Woodside Arcade Repair

I started to work on the Bally Firewall home edition. This pinball machine looks very simple compare to any commercial version. No coin door and very simple backbox and below the playfield components.

The game fails to stay powered on; specifically, the circuit breaker adjacent to the power button trips immediately upon startup, indicating a direct short. Initial inspection below the playfield reveals a burnt and "crusty" left slingshot coil, which appears to be the primary source of the failure. Upon disconnecting the coil the game nows boots suggesting the coil was lock on probably by a failed transitor.

Found a burn transistor on position C4 with clear signs of failure. The failure burn also some of the pads. Burn part was a TIP115. Im replacing with a TIP107 which has more Vce (100v vs 60v) and more Ic Max (8A vs 2A). Same B-C-E. The game now boots and play the slingshot works but I have some dead lamps (with good bulbs) and dead switches and no sound.

Found two more dead transistors that might explain the dead lights and not working switches. Replace them with TIP107.

I also found a whole row of lamp sockets on the backbox board that had melted. I think those were poor quality or bad spec. They should not melt with the normal bulb heat—something to replace with LEDs in the future. I replaced all of them with new lamp twist sockets.

Before trying to fix the sound I replaced all the tired caps on the board.

It's alive. After replacing the burned coil and transistor the game boots and is playable.

The LM3900 is the prime suspect of the sound. In series 1 boards, only 3 or 4 things can go wrong. The only one that's difficult to replace is the Mostek PSU, but I decided to replace the LM3900 first and boom! sounds back. Job done, happy pinball.