Full ball trough opto test in switch edge test

Steps

• Dim the room, power up and go to switch edge test T.1. Check each transmitter LED with an infrared card or camera.
• Shine a small flashlight or TV remote into each receiver; each should register (room light can also trigger them).
• With all balls removed, the trough optos should show as squares (unblocked). If there are no squares at all, the playfield has lost its opto 12 V: check fuses F115/F116 on WPC-S and earlier, or F101/F109 on WPC-95.
• Roll a ball slowly down the trough and watch each square turn to a dot as it passes. With the ball at position one, push the shooter kicker up by hand so the trough jam opto turns to a dot.
• Fill the trough, then remove balls one at a time, a few times over, looking for an opto that does not change reliably.
• Empty the trough, close the coin door and work the flippers, watching the trough column for flicker; then thump the playfield near the flippers with your fist. Flicker means a cracked resistor, broken opto lead or cracked header solder.
• Leave it in switch test with no balls for 20 minutes within earshot (some games leave test after 15 minutes). A bong means a switch changed; the display shows the last switch.
• If all of this passes and random multiball continues, look for divots in the trough.

Systems

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

Related tips

• Opto ball troughs from Indiana Jones on
• Old and new WPC ball trough designs
• Replacing trough transmitter and receiver optos
• Remounting early trough opto boards on grommets
• Test the shooter lane switch when chasing trough faults
• World Cup Soccer and later trough opto boards carry only the optos
• Testing optos in switch edge test
• Random multiball or game never ends on early opto troughs

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