I got a bit of time to do some poking around on the main power board today.
I measured the output voltage after the bridge rectifier, 160v seems ok
Then i measured the output of the boost converter, HT. That was also 160v
hmmm, seems like the switching circuit is toast.
I have to say, the first measurement I took was good. 392v, but this was the only time I got this.
Also, when this rail was present the right display was working. Mostly, like in the video I posted earlier.
Once the displays died so did the HT rail. I haven't been able to get that back.
I also measured the other rails, not expecting much as they are derived from the HT rail.
+18vprim -- measured 11.5v
+12vprim -- measured 10v
Interestingly the two 3W resistors on the main board that are charring the PCB are located in the boost converter circuit acting as snubbers for the switching node.
At the moment, I am thinking a few things.
A. There is something gone bad in the boost converter, find that...replace part(s)....fixed
B. There is something wrong with the PFC section (IC4) If thats the case it looks like replacing IC4 would fix the problem.
C. There could be a problem with the control circuitry around IC1. The relay is working but the SS signal to startup the PFC and drive the boost converter may not be present.
A seems most likely to me, but I could be wrong. Considering the gate drive circuit for Q5,6,7 is powered by the +18vprim rail which is reading in at 11.5v I am still kind of stumped. To top that off the +18vprim rail is derived from the HT rail by IC2