RM-503 oscilloscope TV project

[Kevin Kuehn]

Because of the way that circuit regulates it's not going to be very happy being brought up slowly on a variac. It needs to have the expected line voltage within a window in order to lock in oscillating. You pretty much need to make sure the filter caps on all the outputs of T602's secondaries are good. The oscillator circuit relies on the -100 volt supply and 85v reference in order to regulate all the secondary voltages proportionally. It's a feedback loop intended to shut down all the secondary supplies if it's not getting the correct reference voltages.

[Yamamaya42]

Originally Posted by Kevin Kuehn

Because of the way that circuit regulates it's not going to be very happy being brought up slowly on a variac. It needs to have the expected line voltage within a window in order to lock in oscillating. You pretty much need to make sure the filter caps on all the outputs of T602's secondaries are good. The oscillator circuit relies on the -100 volt supply and 85v reference in order to regulate all the secondary voltages proportionally. It's a feedback loop intended to shut down all the secondary supplies if it's not getting the correct reference voltages.

I suspect the other filter caps are very leaky, even though they did not get boiling hot like that one did that I replaced, after all it's almost 50 years old, and when I took that one apart, it was dry and crystalized. as shown in a prev post, so even though the DVM says they are OK, I do not trust them any farther than I can comfortably spit a rat, and not to bring up the old reform / replace argument, I am going to STILL follow my personal belief that all old electrolytic caps beyond 40+ years in the PWS should be replaced.