up. Oh well, long live for meter. Would be interesting to know cal data, if you feel sharing.

I might find some testlogs of DCV and OHM tests of it, but that will need effort :(.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on July 29, 2016, 01:03:48 am
here you go... https://xdevs.com/doc/Keithley/2001/K1/cal/KEI2001_CAL.pdf (https://xdevs.com/doc/Keithley/2001/K1/cal/KEI2001_CAL.pdf)

edit:link updated
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on August 04, 2016, 05:14:43 am
Hi,

I got a shipment of new parts from Keithley to complete my 2001 restoration. I bought my unit for $30.00 Canadian. I did the 're-cap and clean' and electrically it is 100%. Now it is time to fix up the outside. I got the meter so cheap I decided to buy new parts from Tektronix. It took about two weeks to get the parts.


New Handle


My unit was missing the handle

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245350;image)

New Rubber Keypad

One of the range arrow keys was broken on mine.

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245352;image)


Metal Case


The metal sleeve was missing.

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245354;image)

Rear Bezel

This part was missing when I got the unit.

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245356;image)

Total Cost around $250.00 delivered to my door.

Regards.

Jay_Diddy_B







Title: Re: Restoration glory of Keithley 2001 DMM
Post by: RobK_NL on August 04, 2016, 06:53:56 am
The transformer costs 320(!!) euro shipped. awful lot of money for a simple transformer. Its from Tek. If somebody got a good one for less I'm still happy to hear!
Only just saw this and jaw dropped. I paid 179 euro last year.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on August 07, 2016, 01:11:11 pm
Hi,

I have to calibrate my Keithley 2001 post fix.

I have good equipment to perform the calibration including:

Fluke 732A
Datron 1281
Fluke 5101 which can be used as source, monitored by the Datron 1281
ESI 4W Resistance standard RS 925


So I am in pretty good shape.

The first step requires a 4 Wire short, using the Keithley 8610. I found this picture of the 8610:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245985;image)


And I have made this artwork:

(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=245987;image)



Does anybody have an original 8610 or know what the other side of the board looks like?

I have read the Fluke white paper that says a low thermal mass is better.

Link: http://us.flukecal.com/literature/electrical-calibration/watch-out-those-thermoelectric-voltages-cal-lab-journal-reprint (http://us.flukecal.com/literature/electrical-calibration/watch-out-those-thermoelectric-voltages-cal-lab-journal-reprint)

Thanks !!

Jay_Diddy_B
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: saturnin on August 07, 2016, 09:26:31 pm
I bought 4-wire short from Fluke: 884X-Short (http://www.newark.com/fluke/884x-short/4-wire-short/dp/55M2652 (http://www.newark.com/fluke/884x-short/4-wire-short/dp/55M2652)). It is nearly identical design to Keithley 8610. There is nothing particularly interesting on the other side :)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: hugo on August 07, 2016, 09:59:23 pm
Quote
I bought my unit for $30.00 Canadian.

I thought the bottom price is 300 USD for an used and abused Keithley 2001 ... congrats to you :clap:
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on August 07, 2016, 11:19:41 pm
If one is patient, it's sometimes possible to get them for 100-200$ abused with missing parts.  :-DD

Seems it's a calibration week for everyone, don't mind if I join too? :)

(https://xdevs.com/doc/Keithley/2001/keis_1.jpg)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Jay_Diddy_B on August 08, 2016, 07:38:42 am
I bought 4-wire short from Fluke: 884X-Short (http://www.newark.com/fluke/884x-short/4-wire-short/dp/55M2652 (http://www.newark.com/fluke/884x-short/4-wire-short/dp/55M2652)). It is nearly identical design to Keithley 8610. There is nothing particularly interesting on the other side :)

Thank you for taking the time to post the pictures.

Regards,

Jay_Diddy_B
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on August 08, 2016, 07:53:38 am
If one is patient, it's sometimes possible to get them for 100-200$ abused with missing parts.  :-DD

Seems it's a calibration week for everyone, don't mind if I join too? :)

Seems you'll never really know what the real voltage is...    >:D >:D >:D
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on August 09, 2016, 11:11:33 pm
but now you know that "42" was just part of the correct answer! :-DD
(to a voltnut, that is)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on September 11, 2016, 04:23:09 am
Hi,

recently I managed to grab 2001 for parts/repair really cheaply. It seems the unit had a long history, manufactured around 1992, A06 firmware, RevK analog board and RevJ digital. Someone already replaced most of the caps on the analog board around 2004/2007 (these were the dates on the caps). I replaced some of them anyway and replaced all on the digital board (these were original and leaking a bit). All the power rails seem OK.

However, my problem is with the ADC board. It is also unusual - it seems Keithley didn't have 7.68 MHz oscillator, so they developed a 2001-132-02A mini board with XTAL, HCU04 & misc to generate the clock. It was failing all the 200.x tests and in consequence some other tests as well.

I've checked the front end switches and muxes and these seemed to work ok, providing on AD_IN 0V, 7V, 10V or 1.75V*5 in various diagnostic modes. Then I noticed that R857 (sits between -15V and NE5534) is damaged, it got burned pretty badly, leaving tar on the PCB and came off the PCB in two parts. I replaced that with a new 100 Ohms and hoped that was the problem, but unfortunately no :( I did some more probing, checked Q806 (as this was the issue for ManateeMafia) etc, and then I must have slipped the probe perhaps (I don't see any other explanation), because the Altera CPLD no longer works. It receives clock and data on SCLK/DATA_IN but DATA_OUT remains silent. Now built-in tests hang on 200.x.

I know it's a long shot, but maybe one of the forum members has a spare 2001 ADC board they could part with (for a reasonable price)?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 18, 2016, 07:11:54 pm
Preparing some 2001 for upcoming sale out  ;)

Initial calibration and check on 10V from Time 9823 MFC.

(https://xdevs.com/doc/Keithley/2001/cal2001_2.png)

Guardband - Both K2002's and 3458A down below, absolute tolerance +/-1.5ppm (Both 2002 calibrated 25/08/2016 versus <30day 732B).
Blue charts - 3 different K2001's.
Dashed brown line - ambient temperature.

Clearly visible ADC performance difference between different league meters  :-DMM
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on September 18, 2016, 09:25:11 pm
Wow those 2002s play in a different league. How does the 2000 hold up against the 2001 ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on September 18, 2016, 10:49:39 pm
I don't have 2000 anymore, it found a new home while ago :)

But I had similar 10V test on 2002+2000+3458 before. Datalog here (https://xdevs.com/time10_k2k/).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: maxwell3e10 on October 04, 2016, 02:10:41 pm
I have a K2001 that at some point started to show "Overflow ADC" on all ranges and functions. On xdevs I found Illya mentioned replacing U315 optocoupler to fix this. Should I check something else before trying to get this chip?

I have an old TLP582 optocoupler on my board in a large package. It seems one can also get them in a DIP-5 package. Would that be OK?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: maxwell3e10 on October 05, 2016, 06:30:39 am
I found another Keithley 2001 to swap the ADC card with and it is the problem with the ADC card, not opto-couplers.

My ADC card has digital signals coming in and out on most pins, so its not dead.
I don't know what the digital data should look like, though. For example DATA_OUT looks a little erratic, not a clear serial pattern.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: kada on October 09, 2016, 12:38:55 am

SKE encountered with the same errors:
Self test reported these error codes:
200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference
Did you find a solution?

I'm sorry for delayed report, the solution (TiN, you was right  :-+) was to update firmware to A08 and I don't have these errors anymore.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: AF6LJ on October 13, 2016, 05:46:11 am
This has been a cool project to follow   :-+ :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 13, 2016, 11:27:45 pm
My 2001 have this problem ,I donot know how to fix it???
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Signal32 on October 13, 2016, 11:29:27 pm
My 2001 have this problem ,I donot know how to fix it???
The err indicator is on ... is the front panel working ? Navigate to the list of errors and tell us what they are.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 13, 2016, 11:34:36 pm
My 2001 have this problem ,I donot know how to fix it???
The err indicator is on ... is the front panel working ? Navigate to the list of errors and tell us what they are.
Error ID=513  AC calibration data lost.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Signal32 on October 13, 2016, 11:40:19 pm
Is that the only error or are there more ? Use <  > to switch between them.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 13, 2016, 11:47:59 pm
Is that the only error or are there more ? Use <  > to switch between them.
This error is not the built-in test error.when the power on ,it will show this error and then turn to the display page like the first picture. This problem can not run built-in test.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 14, 2016, 12:29:45 am
Just run AC calibration. It does not need any external equipment.
Do you have any other errors from self-test?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 14, 2016, 02:08:59 am
Just run AC calibration. It does not need any external equipment.
Do you have any other errors from self-test?
Thank you ,I will run AC calibration later .but now the 2001 have a big problem ,the panel display  "-------" ,like my first picture,when i run self-test the 2001 will crash, i must reboot it . 
the +5V ,+15V ,-15V ,+38V ,-38V is OK.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 14, 2016, 02:28:35 am
?rash? What you mean by crash?
If its turns off or hangs, turn the unit immediately off and read this thread from the first post :)

------- is default state if measurements system is not armed and waiting for trigger.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 14, 2016, 03:00:34 am
This 2001 made in 1993 or 1994.
I have read your blog,i have replace all electrolytic capacitors ,except the 15000UF/16v.
I replace the LM311,NE555 and fix the power problem.
The crash means the display have no changes when i press any keys. Always display -------,How to jump out this status? Thanks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 14, 2016, 03:06:02 am
Even MENU button?
Is there any electrolyte on the boards or trace damage?
What is digital 5V voltage on digital board?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 14, 2016, 10:17:51 pm
The MENU button is ok.
There is a little  electrolyte ,i have clean it ,no trace damage.
digital board 5V is OK.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 14, 2016, 10:31:55 pm
How about self-test result then? :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 14, 2016, 10:59:12 pm
Sometimes when the power on,the "ARM" will show on the top ,i can run self-test ,the result is ERR 200.2 ,200.3.
 sometimes i reboot it ,the "ARM" will not show there,the display always "-------",the self-test can not run finished ,the display will stop at any page,then all the buttons are not work.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 14, 2016, 11:03:18 pm
Check your digital board or/and transformer and mains circuitry. Processor feeling sick, hence the hangs and communication errors (200.x)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 14, 2016, 11:21:58 pm
Thanks ,i will check it .
Is it necessary to replace the 15000uf/16v on the digital board ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on October 14, 2016, 11:45:23 pm
This may sound like a very stupid suggestion, but is there any chance that the trigger (or some other) button on the front panel is jammed on? I had a very similar "facepalm inducing" repair a few months back (not on a Keithley though).

