Trough switches come and go.

Intermittent trough sensing: cracked header pin solder

Cause: Vibration cracks the solder joints of the connector header pins on the trough boards.

Checks

• Inspect the header pins on both trough boards.

Fix

• Reflow the solder on every header pin on both boards.

Systems

• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Test the shooter lane switch when chasing trough faults
• Random multiball from cracked blue resistors on trough boards
• Bench testing a trough transmitter board
• Old and new WPC ball trough designs
• Opto ball troughs from Indiana Jones on
• Remounting early trough opto boards on grommets

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