Random or continual multiball.

Random multiball from cracked blue resistors on trough boards

Cause: The large blue power resistors on the trough opto boards crack or their leads break, usually right at the board.

Checks

• Inspect each blue resistor and its leads closely.

Fix

• Replace, don't repair: use 270 ohm 2 watt resistors, never a lower wattage.

Systems

• WPC DCS

Games

• Indiana Jones: The Pinball Adventure
• Judge Dredd
• Popeye Saves the Earth
• Star Trek: The Next Generation

Related tips

• Random multiball or game never ends on early opto troughs
• Intermittent trough sensing: cracked header pin solder
• STNG random multiball after the trough upgrades
• Balls hang in the trough: divots in the trough metal
• Bench testing a trough transmitter board
• Old and new WPC ball trough designs
• Turn ends while a ball is still in play in Final Frontier: flaky trough opto
• Opto ball troughs from Indiana Jones on

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