This is actually on one of my personal games. Contrary to popular belief, even though I own and work on a lot of pins, I don’t really play them that often. Actually, its very rare for me to play a game at home by myself.
However, tomorrow I am having some people over for a semi-regular pin night get together, so I wanted to make sure everything was up to speed. Upon firing the games on, I noticed Whirlwind’s display was missing. Tried reseating some cables and doing easy checks first, no dice.
Checked the fuses for the +100 and -100v circuits in the power supply, they tested good. Next was checking the pinout reading on the board. The -100vdc was practically non-existent, so I pulled the board and checked the 39k ohm resistors first since they are a popular failure point on System 11 games. Sure enough, the 39k ohm resistor in the -100vdc circuit was open.
Luckily, I had some sturdier 2 watt 39k’s on hand. Didn’t even throw this on the bench, just quick and dirty replaced it beside the machine. Popped the board back in and viola, no man down for the get together tomorrow night.