No coils work and TP4 reads nothing.

No 43 V for the coils

Cause: Blown FU1 or a failed bridge rectifier BR1.

Checks

• Check FU1 (5 A slow-blow).
• If FU1 blows again at once, test BR1.

Fix

• Replace BR1 (35 A, 200 V) if shorted, then FU1.

Unplug the game before pulling fuses or working on the power supply; the transformer side carries line voltage.

Systems

• Bally 6803

Related tips

• Power supply test points and their voltages
• No +5 V at TP1 or no 14 V at TP5
• Replacing the 78H05 +5 V regulator
• Power supply test point ranges
• Strange intermittent faults from power supply solder joints
• Bad +5 V bridge diodes D1-D4
• +5 V still bad with good C1 and diodes
• Coil fuse FU1 blows the moment the game is switched on

Source: Repairing Bally 6803 Pinball Games from 1985 to 1989, Clay Harrell (pinrepair.com)