Anyone have real tech info on HP54201D (Digital Storage Scope)

[Warren Wolfe]

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