With 10J3 unplugged the sound board test plays everything, but in the game only some sounds or one speech phrase work. The solenoid test seems to play each sound, but one sound may just be the previous one still playing.

Sound test fine but many game sounds missing: a sound line stuck on

Cause: One of the five sound lines from the driver board is stuck on (a shorted sound driver transistor, its pre-driver, the 7408, or the solenoid PIA). With one line stuck, only half the sound combinations can play.

Checks

• Step through solenoids 9-13 manually (Auto/Manual in while in the coil test, Advance to step) or ground each sound transistor tab, listening for each one.
• In attract mode, briefly unplug and reconnect 2J9 or 10J3: if the missing sound plays the moment it is reconnected, a line is stuck on (confirm with a logic probe).

Fix

• Replace the sound driver transistor and its pre-driver, then the 7408 (in-circuit tests are only about 95% reliable), then the solenoid PIA.

Systems

• Williams System 3
• Williams System 4
• Williams System 6 / 6A

Games

• Alien Poker

Related tips

• Use the solenoid test to check the sound lines
• Missing words or sounds from cracked connector pins
• Wrong sounds play
• Background sound never stops at game over: sound-line driver chip
• Garbled sound at game start and no background sound: driver board header joints
• How System 3-6 games trigger sounds
• Quick sound checks by grounding
• Sound EPROM files used by System 3-6 games

Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Three, Clay Harrell (pinrepair.com)