J
Jason D.
It IS HV shutdown on brights or more accurate, current overdrawn
through sum total of 3 CRTs. Triggers the SCR (Q903) There is
network of 2 resistors and two caps, transistor and the divided
voltage goes through a zener to the protection circuit. That circuit
takes off the 6.3V heater and 240V cathode taps on the flyback.
Funny, when I narrowed down to green CRT, it didn't have diagonal
lines even at max, just reduce the pot on that CRT stops the shutdown
but the greyscale is bad. Focus is staying good. But the size of
picture still increase if I turn up the contrast via user control.
As a check I did this reduction on a blue CRT and leave the pot stock
on Green, it doesn't trigger as much compared to green CRT that needed
much reduction.
This is bit diffcult because the sum of current through three CRT at
defaults triggers but pull one of CRT board and won't trigger the
shutdown. No coolant leak.
What now?
Cheers, Wizard
through sum total of 3 CRTs. Triggers the SCR (Q903) There is
network of 2 resistors and two caps, transistor and the divided
voltage goes through a zener to the protection circuit. That circuit
takes off the 6.3V heater and 240V cathode taps on the flyback.
Funny, when I narrowed down to green CRT, it didn't have diagonal
lines even at max, just reduce the pot on that CRT stops the shutdown
but the greyscale is bad. Focus is staying good. But the size of
picture still increase if I turn up the contrast via user control.
As a check I did this reduction on a blue CRT and leave the pot stock
on Green, it doesn't trigger as much compared to green CRT that needed
much reduction.
This is bit diffcult because the sum of current through three CRT at
defaults triggers but pull one of CRT board and won't trigger the
shutdown. No coolant leak.
What now?
Cheers, Wizard
