Got this Sunset Riders PCB for a repair:
Gameplay and graphics were OK but music was accelerated and distorted:
Music is generated by the YM2151 sound synthesis chip widely used in many arcade systems:
For first I checked its clock input pin and measured frequency was fine (3.579 MHz) :
When I piggybacked a good chip on it correct music tempo was restored:
Replacing the chip fixed the issue completely.