Ground mod step 5: direct ground wire to the driver board

Steps

• Below chip Z10 find the wide trace that joins pin 7 of Z10, Z11, Z7, Z5, Z3 and Z1.
• Scrape off the solder mask and solder on about 18" of wire, keeping clear of the resistor row below and the thin Z2 pin 11 trace above.
• Or use the lower lead of the upright capacitor at the upper right of the board.
• Put a fork terminal on the other end and bolt it to the power supply frame (on 80B, to the ground plane bolt at the upper right of the backbox).

Systems

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

Related tips

• Optional ground mod steps 2 to 9: driver board ground jumpers
• 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
• Use heavy wire for the optional driver board ground jumpers
• Optional ground mod steps 10 to 12: cut the Q64 loop trace and tidy up
• Test driver board outputs by grounding transistor tabs
• First power-up, step 5: add the driver board, then coil power
• Diode-test a driver board 2N6043

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