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on October 15, 2016, 01:10:43 am
This may sound like a very stupid suggestion, but is there any chance that the trigger (or some other) button on the front panel is jammed on? I had a very similar "facepalm inducing" repair a few months back (not on a Keithley though).

McBryce.

Thanks,I check it already when this problem happened. :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Le_Bassiste on October 15, 2016, 02:36:16 am
Sometimes when the power on,the "ARM" will show on the top ,i can run self-test ,the result is ERR 200.2 ,200.3.
 sometimes i reboot it ,the "ARM" will not show there,the display always "-------",the self-test can not run finished ,the display will stop at any page,then all the buttons are not work.

i have one KEI2001 that had similar symptoms like yours: on cold-start (meaning that it was _cold_ on start-up, left off for a day or so), it came up with standard boot screen but then repeatedly ran into and out of DC OVERVOLTAGE, although range was set to AUTO and inputs shorted. on top of that, REAR annunciator was blinking with slow and irregular patterns. of course, self tests failed with similar results like yours did. these symptoms went away after about 10 mins of warm-up, and then the meter worked fine. 
ribbon cable that connects digital and analog board had flakey contact inside the connector on analog board. replaced connector with 0.100" 20pin two-row male header and made completely new cable. all good now.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on October 15, 2016, 12:10:21 pm
Good point from Le_Bassiste! Could be very possible, as that cable is the only interface between digital brains and analog world. Optocouplers near cable are another component worth checking.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on October 23, 2016, 04:22:12 am
Finally, I managed to repair my 2001, I think.

My meter had most of 200.x and 200.1 errors. Leaky old caps on the digital board (replaced) and somebody replaced the caps on the analog board around 2004-2007 (replaced those as well and the fan too). All the supplies seemed ok, but the errors were still there.

I found that resistors through which +-15V is supplied to the NE5534 on the ADC board are broken. One burned badly, leaving tar on the PCB, second one failed on high resistance/open. Replaced these resistors as well.

I've tried running comprehensive calibration, but it failed during open inputs step with error 354 = "200 mV offset out of spec". Then I've started chasing red herrings, replaced diodes in the power section, replaced the shift registers, some of the DG switches, NE5534 on the ADC board, desoldered the optoisolators and tested them on a protoboard - nothing helped. After all this messing around things got even worse and a dozens of new errors appeared.

But with TiNs help and some legal tender I got a new ADC board. With that I was able to run the calibration procedure with some poor artifacts (linear psu, 20k and 1M from a DIY decade). Things improved massively and I was only left with the errors that kada and SKE had: 200.1, 200.6, 200.7, 201.2 and turns out these can be fixed with upgrade to A08 (from A06). So once I got an UVC lamp (only had UVB) and a special PLCC44 adapter (the one I got with TL866 didn't work with 27C4096) I've upgraded the firmware and self tests passed.

I've started measuring some resistors that TiN kindly gave me, along with measurements from his 3458A, and I've noticed completely bonkers measurements on the megaohm ranges.

Now I wanted to improve things a bit, peroxide treatment (but the 25 year old paint on the display lens didn't survive kapton tape :/) worked nicely and while I was going to order DS1245 for MEM2 option I've ordered slightly better calibration artifacts, because I don't have anything top notch yet (multi-LM399 or LTZ1000) from Farnell: Y006220K0000T9L (20K 0.01 1 vishay-ppm/C), PTF651M0000BZEK (1M 5ppm/C), two ADR01BRZ to put in series and LT5400BCMS8E-8 9K/1K divider to divide ~20V to 2V.

And with these the calibration failed! Error 385, 20 MOhm 2W gain out of spec. High ohm resistors are a nuisance so I figured out that my soldering spree panic on the analog board left a mess affecting ohms current sources. After cleaning everything under a microscope, every guard trace, resistor cases, with dozens of cotton swabs and isopropanol the calibration worked!  :-+ I could even measure 1GOhm resistor.

(https://s22.postimg.org/gldokplap/k2001.jpg)

Important lesson here is that self-test depends heavily on the calibration constants (which may be wrong or corrupted) and even these elaborate self-tests don't test everything that comprehensive calibration procedure tests. I still wonder what killed the resistors on the ADC board and worry that there might be something more wrong (a lot of the stuff is connected to +-15V rails).

I calibrated K2001 against my 3457A, as it seems most stable and extremely well aged (this one was closest to the resistance measurements done by TiN). Also, I really like this meter as it has most functions quickly available from the front panel, has offset compensation, 3 GOhm range, some autocalibration, no VFD but then I don't have to worry and it often runs 24/7 (also no fan) and does 7 digits in math mode - averaging. Unfortunately, it is not otherwise volt-nut friendly due to 3V front end arrangement. Transfer accuracy from a multimeter to a multimeter using some random voltage references wasn't that great, but none of my meters are calibrated anyway, it was more of a sanity check. Funny thing, when the GPIB cable is connected I get 104.1 error (GPIB handshake) but GPIB seems to work otherwise (well just *IDN? from ibtest, need to test more, luckily I have some NAT9914 chips at hand).

Now the meter occupied the last available space on my workbench and I want to build a more stable reference (multi-LM399 or maybe LTZ1000) and check how stable the meter is, drift, tempco maybe, etc. I also need to test some other functions (AC, current) more in depth to double check if there are no surprises that self-tests don't catch. Performance verification, even basic one, of such meter is definitely not an easy task.

(https://s17.postimg.org/6ultnnn9b/mylab.jpg)

Then if it turns out it is roughly OK I'll have to probably calibrate (low level calibration) this meter. I don't feel like spending more on the calibration than on the meter, also Tektronix has been annoying me for a long time, either once I wanted to buy 2000 benchkit parts and they gave me silly lead times, or other times I had to create an account there, as I was downloading TLA stuff or I wanted to download a datasheet for an SMD oscilloscope probe that I got off ebay. It was enough to trigger their marketing department and I started getting annoying phone calls. Now they stopped calling, but I still get emails telling me to buy TBS2000 or other crap - they seem really desperate. Anyway I couldn't even find UKAS Schedule of Accreditation for Tektronix (not that I need certificates, I was just curious on the DC 10V specs, Keysight UK has 0.8ppm). I'll ask RS Calibration for a quote. On their price list it says 62 GBP for a bench meter. They might not do 7.5 digit, but at least they could transfer whatever they have currently in their Fluke calibrator - better than nothing. I hope they have GPIB scripts for K2001.

Overall, I quite like this meter. Maybe not as much as 3457A, as I have to go through multiple menus and the average display from readings stored in a buffer are using engineering notation with only 4 digits after the decimal point, but on the positive side it has big VFD, sensible ranges with GOhm impedance up to 20V, thermocouples and similarly to 3457A offset compensation as well as scanner card option.

I would like to thank the forum members for helpful posts here and TiN in particular for providing me the ADC board, as well as putting a lot of effort on writing articles about his repair adventures - it probably takes as much time to write and take pictures as it takes to repair some things.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on November 03, 2016, 03:38:34 pm
How about credit where credit is due? I mentioned this technique in TiN's K2000 thread here (http://www.eevblog.com/forum/repair/repair-old-keithley-2000-teardown-and-fix/msg934047/#msg934047). I came up with this crazy idea one day, decided to try it on a Keithley 199, and it worked like a charm. I am certain that I am not the first to do this but I hadn't heard of anyone doing it.

Received an Agilent device today with an extreme dent in the front face - very extreme! I've used heat before to form plastic and it has worked so/so. Thought I'd give it a go tonight when I remembered this thread.
I think it turned out very good. The heat was probably a little bit high from my heatgun but there was never a chance to make it look 100% original. The main goal was to get it back into shape so that when a rubber boot was put on it was completely hidden. With the original dent it was very obvious and looked terrible even with a rubber boot in place.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 03, 2016, 07:58:55 pm
Thanks lukier! Congrats!

One day I will write a post like you, my K2001 is still under my bench  |O .

A couple of little questions...

the one I got with TL866 didn't work with 27C4096

Why? Not fitting well... made in China crap?

but the 25 year old paint on the display lens didn't survive kapton tape :/

So the kapton tape peeled the paint off?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on November 03, 2016, 08:22:32 pm
Why? Not fitting well... made in China crap?

No, different routing of pins and AFAIR TL866 software doesn't support 27C4096 in PLCC44 packages, just DIP40. So to mimick DIP40 one needs adapter like this:

http://www.ebay.co.uk/itm/111553438268 (http://www.ebay.co.uk/itm/111553438268)

So the kapton tape peeled the paint off?

