U9 signals with the test EPROM running

U9 pin 3 and pin 37 (the two clock phases): about 2.4 V on a meter. Pins 2 and 4: +5 V. Pin 5: about 2.8 V. Pin 34: high with very short negative spikes. Address pins 9-24 should pulse, except pins 17, 18, 19 and 23 (A8, A9, A10, A13), which sit at 0 V with this program. No clock means checking U15 and U16.

Systems

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

Related tips

• Jumpers for a -35/-133 MPU running two 2732 EPROMs (U2 and U6)
• Using the test EPROM memory test
• Setting up an MPU for the test EPROM
• Making the test LED for the test EPROM
• Checking the PIA outputs with the test EPROM
• Never use a TMS2716 EPROM
• Which EPROM format to burn
• Mod1: two 2716 EPROMs at U2 and U6 on a -17 or M-100

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