HP 54645D Oscilloscope Trigger Problem

[NickAmes]

I have an HP 54645D oscilloscope with a trigger system problem. The edge, glitch and pattern triggers don't work on the analog channels. It also fails the Trigger Hysteresis self-calibration.

Everything else seems to work fine. The digital channels trigger properly, and the TV and line triggers work on the analog channels. It passes the self tests, as well as the first four self-calibrations (analog channel gains and offsets). Unfortunately, because it fails the Trigger Hysteresis self-cal, it won't save the results, so both analog channels have an offset.

I've done some probing around the trigger area of the scope, but it's over my head. I haven't been able to find a schematic or CLIP (Component-Level Information Package) available online. There seems to be a problem with the channel 2 level comparator, but I'm not sure if that's the cause of the issue.

Any information would be helpful, and I would be willing to pay money for a copy (even just to borrow) of the schematics for this scope or the 54645A.