Yup. Maybe I should've ignored that and just apply peroxide without worrying about the paint. I think the display lens can be removed entirely as well.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 03, 2016, 08:57:05 pm
Ok, getting ready for my sick puppy.

Tamiya Extra Thin Cement - Ordered
12% Peroxide - Ordered

It will be a long journey... my K2001 was used in Canada to monitor the liquid temperature in a wine production process. It passed all the self checks... but there will be some surprise inside... if only my day would have 48 hours...

I think the display lens can be removed entirely as well.


I´ll try that... like macboy did

http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg937701/#msg937701 (http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg937701/#msg937701)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 04, 2016, 12:18:45 am
So yesterday I was testing my new DB62 decade resistor and after many hours of switching and tests I found it maybe still in spec.
It was a maybe because I wasn't able to test the 100K Ohm and 1M Ohm with my K2001.

After two years of using it I found repair job I made two years ago wasn't complete because it still has a problem with high range resistance measurements. The problem seems affecting all Ohm ranges, but it became significant at 200K Ohm range, getting worse at 2M ohm, culminating with almost not working at 20M, 200M and G Ohm.

I noticed multimeter was out of specs in some Ohm ranges one year ago when I was testing my 100K Ohm 0.005% Vishay "standard resistor", but because I really never used this high Ohm ranges I never had a chance to realise it was so bad.

Initial diagnosis:

  - seems not a leakage problem, in G Ohm I can read OL
  - self test always passes with no error

First things to do is check current source circuit and all relevant analogue switching stuff. Most probably is one switch gone bad.
Actually digging in schematics and self test description ... to get a clue how Ohm measurement circuits works.
Seems I win a new repair for free.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 04, 2016, 12:24:21 am
mimmus78, self tests no problems right?

And with these the calibration failed! Error 385, 20 MOhm 2W gain out of spec. High ohm resistors are a nuisance so I figured out that my soldering spree panic on the analog board left a mess affecting ohms current sources. After cleaning everything under a microscope, every guard trace, resistor cases, with dozens of cotton swabs and isopropanol the calibration worked!  :-+ I could even measure 1GOhm resistor.

is your board clean?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Alex Nikitin on November 04, 2016, 12:42:13 am
Initial diagnosis:

  - seems not a leakage problem, in G Ohm I can read OL
  - self test always passes with no error

First things to do is check current source circuit and all relevant analogue switching stuff. Most probably is one switch gone bad.


I would first check the input current on DC Volts (10V and below) - leaky JFETs (protection and switching) would create a problem on DCV and OHM inputs.

Cheers

Alex
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 04, 2016, 02:16:11 am
>> is your board clean?
>> I would first check the input current on DC Volts (10V and below) - leaky JFETs (protection and switching) would create a problem on DCV and OHM inputs.

I did a small repair on this meter, one analogue switch involved in current measurement was half working. The culprit was found on 20 minutes investigation, the component easily replaced and all cleaned with IPA.
I'm sure I didn't contaminated it, but who knows what did previous owner!?

I remember there was also a bodged mod on some JFET (Q550) that probably was made by previous owner. I posted a photo here few years ago of this bodge, but at this time there wasn't public available schematics so I wasn't able to speculate for what it was done.
Maybe it is some goofy attempt to repair the meter made by by previous owner for the same failure I fixed.

I can see some noise starting at 10K and it really show up at 100K, don't think contamination can have this high effect at this "low" Ohm levels.
10V is 11PPM away from another K2000 since two years. Noise at 10V is as specs and comparable with noise of other K2001s owned by other members here.
I used 100mV some time but I do not remember problems there.

Think I have enough stuff to work out for now ... and as usual any suggestion is appreciated.
I'll keep you all "K2001 aficionados" updated.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 04, 2016, 07:29:52 am
So this the bodge ... I checked with microscope and I can see some glue on the wire. At least it's seems some "definite" modification and not a temporary attempt.

Also 100mV range is clean.

(http://uploads.tapatalk-cdn.com/20161103/f3eb210dbc3237673f97443261799456.jpg)

Inviato dal mio Nexus 6P utilizzando Tapatalk

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on November 06, 2016, 01:23:14 am
I got my meter warmed up, so I've decided to measure the Ohms current sources. Maybe someone will find that useful or other users with more reliable K2001's than my still-uncertain-recently-repaired one can provide their own data.

I've used Keithley 485 Picoammeter for all ranges except 20 Ohm, where it is out of range of K485 so I've used 3457A in the current range.

Ohms RangesCurrent
20 Ohm~ 9mA
200 Ohm, 2 KOhm0.981 mA
20 kOhm89.3 uA
200 kOhm7.09 uA
2 MOhm772.7 nA
20 MOhm70.72 nA
200 MOhm, 1 GOhm4.394 nA

Keithley 2001-TCSCAN manual, in the calibration section (page 4-10) mentions that on the 200 kOhm range the sourcing current is 7 uA, so at least in this range my meter seems OK.

I've tried to measure the input bias current on the DC Volts low ranges, but it is well below my K485 sensitivity and measurement setup (BNC cable with a BNC to Banana adapter, no triax). Similary, I've tried connecting 1 GOhm resistor to K2001 on the DC range (200 mV) and the readings are just jumping around between -70 mV to +20 mV.  :-//
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 06, 2016, 09:22:24 am
So situation kinda getting worse.

Now self test always give me errors 304.6 and 306.7.

Sometimes also lower tests up to 304.3 give me some errors, but this depends on humour of the multimeter (maybe some part gets hot).

I figured out I have some leakage somewhere, here is what I found when running test 304.3.

(http://uploads.tapatalk-cdn.com/20161105/a8d832e4619c7f71800b3eb310a92f08.jpg)

This error give me just time to take a note because now 304.3, 304.4, 304.5 are working again.

So I made some analysing the circuit and I was almost sure my leakage was caused by one of this Q320, Q312 or Q324.

I removed all three fets, replaced Q324 with a 30ohm resistor between source and drain and by running test 304.6 I demonstrated I was wrong and leakage is still there.

Will continue investigation tomorrow ... if anyone have any idea how to solve this puzzle, I will appreciate.

Domenico

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 06, 2016, 09:29:11 am
I propose replace shift registers 14094 and all analog switches (DG411/DG404/DG211). It is much faster than troubleshooting these failures.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 06, 2016, 10:40:23 am
Yes plesa: I'm starting thinking to brute force attack too ...

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 06, 2016, 10:45:51 am
Yes plesa: I'm starting thinking to brute force attack too ...

Inviato dal mio Nexus 6P utilizzando Tapatalk

It is not brute attack, the components are cheap and it is more efficient to replace them all. It is difficult to find where leakage is.
Keithley also repair multimeters this way. They will replace few components and in case it does not help you will receive discount on new meter :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 07, 2016, 07:09:16 am
Gotcha! Test 304.6 was ok without U325 ... little bastard!

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 07, 2016, 07:48:29 am
Gotcha! Test 304.6 was ok without U325 ... little bastard!

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Replace them all, it is really worthwhile. It needs to be calibrate again anyway.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 07, 2016, 07:55:05 am
Seems nobody in Europe has stock!
Ebay or get from USA?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 07, 2016, 08:15:07 am
Seems nobody in Europe has stock!
Ebay or get from USA?
wait what you want to replace?
DG411 and shift register MC14052 Farnell has on stock.
If you needs something special drop me PM, I will check my local inventory for Keithley repairs :)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on November 07, 2016, 08:30:57 am
Seems nobody in Europe has stock!

What about Farnell?
http://uk.farnell.com/on-semiconductor/mc14052bdg/4000-cmos-smd-4052-soic16-15v/dp/9666419 (http://uk.farnell.com/on-semiconductor/mc14052bdg/4000-cmos-smd-4052-soic16-15v/dp/9666419)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 07, 2016, 08:43:47 am
I need MC14052BCP in DIP 16 package.

It was not ROHS part, so nobody use here Europe anymore.

I asked some eBay guy if he is sure parts he sells is genuine ... let see tomorrow what will reply.

Anyway if you have this part, we can arrange something.

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on November 07, 2016, 08:57:33 am
You could likely get away with an CD4052B part. It might be slightly different parameters but most of them overlap and speed should not really matter.  This one is available, e.g from tme.eu.

One might have to select for low leakage samples: typical values are good, but worst case performance is likely not good enough.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 07, 2016, 09:02:11 am
I need MC14052BCP in DIP 16 package.

It was not ROHS part, so nobody use here Europe anymore.

I asked some eBay guy if he is sure parts he sells is genuine ... let see tomorrow what will reply.

Anyway if you have this part, we can arrange something.

Inviato dal mio Nexus 6P utilizzando Tapatalk

http://se.farnell.com/texas-instruments/cd4052be/ic-mux-demux-4ch-4052/dp/9589538 (http://se.farnell.com/texas-instruments/cd4052be/ic-mux-demux-4ch-4052/dp/9589538)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 2N3055 on November 07, 2016, 09:48:35 am
RS has CD4052BEE4 ... RS cat no : 121-9243

it might have a bit better leakage... they are cheap, maybe buy few and sort the best ones...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 07, 2016, 10:33:28 pm
Ti CD405xB seems to be OK, but compared to original Motorola part it has is far less flat in R(on) response ... because this IC is part of the resistance measurement I think R(on) flatness if very important.
So or I stick with Motorola part or I need to check if this R(on) flatness is really important there.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 2N3055 on November 07, 2016, 11:19:37 pm
I think they are in high impedance path switching ranges...
 But whatever you do change BOTH 4052 to have same type... Looking at the schematics, it looks like they are balancing them both...... So having two 4052 of the same type, manufacturer might help...

