[time-nuts] HP-5370B Running Hot...

[Greg Burnett]

Good advice Burt.

While we're on the subject of over-heating issues, on instruments with fan 
filters, I'd like to mention the importance to clean their fan filters at 
regular intervals.

See:
http://www.hparchive.com/Bench_Briefs/HP-Bench-Briefs-1995-01-03.pdf

Greg

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Burt wrote:
...One day whilst I had my back turned on it the pass transistor
in the power supply shorted and in turn took out most of the devices
on the mother board turning the mother board into a wind chime
vane.  I was fortunate enough to find another mother board, replaced
it and it now was up and running again but still too hot in my ongoing 
opinion.

Here's what I discovered: On the rear of the HP-3336A are two power
selector switches.  Instead of mine being set to 120 VAC I discovered
they were set to 100 Volts.  I don't know why or how they came to be
set at 100 VAC since the instrument came from a local engineering
firm, not Japan.  Maybe somewhere along the way one of the switches
simply got bumped.  Anyway, it was just one position off from where
the combination should've been set.  Correcting the primary voltage
selector cleared the heat problem and the instrument, with my monster
heatsink, now runs quite cool.  So, for whatever little bit it might
be worth, if you think it's running unusually hot, check the voltage
selector switches on the rear and possibly the primary DC voltages
into the regulators.

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