G07 FBO 13" HV but no neck glow

InstantArcade

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G07 FBO 13" Troubleshooting

I just picked up a dig dug cocktail that plays blind.
It has a 13" GO7 FBO in it, that seems to have HV ( I can hear the line frequency oscillate and feel static on the screen ) but it has no neck glow.

Before I go to the trouble of pulling the monitor, is there any common cause of these symptoms?
 
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Okay, I've investigated it further, and I'm not sure there is HV. Although something is getting in there because after disconnecting everything I got a bit of a bite from the neckboard.

F901 and F902 are fine, the rectifier diodes are also fine. I went over the caps with an ESR meter and found c408 and c412 were bad. I replaced those but before I put things back together I tested the two chassis transistors.

The regulator seems to check out okay, but the hot is fried. Not dead short but measuring 0.035 each way which can't be good. The flyback looks like it's in good condition (can't see any cracks or burns), but not sure I want to gamble on it being good now that I know the HOT is toast.

Can anyone tell me how to test the flyback?
 
I suppose it's easier to just replace the flyback anyway. Are the replacement ones more robust than the originals?

Also, I noticed after having the chassis on my bench, that L502 was quite magnetic. Is this normal?
 
Is it possible that the monitor is charging up and having HV and then it is dropping out.
Maybe the xray protection is kicking in.
Whats the B+ voltage at the large power resistor?
 
I think the HOT is bad, it measures 0.035 each way even when removed from the chassis, so that's not good.

I've emailed Bob Roberts to see if he carries the flybacks for the 13", I might just do a complete overhaul on it.
 
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