[volt-nuts] Keithley 2001 vs HP 3457A multimeters / Any problems to watch out for on Keithley 2001? (Todd Micallef)
Illya Tsemenko
illya at xdevs.com
Fri Jun 24 12:38:49 EDT 2016
Aha! :)
Hi David,
First few sour points to make sure you got what to expect.
* 520$USD is bit steep for 2001 from 90's you got, and VFD seem to be
fairly faded according to auction pics.
* It may be still have issues internally, even though showing reading
does not reveal anything in first glance.
2001's are fairly capable DMMs and I personally dealt with no less than
7pcs of them over last years. Currently I still own four units of same
age as your win (judge from S/N). While they are worse than 2002/3458 in
terms of stability/noise, I would not trade my 2001's to fancy
3446X/34470 meters.
Also 2001 support scan-card addons so you can easily expand DMM with
scanner function, or even nanovolt-preamp if you dedicated enough. I'm
working on nanovolt support with 2001, but that's long story. Some
details with DIY card I covered here: https://xdevs.com/review/ema10/
To get you ready:
1). It's bit tricky to setup and need little bit of time to get familiar
with, but otherwise on par with modern 34470/DMM7510 with bit worse
resistance/current specs. No RS232, so bit more expenses to come for
GPIB interfacing if you don't have that already.
As Todd pointed out already to my repair article, some bits of info are
linked there, as well as firmwares and documentation.
Here's example test log with reading 1mV DC voltage with three meters :
2001,2002,3458. https://xdevs.com/datalog_tcomp/
2001 also using almost exactly same ACV TrueRMS converter as 8.5 Model
2002, so that's good too if you into AC stuff.
I also have thread on EEVBlog:
http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/
in case you missed it.
2) I never played with 3457A, but 2001 should offer better stability,
less noise and more functionality in smaller package. I do take 2001
with me to remote locations sometimes to do some testing, thanks to it's
relatively small size and weight.
4-5) You should update firmware to A08, which I hosted on links above,
if you desire to have meter calibrated by accredited lab, such as
Tektronix service center. Otherwise they might charge you for replacing
simple PLCC ROM. Your digital board is older version, so you tied to
A-version smaller firmwares w/o support of unobtanium nanovolt Keithley
1801 preamp. You will not loose existing calibration on firmware update.
6) This is my favorite part. Here's what you have to do:
* Receive meter, take the cover off
* Remove transformer, carefully remove plastic cover of analog board
(top side)
* Get the board out.
* Replace ALL electrolytic capacitors on it. Follow my article for
details. This is requirement, believe me.
* If you already see gunk, liquid from caps - carefully clean board,
restore any damaged traces/parts. If it leaked under ICs - you have to
desolder them, clean in IPA thoroughly and solder back.
* If your VFD too dim and you desire bright nice glow - you can buy
Keithley 7001 switch with good screen from ebay (they can be found for
100-150$) and swap VFD. Not worth to bother asking Tek for new VFD, they
sell front panel board only for ridiculous tag.
* Replace caps on bottom digital board.
* Install memory option if you like
* You can deyellow plastic front panel with peroxide:
https://xdevs.com/guide/plastic_bleach/
* Enjoy the meter.
I sent one of 2001's for official cal here in Taiwan, it was 500$ for
full cal with data. Cheaper than 8.5 DMMs but still bit pricey. To do
user calibration you will need very stable 2V, 20V, 20kOhm and 1MOhm
standards. Make sure you have meter running at least for a week before
sending to cal, to get everything stable.
P.S. there is no much point in 8.5th digit from 2001, as it's just down
in noise.
BR,
Illya
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