Ms pac man : playable but all white screen

Smart Bomb

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Working on my ms pac stand up cab. The board was 100% working..solid!....it was setting out of the cab in my arcade..just setting there untouched..it worked perfect yesterday....i put it in my ms pac cocktail, which has a bad board, to do some monitor adjustments to the cocktail monitor.

Anyway...i put the working stand up board in the cocktail and it wont boot up..its in a boot loop....but for a flicker of a second i get the "ok" text......so i take the board out...reseat everything...still in a boot loop.

So i then take the ribbon cable off...take the z80 out of auxiliary board..put it in the spot where ribbon cable was and no more boot loop and goes to the pac man screen but its an all white maze.....now, i never did this ribbon cable/z80 replacement test before and ive read the game supposed to look odd so i figure the white screen is part of the odd look.....so i put it all back together as it should for ms pac and the screen comes up but again, its all white as u can see in the pic....

So i shut it down for the day and will work on it again next weekend...i wanted to post this now to see if anyone had any suggestions what to address first.

It is not the monitor...i put the board in the stand up and the cocktail and both images were the same...the characters have color but its all whitewashed.


Again, it was a perfectly working board..out of the blue this happens.

Its not auxillary card or ribbon cable...i used another working set and got the same whitewashed result.
 

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With the maze missing, I'd look at the character eproms first specifically 5E is where the maze is.
 
I know you said you put the board in both games but it's not clear if you put the board back in the upright again after you put it in your cocktail. If you haven't you should do that first to make sure that the problem 100% follows the board. Because it looks like maybe you're missing blue on your monitor.
 
I know you said you put the board in both games but it's not clear if you put the board back in the upright again after you put it in your cocktail. If you haven't you should do that first to make sure that the problem 100% follows the board. Because it looks like maybe you're missing blue on your monitor.

The problem 100% definitely follows the board.
 
It is not 5e_i put in a working 5e from a different working ms pac board...same result..still looks like the pic in original post.
 
This has been resolved, but nothing was replaced.

The board itself stopped working all togther so today i reseated every socketed chip just to get me back to the all white screen at least.

In reseating the chips, 6 chips legs broke on 5 chips...some of those chips legs even broke flush so i figured i was screwed.

I cleaned the chips nubs as best i could with an emery board file. I soldered spare cap legs in place of the broken legs. Put it all back togehter and not only is the all white screen gone, the game is back to normal and 100% playable with perfect screen colors.
 
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