Baby Pac-Man and Granny MPUs look for 6 V AC, not 43 V
On these -133 games the final zero-crossing test watches a 6 V AC feed rather than the 43 V solenoid supply, through PIA U10 port CB1. They skip the sixth test, so a good board gives six flashes in all.
Systems
Games
Related tips
- Convert a -35 MPU to a -133 for Baby Pac-Man and similar games
- MPU on the bench always stops one flash short
- Converting a -133 MPU to a -35
- Reading the MPU flash code
- Replacing the MPU reset section with a DS1811
- What each MPU LED flash proves
- What a good MPU does straight after the last flash
- MPU U9 voltages that show a working reset section
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part Two, Clay Harrell (pinrepair.com)