I have sst with a color dmd. It has all stock boards though and I haven't experienced these problems on any of my color dmd pins. With that said, my gut would also think the sound/cpu board is the culprit. Some other component related to the display may have been affected when the sound damage occured.

Wish I could help out more and good luck.

Here are some things to check according to Pinwiki: http://www.pinwiki.com/wiki/index.php?title=Sega/Stern_White_Star_Repair#Display_problems

The Rottendog power supply board has a known problem for the unregulated 12V output in that it's actually driven from the 12V regulated output. This is a change from the factory boards where the unregulated output is actually unregulated and just comes from the bridge rectifier.

Check your 12V supply, it's probably too low and struggling to power both ColorDMD and Pinsound. The ColorDMD will actually function well below 12V which is why the menu screens are working. You're issue could be with the display board...

The video freeze problems are coming from the display board and likely a result of additional 5V issues. If Rottendog is using the 12V regulator output to feed the 5V regulator (as the factory board used the 12V bridge to feed the 5V regulator), then a weak or fluctuating 12V would cause problems for 5V as well and explain the display board issues.

If the display stopped showing video all together after you started reseating cables, please make sure
(1) The Whitestar display board (large one on the rear of the display) is receiving 5V on the two-pin power connector
(2) The two ribbon cables plugged into the Whitestar display board are seated correctly with the red stripes closest to the corners of the board.
(3) The ribbon cable plugged into the ColorDMD controller board has the red stripe closest to the buttons

If you need additional help, please contact us directly at [email protected].

EDIT: Here is a correction to a some things I posted above for SST (was thinking about DE factory boards and SEGA is different). Below is schematic for the original power supply board. 12V unregulated comes out on J16-3, fed by the 12V bridge in yellow. 5V comes out on several pins fed from the 5V regulator in red. It is driven by a different and dedicated bridge (in blue). So for the factory board, 12V should not impact 5V at all.

SST_PowerBoard (resized).png

Unfortunately I can't track down a schematic of the Rottendog SDB004 to compare. However here's a discussion of the known problem that exists for the Rottendog DE power board. https://pinside.com/pinball/forum/topic/rottendog-data-east-power-supply-board-design-issue

Unlike the DE board above , the 12V regulator is not on this board, it's on the audio board. So the Pinsound and ColorDMD are both directly pulling current from the same 12V bridge and the output is unregulated. Large current surges could result in voltage fluctuations at the output of the bridge.

It looks like the 5V regulator on the RD SDB004 might have a jumper option as to which bridge is driving it. You should check to see if this is jumpered to connect to the 12V bridge. If so, voltage fluctuations on 12V could be causing 5V to swing and could result in odd logic behavior or data communication problems between the boards.

RD_SDB004 (resized).png