Electronics > Metrology

Data Precision 8200 calibrator - repair and other fun stuff

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Rax:

--- Quote from: Kleinstein on February 26, 2023, 07:53:18 pm ---My suspicion is with a thermal effect. 10 minutes souds like a reasonable time frame for this.
The feedback divider in teh calibrator with 10K and 90 K is quite low value and thus quite some heating expected.
Compared to this the divider in the DMM is likely less of an issue as it is likely made also for higher voltage (e.g. 1000 V range).

For a test one could check what happens at a low voltage like 70 V: this would be about half the effect of heating, but a comparable fraction of the voltage for an effect due to amplfier settling or dielectric absorbtion.
The heating effect in nonlinear and not just a settling problem.

--- End quote ---

This makes sense.

branadic:
I have upgraded AN3200 with an over 8000 h pre-aged ADR1399. I had to adjust R7 as well as R8+R9 from original 1.14kΩ to 1.7kΩ to have enough of margin left for adjustment on the 20Ω pot. Attached a 1h measurement taken with S7081 in 7.5-digit mode.

Edit: Repeated the measurement with S7081 in 8.5-digit mode and eventually verified the measurement with R6581D and indeed noise improved.

-branadic-

Rax:

--- Quote from: branadic on March 23, 2023, 05:58:27 pm ---I have upgraded AN3200 with an over 8000 h pre-aged ADR1399. I had to adjust R7+R8 from original 1.14kΩ  to 1.7kΩ to have enough of margin left for adjustment on the 20Ω pot.
-branadic-

--- End quote ---
I'm not sure I follow - R7=3.01k, R8=5.3896k - how exactly did you have to replace these? Specifically, what were their replacement values?
Thank you for sharing these results and work.

Rax:

--- Quote from: branadic on March 23, 2023, 05:58:27 pm ----branadic-

--- End quote ---
branadic - this is completely unrelated, but I see all these cool graphs and charts on EEVBlog - what's the high level approach here? Automated readings over GPIB, logged some way on the computer and plotted through another something? I candidly am at this clueless level with this kind of data visualization, but I'd love to explore it.

branadic:
It's actually a low level approach, some Raspberry Pi and GPIB magic in the background aquiring and storing data on a local drive, I still work completely script based, no fancy packages and libraries involved and the rest is simply LibreOffice visualization im I'm lazy re GNU Octave for the more interesting data, that I analyze each evening on the couch :)

-branadic-

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