Hello,
I recently acquired a HP 3651A. When I first got it, it didn't want to turn on. After some troubleshooting I replaced a diode package in the power supply (picture attached). It seems to work, but unfortunately the screen is compressed. What could be causing this? Anybody is more familiar with CRT drivers than me. I'm at least 95% sure that the digital display driver is working properly. Anyway probing around, the fast sweep synchronizer signal seems to be what it should be (FSYNC)(The service manual has pictures). The only anomaly I have seen is the LowPdrive (pulse drive) and FSYNC seem to be a little bit out of alignment. (see picture) Usually they are supposed to be aligned
If anybody is interested in what I'm saying, have a look at the service manual.
(Start at page 214 for the analogue display)
http://www.ko4bb.com/manuals/174.148.87.57/HP_3561A_dynamic_signal_analyzer_service_manual_V2_1983.pdfIf you don't care at least I have some photos! Very nicely built that's for sure!