Test the driver transistors while the board is out for the ground mod
Before the ground work, test every driver board transistor and replace bad ones; it takes minutes with the board already out. Have MPS-U45, MPS-A13, 2N3055 (with its 9.1 ohm resistor) and 2N6043 spares, four connector pins for A3-J1/A1-J4, and about 10 feet of 18-gauge wire.
Systems
Related tips
- Test driver board outputs by grounding transistor tabs
- Ground mod step 5: direct ground wire to the driver board
- Optional ground mod steps 2 to 9: driver board ground jumpers
- Optional ground mod step 1: ground the 2N3055 cases on the driver board
- What the System 80 driver board transistors drive
- System 80 driver board transistor types
- 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)