Testing TIP36c, TIP102, TIP107 and pre-driver transistors in the board

Steps

• Game off, meter on diode test.
• TIP36c: red lead on the metal tab, black on each outer leg in turn: 0.4-0.6. Black on the center leg (collector), red on the tab: zero. Black on the base (left/top) leg: red on the center leg reads 0.4-0.6, red on the right/bottom leg about 0.2.
• TIP102: black lead on the tab, red on each outer leg: 0.4-0.6. Red on the center leg: zero.
• TIP107: red lead on the center leg or tab, black on each outer leg: 0.4-0.6. Black on the center leg with red on the tab: zero.
• 2N5401, MPSD52, 2N4403 (no tab): black lead on the center leg, red on each outer leg: 0.4-0.6.
• Any other reading means the transistor is bad.

Systems

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

Related tips

• Replace the pre-driver along with a failed driver transistor
• 20-second test for shorted coil driver transistors
• 20-second check for shorted TIP102s
• Testing a coil diode on the driver board
• Taking the power driver board out of the backbox
• Coil locks on as soon as the coin door closes: transistor shorted by the old coil
• Learn the power driver board layout first
• Testing a 74LS374 driver latch with the diode setting

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