Ms. Pacman cocktail randomly resets

MC35

Member

Donor 2011
Joined
Sep 14, 2011
Messages
549
Reaction score
4
Location
Friendship, Wisconsin
O.k. I finally got the monitor working. There are several problems now that I can see and play the game.
1. When the Ms. Pac aux board is plugged in the game works, but after a few minutes and it heats up, the game randomly "reboots" and runs back through the initial power up. When I slide the test switch, it says memory ok. I can remove the Aux board, and put the processor on the main board and play the game on the Pacman levels and this doesn't happen.
2. I believe I have the Pacman Humm bar. There is a faint bar that moves from top to bottom. Twobits posted a grapic of what the Humm bar is, but the bar I have doesn't distort the screen and isn't as rapid as the one they post. Is this still a fuse block issue? There is no metal cover for the fuse block.

I suspect that after the problems I had with the monitor, these would be easy fixes for me, I just need to be pointed in the right direction.
Thanks
 
1. When the Ms. Pac aux board is plugged in the game works, but after a few minutes and it heats up, the game randomly "reboots" and runs back through the initial power up. When I slide the test switch, it says memory ok. I can remove the Aux board, and put the processor on the main board and play the game on the Pacman levels and this doesn't happen.
Sounds like you have your answer. That ribbon cable out to the Aux board is easily damaged. It's inexpensive and you should probably replace it.
2. I believe I have the Pacman Humm bar. There is a faint bar that moves from top to bottom. Twobits posted a grapic of what the Humm bar is, but the bar I have doesn't distort the screen and isn't as rapid as the one they post. Is this still a fuse block issue? There is no metal cover for the fuse block.
Most often yes -- Pac has an early design for power distribution that really susceptible to that problem. Replace the fuse block, replace the socket that connects to the board, examine the board's edge connector (male) for any burned-up connections. If there's still a rolling bar then you may need to go further.
 
Thank you. The ribbon cable is brand new, however it came with a socket that I have not replaced yet. I will investigate and see if that will help.
Regarding the the bar, I will remove each contact from the connector tonight, clean and reseat. I think I will need the edge connector replacement from Bob Roberts.
Slowly this is comming back to life.
 
o.k. So I replaced the socket on the Aux board for the ribbon cable and replaced C-1 and C-2 on the aux board. It worked great for about an hour. Now it is resetting again. Any thoughts.
 
Your problem is DEFINATELY on the fuse block.

The hum bar is a classic fuse block problem. The reason it's working as a Pac Man and resetting as a Ms. Pac Man is..... drumroll..... believe it or not, a Ms. pac Man uses more power than a Pac Man, to drive the extra chips and the extra board!

I had one do that exact same thing, drove me crazy.

Take the fuses out one by one, clean them with some sandpaper or something, and pinch the fuse holders closer together so they hold the fuse tighter. You may bust one of the fuse holders when you do this, or find one that's broken. You need to replace the whole block if you can, you can order the stuff from Bob Roberts.

After you do that, take a file or some sandpaper or something and clean the pins inside the edge connector for the gameboard. Also clean the edge pins that it connects to.

Once you get the power nice and strong to the board, your reset issues will go away, and your humbar will be gone.
 
BTW, a Pac Man board will boot with one of the 4 fuses blown! I've seen that before too, so make sure that all 4 of your fuses are fine.

Take a multimeter and set it on 'ac', check the voltage between the left side of the top two fuses. Now check the voltage on the RIGHT side of the top two fuses. It should be really close.

Now check the voltage between the bottom two fuses, on the left side. Now check it on the right side of those two fuses. It should be really close. If you see a big drop, you still need to work on the fuse holders.

When you do that, don't check the voltage on the actual fuse, check it down where the wire solders on, this will ensure that your'e testing all the way through the fuse holder, and everything's making good contact.
 
The edge connector is definately in need of some cleaning/repair. I'll give the fuse block a good once over as well.
Thanks guys.
 
Fuse block made all the difference in the world. I'm amazed. Next step is replacing the dege connector via Bob Roberts.
Thanks guys.
 
Back
Top Bottom