MPU board test point voltages

TP1 and TP5: +4.9 to 5.2 V DC. TP2: +12 to 14 V DC. TP3: about +21.5 V DC, taken from the 43 V solenoid supply. TP4: ground. On a -133 MPU (1N4148 fitted at R113) TP3 reads about 5 V instead.

Systems

• Bally MPU AS-2518-17
• Bally MPU AS-2518-35
• Stern MPU-100
• Stern MPU-200

Related tips

• MPU board test points
• Testing an MPU in the game with only J4 connected
• Why the MPU has ROM jumpers
• Telling a -133 MPU from a -35 or -17
• Converting a -133 MPU to a -35
• Setting up an MPU for the test EPROM
• -17, -35 and -133 MPU boards compared
• Telling a -17 MPU from a -35 by connector J5

Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part One, Clay Harrell (pinrepair.com)