Tek 603 - recapped LV board, now moving on to other problems. Advice on -30V reg?
I've been working on a 603 XY and began by recapping and testing on
Variac, which cleared up display bloom and a squiggle.
What I have now is:
* a somewhat defocused (2-3mm), very bright spot
* unresponsive intensity control
* focus control has effect but cannot focus spot
All the above seems to indicate a HV issue. I am waiting on a HV probe
so I don't have a measurement yet. But, possibly related:
Was not able to bring the -30V into spec, rails currently measure
+215: about 250
+15: about 17.7
-30: about -36
The -30V adjustment is R878 trimmer but it has no effect on the voltage.
I'm looking at the regulator section schematic, I've checked the VR870
zener and it's nominal ~ 6.2V.
I'm pretty new to repair so I was hoping for a pointer or two to where I
could look at re this initial inability to regulate or trim -30V.
I believe this is the most relevant part of the schematic: