Jr Pacman Ram or Z80, or ROM Issue?

bluestreak

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This is a field kit board in a Ms-Pac cabinet and it comes up with different garbage on the screen when powered up. Screen never changes once powered up. Diagnostics is dead. Voltages seemed to check out OK.
How does everyone check their RAM chips? Not sure if it's the Z80 processor having issues, Rom's or Rams.
Any suggestions on where to start checking the components and how?
It had been working a while back and then just quit.
 

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So here is what I tried so far and it's a bit strange on the results. I purchased a Ms-pacman "working boardset" a few weeks back that did not work when it arrived...Suprise! So today I took the Z80 processor from it and put it in the Jr pac board. Jr pac now worked...sort of.
The characters are running over the barriers and jumpy. (not smooth movement).
Looking on Arcadegameover site, now I see an exact scenario description. So does that mean the Jr pac has multiple issues or me not knowing much on the Z80 processors, are there differences in the procs that make them not quite compatable between the Jr pac and Ms-Pac.
BTW, the Ms-Pac only made noises and no video after the proc swap.
Alone and confused....
 
Sounds like both your Jr. Pac-Man and Ms. Pac-Man boards have problems...
My guess would be it needs more fixes.
 
Thanks, I think I have it tracked down to the video ram being the issue on this board. Going to order some 2114 chips this week. Still not sure what's the problem on the Jr Pac-Man as it appears a bit harder to locate information on that specific board than it is for the Pac-man and Ms Pac-man. And they are different. I did replace the Z80 CPU and I'm a bit closer.
 
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