I should give some background. I got this TFTC that needed put back together. I got that done and got a replacement MPU booting...

Found a couple bad transistors causing switch matrix problems, game is then working 100% for about two weeks. After playing about 40 games on it... Display goes out. Start testing fuses... I notice that quite a few are overfused badly. Once I get all the correct value fuses in the power supply, the 0.5 amp display fuse blows. I rebuilt the PS and high voltage part of the PS, 0.5 fuse still blows. I give up and buy a new Rottendog DPS004 power supply.

While waiting for the new power supply, I pull the DMD from TFTC and test it in my WPT. Works perfect.

Today I installed the DPS004 power supply that arrived. 5VDC is low (4.7VDC). I install a 250K resistor per the instructions that shipped with the power supply. Now getting the proper 5.0-5.1VDC when tested on all boards in game. Still nothing on the display.

I swap working ribbon cables in from another game, no change.
I replaced the small 100uf 25V filter cap on the DMD controller board, no change.
I burned a new TFTC 27C040 display EPROM, no change. (Yes R11 is removed!)
I installed a new 68B09EP CPU in U11 of the DMD Matrix Controller Board, no change.
I installed a working MS62256L RAM into U8, no change.

I'm convinced that the DMD Matrix Controller is bad unless there is something I am missing. I don't have the ability to burn the custom PAL chips on that board and a replacement is $160+shipping.

Here are the voltages I currently get at the P1 connector of the display.

Pin1 -116.4VDC
Pin2 -104.8VDC
Pin3 KEY
Pin4 GND
Pin5 GND
Pin6 5.0VDC
Pin7 11.7VDC
Pin8 71.5VDC

At all of the DMD controller IC's I get exactly 5.00VDC throughout the board.

Can I easily check anything else on the DMD controller with a handheld logic probe perhaps?
I'm fairly certain that the DMD will display the game's display ROM version even if no MPU/driver board is present in the game. So, I'm ruling out the MPU/driver board as the problem.

It is a Cherry display. I have 2 other good tested displays, both of which are Cherry's, and neither work in the TFTC.

I don't think that thread is relevant, even though I'm using Cherry displays... All the voltages pushing out to the DMD itself are in good ranges(given above). Also, the Cherry displays both tested good in my WPT after testing them in my TFTC for an extended period of time.

I'm still looking for some advice regarding the probing of components on the DMD controller board. Can't really find many resources on the web about fixing that specific DE/SEGA board... I only seem to see DE power supply fixes regarding DMD failure.

Still confused about that MPU reset pulse. The display controller board SHOULD come on and display the ROM info, even if the MPU is not installed in the game. I know that because when the game did not have an MPU in it (a month ago) and I powered it on, the DMD came on and displayed this info.

Pin 37 on the 68B09 reads 4.99VDC when I tested it just now. I guess one PAL chip or both are likely bad? Do those 2 PAL chips all contain the same code on every game that uses them?

Just a follow-up. I borrowed a new Rottendog DMD controller board and it has fixed the issue. I have used it to test all my parts and I still have no clue why the original just "gave up" on me. Seems crazy. I tested all 3 displays using the new DMD board and they all work perfectly in TFTC.

Thanks to viperrwk for explaining the DMD board operation. Maybe some rainy day I will try to program some PAL chips and get it working.