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(Topic ID: 271041)

WPC Sound Board Repair Advice


By SeymorGoldfarbJr

4 months ago



Topic Stats

  • 7 posts
  • 4 Pinsiders participating
  • Latest reply 4 months ago by SeymorGoldfarbJr
  • Topic is favorited by 1 Pinsider

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    Sound Board (resized).jpg

    #1 4 months ago

    This is in regards to my Gilligan's island sound board (A-12738-20003). The back story is the sound was very scratchy when I bought the game. I took the easy route and bought Marco cap kit for it. The board was clearly worked on in the past. I replaced all the caps except for the two large caps as they looked newer. The game sounded better but not great. I then replaced the two larger caps. When I put the board back in the game to test it, I accidentally connected both sound plugs (J504 and J505 ) to the positive output (pin 2 on each connector, J504-2 and J505-2) instead of pin J504-2 and J505-3. Within a few seconds I could smell a chip or component burning and I shut the game off. There is absolutely no sound output from the board now.

    I order a new amp (U1) and replaced that, no change. I swapped out the three sound ROMs (U14, U15, U18) and the three other socketed chips (U10, U11, U13) into a known working board and it still worked perfect, so I know those components all are good along with the speakers in my game.

    The R20 resistor looks like it got pretty warm. It measures around 2.5 Ohms. It should be a 1 Ohm resistor. I have not replaced this yet as I don't have the correct resistor in stock.

    I'm looking for suggestions on what components I likely damaged which I should check or replace?
    Sound Board (resized).jpg

    #2 4 months ago

    You might want to check U3 the -12v Voltage regulator and also U4 12v Regulator.

    #3 4 months ago

    Also check R23 and R24, in case the board came from a different game.

    #4 4 months ago

    Is there a rebuild kit for WPC sound boards that I can purchase?

    #5 4 months ago
    Quoted from whthrs166:

    You might want to check U3 the -12v Voltage regulator and also U4 12v Regulator.

    I measured at the voltage regulators:

    7812 - 26VDC in, 12 VDC out
    7912 - 0.4VDC in, 0.6 VDC out

    Does that indicate the 7912 is bad, or that I lost voltage somewhere before the regulator?

    #6 4 months ago

    Those voltages don’t sound right. Check the schematic I don’t remember what you should see there.

    #7 4 months ago

    I figured it out. The top side trace on C24 did not have continuity to the negative side of the cap. I fixed that and the sound board works again. Unfortunately, the static in the sound persists.

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