For the last 6 months or so, I've been working on a project game that has been passed around upstate NY like a bad penny. It's a 1978 Playmatic Last Lap-- very cool and unique playfield layout, and the (few) videos on youtube of gameplay look like fun. It appears that working playmatic SS games in the US are frighteningly rare.
With scant, almost non-existent documentation, this project has proven difficult. A couple of friends and I have spent more time troubleshooting these board (and their totally obsolete parts) than I care to talk about... but I finally have some success to report. Last week, I was able to secure some replacement boards from someone who parted out another playmatic machine, and using the replacement MPU plus the decoder and thryistor boards that we have rebuilt, I was able to get the game to complete its boot sequence, it goes into attract mode, allows me to add credits, and start a game!
There are still however, issues that need to be overcome...
- upon starting a game, the ball is kicked into the shooter lane, but the kicker remains locked on.
- The drop target bank doesn't reset
- the flippers don't work
- the playfield switches don't work.
- the scoring displays either don't work at all or display gibberish. I know the voltage from the decoder board is good, as it operates the credit and ball in play displays.
I suspect that the first several issues may relate to the bridge rectifier under the playfield, which I will test tonight and replace as necessary.
Anyway, I just wanted to share some of the successes, I'm happy that it finally seems to be moving in the right direction.
If you've got any other ideas for things I should be looking at and testing, I'd welcome any and all advice.