G07 Vertical Collapse after adjusting B+

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I had been running this monitor for a few hours every week for the last month (maybe 10hrs total) after replacing:
- Caps
- Flyback
- HOT
- F901
- D503
- R908
- Reflowed Connectors

Today, I realized that I hadn't checked the B+ so I adjusted it from 118 to a steady 120.

I coined up, and played for a few minutes until the vertical deflection went 'blip' 'blip' then into a collapse. The game still played, and a light smell of 'magic smoke' wafted from the coin door.

From the threads that I've found on G07 VC, It seems like one (or more) of these are the likely culprit.
- FR401
- Vertical Transistors
- IC501


Have you guys ever had one of those 'let the smoke out'? The FR401 maybe?
Also, I've been trying to figure out an equivalent for 2sd478 (not NTE). Anyone know of one?
 
Last edited:
When you replaced the caps did you replace C402 2.2 ufd 16V tantalum capacitor? If it shorts you will get vertical collapse. It's not listed in any of the flow charts.

Ed
 
Is that the little blue one next to IC501? I couldn't find C402 labeled on the component layout.

When you replaced the caps did you replace C402 2.2 ufd 16V tantalum capacitor? If it shorts you will get vertical collapse. It's not listed in any of the flow charts.

Ed
 
I had been running this monitor for a few hours every week for the last month (maybe 10hrs total) after replacing:
- Caps
- Flyback
- HOT
- F901
- D503
- R908
- Reflowed Connectors

Today, I realized that I hadn't checked the B+ so I adjusted it from 118 to a steady 120.

I coined up, and played for a few minutes until the vertical deflection went 'blip' 'blip' then into a collapse. The game still played, and a light smell of 'magic smoke' wafted from the coin door.

From the threads that I've found on G07 VC, It seems like one (or more) of these are the likely culprit.
- FR401
- Vertical Transistors
- IC501


Have you guys ever had one of those 'let the smoke out'? The FR401 maybe?
Also, I've been trying to figure out an equivalent for 2sd478 (not NTE). Anyone know of one?

Smoke usually come from resistors

you might confirm R420, and R522, R523 need the 12vs to the IC as well.

lift one end of each part if not obvious its open..
 
I checked R522 & R523. Both were within spec. My board didn't have an R420 (unless you were making a smoke-joke).

FR401 was indeed bad, so I replaced it. It powered up great, deflection was fine, then it collapsed for a half-second and the smell of magic smoke wafted out again. I left it running - expecting the collapse to happen again - but it hasn't.

Would failing vertical transistors cause R401 to burn up?

Smoke usually come from resistors
you might confirm R420, and R522, R523 need the 12vs to the IC as well.
lift one end of each part if not obvious its open..
 
R 420 is between the vertical
Transistors. On schematic

You need to replace the vertical
Transistors both for best results
Not test with meter. Just replace
And FR401.. all at same time.
 
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