Hi everyone, I recently had a friend of my repair a broken 34465A that I bought. He manage to repair it but then it also had a problem where all DC ranges would drift over a few minutes. Problem was traced to a bad ADC buffer amp (OPA827). Now the unit will hold cal and not drift.
But another problem arise. For some reason, all DCV ranges will accept new values except for the 10 VDC range. Even when supplying 10 VDC and entering 10.000000VDC exactly, it will still show a 7mV error that just can not be calibrated away.
Could it be the 10VDC range has drift so much that it's outside the adjustable range? Could the new replacement buffer IC plays a role?
It also has a Cal count of 271, which seems like a lot.