Game is dead; the power supply shows no +5 VDC at TP1.

No +5 V at TP1 or no 14 V at TP5

Cause: Blown FU3, a shorted bridge diode in D1-D4, or no 14 VDC reaching the regulator.

Checks

• Check fuse FU3 (upper left of the power supply).
• Measure TP5: it should be about 14 VDC. Without it there can be no +5 V.
• Test diodes D1-D4 with the meter on diode setting; a short blows FU3.

Fix

• Replace any shorted D1-D4 diode, then replace FU3 with a 6 A slow-blow.

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 point ranges
• Strange intermittent faults from power supply solder joints
• No 43 V for the coils
• Replacing the 78H05 +5 V regulator
• Bad +5 V bridge diodes D1-D4
• +5 V still bad with good C1 and diodes
• Check every power supply fuse before first power-up
• 6803 power supply fuse ratings

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