Slingshots and pop bumpers feel weak and sluggish, as if the mechanisms were worn, even after the boards have been rebuilt.
Slings and pop bumpers feel sluggish: backbox boards loose with missing mounting screws
Cause: The backbox boards were held by only two screws each, mostly on one side, so they flopped about. Fitting all the mounting screws made the coils clearly stronger, most likely through a better ground path to the backboard.
Checks
- Look at every board in the backbox and count the mounting screws; check that each board sits firmly on its standoffs.
Fix
- Fit the missing screws so every board is held firmly.
- On System 6 and 7, take care that the screws do not pull the CPU and driver boards out of line with the 40-pin connector between them or let solder points touch the backboard: thin washers between board and backboard and an insulating sheet behind the CPU board's pins were used here.
Systems
Games
Related tips
- Coil still locked on with good transistors and gate
- CPU locks up as soon as the driver board is connected
- System 6 and System 7 driver boards can be swapped for testing
- Spare transistors for driver board and power supply
- Hyperball driver board is unique
- Replace burnt 3 watt lamp resistors with 5 watt
- What each 6821 PIA does
- A low resistance coil points to a bad driver transistor
Source: Pinball Repair help group!! (Facebook group)