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Author Topic: Keithley 2002 repair help  (Read 2670 times)

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Online nikonoid

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Re: Keithley 2002 repair help
« Reply #50 on: June 20, 2017, 03:17:37 AM »
I finally assembled the instrument back together, gave it 24 hours of warm up and now started to verify performance before sending it to be calibrated.

I would like to thank TiN, Le_Bassiste, Kleinstein, Samogon and others who helped me though the process :-+.

Performance evaluation in NORMAL speed mode (NPLC1, I think):

Copper short on 200mV range after long warm up fluctuated a bit between -1.3 and -1.6uV.  StDev=93nV over 1000 readings.

5 volt reference from DMM check plus ("5.0000" as of 2 years ago when I bough it) gave me 5.0000295 or 5.9ppm out.  StDev=1.3mV (0.26ppm) over 1000 readings. So pretty good for the reference and a meter.

Bias with 10MOhm resistor on 200mV range measured  120uV (for some reason it was a bit less when meter was not fully assembled and not completely warmed up). So 12pA of leakage

Resistance worked fairly well comparing to my other meters and standards, however noise on resistance was somehow higher than what I would expect, especially at 1MOhm:
Code: [Select]
Nominal(Ohm)    Measured      ppm      StDev     StDev(ppm)   Readings
10,000,000.00   9,999,711    -28.9     15            1.50     1000
 1,000,000.00   999,942.6    -57.4     1.5           1.50     1000
   100,000.00   100,000.89     8.9     0.074         0.74     1000
    10,000.00   10,000.131    13.1     0.0038        0.38     200
     1,000.00   999.98898    -11.02    0.000131      0.13     200
        10.00   10.00081      81       0.000010      1.00     200

Please let me know if these look ok before sending for calibration an if there are any additional parameters/test I can ran before shipping it out. I am considering using 4GTE company. They have Fluke 5700a they can calibrate it on. If you have other recommendations for good and reasonably priced calibration lab in US, it would be great to know.

On the strange side, I found two things: meter is reporting internal temperature 27F above calibration temperature. How could it be? The calibration date is from 1999 (about a year after the chips date).

Another peculiarity is that at some point meter gave me very jittery Ohms reading. When I went to General menu to check Line Sync is was displaying 400Hz despite my power being 60Hz. Single power cycle of the meter fixed it and now it properly shows 60Hz. Have you seen something like this?
« Last Edit: June 20, 2017, 11:31:07 AM by nikonoid »
 

Offline Samogon

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Re: Keithley 2002 repair help
« Reply #51 on: June 20, 2017, 05:25:08 AM »
What 4GTE quotes are?
Simple cal without cert quoted 600 from Tektronix
 

Online nikonoid

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Re: Keithley 2002 repair help
« Reply #52 on: June 20, 2017, 11:57:45 AM »
I thought 4GTE was $240. I will have to call them tomorrow to confirm if it is with data or not. They previously did a good job for me.

Any other suggestions?
 
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