(Topic ID: 241036)

Tech: MM - DMD Issues??


By PinPlayer2

6 months ago



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  • 14 posts
  • 6 Pinsiders participating
  • Latest reply 6 months ago by PinPlayer2
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    #1 6 months ago

    Hi All, On my Willams MM - Original, I turned it on and noticed that the DMD was wavering and all the middle was out and around the edges was wavering an lit. The more I have had it on troubleshooting it, Now the DMD is totally out.

    Game has worked flawlessly for 11-12 years I've owned it.

    Here is what I've checked:
    1) I put in a spare DMD that is used but worked last time I used it but had one or two dots weak. Nothing it is totally dark
    2) All 6 LED Power Driver Voltages LED's are lit signifying I have all my voltages
    3) LED 501 is flashing at it normal rate for the +5VDC
    4) All 3 CPU LED's are working as manual indicates they should
    5) I tested AV Board J605, pin 1 & 2 and I am getting 87.6 VAC
    6) At J604, with the DMD connector unplugged, here are my readings:
    Pin 1 = -1.7 VDC
    Pin 2 = -1.3 VDC
    Pin 6 = 0 VDC
    Pin 7 = 0 VDC
    Pin 8 = 0 VDC

    At the DMD with connector connected:
    Pin 1 = -1.7 VDC
    Pin 2 = -1.3 VDC
    Pin 6 = 0.08 VDC
    Pin 7 = 0.1 VDC
    Pin 8 = 0.1 VDC

    What is my problem, anything else I need to check?
    Trying to figure out where my problem is.

    Thanks for any help!

    #2 6 months ago

    Also the whole game plays normally and all other functions are normal

    #7 6 months ago

    Thanks DumbAss, yes i had checked those two fuses in circuit but i wll definitely check them out of circuit.

    On the voltages, I clearly checked them in DC Voltage, the only AC check I did was on pin 1 & 2 of J605. I thought that was weird to as the LED on AV Board that flashes slowly signifies the +5VDC

    I'll check tonight and report back.

    Thanks for the help, greatly appreciated.

    #8 6 months ago

    Also the answer your question, I had the black lead clamped onto the ground strap on the bottom left of corner inside backbox beside the grounding screw/lug and then used only the red lead of Voltmeter. I am using a premium meter as I have a Fluke 87

    #9 6 months ago

    Hi Guys, I want this fixed ASAP, I ran home and rechecked this again, here are my findings:

    I removed all fuses on the AV Board and all checked good

    I did a recheck and secured a better ground and got more accurate readings:

    I tested AV Board at J605, pin 1 & 2 and I am getting 86.1 VAC

    At J604, with the DMD connector unplugged, here are my readings:
    Pin 1 = -116 VDC
    Pin 2 = -91 VDC
    Pin 6 = 5.03 VDC
    Pin 7 = 11.66 VDC
    Pin 8 = 2.2 VDC

    At J604, with the DMD connector plugged connected to DMD, here are my readings:
    Pin 1 = -116 VDC
    Pin 2 = -104.9 VDC
    Pin 6 = 5.03 VDC
    Pin 7 = 11.66 VDC
    Pin 8 = .63 VDC

    At the DMD with connector connected:
    Pin 1 = -117 VDC
    Pin 2 = -105 VDC
    Pin 6 = 5.0 VDC
    Pin 7 = 11.66 VDC
    Pin 8 = 0.6 VDC

    Next Steps?

    #11 6 months ago
    Quoted from Mageek:

    You have no 62V , if it's not a fuse you will likely need to rebuild your high voltage section.
    https://www.greatplainselectronics.com/proddetail.asp?prod=WPC95-HVP-KIT

    Thanks, yeah from what I reading that's what I am thinking too!

    #14 6 months ago

    Hi guys, thanks all you prompt for the feedback. I am getting someone who knows board work well to go through it all.

    FYI..... I did try a known good DMD in the game and nothing, dead, it's the board for sure.

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