What bad chip makes Ms Pacman look like this?

Mangler90

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I recently bought a Ms Pacman, when I plugged it in the screen gave me these rolling ms pacman characters that then go blue for a few seconds then roll again in various colors. Would anyone know which chip would do this? Or could this be a voltage issue?
 

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A video would help... but i think its a voltage issue.

Check your +5v and try to get it up to around +5.35v
 
A video would help... but i think its a voltage issue.

Check your +5v and try to get it up to around +5.35v

WHAT?

There's no voltage adjust on a Pac board.

Check the CPU socket on the main board and the ribbon cable to the daughter board. It looks like a bad cable/socket.

Pull the CPU from the daughter board, pull the ribbon cable from the main board, and install the CPU on the main board where the ribbon cable was plugged in.

BE CAREFUL: DO NOT remove the ribbon cable by pulling on the cable! That is how the cable gets damaged in teh first place. Also DO NOT plug the CPU in backwards. Watch the notches on the socket and on the silkscreen to see which direction to plug it in.

If it works with the CPU plugged into the main board (it's normal for Ms Pac to look like she's walking on her lips when you do this) then replace the ribbon cable.

RJ
 
Its not booting, check row 6. Eliminate the ribbon cable and install a z80 in its place to troubleshoot. Could very well be bad eproms or sockets and the ribbon cable is a usual suspect.
 
Sorry... CM is right, but i was assuming you had a switcher.

I have had many PM and Ms PM boards (as well as Galaga) not boot and +5v or even +5.25v

Nothing wrong with the board... Just aged components. Giving it a bit of extra juice would get them to boot.
 
Thanks for the responses guys.

I pulled the ribbon cable and replaced it with the CPU chip. I then followed the other instructions and tried placing a Z80 in the same slot. Both chips produced the same results and the picture attached is the result from both chips. It may be worthy to note that there isn't any sound either besides the speaker hum.

Along with this on row 6 there is a slot labeled 6D that does not have a chip in it. And for slots 6E,F,H and J I am not sure how I can test them without buying new chips.
 

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Are those ceramic EPROMs or the black epoxy PROMs? If they are the PROMs they will probably have tarnished legs. Clean the inside surface of them then reinsert them.

RJ

PS: Don't plug them in backwards or mix 'em up.
 
Could be anything and it's hard to know just going by a pic. A video would make it a little clearer (preferably from power-on) but still. Couple of questions:

- Does the game coin-up / play blind? ( i.e. sounds + responds to coins / inputs )
- Is the display static or does it seem to randomly put crap on the screen.

If the game *doesn't* play blind, check the z80's reset pin. It should be high. If it's a constant low, check the schematics and follow the trace to the watchdog portion. If it's pulsing, the watchdog's working but the CPU isn't able to reset the watchdog, which could be a number of things (bad rom/ram, bus contention).

If it *does* play blind, it can still be any number of things but at least it's restricted to video. Judging from the pic the graphic roms seem to good, as are the shift-registers and the horizontal / vertical timing chain, unless the picture's rolling / cranking out crap. Since you had sprites visible, line-ram seems to be okay too. Could be the VRAM-addresser or a bad RAM.

Not much to go on but keep us posted and, if you can, post a video!

-Y
 
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channelmanic: I pulled all the proms and eproms and cleaned the legs.

Yzoer: I tried to post a video but the site wont let me. I dont know if it has to be a certain file type or size, I tried to keep it small. Any thoughts on that? The coin door and control panel don't do anything. When I change the setting from play to test nothing happens and I do have the door electrics hooked up. So in other words the game "doesn't" play blind. Can you help me out with the Z80 reset pin. I am not sure which pin that is and I am assuming I should be checking it for voltage close to 5v?

Thanks again for the help.
 
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I've got a bootleg Ms Pac board that looks almost identical to that when I hook it up. Unfortunately, I have no idea what's causing it, but I know it's not the Z80, as I've swapped it with known working ones.
 
channelmanic: I pulled all the proms and eproms and cleaned the legs.

Yzoer: I tried to post a video but the site wont let me. I dont know if it has to be a certain file type or size, I tried to keep it small. Any thoughts on that? The coin door and control panel don't do anything. When I change the setting from play to test nothing happens and I do have the door electrics hooked up.

Thanks again for the help.

I usually post the videos to you tube and just post the link here
 
This looks like the same problem I had two years ago. I replaced the 2114 at position 4N and all was fine after.
 
Your board is not booting therefore its not going to 'play blind' or have any game sounds at all. It could be caused my alot of things but most common would be any one of the 2114 rams, Z80, eproms on row 6 or the sync bus card. As far as power goes, measure across cap C3 and you should have 5v. If you have 5v there then move on.
 
I messed up. I reattached the photos. The image with all the garbage on the screen is without the 6D chip. Once I added the chip I have the black screen with the few MS Pacman that roll then stop facing down for a sec then roll again. At this time there is also a Z80 chip in place of the daughter board.

The C3 cap read 5.14v.
 

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