This is probably a long shot, but … I have this Protek (aka Hung Chang) P3502 Oscilloscope that has some issues. Does anyone have a service manual or schematic diagram for this scope?
A couple of power resistors (I am guessing they’re either part of the vertical or horizontal amplifier section; I can’t tell which) were getting super hot. I figure either too much current due to a shorted component or due to overvoltage from the supply.
Trying to figure this out without a circuit diagram is a nightmare. Trying to create a circuit diagram by tracing circuits is… shall we say… challenging. 
So thought I’d ask around for a manual. Thanks in advance.
Thanks!
Michael