All sounds and speech play correctly from the sound board's own test button, but during a game the wrong sounds play at the wrong times (for example the heartbeat after the game ends).

Sound test fine but game plays the wrong sounds: cracked joint on sound select header

Cause: A cold solder joint on the sound board's J3 header, which carries the five sound select lines from the MPU; with one line missing the board decodes the wrong sound numbers.

Checks

• Use the sound board test button: if it plays everything correctly, the board's sound section is fine.
• With a logic probe, check each sound select line at J3 for activity while the game plays.
• Inspect the J3 header pins for cracked joints.

Fix

• Reflow (or replace) the J3 header pins and repin the connector if needed.

Systems

• Williams System 6 / 6A

Games

• Gorgar

Related tips

• Setting up a sound board for speech
• Sound board jumpers for sound-and-speech games (2K ROM)
• A word missing from a speech phrase
• Sound test works but sounds missing in play
• Missing words or sounds from cracked connector pins
• Sound self-test passes but some game sounds never play: bad PIA on the sound board
• Speech cuts in and out when the ribbon cable is moved
• No sound in play or solenoid test, and grounding inputs does nothing

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