After fitting a new replacement sound board, the start-up sound plays but game sounds and sound test give only a faint crackle. Test points and LEDs on the sound board are correct.

New sound board gives only a faint crackle: set MPU DIP switch 23 on

Cause: MPU DIP switch 23, which tells the game what sound hardware is fitted, was off.

Checks

• Make sure the sound board is the right model for the game.
• Check the sound-related DIP switches on the MPU against the manual.

Fix

• Turn MPU DIP switch 23 on.

Systems

• Stern MPU-100

Games

• Dracula

Related tips

• No sound after fitting a new MPU and sound board: check ribbon direction and sound DIP
• One sound missing in sound test (the 100 point sound): failed 7408 on the sound board
• Stern SB-100 sound board screeches until a game sound plays
• Sound module -32 and -50 test points

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