(Topic ID: 300988)

Williams Gorgar - voltage issue on driver board

By tomservo

21 days ago



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  • 3 posts
  • 2 Pinsiders participating
  • Latest reply 10 days ago by tomservo
  • Topic is favorited by 1 Pinsider

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#1 21 days ago

I recently picked up a non-working Gorgar, but I seem to have it mostly working again. All populated scanbe sockets have been replaced (before I got it), and I just put new 40-pin board interconnect connectors on it.

One of the things I've been working on is trying to get the sound & speech working. All sounds & speech work with the test switch on the sound board, and I also put them in my Firepower, and it works fine in there. So while probing around on the driver board checking for voltages on the solenoid TIP 120/102's with the game in attract mode, I noticed that the whole bank of transistors Q25-45 (circled in red in the photo) have no voltage. All the ones above it, Q2-23 measure at expected coil voltage ~39/40VDC.

BTW - I know the resistors are missing at Q41. The knocker was seized and coil burned up, taking out Q40/41. I'm just waiting for the new resistors to come in, I didn't have those on-hand.

Any thoughts on where I should look next to see why I'm not getting voltage to that whole bank of transistors?

Thanks!

Gorgar-Driver (resized).jpg
#2 15 days ago

Look for a broken trace between Q25 and Q27. Those TIP120's are all fed from a common buss that starts at 2J10. It looks like that buss starts at Q45 and works down to Q15.

#3 10 days ago
Quoted from jscaptura:

Look for a broken trace between Q25 and Q27. Those TIP120's are all fed from a common buss that starts at 2J10. It looks like that buss starts at Q45 and works down to Q15.

Thanks for the pointer, found it! Got that fixed now!

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