@Castellen Thanks for the document link to your webserver, there's lots of interesting things on there
I think the schematics I've been using is pretty close to my monitor, it has a different H.O.T but maybe that could have been changed in the past. The Flyback is labeled as T202 but mine is T201.
Also pin 4 of the flyback is not connected to earth like mine, but I think that must be an error in the diagram, as I think pin 4 would be part of the X-Ray protection system.
I was thinking along the same lines as you, that it could be a power supply issue, but the more I thought about it and the history of this repair:>
>The monitor was working well until it started the high-pitch-whine and smoking.
> Replaced H.O.T circuit components and now get high-voltage to the screen for a second.
It made sense that it could be the X-Ray protection, so I disconnected pin 8 of IC201 (the X-Ray pin) and tried the monitor on reduced voltage.
I reduced the voltage with a very crude home-made current protection device, made out of a light dimmer switch and a 60w light bulb
The monitor powered up and stayed on, the LED was flashing but I think that was just because it was running on low voltage through my very crude current restrictor.
When I cut the power, I got a very bright white spot on the screen for a second or two.
I've not tried it on full mains yet, because I don't have a lead X-Ray proof suit
So from that experiment it must be the X-Ray protection circuit that was cutting off the monitor.
One thing I never mentioned was that the original flyback was a DCF-1580, but I replaced it with what is supposed to be a compatible MSH1FCT31.
After some reading-up about this type of protection circuit on CRTs, it says it can be cause by:
> a capacitor in the HOT circuit that's changed in value (I will check or replace them).
> a faulty Flyback (maybe it got damaged because it was switched on for a second with those faulty components)
> wrong B+supply voltage (Wait!
thinking-outloud I think I tested this and it was 109v, I was thinking it should be 110v so thought it was ok, but now I see it should be 105v?
?)
I did have more to say here, but now I think I better check that B+supply again, that is the voltage that goes to the HOT circuit winding of the flyback? pin 7 on my diagram, right??? And can be adjusted somewhere?
Thanks for sticking with this, maybe I might need to get help from a TV CRT repair group, as messing around with this monitor with protection disabled is a bit scary lol