So, I've been working on a Gottlieb Touchdown. Up until this point, the electronics have been working fine.
I plunged he ball, hit a rollover, hit a pop bumper, hit a slingshot, and the slingshot started machine-gunning. I turned the game off, adjusted the slingshot switch.
When I turned it back on, it wouldn't go into attract mode.
The player 1 & 3 displays show the number "1" and sometimes alternate to the number "0". The credit display occasionally shows gibberish or flashes zero along with the other displays.
After attempting to troubleshoot by checking voltages, swapping in a power supply, and swapping the old one back, all of a sudden, the knocker started firing as soon as I turn the machine on. It alternates between 4 knocks, 3 knocks, and 2 knocks. But, sometimes when I turn the game on, it doesn't fire the knocker at all. It's very intermittent.
The manual and System 80 service manual don't seem to have anything that fits these symptoms.
I thought I was all ready with this machine to bring to Allentown to have out for free play, but now that it's acting strangely, I'm not so sure I should go through the trouble of bringing it.