Loud static or hum from the speaker between games even after recapping, reflowing and repinning the sound board. Unbolting the board so it floats makes it quiet.

Loud static from the speaker between games: isolate the sound board mounting

Cause: A ground loop: the sound board keeps its amplifier and logic grounds separate, and grounding it through the mounting screws or poor connector grounds adds noise.

Checks

• Loosen the sound board so it is not touching the mounting, power up and listen; if the noise stops, it is a grounding path.
• Check the ground connectors between the rectifier board and the solenoid driver board.

Fix

• Mount the sound board on insulating (nylon) washers so the mounting screws do not ground it.
• Keep the backbox ground braid connected.

Games

• Playboy

Source: Pinball Repair help group!! (Facebook group)