Recently got a Keithley 2000 which consistently failed it's VAC test 402.2 in the self diag. I also found its AC volt measurement were around 4% out, while the DC is pretty much bang on within 0-2 counts with my chinese Hao Qi Xin volt ref.
I'm posting this because at least 2 others on the internet have had the same fault but not appeared to resolve it or document resolving it. Also, I wouldn't mind part identification too.
I pretty quickly found SOT23 resistor network R110 was reading 1.6k instead of 1k (in-circuit) on one if its resistors. There is another one of these devices nearby, R133 which read 1040 ohms in circuit.
The repair manual has a description
RES NET, 9K-1K, MICRO DIVIDER and Keithley part number
TF-246-2. As can be seen in the pic, its only identifier is
A4EAnyone have any idea what it is? The best I can come up with is Vishay MPMT10019001.
Before I get the right part I decided to bodge the existing high 1k6 junction with the closest to get it to 1k I had on hand - a 3k3 0805 in parallel.
It appears to have fixed it. Measures 1070 ohms in circuit and I have ran the VAC tests in a loop for an hour - no problem.
I still have a 4% out on 10VAC range readings, so I guess a DIY recal is in order on the VAC only. When I get the proper part I may get a real calibration/adjustment.