(Topic ID: 311356)

DMD turns on for a few seconds and then off Whitestar

By radix

3 months ago



Topic Stats

  • 4 posts
  • 3 Pinsiders participating
  • Latest reply 3 months ago by radix
  • Topic is favorited by 2 Pinsiders

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#1 3 months ago

Hello all,

I have a 1st gen Harley-Davidson, when powering up the DMD only turns on for a few moments during which it displays the game name and display ROM version. It then goes dark and shows nothing again. The game boots as normal. I switched out the display controller board with a known good one swapping the ROMs and am still getting the same issue. I also changed out the ribbon cable and DMD itself to test it, same behavior where it shows the display version for a few moments and then turns off.

I have double-checked all the cables are correctly connected and pushed on the ROMs to ensure they are seated on the CPU and display controller board.

I do not get what the issue could be. Any thoughts? Thank so much for the help!

#2 3 months ago

The display board is not receiving commands from the CPU over the 26-pin ribbon cable.

The splash screen that you're seeing at boot time is the display processor's boot screen. After that the display processor will idle and wait for commands over the 26-pin ribbon cable. When a command is received, the display processor responds by sending an animation to the DMD.

If you've tried swapping the display controller and ribbon cable, the problem may be with damage to the data output buffer (U201) on the CPU board.

#3 3 months ago

The very first thing to do is confirm that all of the voltages are correct and are making it to the DMD.

ALWAYS test the voltages before doing anything else.

3 weeks later
#4 3 months ago
Quoted from Dmod:

The display board is not receiving commands from the CPU over the 26-pin ribbon cable.
The splash screen that you're seeing at boot time is the display processor's boot screen. After that the display processor will idle and wait for commands over the 26-pin ribbon cable. When a command is received, the display processor responds by sending an animation to the DMD.
If you've tried swapping the display controller and ribbon cable, the problem may be with damage to the data output buffer (U201) on the CPU board.

Thank you so much Dmod, I removed U201, put in a socket and a new NTE NTE74HCT273 IC and it works as it should now. You where a huge help, thank you!

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