Good day everyone. - A few things right off the bat. Thank you for providing this resource. Next as a long term web author and webmaster, I DID USE THE SEARCH FUNCTION.
I did not find anything that was of help to me specifically for the failure mode of one of my prized, go-to bench meters, the Keithley 196.
Due to time constraints, other factors and a ridiculously low sale price, when my original failed, it seemed best to just purchase a replacement and put the malfunctioning meter on the list of required repairs and calibrations. I have yet to open the meter up, but I thought it might be worth posting about the failure to see if this is a common or known failure mode.
One AM I got up and went into the lab and fired up the 196 for warm up and right out of the gate, in all ranges -it simply reads 6.5 digits of totally random numbers. Connecting test leads to anything in the appropriate range seemed to do little and more likely nothing to the errant erratic display. The numbers change at the meter's sampling frequency. Since the time this happened and I retained a replacement and calibrated it, well fixing my original meter has gone for far too long on the back burner.
So, while yes, the first things I would do is check the voltage rails and regulation for deviation (or insanity in this meter's case) as a starting point and I do have some other notions as far as good paths to follow to try my best to locate the issue(s). Of note, I smelled no magic smoke emitted by the unit at any time.
The simple question is, instead of 3 hours of troubleshooting (and hoping for success) has anyone experienced this type of failure with a Keithley 196? It would save a lot of my overbooked valuable time if this is a common failure and someone has a direction to point me in.
Reality speak is that while I know with enough time spent I can get the unit operational and ready for re-calibration, but that could mean me poking around in all of this spare time I do not have and hope I can find the root cause for the failure. All I know about the time it failed was simply I walked into the lab and turned it on to stabilize it and that a mere 10 or so hours earlier it was in use with no issues before shutdown.
The ESP that I don't have makes me think a voltage regulation issue or perhaps an E/EPROM failure.
Bottom line, has anyone had a Keithley 196 fail in this manner? And if so, what was determined to be the root cause? Thank you all in advance, if this failure has been seen on other 196's and they were repaired, a response could make a huge difference in the time I have to put into this meter - which I really do like a great deal and am low on time to allot to the issue.
PS: All of the self diagnostics seemed to work properly, but that "might be" disputable as that was well over a year ago.
Regards,
Douglas W.