Fixing a dead dot matrix display board

The other day the DMD just went “poof” on one of my machines.  After doing a little research, and checking connections and things, I realized the DMD board died.  In this installment, I walk through the process of rebuilding the power supply-portion of a Bally/Williams WPC DMD board.  In part 1 I describe what I’m doing and introduce you to the tools I’m using.

 

Next up, let’s talk about using a meter to check circuit board traces as we go along..

Desoldering and replacing components.

Now the moment of truth!  One thing I want to add is pay very close attention to each item you are replacing on these boards.  Two diodes, capacitors or transistors may look alike, but have slightly different values or part #s.  The three power transistors and the diodes are not all the same.  You may have to bust out a magnifying glass to note the different in the markings on each part.  This should also be cross-referenced with the schematics and/or parts list from the game manual.

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6 thoughts on “Fixing a dead dot matrix display board

  1. I’m having exactly the same problem with my RS. Did you find out what fried the HV section? Has your STTNG been working or was some other issues with display or power supply?

    • My STTNG is working fine. The heat and stress on the high voltage part of the video board causes components to fail. Replacing certain parts made it work reliably again.

  2. Thanks for doing this video, I’m getting ready to do the exact thing on a STTNG. Great job and keep up the good work.

    -Dave

  3. Brilliant set of videos and EXACTLY what was needed to give me the confidence to repair my Theatre of Magic myself. One question though – how can you be sure that it is not either the DMD itself which has failed, or the power supply TO the DMD board? Many thanks for you efforts!
    David

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