Testing a switch diode out of circuit

Steps

• Unsolder one diode lead from its lug.
• Meter on diode test: black lead on the banded end should read 0.4-0.6; reversed, no reading.
• Reconnect it, or replace it if bad.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• Testing a leaf switch diode in place
• Fitting a new switch diode the right way round
• Testing CPU switch rows and columns with a diode and clip lead
• System 80 switch matrix diodes
• Spare diodes for coils and switches
• Switch row (return) circuit on the CPU board
• Test the switch column drivers with a diode jumper
• Test the switch row inputs with a diode jumper

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