(Topic ID: 83531)

What the heck where they doing? (WPC-89)


By dhalem

5 years ago



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  • 8 posts
  • 6 Pinsiders participating
  • Latest reply 5 years ago by johnwartjr
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20140308_080342.jpg
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#1 5 years ago

I recently picked up a Williams IJ and found the hack seen in the pics below. The capacitor at C31 on the MPU board is bridged with a test lead to TP2 on the power board on one side and the ground of the board on the other. I have no idea what they were trying to do and have left it alone for now, but I'd like to understand it and fix it properly if necessary.

20140308_080409.jpg20140308_080342.jpg

#2 5 years ago

Looks like they're robbing the +5v power from the test point and supplying the CPU board with it.

Assuming the game doesn't boot if you remove it?

#3 5 years ago

I haven't tried removing it for fear of rocking the boat. I can do so tonight. Assuming that is the case, what's the right way to track this down and fix it?

#4 5 years ago

PM sent.

#5 5 years ago

See that little Z connector in the bottom right of the second picture? That's a good place to start if you're not getting 5v from Power Drive to CPU, it's a common failure point.

#6 5 years ago
Quoted from dhalem:

I haven't tried removing it for fear of rocking the boat. I can do so tonight. Assuming that is the case, what's the right way to track this down and fix it?

If the 5v isn't making it to the CPU board without that jumper, then the game won't boot. No harm in removing it from the jumper for a moment to test it out...just don't short it on something else. If it boots with the jumper there, the question is does it play okay without resetting...if yes....why was it there in the first place? If no, then......go from there. If it doesn't even boot without the jumper, then you know the 5v isn't getting to to the CPU board...or if it is, there's something borked on the CPU board itself, but it's a lot better starting point.

#7 5 years ago

They are cheating a failed connector. Mesure the +5vdc with jumper in place. Measure 5vdc with jumper removed. If voltage dips down, you have conenctor issue. As others have pointed out, the "Z" shaped connector is where i would at first.

#8 5 years ago

Agreed. Pretty common hack. At least they used jumper leads - I've had a few soldered to the test points and the caps. Replacing the connector would cost a buck and take 10 minutes....

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