The HP 8600A Problem has Returned

[Chris K]

Ok that makes sense to me….surprisingly! I’ll go from a cold start tomorrow evening and monitor the voltage across the resistor continuously. I’ll let you know what I find.

[Chris K]

I didn't get a chance to turn the unit off last night (fell asleep ). This morning, after running sealed up and warm all night, the readout was frozen and the voltage was 4.6V. The voltage across the resistor was the same, around 325mV. I froze the 3055 power transistor and the voltage at the test point fell further to 4.1V. When it returned to 4.6V, I froze the resistor and the voltage came up to 5V but it did so slowly. When it fell back to 4.6V, I froze the 723 and it immediately shot up to 5V.

I'm not sure if there's any information that you guys can glean from this but there it is. I turned the unit off. Tonight, I'll do the cold start and measure the voltage across R12 and see what the baseline looks like and we'll go from there I guess??????