Firing a coil or flasher from its TIP122/102 driver tab

Steps

• Put the game in diagnostics; remove the backglass.
• Look up the driver transistor for the device in the manual.
• Clip a lead to the backbox ground strap and briefly touch it to that TIP122/102 metal tab: the device should fire.
• For a multiplexed device, also ground the Q7 tab (before Big Guns) or Q8 tab (Big Guns and later) to switch the A/C relay and try again.
• If the device fires here but not in the solenoid test, suspect the driver or pre-driver; if it does not fire here but did when grounded at the coil, suspect wiring or a connector between board and coil.

Only do this on TIP122/102 drivers. Grounding a TIP42 or TIP36 tab this way can damage the board.

Systems

• Williams System 11
• Williams System 11A
• Williams System 11B
• Williams System 11C

Related tips

• Quick check of all TIP122/102 drivers before first power-on
• Use TIP102 when replacing a TIP122
• Lock diverter locks on at power-up and gets hot: shorted driver transistor Q22
• CPU and driver board transistors by position
• Testing driver transistors in diode mode (board out of game)
• When a driver fails, replace its pre-driver as well
• Diverter coils dead and flippers live at game over: 7402 at U50
• Quick lamp row test: ground the row driver tab

Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)