from the tech guides at http://techniek.flipperwinkel.nl/desega/index2.htm#trans
Testing TIP122/102 Transistor and Down-Stream Wiring/Coil.
If the coil fires in the above test, there may be a transistor problem. Next test the TIP122/102 transistors. Only do this for the TIP122 or TIP102 transistors! Damage can occur if this test is done on other transistors (like TIP42 or TIP36). This test will test everything from the CPU board down to the coil itself. If the TIP122/102 and coil pass this test, and the coil still doesn't work in game play, the problem is more "up stream". All that is left is the 2N4401 pre-driver transistor, and the logic TTL chip that ultimately controls the whole process (a 7402 for the special coils or 7408 for the constant power solenoids), and the PIA 6821 chip.
Note the TIP36c transistors can be indirectly tested using this method too, BUT the TIP122 pre-driver must be grounded. All TIP36c transistors use a TIP122/TIP102 as a pre-driver. If the metal tab on the pre-drive TIP122/TIP102 is grounded, this will activate the TIP36c, which will energize it's associated coil.
Game is on, and in diagnostic mode (push the green coin door button down, and press the black button on games Frankenstein and before to go into diagnostics mode).
Remove the backglass.
On games WWF Royal Rumble and later, close the coin door.
Find the transistor that controls the coil and/or flasher in question (refer to the manual).
Attach an alligator clip to the grounding strap in the bottom of the backbox.
Momentarily touch the other lead of the alligator clip to the metal tab on the TIP122/102 transistor (only works on these, may damage other transistors).
The coil or flasher should activate.
If the coil or flasher does not fire, it may be a transistor that is multiplexed through the L/R relay.
To energize the L/R relay (which will fire the other coil/flasher that is multiplexed), attach another alligator clip to the grounding strap in the backbox. Connect the other end of the alligator clip to the metal tab of transistor Q29. This will energize the L/R relay on the PPB or MRB board.
If the coil or flasher does not fire, and the coil or flasher did fire in the previous test, there probably is a wiring problem. A broken wire or bad connection at the connector plug would be most common. It is also possible a driver or pre-driver transistor is bad. Use the DMM meter to test the transistors on the board (see Transistors Testing Procedures for details).