All eight switches on one strobe (row) fail in switch test, for example coin, start, door and tournament buttons on strobe 0.

A whole row of eight switches dead

Cause: Most likely the 1/4 W 220 ohm series resistor for that strobe on the under-playfield A17 diode board has burnt open. The strobe MosFET on the driver board is a less likely cause.

Checks

• Test the strobe MosFET (for strobe 0, Q33) with the meter's diode range.
• Follow the strobe wire: it daisy-chains through lamps to the A17 board, passes its 220 ohm resistor and changes colour (strobe 0 goes from yellow/black/black to green/green/green).
• Check the resistor on A17 for that strobe.

Fix

• Replace the burnt 220 ohm resistor.

Systems

• Gottlieb System 3

Related tips

• Switch diodes are on the A17 board, not the switches
• Lamp and switch matrix size and drivers
• Flippers dead in a game
• Testing a dead coil or flasher
• Diode-testing the 12P06 strobe MosFETs
• Lighting a whole lamp column by hand
• Spare MosFETs for the driver boards
• Logic chips worth stocking

Source: Repairing Gottlieb System 3 Electronic Pinball Games from 1989 to 1996, Clay Harrell (pinrepair.com)