Replace the pre-driver along with a failed driver transistor

A TIP102 is pre-driven by a 2N5401 (WPC-S and earlier) or MPSD52 (WPC-95); both cross to NTE288 and either can be used. A TIP36c has two pre-drivers: a TIP102 plus a 2N5401/MPSD52. The pre-driver sits next to its driver; the schematics or the solenoid test help name it. Replacing it is optional if it tests good, but it was probably overstressed.

Systems

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

Related tips

• Which transistor drives which WPC solenoid and lamp circuits
• A coil or flasher energizes as soon as the game is turned on
• Pre-Fliptronics: flippers work even with no game running
• Testing TIP36c, TIP102, TIP107 and pre-driver transistors in the board
• 20-second test for shorted coil driver transistors
• How a Bally display board drives its glass
• Rebuilding the +100 V section of the power supply
• Testing loose transistors on the bench

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