G07 HV shutdown

ieure

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Donor 2014-2015
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So I have this G07 that was dead. Blown F901 & shorted HOT. Replaced both and it comes up, but goes right into HV shutdown. Works if I pull X701. Measuring B+ gives 141v. The b+ voltage doesn't seem to change at all when I adjust R909. I measured R909 with a meter and it seems to be working fine.

All the diodes in the rectifier test good. I pulled and tested X901, X902, and X04. They all tested good. I swapped X04 with one from a parts board. Same problem. Lifted a leg of R908 to test it, and it tests fine.

I did some searching and other threads mentioned C511 causing this issue. I pulled it and it tested okay. I was going to swap it out anyway, but the only one I have meters at 70uF instead of 47uF, so I just reinstalled the component that was there.

Not sure where to go from here. Maybe R910? Can I measure that in-circuit, or do I have to lift a leg?
 
Describe the other maintenance to this monitor. Is the flyback original? Has it been capped? Or, did you just replace those parts?
 
Describe the other maintenance to this monitor. Is the flyback original? Has it been capped? Or, did you just replace those parts?

Doesn't look like anything else has been done to it. I haven't done anything other than what I said. Flyback looks original, but doesn't indicate trouble — no cracks or anything.
 
This thing is still just killing me. Took another pass through today. Because R909 changes resistance but B+ doesn't seem to change, I had a hunch that R909 or R910 might be bad. They seem fine. I checked a bunch of other resistors: R906, R907, R903-4-5, R910, R912 — all fine. R909 was only going up to 1.8Ω, so I replaced it. No change.

Currently suspect X901. Looks like it should take 121v on the base, 145v on the collector, and emit 120.6v. Base and collector voltages seem okay, but the emitter is putting out ~140v. Even though it tested okay, there could be something wrong in there, so I guess I'll swap it out and see what happens.

Anyone run into anything similar before? I'm about to give up on this chassis.
 
Okay, I give up. Swapped X901 & X04 with new components — no change. Leaving this here for posterity.
 
You have a crack in the deflection board. Pull the chassis, flip it over and start checking continuity from point to point on each trace until you find the crack. Then check all areas around the crack..
 
Did you replace the flyback? Your new work doesn't indicate.

Check for cracks in the PCB.

What is the B+

Did not replace the fly. B+ is around 160v with X701 removed. I haven't gone over it with a fine-toothed comb, but there are no obvious cracks in the PCB. It was in a game and working for ages before abruptly ceasing to function, so I don't know where a crack would have come from.
 
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