Now you made me curious...  I'm gonna look into circuit a bit more later....

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 08, 2016, 02:12:28 am
Got 15 items from a DE ebay seller I hope they arrive in reasonable time ... I found this part is also classified as military part with export restriction.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 12, 2016, 06:33:26 am
Got 15 items from a DE ebay seller I hope they arrive in reasonable time ... I found this part is also classified as military part with export restriction.

The waiting for parts is killing me ... really tempted to go to local electronic parts store and slap in a 4052 or whatever compatible one.

Anyway specs are 30ppm for lowest ohm ranges so I think they are calibrated out some way.

There is ohmcal signal going to ADC ... and it's just before switch, I think this is used to calibrate out switch resistance.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 12, 2016, 06:40:15 pm
Huh, I remember there were some posts talking about LTZ1000 upgrade on K2001, which I wanted to comment on, but they are not here anymore?
Or it was other thread? Yup, it's here! (http://www.eevblog.com/forum/testgear/do-i-have-exceptional-keithley-2000-or-poor-keithley-2001/msg1061443/#msg1061443)  :palm: :phew:

I'll be opening one of 2001s soon, could try some stuff!  >:D

K2002 btw using MAX326 (https://www.maximintegrated.com/en/products/analog/analog-switches-multiplexers/MAX326.html) ultra-low leakage switches for current source switching instead. They are available in DIP too, but I didn't check if pinout differs.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on November 12, 2016, 08:19:01 pm
The max326 likely has a different pinout, but there is an mx4052 as an direct, better specs  replacement for the cheap CD4052 / MC14052.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 12, 2016, 11:55:19 pm
I'll be opening one of 2001s soon, could try some stuff!  >:D

Can't wait to read about Doctor TiN taking care of his K2001 patient!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 12, 2016, 11:57:28 pm
All four my patients are actually healthy. I just got lured by that LTZ talk...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 13, 2016, 01:20:05 am
Kleinstein: maybe max4052a?

Don't know Motorola is still more flat/linear on Ron vs Vcom and temperature variance.

Because value of this Ron must be calibrated out I speculate this factor maybe important to be as constant as possible or you may introduce more noise in the measurement.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: lukier on November 13, 2016, 01:23:55 am
Another weekend, so more measurements of K2001 for reference. This time input resistance on 20V and 200mV ranges.

I've used the voltage divider method with this 1 GOhm resistor in series with a TTI DC linear PSU:
http://uk.farnell.com/ohmite/sm104031007fe/resistor-10kv-1-gig-1/dp/1550776 (http://uk.farnell.com/ohmite/sm104031007fe/resistor-10kv-1-gig-1/dp/1550776)

Measured as: 996.2889 MOhm. Meter set to DC, 10 NPLC, AZ, LINESYNC. I've used two voltage measurements, one random instantaneous reading and a mean of 100 samples in a buffer (but K2001 reports that with limited precision).
V1 = voltage from the PSU, V2 with 1 GOhm resistor in series to form a voltage divider with the multimeter.

RangeV1 [V]V2 [V]R [GOhm]
20V10.0025189.989635772
20V10.00009.99471878
200mV0.199932020.1791151028.572
200mV0.199900.179368.699

I'm a bit worried about the 200mV range, as it is slightly under 10 GOhms and Keithley specifies > 10 GOhm on all low ranges. Maybe this is due to my poor measurement setup (normal banana test leads, although I've cleaned the resistor with isopropanol before taking measurements).

In the next episode I want to run TiN's DMM noise tests, but for that I need to prepare my GPIB setup and rewrite EZGPIB scripts into Python + linux-gpib.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on November 13, 2016, 03:31:22 am
The max4052 is specified at much lower R_On, 60 Ohms compared to around 600 Ohms for the MC14052. Thus resistance variations are also much lower. Still the specified leakage is lower. It is just the max4952 is a dedicated high quality switch, whereas the MOS4052 is a cheap part from the logic part family. So the price is something like 10 times as high). Getting a dip version might be difficult though.

For the input resistance, one should treat the input current more like a bias current that is slightly voltage dependent. So even with no external voltage one would see an input current. Depending on the individual instrument and temperature the current can be different. The relationship is often also nonlinear: like low current in the +-15 V range and increasing close the the ends of the range.

Having a 20 mV drop on the 1 G resistor is an input bias current in the 20 pA range - this a good value.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on November 19, 2016, 08:52:38 am
If you want new VFD for Keithley 200x/24xx/26xx/700x send me PM (price will be about $100).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 20, 2016, 10:33:23 am
It seems I finished repair of my K2001, ohm ranges are now all "working" even if now calibration of ohm ranges is upset.

At the end I replaced the Motorola MC14052 with same part from ON (datasheet was exact copy of the Motorola one).
With this new part I have no more leakages at any range and self test passed without any error.
I tested all high ranges up to G ohm with a 10M resistor and all ranges seems few counts from each other.

I compared ohm measurement noise of this meter with the K2000 and I noticed something strange to me.
I know this meter is more nosier than K2000, but comparing both meters in the same condition my K2001 is much noisier that the cheaper brother.

I'm testing both meters in the same conditions:

 - 1M ohm metal film resistor stick directly in multimeter by using TiN method (cotton buds)
 - 10 NPLC
 - no filter
 - range 2M (1M for K2000)
 - 2 hours meter warm up
 - 10 minutes wait time after you stick the resistor to the meter

K2000 stabilise immediately and all measured values are at maximum of 1 PPM apart (1 count).
K2001 have average jumps of 5PPM and occasionally it jumps of 10PPM (50 to 100 counts).

Does it looks normal? Maybe we need to send current source op amp into retirement too.

Anyway the strange thing is that the lower ranges are much better. For example 10K resistor at 20K range has only 3 to 5 digit jumps (that is 0.5 ppm).
This is the same ppm noise specified for the 10V range, that is also as best as you can go.
Also if you measure low ohm (10K or 100K) values in high ohm ranges noise calm down.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 2N3055 on November 20, 2016, 10:43:33 am
ON Semi  IS Motorola... It is spin of old Motorola semiconductor division... Processor division was spun off as Freescale...

Good to hear it works now!!

K2001 being noisier than K2000 seems to be a fact.. I don't remember details, search for a topic exactly about that here on forum..
It seems to be normal behaviour, or at least common behaviour.. I think you might contribute to discussion there..

Buona notte Mimmi!!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 20, 2016, 10:59:27 am
Quote from: 2N3055 on Today at 10:43:33 (http://www.eevblog.com/forum/index.php?topic=21117.msg1074339#msg1074339)

K2001 being noisier than K2000 seems to be a fact.. I don't remember details, search for a topic exactly about that here on forum..
It seems to be normal behaviour, or at least common behaviour.. I think you might contribute to discussion there..
I know it's noisier I also made a direct comparison of the twos (check below) but still seems too much in this case.
I will appreciate if someone can make a test in the same conditions. I have to decide if to send it for calibration or continue the troubleshooting ...












(http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/?action=dlattach;attach=271777)

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on November 20, 2016, 11:38:55 pm
For comparison I would do the measurements without filter - there can be different types of filters and one might end up getting unfiltered number via GPIB while filtered data are shown.

The Ohms ranges of the K2001 might have a slight design flaw: using the LM399 for the current source, but the zener reference for the ADC. The Ohms circuit also is quite complicated and I don't really understand it, but it does not look really low noise with quite high resistors, and not that much voltage at the current setting resistors. It looks more like made to also provide the very high resistance ranges, but compromising on the rest. So a relatively high noise level for the Ohms ranges might be normal. It could also be different for the low range like 1 K and high ranges like 1 M.

It would really make sense to have comparison data, before trying to fix something that is not broken, but just a poor design.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 21, 2016, 12:13:50 am


As I get "normal" noise with low value resistors also on high ohm ranges  I think this is normal ... So I will not touch again unless I'm sure there is really a problem.

The real surprise is how better is K2000  vs K2001 on noise. Wondering if LTZ1000 experiment will be more appropriate with this meter than K2001.

Change reference, change ohm circuit reference resistors, change current shunts (AC to DC chip is the same) and you will have a hell of multimeter.

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 21, 2016, 03:49:24 am
I have opening for "free" sampling hours next week, as will be doing other stuff, and can plonk 2002, few 2001s and 3458 to measure same batch resistors over next days for comparison.

Just tell me ranges you want to compare and settings. NPLC 10, no filter, 4W with AZ I assume?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 21, 2016, 08:59:18 pm
Hi TiN I made those checks:

All test run for 30 minutes at least, sampling as fast as I can (1 sample every 2 seconds circa with this settings), meter was on for some hours.

Workflow:

I think it will be useful to investigate also voltage drop noise on resistor with oscilloscope during measurement.
I kinda find something weird yesterday when I was checking resistor voltage drop with multimeter but didn't have time to investigate if is measurement process artefact or if is really noise.

I've attached here charts and ods files with raw data (open office spreadsheet file format).
I noticed that once you look at noise in ppm of range it became not that bad ...
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 23, 2016, 03:13:51 pm
I don't have enough 1M resistors to do so, so let's start with DCV first to set the minimum noise level floor.

Added some datalog data over meters (2x2001, 2x2002, 3458) to compare into DMM noise thread. Here's the link (http://www.eevblog.com/forum/metrology/dmm-adc-noise-comparison-testing-project/msg1076570/#msg1076570).

Results so far:

3458A : <1.2 uV noise ~0.12 ppm/range
2002-4 : <2.5 uV noise ~0.125 ppm/range
2002-6 : <2.5 uV noise ~0.125 ppm/range
2001-20 : <15 uV noise ~0.75 ppm/range
2001-21 : <22 uV noise ~1.1 ppm/range
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 24, 2016, 04:03:58 pm
(https://xdevs.com/doc/xDevs.com/dmms_noise2.png)

2001-22 at the end of the graph. Obviously it's sick with noise >3ppm/range and wild jumps.

