Mandatory pop bumper driver board update
Steps
- Mark which pad C3's negative lead used, remove C3 and fit a new 4.7 mfd 10 V capacitor the other way round, so its positive lead (to 74LS121 pin 10) is toward the board center; cross out the old marking and fill the spare pad with solder.
- Replace diode CR1 with a wire jumper.
- Replace C4 with 47 mfd or larger (100 to 200 mfd) at 10 V.
- Reflow the header pins.
- On the solder side, add a 4.7 mfd electrolytic across header pins 4 and 5, negative to pin 4, to stop noise firing the pop.
- Remove Q1's screw that has a trace to it, tin that lug, and refit both screws tight.
- Diode-test Q1 from the bottom screw (case) to each leg: 0.4 to 0.6.
Systems
Related tips
- How the System 80 pop bumper driver board works
- Bench check of a pop bumper driver board
- Common failures on the pop bumper driver board
- How the pop bumper driver board fires its coil
- Using a pop bumper driver board as a timer for motors and toys
- Original pop bumper driver board values (A-19741)
- Add power and fire LEDs to a pop bumper driver board
- Under-playfield pop bumper driver boards protect the coils
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)