8 Feb
2007
8 Feb
'07
11:25 p.m.
On Thu, 2007-02-08 at 07:45 -0500, Dave Dunfield wrote:
Does anyone here have technical information or
experience with the HP54201D
Digitizing Storage Oscilloscope.
I used to repair them, from time to time.
I'm specifically looking for information/help with
the analog triggering circuits.
I've obtained the HP "service manual" for this scope, and it is absolutely
useless,
no schematics, not technical descriptions... Basically, it says "Plug the scope
into your HP scope tester, press GO and replace any boards which are listed
as FAILED".
That's the "HP Way" to repair.
This morning, it's been on for over three hours
and it's still triggering
continously, even with no signal inputs (leads disconnected). Triggering
calibrations fail consistantly for both channels. So I think it has finally
gone bye-bye.
When it works, this scope is awesome - I would really like to get it
working again - any information/help would be greatly apprecaited.
A quickie: Check the power supplies for ripple. I don't remember
the tolerances, but they ARE small, somewhere in the single digit mV
range. Ripple on the power supply gets into the triggering circuits,
and is taken as input, firing off the trace. It's worth a shot -- it's
REALLY easy to check. AC voltmeter to the supply...
Peace,
Warren E. Wolfe
wizard at voyager.net