One thing I was thinking about A/D noise of 2001, perhaps one can try using lower noise zener on ADC board. For example chinese 2DW232?  ;)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 24, 2016, 07:19:10 pm
One thing I was thinking about A/D noise of 2001, perhaps one can try using lower noise zener on ADC board. For example chinese 2DW232?  ;)

Hi my friend...

If you have one why not?  >:D Just replace the VR801 and ready to go... may be fine tuning on the bias current (R854 value) but yeah piece of cake.

What I don' t like in the K2001 design is that has a separated ADC VREF (not using the LM399 one) and moreover this one is setting also the bias current on the LM399 --> Why this is not the case in the K2000? And also in the K2002 (I could be wrong here.. just did 5 min investigation...)? ... so why only the K2001 is ADC noisy and there other two look good? mmmm

Just to confirm I have the right understanding (hope to be right):
VR801, 2DW232 are short time references: they don't jump but they drifts slowly in the long period ("worst" TC).
LM399 or  LTZ are long time references: they could have a pop corn noise (ppm jumping) but in average they are solid constant in the long period (better TC).

On the side, not ADC related, U328 AD707 (OPAMP for current bias on the LM399) why not replace it with something new? Didn`t check to much but it seems there are better OPAMPs out there pin to pin compatible. Are there other pin to pin compatible better devices replacement which could improve the references circuits?

Just writing straight off my brain.. sorry to all if I dropped something very stupid here, I have so much respect for all of you dragons thanks for reading this.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 24, 2016, 07:49:34 pm
K2002 ADC is very different to 2001's, and using lower voltage or *1.5x LTZ reference (from LT1043 flying cap blocks).
For 2001 you are pretty right, with autozero enabled 2001 measures LTZ ref, then signal, then zero reference, and based on these calculate the measurement reading. So stability of VR801 not need to be any special, as whole cycle is fast. There is also switching block to provide higher than 7V reference voltages.

Maybe Keithley was trying to get better long-term stability out of LM399 (to keep it still yet cost-effective 7.5d meter), and hence designed all this thing. On 2002 there was no such constrain, hence much more expensive LTZ1000 circuit and different ADC topology.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 24, 2016, 10:58:05 pm
So stability of VR801 not need to be any special, as whole cycle is fast.

Even more, according to here

(http://www.eevblog.com/forum/metrology/diy-low-frenquency-noise-meter/?action=dlattach;attach=225203;image)

the magic 2DW23x is even better than the holy LTZ1000, so my plan to put a LTZ1000 there is just blown in the wind...

Ok, who will be the first to test a 2DW23x there? If nobody shows up I raise my hand... it will take time since I do not have a 2DW23x available yet.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 24, 2016, 11:17:42 pm
I don't think it can be so easy to reduce noise ... but worth a try ... anyway I'm not brave enough to try it on my own meter.

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: zucca on November 24, 2016, 11:24:13 pm
I don't think it can be so easy to reduce noise ... but worth a try ...

yeah, there are a lot a variables to check (power supply voltage stability, noise from OPAMPs, divider, amplifier... etc.. ) but worst case we will know what is the impact of the ADC reference in the K2001 noise.

PS: FYI Kleinstein suggested here (http://www.eevblog.com/forum/testgear/do-i-have-exceptional-keithley-2000-or-poor-keithley-2001/msg1063600/#msg1063600), a bigger C821>.33µF could also help.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on November 25, 2016, 01:29:39 am
I'm brave! 4 time brave.
Actually thank to zucca and mimmus, now I narrowed issue with flaky meter to ADC board. Swapped board from 21 meter - noise is okay now :). Lets swap the zener, plonk 1uF polycarb cap on C821 and let her roll! 3458 beware, we are coming! Ha, not really.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on November 25, 2016, 01:37:31 am
Well than you need to put another 200 EUR worth of components to use the LTZ1000 as reference and scrap this hopeless LM399 ... I may know a board you can use  :-)
This may be good for the 10V range, but unfortunately the rest of ranges remains in the same 6.5 digits league.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on November 25, 2016, 05:16:25 am
Before exchanging the reference, I would you just measure the noise of the zener reference - at least of one has a suitable instrument (e.g. noise tester / AC coupled or low noise DMM (may need extra ref. to measure only difference)).

One point would be comparing the noise for reading a short and reading a low noise DC source.

Using the second reference and do the adjustment to the LM399 for every AZ cycle would be strange, as this would add quite some noise - though it would eliminate drift from the integrating resistors. Its a little like doing an simplified ACAL on the 3458 before each reading: it reduces drift, but also add time and thus noise, as less time is available for the actual measurement.

The more logical way would be a slower (e.g. average over 10s of readings) correction of drift from the reference and integrating resistors.

Increasing C821 would make sense if the zener is noisy - so the DW232 should not need it, the old zener might profit from something like 100 µF. The point is reducing noise in the 1-10 kHz range. The switching frequency for the ADC seems to be rather high - so jitter from the reference switching and maybe charge injection could be an issue. Also only switching the positive reference and adding a constant negative parts adds some noise. So the ADC is by design not very low noise.

The AD707 at the LM399 is not an issue: the noise of the LM399 is something like 10 times higher. I would be more concerned about switching noise from the LTC1043 might have an influence on the LM399.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on December 02, 2016, 08:30:32 am
One for K2400 SMU and second for K2001 :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on December 02, 2016, 08:41:02 am
And the one for me?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on December 02, 2016, 08:54:20 am
And the one for me?
Ask Keithley Santa :) (There is second plate, which is much more bigger)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on December 02, 2016, 08:55:12 am
 :-DD
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on December 02, 2016, 09:25:55 am
Has I told you I decided to sell my K2001 ... don't know if it worth to replace the display.

But before I sell it, I need to fix the front panel buttons, they are really too wearied and annoying too use.
Any good method? The most convincing i found is to glue some aluminium foil with superglue on the remains of the carbon pads.
Is there something less crude ensured to work? Or may I ask to the old witch (Befana here in Italy) if she has a membrane buttons?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on December 02, 2016, 04:50:15 pm
Has I told you I decided to sell my K2001 ... don't know if it worth to replace the display.

But before I sell it, I need to fix the front panel buttons, they are really too wearied and annoying too use.
Any good method? The most convincing i found is to glue some aluminium foil with superglue on the remains of the carbon pads.
Is there something less crude ensured to work? Or may I ask to the old witch (Befana here in Italy) if she has a membrane buttons?

Contact service center for new keyboard. is the solution I suppose. Or try to ask here, I have only keyboard from 7001.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on December 02, 2016, 06:19:54 pm
OK I try ... I already contacted them for the FVD but they told me they do provide only the full front assembly. Anyway worth nothing asking again ...

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on December 02, 2016, 07:46:42 pm
Has I told you I decided to sell my K2001 ... don't know if it worth to replace the display.

But before I sell it, I need to fix the front panel buttons, they are really too wearied and annoying too use.
Any good method? The most convincing i found is to glue some aluminium foil with superglue on the remains of the carbon pads.
Is there something less crude ensured to work? Or may I ask to the old witch (Befana here in Italy) if she has a membrane buttons?

I've fixed these in the past by removing a 0.5mm slice from the back of the buttons of an old TV/DVD remote with a sharp blade. Then removing the same amount from the device I wanted to fix and gluing the "good disk" onto the button being repaired. The device I repaired is still working fine after 2 or 3 years.
(Did that make sense, I haven't had any coffee yet this morning).

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: mimmus78 on December 02, 2016, 07:48:40 pm
Sure makes more sense than aluminium foil :-)

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Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 2N3055 on December 02, 2016, 07:53:54 pm

I've fixed these in the past by removing a 0.5mm slice from the back of the buttons of an old TV/DVD remote with a sharp blade. Then removing the same amount from the device I wanted to fix and gluing the "good disk" onto the button being repaired. The device I repaired is still working fine after 2 or 3 years.
(Did that make sense, I haven't had any coffee yet this morning).

McBryce.

My usual line is "didn't have my THIRD coffee yet..." LOL..

Would you be so kind and tell us what glue you used...

Regards,
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: McBryce on December 02, 2016, 08:00:19 pm

I've fixed these in the past by removing a 0.5mm slice from the back of the buttons of an old TV/DVD remote with a sharp blade. Then removing the same amount from the device I wanted to fix and gluing the "good disk" onto the button being repaired. The device I repaired is still working fine after 2 or 3 years.
(Did that make sense, I haven't had any coffee yet this morning).

McBryce.

My usual line is "didn't have my THIRD coffee yet..." LOL..

Would you be so kind and tell us what glue you used...

Regards,

I used a gel type superglue like this one: http://www.loctiteproducts.com/p/sg_ug_cntrl/overview/Loctite-Super-Glue-ULTRA-Gel-Control.htm (http://www.loctiteproducts.com/p/sg_ug_cntrl/overview/Loctite-Super-Glue-ULTRA-Gel-Control.htm)
Using a gel means it doesn't accidentally run anywhere it shouldn't. Make sure you get the position correct first time, this stuff sticks forever.

McBryce.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: 2N3055 on December 02, 2016, 08:02:25 pm
Super, I have it available here.. Thanks !!
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on March 20, 2017, 04:28:56 pm
Hi y'all,

I've been through the thread twice posted on the plug in unit thread and
they suggested that I come to this one, so I am.

I belived I have a working unit that got dinged by UPS.

