Indiana Jones to Demolition Man games have two LM339 opto boards

From Indiana Jones up to Demolition Man, both the under-playfield opto board and the trough opto board carry LM339 comparator chips, so either can cause opto faults. Starting with World Cup Soccer 1994 the LM339 chips moved to the under-playfield board only and the trough board became much less trouble prone.

Systems

• WPC DCS

Games

• Corvette
• Indiana Jones: The Pinball Adventure
• Judge Dredd
• Popeye Saves the Earth
• Red & Ted's Road Show
• Star Trek: The Next Generation
• The Flintstones
• The Shadow

Related tips

• All playfield optos dead after replacing one opto: failed 16-opto board
• Every opto dead and opto board LED off: check the J118 ground
• Turn ends while a ball is still in play in Final Frontier: flaky trough opto
• Cannon won't turn on the third multiball shot though it tests fine: flaky opto wire
• Idol optos missing from switch test: use idol test, then fix connectors
• Ground short rows 2 and 3 and Idol switch error on a cold start: failing 10-opto board
• Judge Dredd flipper fires sporadically and hums when held: dust in the flipper opto
• Eddy sensors: electronic ball switches under the playfield

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Three, Clay Harrell (pinrepair.com)