Jumper TP1 to TP3 on the solenoid driver
The regulated 5 V leaves the driver board and comes back through J3, straining its pins. A wire from TP1 to TP3, on either side of the board, relieves J3. Make sure it goes to TP1 and not TP5 just above it: TP5 is unregulated 12 V and would destroy the MPU chips.
Systems
Related tips
- Solenoid driver/regulator board test point voltages
- Solenoid driver/voltage regulator board test points
- Solenoid driver board: how the MPU selects a coil
- Solenoid driver board: test points and regulators on the layout aid
- Adding a ground jumper at C23
- Ground mod for the solenoid return at J3 pins 23-24
- Solenoid driver TP1 below 5 V with TP5 normal
- Rebuilding the solenoid driver board high-voltage section
Source: Repairing Bally Electronic Pinball Games from 1977 to 1985, Part One, Clay Harrell (pinrepair.com)