Here is the first issue:

Notice the glass in the upper left?

||
||
\/
(http://)
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on March 20, 2017, 05:21:27 pm
Then moving forward with help from Plesa bought a VFD from him
I am now at this point:

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on March 20, 2017, 05:32:40 pm
I assume after the Built in Test (BIT) and Diagnostics
if there was an issue, it would show up on the display
instead of "press any key to exit". 
I saw the tests as they were performed -- Successfully.

At present I can't take any measurments.
I just get a screen with

--------------------

I"ve gone through the manual, and find no mention of overload.

I assume the meter was used via GPIB and had a card in it. 
The back cover plate wasn't with the unit.

Is there a simple method of seeing the data in the unit?
Is there a method to return the meter to default mode
without losing the stored data?

I finally have a Prologix GPIB to USB device that I've never used.
It looks new in the box.

Are there any scripts/programs available that will work from PC to
the keithley 2001 to view the data that is in it?

This is my first go round with it and any guidance would be
appreciated.

--Spike

POST SCRIPT:

After I confirm the functioning of the meter the next step I'll do is replace the
old electrolytics.  I don't see any signs of leakage yet...Time probably isn't on
my side though.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on March 20, 2017, 11:17:34 pm
I know it sounds really stupid, but press the TRIG button. These are complex system multimeters, and they will only take measurement how and when you tell them to.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on March 21, 2017, 06:05:47 am
Thanks Macboy,

it is taking measurements now.  No, I didn't take it as sounding really stupid...my HP34401As just read,
no issues.  Since this is my first Keithley and a 2001 at that, there is a learning curve.  So I'm doing my best
with a little help from my friends.

I need to figure out it current programming (unsure of correct terminology) and
see why it is doing what it is doing.

I'll check some on the you tube vids also.  I wish I had a had copy of the manual
I hate reading  things online.  But maybe I should get a big screen monitor/TV
and just put it on the bench somewhere or hang it....maybe a wi fi one....

That and GPIB and Caps.

-- Spike
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on March 21, 2017, 04:10:22 pm
I know it sounds really stupid, but press the TRIG button. These are complex system multimeters, and they will only take measurement how and when you tell them to.

You can say that again. 
I found what you described for me in the manual, pdf page 88.
It's the 500 version operation manual.


QUESTION for anyone:

If I change the electrolytic capacitors on the boards...
I assume that calibration is changed and I need then to
get is calibrated, right? 

That is only a $600 USD option?


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Signal32 on March 21, 2017, 04:15:27 pm
If I change the electrolytic capacitors on the boards...
I assume that calibration is changed and I need then to
get is calibrated, right? 

That is only a $600 USD option?
If you're careful about changing the filtering caps, you shouldn't need to recalibrate it. Technically your calibration was invalid 1 year after the last one and certainly when you opened it up to fix the VFD.
Also, you can get calibration much cheaper from independent labs, I recall somewhere around 150-200 being the lowest quote I could get.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: casinada on March 21, 2017, 04:32:21 pm
Don't worry, just test it with a new 9V battery, if is around 9 voltish you're good  :-+
Welcome to the 2001 club  :)
 
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: USMC_Spike on April 05, 2017, 07:33:09 am
@Signal32, casinada:

Okay, then I shall order the caps, then install as time permits.


Now Casinada...it's dis-concerning that we just measure a new a 9V battery
and if it is close well that is good enough.

Though I can cross reference with HP34401As and HP3457A too.
Just to figure out how close.  If I had a very very good lab standard.
I have a hobby 4 digit that I should put into service for the measurments
also.

Somewhere I have a lab grade powersupply but It isn't a lab standard though.

BTW, with everyone's help I got this 2001 going for the first time since I've owned it.

Thank you all,

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on April 12, 2017, 08:25:23 pm
My 2001 have a  power problem ,when the power on, the R100(470?) is very hot, there have no voltage output? anyone know the reasons and how to fix it ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 12, 2017, 09:13:43 pm
MOSFET is likely dead, perhaps because of capacitors went poo and leaked stuff around, causing disasters.
Replace all capacitors, clean all goo very carefully, check every component in affected areas, then try again :-BROKE.
I'd suggest first not connecting secondary power to analog board to prevent more disasters, before you sure power supplies are good.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: kazik70 on September 02, 2017, 06:12:30 pm
Hi, I need to know the resistance between GND and +15v, will you help?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: plesa on September 03, 2017, 01:32:55 am
Hi, I need to know the resistance between GND and +15v, will you help?

What is idea behind? 1st check the transformer output voltage disconnected and check the +15V regulator and rectifier, all are close to each other.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: kazik70 on September 03, 2017, 02:15:06 am
I do not have to check, because all power supply are ok.
There was a crash on the + 15v line and I do not know if I've caught all the broken chips.
I have 74ohm on this line. Not too much. Will you check it for me, please?
I would like to make an order for parts, but I do not know if it's all over.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on June 30, 2018, 12:41:33 am
Hello,My 2001 have a problem,when the power on,The ARM is not display,so it can not test anything。what is the problem with it ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on June 30, 2018, 01:26:11 am
Likely no problem. You just need to read manual about triggering meter.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Mr. Scram on June 30, 2018, 02:31:59 am
At least have the decency to put some NSFW tags on this thread. You're going to get me caught watching electronics porn on the job with threads like these.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on July 01, 2018, 10:37:27 pm
Hello,I have read it,config-trig-Arm ,but it can't save the settings, when i setting  in confirm page,the display will freeze, the same as the test page and the Reset page,is the digital board have same problem?thanks.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 02, 2018, 12:22:51 am
Could have problem. If meter is old, taking it apart and replacing all electrolytics is mandatory. There is enough information and photos in this thread to understand why is it so  :scared:.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: connor on July 02, 2018, 01:29:11 am
thanks,this is a very old meter ,the first calibration is 1994 ,I have read you blog,and i have changed all the Electrolytic capacitors, so is there any suggestions?
The TP601 in digital board is AC 2.5V or DC 2.5V? The other voltage is normal except this one.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on July 02, 2018, 02:30:48 am
I didn't ever test TP601 before, you can check schematics for what it does.
Bad VFD DC/AC/DC module can be also reason for digital board to hang randomly.
I had to replace those in few meters before.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Robert763 on October 01, 2018, 04:58:44 am
Well threads been quiet, so here goes,
I just aquired a 2001 unexpectedly. It was on a test equipment dealers "spares or repair" pile at a Hamfest. Marked as "dead" and £25 I got it for £20 ($25). It's a early one '92 date codes and A06 firmware. Investigation sshows it's not too bad visually but C624, C630 and the VFD inverter are missing from the digital board.
I've ordered a full set of electrolytics and will lash something up for the VFD supplies. Further reports when the capacitors are replaced. The 2001 is a a lot smaller than my other 7.5 digit meters (Solartron).
I note that a couple of contributors have commented that C116 and C117 are underrated at 35V as they are part of the 38V bootstrap suppy. This is not correct, the capacitors are part of a voltage doubler and are in series with C114/C115 so see about 1/3 of the supply. Even if they saw half the supply it would only be 20V so 35V is OK. Nothing wrong with using 50V capacitors if all other ratings are similar, but lower voltage capacitors in same size and range tend to have higher ripple current ratings.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on January 15, 2019, 03:21:38 am
Yes! I got a Keithley 2001 !  :-+
Now I have to get it to work again  ;)

So I got a nice Keithley 2001 from a friend: status broken does not work.
The unit came from a testrack and thus misses its hinge and feet, not that important to me.

Mains fuse was blown, but before replacing and trying first inspect what could have caused this.

Ofcourse I was curious to see what was going on under the hood.
Knowing the horror stories of leaking caps with these beauties I was afraid what to find.
On first short inspection not that much seemed to be going on.
No obvious oxydation or blueish copper salts on the components but there was this oily stuff... hmmmmmmmm

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on January 15, 2019, 03:22:24 am
Desoldering the el-caps reveiled the real damage, except one all capacitors were leaking and these were real Nichicon, so far for japanese quality ;)
Bad series probably or thermal abuse over the years.

Most terrible experience thus far:
1- soldering this gunk releases an odor similar to a 25 year old cat peeing on a hotplate.
2- pulling the capacitor slowly and carefully while heating both pads and still find the oxydized/rotten vias attached to its feet.

Next steps is to clean up the mess with losts of IPA and a toothbrush and see how far I can get with replacing the caps and bodgewires.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on January 15, 2019, 03:28:18 am
For the initial clean up of the electrolyte water (e.g. deionized) is more effective than IPA. Pure IPA is not good in solving salts.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 15, 2019, 04:01:02 am
Based on photos you must remove ALL components at 5cm radius from electrolyte pond , clean board very very well, and replace parts back in. I would recommend just ordering new parts, most of them are just cheap ICs , resistors and caps.

Maybe you spend 50$ on parts and wait few weeks, but its better than powering meter with almost 80 volts floating supply and making a nice electrolysis station under not cleaned parts instead of working DMM.

Also blown fuse indicates that mains section need same treatment, and perhaps big ceramic resistor is open. Perhaps my meter (https://xdevs.com/fix/kei2002_u2/) can act as example.

