(Topic ID: 276406)

Dead DMD on Alvin G.

By JReedie

3 years ago


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  • 16 posts
  • 7 Pinsiders participating
  • Latest reply 3 years ago by JReedie
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    #1 3 years ago

    Hi folks so recently my Mystery Castle killed it's DMD. I've swapped out the DMD itself, reseated all the connectors, fuses are all fine, everything I can think of seems fine. The DMD controller is also getting it's correct voltage so not sure what else could be the problem?

    Any ideas would he greatly appreciated as I have no idea when it comes to Alvin G. Machines lol

    #2 3 years ago

    Ribbon cable?

    #3 3 years ago

    Yep both ribbon cables tested out fine too

    #4 3 years ago

    Maybe one of the ROM chips needs to be reseated?

    #5 3 years ago

    Can you please post the voltages you measured? Tested the DMD in another game?

    2 weeks later
    #6 3 years ago
    Quoted from PinballManiac40:

    Can you please post the voltages you measured? Tested the DMD in another game?

    Okay so the DMD controllers LED is lit so it's powered up, measuring the outputs of the DMD controller at J103 I get:
    Pin 1: - 4.1v
    Pin 2: 5v
    Pin 4: 0
    Pin 5: 0
    Pin 6: 5.2v
    Pin 8: 69.9v

    So I'm presuming the problems are with pins 1 (-125v) and 2 (-113v) anyone know what could of caused this?

    #7 3 years ago

    Contact Mike Pacak, he has them in stock.

    #8 3 years ago
    Quoted from MrBally:

    Contact Mike Pacak, he has them in stock.

    Thanks but I'm looking to fix this one I have, just looking for guidance as unfamiliar with Alvin G. Games.

    #9 3 years ago
    Quoted from MrBally:

    Contact Mike Pacak, he has them in stock.

    If he ever answers you!
    Few folks I know have been trying to contact him, nothing.

    #10 3 years ago
    Quoted from JReedie:

    So I'm presuming the problems are with pins 1 (-125v) and 2 (-113v) anyone know what could of caused this?

    Yes. Faulty parts after 30 years.

    Coin op Calderon I believe can do repairs this board. I would also test the DMD in another game.

    #11 3 years ago
    Quoted from PinballManiac40:

    Yes. Faulty parts after 30 years.
    Coin op Calderon I believe can do repairs this board. I would also test the DMD in another game.

    Have already swapped out the DMD with a known working spare and that didnt work either, it's not the DMD sadly

    #12 3 years ago

    No. I am saying to move the Alvin G DMD into a different DMD game to be sure the DMD works. This is to make sure you don't have 2 issues.

    The DMD controller board is not supplying the correct voltages so no matter what DMD you put in the Alvin G game, it is not going to magically work.

    #13 3 years ago

    Either way you will need to rebuild the high voltage section of the display driver board. Have you taken it out and inspected it? Component lists are in the manual on IPDB and seem complete. The circuit seems similar to most other DMD games of the era; you may be able to use most of the parts from a WPC display controller rebuild kit.

    1 week later
    #14 3 years ago

    So a quick update: I've rebuilt most of the high voltage circuit on the DMD controller. Still waiting on filter caps to replace C109 & C108. Turns out that both 47kΩ resistors at R102 and R103 were dead, so was hoping replacing those would solve the problem, sadly not.

    So my voltages at the DMD are now reading:
    Pin 1: -112v (should be -125v)
    Pin 2: -98v (Should be -113v)
    Pin 4: GND
    Pin 5: GND
    Pin 6: 5.2v
    Pin 8: 69.9v

    My 98v AC coming from the transformer is high at just over 110vAC.

    So I'm getting a little sign of life on the DMD, will get a few random dots fire up then slowly they start to disappear until the whole display is out once again. I've replaced the ribbon cable from the DMD driver to the DMD and that made no difference, so I'm now suspecting the CPU or the CPU ribbon cable. Would be interested to hear your thoughts/ideas.... I miss my mystery castle IMG_20200925_013534 (resized).jpgIMG_20200925_013534 (resized).jpg

    #15 3 years ago

    Your voltages seem fine to me.

    Quoted from PinballManiac40:

    move the Alvin G DMD into a different DMD game to be sure the DMD works.

    2 weeks later
    #16 3 years ago

    Replaced U23 on the driver board with no luck. Completely running out of ideas now, any thoughts anyone?

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