What the System 80 reset (watchdog) board does
From Devil's Dare (System 80A) on, Gottlieb fitted a reset board above the CPU board, plugged into its 40-pin TC1 socket plus a jumper wire so it can watch the displays. If the IRQ signal or the display digit strobe stops, it pulses the 6502 reset. On Haunted House and earlier the socket is empty. Without it a crashed CPU can leave displays, coils and driver transistors switched on until they burn.
Systems
Games
Related tips
- Replace the System 80 reset circuit with a DS1811 chip
- Game won't boot, or keeps rebooting, because of the reset board
- Reset section zener VR1 burnt on a System 80 CPU board
- Updating pre-Ice Fever reset boards to protect RAM Z5
- Dead CPU board: check the reset line first
- Niwumpf replacement CPU board takes about 10 seconds to show scores
- First power-up, step 4: add the CPU board one connector at a time
- Displays show 000000 at once and scroll; start does nothing
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part Two, Clay Harrell (pinrepair.com)