Testing a leaf switch diode in place

Steps

• Leave all wires on and do not close the switch.
• Meter on diode test: black on the banded end, red on the other end: 0.4-0.6.
• Reverse the leads: no reading.

Systems

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

Related tips

• Testing a switch diode out of circuit
• Switch diode failures and what they look like
• Testing CPU switch rows and columns with a diode and clip lead
• Test a lamp socket diode in place
• System 80 switch matrix diodes
• Spare diodes for coils and switches
• 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)