Optional ground mod steps 10 to 12: cut the Q64 loop trace and tidy up

Steps

• Component side, lower left: cut the wide trace to J5 pin 15 that loops round Q64 and the board cut-out (a design error).
• Solder side: wire Q56's bottom pin (emitter) to the via about 1/2" below and left of it, and on to the wide trace at Q54's bottom pin.
• Fill or reflow any empty or sunken vias and any short-cropped joints on the rest of the board.

Systems

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

Related tips

• Optional ground mod step 1: ground the 2N3055 cases on the driver board
• Ground mod step 5: direct ground wire to the driver board
• Test the driver transistors while the board is out for the ground mod
• Use heavy wire for the optional driver board ground jumpers
• What the System 80 ground modifications achieve
• Test driver board outputs by grounding transistor tabs
• First power-up, step 5: add the driver board, then coil power
• Coils lock on and burn because of the Gottlieb ground fault

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