Baby Pac-man Battery on MPU

Yesterday I had the opportunity to go and play a nice Baby Pac-man here in Indianapolis. I had been trying for a number of months now to coordinate an opportunity to play a Baby Pac-man either here locally, or on one of my trips this year to Milwaukee or to Michigan, but with little success. I had never played Baby Pac, and was particularly curious about how in depth the pinball portion of the game was and equally what the video maze game portion was like.

Part of the problem was finding a working Baby Pac-man. Of the 7,000 units made by Bally Midway in the early 80’s, a lot of the Baby Pac’s are arcade collectors “Project Games”. I don’t know enough about the game to know if there are a lot of non-working Baby Pac arcade games because of the unique game itself with the pinball / video combination, but I do know that the battery on the MPU board causes problems.

The Baby Pac-man I played last night was in decent condition. The playfield had some wear, the control panel was beat up but nothing a new Baby Pac control panel overlay wouldn’t fix, and the sideart was missing from the right facing side. But this Baby Pac had been HUO for at least 10 years, if not up to 15 and beyond. The cabinet was in solid shape, and the most important fact, the game worked.

This Baby was out of my price range, (1K!) but I still wanted to investigate it as best I could. Knowing that these were general home owners who had used the arcade game without ever having issue, I was betting that the original battery was on the MPU board and had never been replaced. Being the less technical person I am, I didn’t want to assume what the battery might look like, so I did a little research.

I emailed one friend, and looked online. I asked about the color of the battery on the Baby Pac-man MPU board, the only experience I had was with my Frenzy, which had that blue battery. Here is what the friend said;

Very easy to see..it will either be white or sometimes yellow…wrapped in plastic cover like the rechargable batteries you see…

I found multiple Baby Pac-man PCB images of the group of board, and found an image of the battery still mounted. (I believe the order of the Baby Pac boards left to right and down is, the solenoid board, the MPU board and the Vidiot Board. The MPU battery that causes the acid corrosion is circled.)

When I got to the owners house and asked if they had ever done any work on the Baby Pac-man, they said no. They had mounted some clips when the control panel wouldn’t stay fastened, putting holes in the side of the cabinet 🙁 But they didn’t even know about the power button, and had never been in the back of the arcade game, let alone done any replacement work of any pcb components.

I took some photos through the Baby Pac-man coindoor, and saw that the battery was still mounted. But I couldn’t recommend to the owners what to do exactly. Should they get in back and remove / replace the battery even though the game worked? Especially since they didn’t care about collecting and only wanted to sell the game at this point.

I haven’t read enough on the subject, my understanding is that batteries on PCB’s usually are for operator settings on how they want the game to play. But, the Baby Pac-man MPU battery also saves high scores, which isn’t a big deal, but if it prevents battery acid damage on the MPU or Vidiot board, it is probably wise to record those game high scores by hand.

So what is the solution? From Marvin3m.com, a great Baby Pac-man repair and troubleshooting resource;

MPU Board Battery Corrosion.
There is a rechargeable nicad battery on the MPU board which often leaks. This can cause all kinds of problems with the MPU board, and even the Vidiot board (which is mounted right below the the MPU board and the battery).

Remove this battery ASAP and discard. Aside from ruining the MPU board, it can also spread its corrosion down the center section of the Vidiot board, all the way to the lower sound section of the board! Of course the .100″ connector pins will be ruined in the process, not to mention the Vidiot board traces and its components.

A remote mounted three “AA” battery pack with a blocking diode is suggested as a good MPU board battery replacement (Show Above).

Bob Roberts sells these remote mounting battery kits for the Baby Pac-man and I guess for use in many other 80’s pinballs. (Shown Above)

This is what I learned about the Baby-Pacman MPU battery and acid damage in less than an hour of research. Have any feedback? Need to correct me? Leave a comment below, would love to hear from you.

Here are some similar arcade posts

• Working on the Frenzy game.
• Sanding Pac-man cabinet, wiring Mr. Do!
• Progress Professor Pac-man cpanel artwork
• Photos of the Professor Pac-man Sideart
• Oh baby! A rare find in Chicagoland

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