Re: HP 8590a error messages

On Wed, 07 Jun 2006 16:59:45 +0000 Maxwell McHamster
<Hobbyist@xxxxxxxxxxxxxxxxx> wrote in Message id:
<4486e761$0$11673$ba624c82@xxxxxxxxxxxxxxxxxxx>:

JW wrote:

Sorry that the schematic I had didn't have the power supply section
(strange, that...) To start with, I would try to isolate the power supply
from the rest of the unit, and see if your voltages return. If they do,
then you're most likely looking for a shorted component elsewhere.

How could you have known? Over 400 pages in that manual, huuuge! ;)

Anyway, I did remove the unit and did the following things:

- Resolder all solder points. Judging from the "dry solder" it
was badly needed. Unfortunately it didn't resolve the issue.

- Removed 2 suspicious Zener diodes, you know...for some
of the minor supply terminals like (-) voltages these could
be used, but it's a rather complex unit so I don't think so,
anyway - they worked fine as far as a normal diode-tester could
tell.

The power supply IS blown, but where... It's a very
complex SMPS unit with at least 3 transformers and 2
minor ones (5 in all), it have some kind of "SMD/SMT"
microcontroller that sits on it's own PCB.

What are the numbers on the micro controller? Are you able to get a
datasheet?

I've checked all resistors, and most capacitors, they
all seem to work just fine.

How did you check the capacitors?

That basically leaves
the transformers and their transistors/IC's/Thyristors etc.

Trace the circuit back from the faulty output(s) looking for shorted or
open semiconductors. Unfortunately, It may be necessary to remove them
from the circuit to do a valid test.

.

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