(Topic ID: 194121)

Frankenstein DMD problem

By Catweazle0172

2 years ago

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  • 21 posts
  • 5 Pinsiders participating
  • Latest reply 2 years ago by Catweazle0172
  • Topic is favorited by 1 Pinsider


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#2 2 years ago


The Sega large display have their own processor board. If you do not get 5vdc on the display board connector, you get this reboot screen.

Here is a link which indicates the steps you can follow to fix yout problem. Go to the display section, 192x64.


I had this problem on the batman forever and replaced the capacitors and BRs to get the 5vdc. Also there is a wiring kit from Marco pinball which gives an alternate direct connection to the display board. You can start with it.


#6 2 years ago

4,95 vdc is not enough, the display board processor must work with 5vdc. The wires you soldered are useless if the voltage outgoing from the power board is 4,95vdc. Try to replace BR1

If the Super Size DMD Still Doesn't Work...
Additionally, the +5/+12 volt bridge rectifier (DB1) on the power supply board may need to be replaced. If this bridge becomes "leaky" (less efficient), it may not be able to supply the robust +5 volts needed on the display board. So if the above modification does not work, replace bridge DB1 next. When replacing DB1 on the power supply board, also solder an 18 guage wire from the "+" lead of bridge DB1 to the "+" lead of capacitor C4. Solder another 18 gauge wire from the "-" lead of the bridge DB1 (the lead diagonal to the bridge's "+" lead) to the "-" lead of capacitor C1. Do this on the solder side of the power supply board. These added wires will help prevent future cracked solder joints on the power supply board.

Lastly, make sure the backbox grounding strap is tight and making good contact to the 192x64 dot matrix controller board. A loose grounding strap can contribute to super size DMD problems.


#8 2 years ago


Your display is most probably good knowing that the required voltage is not supplied. Also 12vdc should be measured. I would test backward looking at the schematics.

1. Does the power transformer provide 9vac to cn1 ?
2. On the power board, do you get 4,95 or 5vdc in TP1, +12 on tp3, -12 on tp4 ?
3. If not +12/-12, 5 vdc, check the tracks continuity, check the diodes, capacitors and resistances, as shown on schematics p81 (see ipdb). maybe ic1 is failing.
4 If you do not get +12/-12 replace the 4 capacitors c11-c14,

Regarding your question, I do not know, you need 12vdc unregulated and exact 5vdc. Why not, maybe a machine boot check will fail but sincerely I have never tried.

#14 2 years ago


5vdc or above is ok. 4.95 was not enough. Good! Is the 5vdc steady ? Don't you measure drops on the board itself while booting ? 12vdc does not make the reboot.
I guess your reboot is just a dmd reboot, not machine reboot, but you can continue the game.

I have just seen your last post. Yes

I also found this thread, in which somewhere someone suggest to replace the ribbon, and it was the issue. Another one asks to check the grounds on the display board and cpu board


Good luck

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