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

Sorry - I know this is a bit OT, but I don't know many places to ask... Does anyone here have technical information or experience with the HP54201D Digitizing Storage Oscilloscope. 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". I've had this machine for a few months. It's always had problems with the analog triggering. When I first got it, channel-1 would not trigger at all, but channel-2 and external triggering worked most of the time. Channel-1 would fail the trigger Hysteresis & Level calibration, Channel-2 would usually pass. I've been using it with Channel-2 triggering, however within the past week, I've noticed that it triggers continuously after power on (Doesn't matter what trigger level etc. you program), but after a few minutes it would settle down and work as before. Thinking it might be a calibration issue, I re-ran self-calibration, and surprisingly Channel-1 passed, after which I could use both channels with full triggering, however both of them exhibited continuous triggering after power-on, and the time taken to settle down has been increasing. 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. Regards,. Dave -- dave06a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.classiccmp.org/dunfield/index.html