Closing a playfield switch scores or acts as a different switch.

A playfield switch triggers the wrong response

Cause: Strobe and return lines shorted together, a shorted isolation diode on the playfield, a bad game PROM, or the control board.

Checks

• Look for strobe and return wires shorted together.
• Test the playfield isolation diodes for a short.

Fix

• Repair the short or replace the diode; then try a new game PROM, then the control board.

Systems

• Gottlieb System 80
• Gottlieb System 80A

Related tips

• A coin chute switch does not register or registers wrongly
• How the switch matrix is scanned
• The slam input has priority over every other switch
• Where to see the switch matrix strobes
• Switch test (step 18) shows switches closed
• The play-test button will not start the test sequence
• Scores light at once and the status display stays dark
• Bookkeeping totals or score levels are wrong or missing

Source: System 80 Service Manual, Gottlieb