Hameg Oscilloscope Troubleshooting Problem

[jts1957]

Much info in manual, but it will answer questions about voltages and feedback.

[laluna]

After I don't know how many hours of cursing and head scratching I have fixed my oscilloscope. It was the bridge rectifier for the +12 volt supply. All the other supply lines use the +12 volt line as a reference so if that goes faulty then all hell breaks loose. The lesson learned is don't suspect the worst. The buzzing in the high voltage CRT supply board was from the 50Hz signal going through the HV transformer. I changed the 10kV Cascade and the HV transformer unneccessarily at a cost of £65. I also suspected arcing in the CRT which would have meant the scrap heap.

Anyway, thanks to my two helpers on ESI, much appreciated.

Dan.

[laluna]

Follow up: I did manage to track down the fault after replacing the cascade and HV transformer at great expense. It was the bridge rectifier in the main LV DC supply All the buzzing and dotted trace was due to half wave rectified DC on the main supply lines. Cost, about 2 pounds sterling. Oh well!
Thanks for all the help and sorry it's late.
Dan.