Testing a microswitch diode without unsoldering it

Steps

• This assumes standard wiring: green wire on the center lug, banded diode end on the far lug, the other diode end and switch wires on the near lug.
• Pull the green wire off the center lug (if it is soldered, use the out-of-circuit test instead).
• Meter on diode test: black on the banded end, red on the other end, and hold the switch closed: expect 0.4-0.6.
• Reverse the leads with the switch still held: no reading.

Systems

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

Related tips

• Switch diode failures and what they look like
• Fitting a new switch diode the right way round
• Testing CPU switch rows and columns with a diode and clip lead
• Testing a coil diode
• Testing the diode on a coil
• Which way a coil diode goes
• Which way a coil diode goes
• Testing a lamp diode

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