Author Topic: Restoration glory of Keithley 2001 DMM  (Read 206556 times)

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Offline Zucca

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Re: Restoration glory of Keithley 2001 DMM
« Reply #675 on: November 24, 2016, 12:24:13 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, a bigger C821>.33µF could also help.
« Last Edit: November 24, 2016, 12:35:22 pm by zucca »
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Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #676 on: November 24, 2016, 02:29:39 pm »
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.
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Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #677 on: November 24, 2016, 02:37:31 pm »
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.
« Last Edit: November 24, 2016, 02:40:56 pm by mimmus78 »
 

Offline Kleinstein

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Re: Restoration glory of Keithley 2001 DMM
« Reply #678 on: November 24, 2016, 06:16:25 pm »
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.
 

Offline plesa

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Re: Restoration glory of Keithley 2001 DMM
« Reply #679 on: December 01, 2016, 09:30:32 pm »
One for K2400 SMU and second for K2001 :-+
 

Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #680 on: December 01, 2016, 09:41:02 pm »
And the one for me?
 

Offline plesa

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Re: Restoration glory of Keithley 2001 DMM
« Reply #681 on: December 01, 2016, 09:54:20 pm »
And the one for me?
Ask Keithley Santa :) (There is second plate, which is much more bigger)
 

Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #682 on: December 01, 2016, 09:55:12 pm »
 :-DD
 

Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #683 on: December 01, 2016, 10:25:55 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?
 

Offline plesa

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Re: Restoration glory of Keithley 2001 DMM
« Reply #684 on: December 02, 2016, 05:50:15 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?

Contact service center for new keyboard. is the solution I suppose. Or try to ask here, I have only keyboard from 7001.
 

Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #685 on: December 02, 2016, 07:19:54 am »
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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Online McBryce

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Re: Restoration glory of Keithley 2001 DMM
« Reply #686 on: December 02, 2016, 08:46:42 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?

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.
 

Online mimmus78

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Re: Restoration glory of Keithley 2001 DMM
« Reply #687 on: December 02, 2016, 08:48:40 am »
Sure makes more sense than aluminium foil :-)

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Online 2N3055

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Re: Restoration glory of Keithley 2001 DMM
« Reply #688 on: December 02, 2016, 08:53:54 am »

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,
 

Online McBryce

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Re: Restoration glory of Keithley 2001 DMM
« Reply #689 on: December 02, 2016, 09:00:19 am »

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
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.
 

Online 2N3055

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Re: Restoration glory of Keithley 2001 DMM
« Reply #690 on: December 02, 2016, 09:02:25 am »
Super, I have it available here.. Thanks !!
 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #691 on: March 20, 2017, 05:28:56 am »
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?

||
||
\/

« Last Edit: March 20, 2017, 05:32:17 am by USMC_Spike »
 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #692 on: March 20, 2017, 06:21:27 am »
Then moving forward with help from Plesa bought a VFD from him
I am now at this point:

 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #693 on: March 20, 2017, 06:32:40 am »
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.
« Last Edit: March 20, 2017, 06:45:10 am by USMC_Spike »
 

Offline macboy

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Re: Restoration glory of Keithley 2001 DMM
« Reply #694 on: March 20, 2017, 12:17:34 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.
 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #695 on: March 20, 2017, 07:05:47 pm »
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
 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #696 on: March 21, 2017, 05:10:22 am »
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?


 

Offline Signal32

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Re: Restoration glory of Keithley 2001 DMM
« Reply #697 on: March 21, 2017, 05:15:27 am »
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.
 

Offline casinada

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Re: Restoration glory of Keithley 2001 DMM
« Reply #698 on: March 21, 2017, 05:32:21 am »
Don't worry, just test it with a new 9V battery, if is around 9 voltish you're good  :-+
Welcome to the 2001 club  :)
 
 

Offline USMC_Spike

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Re: Restoration glory of Keithley 2001 DMM
« Reply #699 on: April 04, 2017, 09:33:09 pm »
@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,

 


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