At power-up two coils fire and stay on until power is cut, and the backbox flashers come on very bright and get hot. Replacing the two TIP102 drivers just moved the problem to other coils.

Coils lock on at power-up and backbox flashers glow: drivers and predrivers

Cause: Several stuck drive transistors, including their small predriver transistors, plus the chips that feed them. Bright flashers also point to a stuck driver for the A/C select relay.

Checks

• Test each coil driver and its predriver transistor, not only the TIP102s.
• Check the logic chips that drive the stuck outputs.

Fix

• Replace the bad driver and predriver transistors and the driving chips; here that was Q16, Q18, Q19, Q22, Q26-Q33 and U19/U20 (socketed).

Pull the fuse or unplug the game; a locked-on coil will burn quickly.

Games

• Jokerz!

Related tips

• A/C relay C-side error, dead 25 V coils: burnt zero-ohm jumper W6 on aux board

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