A couple weeks back I had visitors at my place... which is a big deal because the last time I had some guests over at my place was in early 2020... a long time ago. I just didn't feel like having anyone over since then.
Anyway, my guests were into the very eclectic and rare games so we were playing 1940 Gottlieb Score Card.
Gottlieb Score Card is a sequence game. The objective of the game is to light a complete number sequence on one of the four cards to win a massive amount of credits.
I repaired the game back in 2020 but before that it took me a number of years just to find all the missing parts I needed to get the project going. I wrote a couple of posts back then about overview and repairs...
So back to the bug... I kept noticing that once in a while the 100's wouldn't reset all the way back to zero when starting a new game. It would reset to 900 when the reset cycle would complete.
I decided to investigate the bug. I had a look at the 100's stepper unit. It's a 30 step continuous stepper. When resetting the game, the unit will step forward to the next zero. There are three positions on the disc that are a zero. I did a number of resets of the game and observed where the wiper unit stopped. It was always in the same spot that it stopped at 900. The two other zero positions would work properly. The bug was definitely electrical.
The unit is also responsible for lighting the 100's and giving the impulse to step up the 1000 point unit.
I took the wiper disk off so I could have a look. I suspected a broken wire on the back. But, checking with the multi-meter, I had continuity. Then I checked the continuity from the wiper and side and it measured open circuit. So I poked the solder glob on the back of the rivet and found a cold solder. Sneaky.
The repair was pretty easy. Using my soldering iron I removed the old glob of solder. Then I cleaned the back of the rivet with a dentist's pick tool and re-soldered the wire with some fresh tin solder and re-assembled the unit.
Job done.
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