Hi all,
I've recently bought a Keithley 2100 off eBay and resistance measurement is not working properly: if I short the leads, it displays a varying resistance of a few kOhms.
Some additional details:
* I am talking about 2wire resistance measurement.
* The same issue is present on both the front and the back input connectors.
* If I switch to manual range, it looks like the 100 MOhms, 10 MOhms, and 1 MOhms ranges are ok; the problems are seen only for the 100 kOhms, 10 kOhms, 1 kOhms, and 100 Ohms ranges.
* I measured the current for all the above ranges and all are in spec (yes, including the ranges with wrong measurement values).
* The self test result is PASS now (initially, I would get error 607, but that seems to have gone now after I replaced U201 and U507).
With regards to 4wire resistance measurement, I tried that as well and, for this one, the behaviour is different between the front and the back input connectors:
- when using the front input connectors, I get OL for all ranges when measuring a given resistance.
- when using the back input connectors, I get the same behaviour as with the 2wire resistance measurements (i.e. works fine for 100/10/1 MOhms, doesn't work well for the rest of the ranges).
Based on the above observations, I would conclude the following:
* for 2wire measurements, I suspect a calibration issue
* for 4wire measurements, I suspect a problem with the sensing part of the front input
Do you agree, or would you have any different thoughts?
Thanks,
George