tron linear power board no +5 (wacko actually)

tron guy

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I use my wacko to test monitor chassis' (g07)

Anyway, I was transferring a chassis back and forth as I generally do when doing repairs.

Anyway game was working perfectly, the next second I only have a blue screen.

I am literally running out the door so I just quickly tested the +5 on the first capacitor. It is something piddly like .8VDC

The next Cap has +12.32VDC

The power board has been rebuilt (a couple of years ago).
Probably one of the bottlecap transistors went out on me huh?

I have to run, I'll work on it later.
 
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pulled both bottlecap transistors and they test good. maybe I'll find time to pull the smaller 3 legged transistor tomorrow to test.

Something in the 5v line though. I have +12 on the middle cap and +15 (or so) on the 3rd.

Though the Base (leg) on one of them has lost it's solder pad, and I cannot tell where it is supposed to have continuity.
 
I pulled all 3 of the heatsink transistors, they tested good, thoigh the tp31 had a lower resding than a spare I had so I swapped it.

I get +5.33 when the 2-15 pin molex' are disconnected, it drops to .8vdc when they are connected. I'm sure I've had this problem before, I guess I'll go look for old threads.

I did run a couple of jumpers from the heatsink transistors where I thought the solder pads were questionable.



Problem solved , U2 was bad.
 
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