Setting up an MPU for the test EPROM

Steps

• Best on the bench: +5 V to TP5, +12 V to TP2, ground to TP4 (no 43 V needed). In the game, unplug J4 on the solenoid driver board first so no coils fire.
• With power off, remove the game ROMs U1, U2, U5 and U6, the RAMs U7 and U8, and the PIAs U10 and U11.
• Burn the test program into a 2716 and fit it at U6. A board jumpered for 2716 or 2732 takes it as-is.
• For a board still set up for 9316 masked ROMs, use a 9316/2716 adaptor socket rather than changing jumpers.
• Connect a test LED to U9 pin 15 (see the test LED entry) and power up.

Systems

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

Related tips

• Test EPROM: the least an MPU needs to run it
• ROM and EPROM types used on Bally MPUs
• Jumpers for a -35/-133 MPU running two 2732 EPROMs (U2 and U6)
• Testing an MPU in the game with only J4 connected
• Using the test EPROM memory test
• MPU board test points
• Set a -35 MPU up once for 2732 EPROMs instead of re-jumpering per game
• MPU board test point voltages

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