Testing a playfield-mounted 2N5875/2N5879 with a meter

Steps

• Game off. Set the meter to diode test.
• Note whether a pull-up is fitted: if one leg carries two wires, it is.
• Red lead on the metal case, black lead on each leg in turn.
• Fitted with a pull-up: both legs should read about 0.4 to 0.6.
• Out of circuit, or fitted without a pull-up: one leg reads 0.4 to 0.6 and the other reads open.
• Anything outside roughly 0.4 to 0.7 means the transistor is bad.

Systems

• Gottlieb System 80

Games

• Black Hole
• Haunted House
• Volcano

Related tips

• Which wire goes where on a playfield 2N5879
• Coil stuck on that is driven through a playfield-mounted power transistor
• Lower playfield pop bumpers lock on or blow their fuse: shorted driver transistors
• Test an under-playfield 2N5875/2N5879 coil transistor
• Coils pulse briefly at switch-on on Volcano, Black Hole and Haunted House
• Replacements for the under-playfield 2N5875
• Volcano playfield-mounted transistors
• Correct wiring of an under-playfield 2N5875

Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)