Agilent E3634a - Error 632 / Help needed

[Lamima]

Hello!

Recently i got i non-working Agilent E3634a power supply and now had some time to start (or better try) repairing it.
Self-test on start-up shows Error 632 which indicates a failure in HW according to the manual:

632 Hardware test failed This test checks the status of voltage and current error
amplifiers for the power circuit. If both amplifiers are not operational, the
power supply will beep and the error annunciator will be on.

Display shows 53,759V / 6,799A. Measured Output voltage is around 0,68V with OR without output enabled.
A first optical inspection shows no burned/damaged parts.

Does anyone have a good advice where to start or what could be damaged?

Regards
Marco

[singapol]

Every repair is unique but you may get lucky. Do a visual and smell test for abnormal things like
bulging tops of caps, burned/charred resistors,cracked semiconductors/ic that indicate catastrophic failure and etc. As the error is 632 look at the power schematic if you know your way around. Measure the voltages
but be careful not to let meter probes slip. You will soon find the fault...hopefully. ou can download the service manual below,the one at Agilent /Keysight does not have the schematics.

http://gerrysweeney.com/hpagilent-e3634a-power-supply-teardown-repair/

[Ordinaryman1971]

I think it's a good video out there on youtube  by Gerry Sweeney about one of those power supplies being fixed.
Your problem may be and probably is different, but there is always something to learn from other ppl experiences.
I hope it helps:

[skennedy]

I repaired one of these earlier this year and it had some pretty horrific damage to the current shunt resistor. I would start by looking at the area around the current shunt resistor. A few opamp and multiplexers go into an adc. The schematic is available so that is very helpful. The design is quite complicated and difficult to fully comprehend. It is important to note that there are at least two ground nets. Mine had a break in the net tie formed by the current shunt leg meaning the ADC was seeing rubbish values. Let us know how you go!

[Lamima]

Thanks for your comments so far.
Yesterday evening i had a look at the vids of Garry Sweeney - quite interesting and well documented repair- but unfortunately no direct help for my problem because the shunt in my power supply is definitively working...
As already mentioned i could not discover any burned parts and at least the fets in the power path are ok to ( i measured the forward voltage of the body diode, so the D-S path is ok).
Today i will try to find some time and start measuring the supply voltages of the op-amps - perhaps only a voltage regulator died

[sahko123]

was this ever resolved or has anyone since resolved a similar issue?