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54645D Trigger Problem

Question asked by names on Apr 26, 2013
I have an HP 54645D oscilloscope with a trigger system problem. The edge trigger does not work on either analog channel (I can't test the digital channels) and it fails the Trigger Hysteresis self-calibration. All self tests pass, and so do the calibrations before trigger hysteresis (analog channel gains and offsets). The TV trigger works, and the scope seems to be fine in all apects except for the trigger.

I have verified the calibrator output and power supply voltages, although my multimeter doesn't have the accuracy required in the manual. I may be able to borrow a more accurate multimeter if this is likely to be the cause of the problem.

Does anyone have an idea on what is causing this problem? Schematics of the 54645D, 54645A, or any other MegaZoom scope would also be greatly appreciated.