Sent from my Lenovo K900_ROW using Tapatalk

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: macboy on January 15, 2019, 04:13:42 am
Follow TiN's advice.
If it isn't obvious, when cleaning, hold the boards so that the dirty runoff flows away from the sensitive parts of the board. Don't just lay it flat, soak it and scrub away. You'll contaminate the entire board with conductive electrolyte, effectively ruining it. This thing is supposed to be able to measure G\$\Omega\$ or nA, and it can't do that if the pixies can flow anywhere they want to over the surface of the board.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on January 15, 2019, 04:53:18 am
Thanks for the advice will sure follow it.
Unsure if all components are easily found but start with clean water then desolder the parts then scrub with bioethanol a d finish with IPA.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on January 26, 2019, 11:27:45 pm
The exposed area is too large to replace all components  :( It is the entire red area.
I am now starting from basics, I have cleaned thoroughly and will repair pcb traces and replace capacitors and then see what the status is.
If the power supplies are ok and I have some life I may continue.

For now I am looking at the capacitors. I saw on the xdevs site they used chemicon capacitors.
At my sources Farnell and TME these are not available, I am thinking about replacing them with the same brand and series, so Nichicon UVZ(M).
At least I think this was a bad batch or was the capacitor choice poorly made by the original designers ?

I also see that the 470uF/63V caps at xdevs have been replaced with lower ESR types, any reason for that, high ripple ? Or just prevention?
Any advice on other brands if the Nichicon are out ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: coromonadalix on January 27, 2019, 12:54:13 am
For a good cleaning, at my job we use VIGON SC 202  or Atron (dont recall the number)

We use an 5-7% concentration and spray it with deionized water and it clean pcb's very very well, anything greasy, flux  etc ..   i found out it remove the leaking caps mess too ... we rince with deionized hot water and put it in a heated chamber 110-120 degree C for 15 minutes.

I dont think all the surrounding parts needs to be changed, but while cleaning, its important not to push the electrolyte further into the surrounding parts.

I had exploded. badly leaked caps on pcb's, with a good cleaning/neutralisation,   surrounding parts never corroded and no ic's where damaged.

my 2 cents

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on January 27, 2019, 03:34:51 am
I would still go with removing all "electrolitified" parts and doing thorough cleaning under packages. If you just clean without removing, electrolyte that remains under package will cost you days and weeks or senseless troubleshooting for leakage and drift issues. Been there, done that, never again.  :) So it's just tedious and time-consuming at start, but after that part is done you will be saving days of time in further repairs (or maybe no need other repairs at all, like my second K2002 which use same components/circuit for marked red area).
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on January 27, 2019, 05:16:00 am
I would still go with removing all "electrolitified" parts and doing thorough cleaning under packages.
You warned about the heat sensitivity of the Keithleys pcb's. So how do you suggest removing esp the ic packages without destroying them by for instance cutting the legs.
I am to afraid to damage pcb traces with heat.

The packages look clean though. The pcb traces affected are all around the caps location, further away I can not see any sign of erosion.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on February 09, 2019, 09:17:11 pm
I recently picked up a Keithley 2001M (advertised as 2001), which came with firmware B16, and decent-looking Nichicon capacitors without any sign of leakage. Thanks to the information on TiN's website, I upgraded the unit to firmware B17, and added the MEM2 option. Everything seems to function correctly, including the self-test, but when I perform the open circuit step of user-level comprehensive calibration, I'm getting error 363, which is described as "200uA gain out of spec". The closest corresponding self-test seems to be 309.1, which routes the 89uA ohms source through the 200uA current range and checks for 89mV at A/D input. Now, I'm a bit stumped where the problem is, as I'd like to avoid desoldering any of the precision resistors, e.g. R344 (900, 90, 9) and R215 (24.5k, 500), the ADC board is mounted upside down over the A/D amplifier/ranging area, and I haven't found a reference locator for the layout (e.g. where is A/D IN?).

Currently, I suspect one of the analog switches for the current ranging, and I'm thinking about replacing all of the ‎DG211BDY/DG411DY parts in this area (U323, U317, U320). I don't think the problem is with the main opamp U322 (LT1007) or the gain selection resistor R215 for 1x/50x, because the unit works fine otherwise, and I haven't received any errors about DC gain, which appears to be calibrated first during open circuit calibration. Rather, while probing the 200uA and ACA switch inputs for current ranging, I see the switches actuate, but there's also a slight ~2mV offset between the input and output of one of the analog switches. Does this seem reasonable?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on February 16, 2019, 05:44:53 pm
Update: I swapped out the analog switches, but the problem still remains. I've also verified all of the current sources (e.g. 9.2mA, 0.98 mA, etc) in two-wire resistance mode, so that's not the problem either. Since I know all the switches are good now, I plan to focus on checking the calibration-related components around U322, the main A/D amplifier, including R340 switched through /ZERO, the 1.75V reference switched through /2VREF, etc, before I consider touching any of the precision resistors.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on February 16, 2019, 05:59:47 pm
Did you check front/rear switch? Check current with scope and actuate switch few times to see if you get same stable behavior every time. AD IN is pin 4 at ADC board. Also run self test many times to see if any rogue errors still might be hiding.

Sent from my Lenovo K900_ROW using Tapatalk

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on February 16, 2019, 06:06:55 pm
Did you check front/rear switch? Check current with scope and actuate switch few times to see if you get same stable behavior every time. AD IN is pin 4 at ADC board. Also run self test many times to see if any rogue errors still might be hiding.

I haven't touched the front/rear switch, everything I've been doing has been with it set to the front. Since it's a physical push switch, can the rear affect anything when it's set to the front? I will check it tomorrow. I'll also check the current sources with a scope, so far I've only measured them with another meter. I've probably run the self-test at least ten times now, but unfortunately it's never found anything.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on February 20, 2019, 05:29:30 pm
Thanks for the suggestions! I checked the output of the current source using the front panel in resistance mode, and something definitely seems weird. With 1M \$\Omega\$ load, the 200 \$\Omega\$ range shows a bit of a glitch in the output voltage, perhaps it's just a bit of noise... But, as I move into the 20k and 200k ranges, it gets significantly worse, with the 200k range showing a drop of ~2.4V at around 2.4 Hz. Unless this is intended behavior, there's definitely something wrong with the current source!

Aside from that, everything else looks fine. Nothing seems wrong with front/rear measurements, and the resistors around the A/D amplifier seem fine, though they're not easy to measure in circuit. I don't see the 1.75V reference, but I'm probably not in the right mode for it to be generated.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on March 03, 2019, 12:17:33 pm
I spent some more time measuring various components, but unfortunately I think I might have been misled by the behavior of the input buffer when it is overloaded. Because I was looking at a 1M \$\Omega\$ load in the 20k \$\Omega\$ range, the voltage was around 12.76V at OHMS ISOURCE, and at 5.7V going into the input amplifier U322, which pushed up +8VF to 12.77V and -8VF to -1.41V. I wasn't able to figure out exactly where the glitch was coming from, but I'm pretty confident the problem isn't with the ohms current source, because everything looks correct during both self-test and normal non-overload conditions.

On the other hand, I'm still no closer to determining the cause of the calibration failure. I've measured and reviewed a lot of the ohms circuitry, but I still don't quite understand how some parts of it operate. For example, I'm not sure what the purpose of comparator U333 and buffer U331 are, the function of the nearby OHMOLD / 10mA BIAS section, and why U331/U333 are connected to the switched capacitor block U330. Also, given the 7V output of the LM399 and the 1.75V reference voltage, I'd expect U330 to be configured for dividing-by-four, but the schematic doesn't match that of the example given in the LTC1043 datasheet.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: openloop on March 03, 2019, 02:41:48 pm
Quote
and why U331/U333 are connected to the switched capacitor block U330

[My understanding:] They just move the reference over to different DC offset. And U331 buffers it.

2.4 Hz pulses are probably from autozero.  Switch it off to check.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kleinstein on March 03, 2019, 08:59:01 pm
I also see the "charge pump" used to move the 7 V reference to a different reference point - this about the only part I like about this implementation.  U331 is just a buffer for this shifted 7 V reference for less demanding use (e.g. bootstrapping the protection and gate drive).

The Ohms current source is in deed confusing. As far as I understood it they use the opto-coupler U537 in analog mode for the current regulation loop with the higher current ranges. U324 does the loop control.

U333 seems to be the regulating amplifier for the very low current source (Hi_ohm). There is a separate current source for the lowest current, that used R354 as it's reference resistor.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on March 04, 2019, 06:35:59 pm
2.4 Hz pulses are probably from autozero.  Switch it off to check.

You're right, they do go away when I disable autozero.

The Ohms current source is in deed confusing. As far as I understood it they use the opto-coupler U537 in analog mode for the current regulation loop with the higher current ranges. U324 does the loop control.

U333 seems to be the regulating amplifier for the very low current source (Hi_ohm). There is a separate current source for the lowest current, that used R354 as it's reference resistor.

Thanks for all the information, it's starting to make more sense now. Yeah, the manual mentions that the current source for the mega/gigaohm ranges uses R354 through OHM ISOURCE, instead of the regular OHMS path through the K300 relay and protection circuit.

I've managed to repair the unit, but it wasn't very satisfying. I ended up connecting a logic analyzer to A/D IN, A/D_DATA, D_OUT, R1_STB, R2_STB, and DC_STB, in order to figure out what the unit was doing/measuring in the open circuit calibration phase that was failing, since the manual provides the full bit patterns for the shift registers. I happened to do a four-wire resistance calibration this time, instead of a two-wire resistance calibration, as I had previously gotten lazy trying to reproduce the problem, since it only happened on the last phase of comprehensive calibration. This time, the calibration succeeded with no errors, so I removed my logic analyzer/probes and re-attempted calibration, which again succeeded, so I fully re-assembled the unit and finally performed actual calibration. I can only surmise that perhaps the fault was indeed in one of the analog switches, which I fixed when I replaced them, but didn't notice because I got sloppy with the calibration.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 04, 2019, 09:30:13 pm
Also keep in mind that you need to perform "manufacturing" low level calibration to do actual adjustment for current and ACV/ACI functions. If current reading is not correct than comprehensive user calibration will still give you out of spec adjustments.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: ddcc on March 05, 2019, 01:50:31 am
Thanks for mentioning it. I'd like to, but I don't have the capability or calibrated gear for that step. Luckily, it's fairly accurate when I check against a DMMCheck.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 20, 2019, 08:05:49 pm
Still busy cleaning  :( , take it slowly, half hour here and there. The nwe caps arrived.

