Data East DMD Issue

Scuba Steve

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Working on my DESW project which came with a non working DMD. I've plugged it into another pin with DMD and got the display to work. What should be my next step in locating the display issue with my Data East pin?
 
Check that the ribbon cable is properly oriented with the red stripe to pin one from both the CPU to the display driver board and from the display board to the DMD. If the one going from the display board to the DMD is installed backwards, you'll get nothing on the DMD.

The next step is to check the voltages at the DMD and the display controller board. Do you have a manual?
 
Yup already checked all the ribbon cables. I do have the manual.

What are your voltages?

Here is a quicky cut and paste from "somewhere".

Summary of Small & Medium sized DataEast/Sega DMD Fixes.
If the dot matrix display is not working on a DataEast game, this is a summary of the things to check:
Check the voltages at the display board: -110, -98, 68, 12 and 5 volts (or within 10% of those values).
Double check the 5 volt connection to the display board.
Check the 18 volt backbox lamp matrix fuse.
Check data ribbon cable from CPU to display board.
On small 128x16 DataEast games, check/replace resistor R95 on the display.
Replace the ROMs on Display board.
 
The manual will give you the voltages at all the pins, so check them at the DMD and the display board. It isn't uncommon for the high voltage section of the DE power supply to go out.
 
I wonder if the 2 eproms board was prone to failure.

I havent checked the voltages yet, but plan to do that tonight.
 
When I restored a DESW, I did this upgrade with the latest DMD chips from MArco.

I can't seem to find the part from marcospec.com. What's the item#? I already have an order build up at that site. I'll just add it my preexisting order.
 
I can't seem to find the part from marcospec.com. What's the item#? I already have an order build up at that site. I'll just add it my preexisting order.

Unfortunately I don't have that info, I did the resto years ago. I was luck to find my post from RPG to get that link.

When you search Marco under StarWars game specific, it doesn't bring up the ROM's for the game?

On a side note, if you have PF lights that are not working, check the fuse holders. They are prone to be bad, inferior quality.
 
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Unfortunately it was at the DMD.

That's good. Now pull the ribbon cable at the power supply and check those pins directly. If your voltage is fine you know you have a bad cable. If not, you're a step closer to finding the problem.

That's about the limits of my pin repair knowledge, it isn't much to begin with. Maybe some of the other guys can advise.
 
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I think Dr_Gonzo means to pull the connector on the PS (CN5) that goes to the DMD (not the ribbon cable).

One thing to keep in mind, when unloaded, some of the high voltages readings may measure low. I have a new Vishay display that does not use the -98v supply from the PS. I kept getting a low reading (-87v) and couldn't figure out why. It was suggested that I put a 10k ohm resistor between the -110 and -98 to load it and then take a reading. I did and the voltage came up and it was fine.

Now if you get nothing at the PS when the high voltage section is unloaded, you have a problem. But if you see some low readings, it could be due to there being no load when you have the connector removed.
 
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