Author Topic: Restoration glory of Keithley 2001 DMM (Read 307011 times)

Jay_Diddy_B · « **Reply #325 on:** June 25, 2015, 03:09:38 am »

Hi,

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

I found a list in the repair manual:

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

Thanks!!

Jay_Diddy_B

macboy · « **Reply #326 on:** June 25, 2015, 12:49:28 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!

Zucca · « **Reply #327 on:** June 25, 2015, 01:16:35 pm »

Mine is like this:

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...

TiN · « **Reply #328 on:** June 25, 2015, 05:50:37 pm »

Seems activity in this thread, yey.

To keep things rolling, here's a teaser:

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 as usual.

Article in progress, stay tuned...

dadler · « **Reply #329 on:** June 26, 2015, 09:29:15 pm »

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

PaulAm · « **Reply #330 on:** June 26, 2015, 09:44:58 pm »

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.

ManateeMafia · « **Reply #331 on:** June 26, 2015, 09:51:25 pm »

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.

dadler · « **Reply #332 on:** June 27, 2015, 02:01:00 am »

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.

Sailor · « **Reply #333 on:** June 27, 2015, 03:42:14 am »

International Customers:
Payment must be made via Bank Wire Transfer only. "NO EXCEPTIONS"

TiN · « **Reply #334 on:** June 27, 2015, 04:03:15 am »

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))

dadler · « **Reply #335 on:** July 04, 2015, 12:19:44 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.

PaulAm · « **Reply #336 on:** July 19, 2015, 12:57:49 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

TiN · « **Reply #337 on:** July 19, 2015, 05:05:57 am »

+15V to analog GND (Lo terminal) : ~75.2 Ohm
-15V to analog GND (Lo terminal) : ~1283 Ohm

PaulAm · « **Reply #338 on:** July 19, 2015, 11:43:41 am »

thanks!

Now to replace that lm399 and see if any self tests clear.

TiN · « **Reply #339 on:** July 20, 2015, 01:31:06 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..

PaulAm · « **Reply #340 on:** July 20, 2015, 02:46:43 pm »

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.

Andreas · « **Reply #341 on:** July 20, 2015, 07:02:15 pm »

Quote from: PaulAm on July 20, 2015, 02:46:43 pm

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

PaulAm · « **Reply #342 on:** July 20, 2015, 07:07:19 pm »

Gah, that's a typo. It's a lm339.

The lm399 is fine.

plesa · « **Reply #343 on:** July 20, 2015, 07:15:27 pm »

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.

TiN · « **Reply #344 on:** July 20, 2015, 11:25:22 pm »

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.

saturnin · « **Reply #345 on:** July 22, 2015, 07:43:28 pm »

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!

robert_ · « **Reply #346 on:** July 22, 2015, 08:24:23 pm »

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.

saturnin · « **Reply #347 on:** July 22, 2015, 09:21:38 pm »

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...

TiN · « **Reply #348 on:** July 27, 2015, 04:57:37 pm »

Tried change LM399 to LTZ1000 module in one of my 2001, so far epic fail.

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..

ManateeMafia · « **Reply #349 on:** July 27, 2015, 08:26:50 pm »

@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.


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Author Topic: Restoration glory of Keithley 2001 DMM (Read 307011 times)

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