[time-nuts] EIP545A 18GHz counter query

[Chuck Harris]

I had the same problem with my 545A, and it turned out
to be a tin whisker thing.  Scrub both the GPIB card, and
the main controller card with a brush, and then blow them
off with compressed air.  Try to get the air close to each
chip and socket, and blow from all angles.  Plug the cards
back in, and I think you will be in for a pleasant surprise.

-Chuck Harris

Chris Wilson wrote:
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>> Chris,
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>> Put a ohmmeter across any of the capacitors on the GPIB board and see what
>> the resistance is.  Since that kills the unit, I suspect the resistance is
>> low (?shorted tantalum) or there is a problem with one of the chips that
>> takes the 5 VDC buss down.  Make sure of the polarity of your DMM, + to +
>> and - to ground.
>
>> Alternatively, there is a short on the +5 VDC line at the connector on the
>> mother board that is 'actuated' by plugging the board in.  Measure the
>> resistance to ground of the +5 VDC buss (power off) with the GPIB board
>> plugged in and not plugged in.
>
>> Joe
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>
> Thanks again Joe, checked the tants on the GPIB board and they seem
> fine, have put this aside until the rest is AOK. Then I'll pull the
> chips one by one and try and isolate the issue.  The 5 v bus seems
> good with the board in or out, too.
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> 29/11/2012 09:27
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