Diode-test a driver board 2N3055

Steps

• These are Q58, Q62 and Q64 (big metal cans) and test the same in or out of circuit.
• Black lead on the case, red on each leg: 0.4 to 0.6 on one leg, nothing on the other.
• Red lead on the base, black on the emitter and then on the case (collector): 0.4 to 0.6 each time.
• Also check the three 1 W 9.1 ohm resistors that go with them read 9 to 10 ohms in circuit.

Systems

• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B

Related tips

• Diode-test the driver board MPS-U45 and MPS-A13 transistors
• Optional ground mod step 1: ground the 2N3055 cases on the driver board
• Test the driver transistors while the board is out for the ground mod
• What the System 80 driver board transistors drive
• System 80 driver board transistor types
• One driver board fits every System 80, 80A and 80B game
• Relay and coin counter transistors on the driver board
• Some 80B driver boards use the coin counter transistors

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