Hello Folks,
The HP4191A reads erratic, measurement errors are pretty random. No error codes displayed, passes self-test, calibration runs through without a problem. The usual displays of HPIB address and option letters pop up several minutes late. After turn-on the only things that light up (dimmed) are the LEDs next to the displays, those that signal "milli", "mega" and so on but the main 7-segment displays remain dark for a while.
The service manual says that the typical cause of this is a power supply fault. However, after taking it apart all voltages are normal right after start-up and I could not find any loose cables.
Hoping someone else had that happen and could you give a hint.
Regards, Joerg
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