Sound works for a while, then the sound/speech supply fuse F8 blows. A new bridge rectifier and a new audio amplifier did not help.

Sound supply fuse F8 blows after the game runs a while

Cause: A fault on the sound power supply / sound driver board drawing too much current.

Checks

• The voltage at F8 is unregulated (around 24-39 V) and can vary; that alone is not a fault.
• Disconnect the speaker and play; if the fuse holds, suspect the amplifier.
• Disconnect the sound board and play; if the fuse still blows, the fault is on the sound power supply board (often its regulator).

Fix

• Repair or replace the faulty sound power supply or driver board.

Systems

• Gottlieb System 80

Games

• Black Hole

Related tips

• Replace C33 on the speech and sound board
• Haunted House and Black Hole sound board DIP switches
• Sound aux supply keeps blowing its 2N6059: shorted capacitor on the 30 V rail
• Some or all sounds missing
• The System 80 sound board generations by game number
• No sound and a burning smell from the sound board: diodes, then the board
• Background sound stuck on after a slam tilt
• Sometimes boots with a long tone and no sound: failed 6532 RIOT on the sound board

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