Sound is weak, thin or out of phase.

Checkpoint and Ninja Turtles: poor sound from miswired speakers

Cause: Some games left the factory with the speakers wired wrongly.

Checks

• Check the colours: right speaker + black-yellow, - black; left + red-black, - red-white; centre + yellow-black, - yellow-white.
• Viewed from behind with the lugs pointing up, the left lug is + and the right lug is -.

Fix

• Rewire the speakers to match.

Systems

• Data East CPU Version 3

Games

• Checkpoint
• Teenage Mutant Ninja Turtles

Related tips

• Slide-out playfields from Ninja Turtles on
• Loud hum from the speakers
• Teenage Mutant Ninja Turtles: CPU and display EPROM types and latest versions
• Check the sound board's regulated -5 V and +5 V
• Sound board versions are not interchangeable

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)