Hi,
I found a Tek 2236 scope in the garbage. After running it for a few minutes, the power supply failed. Powering the scope from a 42 volt supply caused the NPN transistors to fail.
I replaced the transistors with the MJE15030 (the hFe was measured to be 40 for both transistors). The scope powers on, but when the transistors get hot the power supply stops oscillating and the scope shuts down. Any ideas as to what could be happening here?
Also, when the scope powers on, the horizontal trace doesn't go all the way to the end. Increasing the intensity causes the trace to expand on the screen, which shouldn't happen. The trace goes from being smaller than the CRT to extending past the edges of the CRT when the intensity is increased.
The scope is from 1984 and the serial number is for the earliest revision.
Board