Now my first thought was to also clean the via's through and through, place a thin wire and resolder.
I find it very hard to clean the smaller via's, they also stink awfull like cat-pee. I wonder are these via's closed ?

Anyone that did this cleaning have additional tips for the via's ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 20, 2019, 11:16:13 pm
Must clean very thorough to make smell go away.
Via's usually not closed but sometimes clogged with soldermask/solder. When I was fixing vias i used tinned strand from wire small enough to fit via, heat via from other side with iron and push strand thru.
Then solder both ends and repeat procedure for all vias under affected corroded area.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 20, 2019, 11:17:24 pm
Ok wow, so how many hours did you spent on your repair in total ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 20, 2019, 11:27:26 pm
Actual repair took not that long. It was more of a learning process. I sold/traded all 2001's long ago tho.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 29, 2019, 06:07:17 am
Well it is alive  :-+
Not fully 100% though, get adc errors.
What is strange is that it seems to work, 10V on the inputs looks ok.

Read the manuals tomorrow to see what is going on.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 29, 2019, 09:49:30 am
Reading this topic the errors will probably be gone if I update the firmware from A05 to A08 correct ?

Looking at my digital board it does not match the schematics of the xdev site.
I seem to have two proms with a sticker A05, one in a socket (U611) and one (U618) soldered to the board, also only one 512kB ROM file on xdev so what is up with that ?
Is there a flash compatible chip just like with the 2000 I can get ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 29, 2019, 11:04:52 am
Ah stripped the sticker from the socketed eeprom and it is a HN27C4096CC-15 which is a 16 bit eprom, so that clears that up  :)
I do have a few ST M27C4002, they look like pin compatible.  :-+
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 29, 2019, 04:00:38 pm
Quote
Reading this topic the errors will probably be gone if I update the firmware from A05 to A08 correct ?
No, those are rather horrid errors, firmware is not a problem.

If you have two PROM digital board, you got lucky and should install B-version firmware , like B15 (https://doc.xdevs.com/article/keithley-instruments/#2001).
I mean for you probably does not matter, but B-firmware allow use of Keithley 1801 in scanner slot.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 29, 2019, 11:20:22 pm
Hi TiN first of all again many thanks for all your hard work on xdev and help here, really appreciate it  :-+
To get back to your answer:

No, those are rather horrid errors, firmware is not a problem.

I would also think so but if you look at the history in this topic it looks different:

- You had a long session with SKE from page 18 onwards he had exactly the same errors without a final solution
- Then Kada had the same errors from post http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg880823/#msg880823 (http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/msg880823/#msg880823)
forward. No solution.

Then this post came and SKE and kada say that firmware upgrade solved the 200.x and 201.2 errors.


SKE encountered with the same errors:
Self test reported these error codes:
200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference
Did you find a solution?

I'm sorry for delayed report, the solution (TiN, you was right  :-+) was to update firmware to A08 and I don't have these errors anymore.

Now I have absolutely no clue why this would solve the issue, perhaps the new firmware overwrites or rewrites the calibration eeprom?
I will make backup of the eeprom first.
But I guess it can't hurt to try it ?

What's your opinion?



Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on March 30, 2019, 03:42:44 am
Backup the cal eeprom data and update the firmware.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 30, 2019, 05:13:17 am
Backup the cal eeprom data and update the firmware.
First done
Second have to do the little to big endian conversion of the rom.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TheSteve on March 30, 2019, 05:29:48 am
If you had firmware A05 shouldn't you be installing A08, which I believe is a single file and should directly program into your eprom.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 30, 2019, 05:58:14 am
Correct but TiN put the rom files as little endian, it needs to be converted to big endian, he has a python script for it, so will need to do that first.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: openloop on March 30, 2019, 12:31:47 pm
Kjelt, I doubt that it has anything to do with firmware.

What are the symptoms? (apart from test errors I mean)
Does the unit make correct measurements in 20v and 2v ranges? Both with applied voltages and shorted?
Does the self test complain the same if you let the unit warm-up for an hour?
Do the proper voltages make it to ADC board when you step through diagnostic patterns? (e.g. 7v, 7v*1.5, 0v, signal, etc.)


Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 30, 2019, 08:11:41 pm
Yes DCV is ok and on par with my K2000.
7V is on ADC in after test and the other I believe 1,75V test passes so ADC is ok.

What I don't like is that some parts of the analogue board (beside the regulators) heat up to 40-45C within seconds, is that normal? Many small parts on the bottom of the pcb so can't see which ones exactly.
Does anyone have a thermal image of their analog board ?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: openloop on March 31, 2019, 12:11:57 am
Quote
7V is on ADC in after test and the other I believe 1,75V test passes so ADC is ok.

Actually it does not mean that. Even if ADC is wonky (but not crazy), autozero can calibrate the wonky out and show more or less correct values.

The difference between test 200.1 and regular measurement is that 200.1 is checking absolute charge-discharge count, but regular measurement is relative to references.

Easy to check.
Short inputs, connect your scope between signal zero ("S COM" on ADC header) and integrator' output (pin 6 of U809 DIP), set range to 20V (for orange-to-orange comparison), turn off autozero (to reduce clutter), and compare scope's traces of ADC's dual slope phase to attached screen shots.
And by compare I mean really compare - dc offset, charge slopes, discharge slopes - everything. Test 200.1 simply counts number of clock ticks (you checked the quartz to be 7.68 MHz right?)  corresponding to charge and discharge periods and compares it to a pre-programmed constant. Of course that constant might be corrupted - then new firmware might help.

Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on March 31, 2019, 02:14:17 pm
Does anyone have a thermal image of their analog board ?

My 2001 notes article have plenty of IR photos on 2001. They do like to get bit toasty  ^-^.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: Kjelt on March 31, 2019, 08:07:28 pm
Does anyone have a thermal image of their analog board ?
My 2001 notes article have plenty of IR photos on 2001. They do like to get bit toasty  ^-^.
No wonder the caps were toast.
Too bad the caps leak instead of dry up. :)
Title: Line sync sketchy
Post by: eplpwr on April 15, 2019, 05:10:01 pm
Hi!

Recently I got a 2001 in good condition. The meter works great, except for one thing: When I enable Line Syncronization (followed by TRIG button) the display updates become sketchy and for long times the display just shows "---------" [VDC/ADC/Ohms/whatever]. So, it seems there is at problem with the mains zero-crossing detection (or whatever method is used to sync to mains). The L-S problem was present when I received the meter, but I have no complaints as it was really cheap - sold as Parts.

This is what I've done to the meter, after receiving it:
- Replaced all electrolytic capacitors on both analog and digital board. The "old" ones had 2008 datecodes and did not show any signs of leaking.
- Upgraded firmware to B17/2001M. Unit was received with B16 firmware (now uploaded to xdevs.com).
- Upgraded from plain SRAM (no MEM option) to MEM2 (DS1245Y). Initialized NVRAM from Secret menu - working good.

I have the Repair manuals, complete with schematics, but I have trouble understanding which net is used for Line Sync.

Self-test passes all tests with no errors.

Is there some obvious solution to my problem that I've overlooked?
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: TiN on April 15, 2019, 09:57:49 pm
Thanks for firmware!

Does your unit pass all self-test in continuous loop  for few hours? Sometimes there is random error due to bad optocouplers between analog/digital, that cause "locks/freezes" like you describe.
What if you gently smack unit on the side, do the readings change (freeze up/reset/etc)? Line sync is FREQ signal that goes into A/D board, so you can trace from there.

Pics would be nice to see, sounds like your meter rather recent.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: eplpwr on April 16, 2019, 06:34:37 am
Does your unit pass all self-test in continuous loop  for few hours? Sometimes there is random error due to bad optocouplers between analog/digital, that cause "locks/freezes" like you describe.
What if you gently smack unit on the side, do the readings change (freeze up/reset/etc)? Line sync is FREQ signal that goes into A/D board, so you can trace from there.

Pics would be nice to see, sounds like your meter rather recent.

Hi TiN!

It seems I can run self-test for several hours without any errors. I didn't think of "smacking" the unit, but after trying that there is definitely somethings going on: after enabling line sync, I get a reading every 10-15 seconds (conversion speed "normal" - default). Between the readings "---------" is shown in display. If I bump the meter (not too hard  :D ) I can unfreeze the meter to get a few readings before meter goes back to "--------" display. So my "average # of readings per minute" goes up when bumping the meter. Something electro-mechanical seems to be going on - just have to figure out exactly what's happening.

An observation: When changing to Line Sync, there is always a number of initial readings for 2-4s after pressing the TRIG button. It's almost like some capacitor was fully charged and then drained of energy, only to be recharged each 10-15s to get a few more readings, before being emptied of charge, again. This is a long shot, I know...

I have to disassemble to meter again to be able to probe the connectors to the A/D board - FREQ specifically.
Title: Re: Restoration glory of Keithley 2001 DMM
Post by: openloop on April 16, 2019, 08:23:44 am
Looking at the schematics, it appears that the main CPU gets its line readings straight from main power transformer taps. Digital board's U628 (page 2 of addendum part 2) is a comparator which detects zero crossings and feeds them straight into the CPU (pin 56)