Questions for my Squawk & Talk Bally folks! I have a Vector with a 100% repeatable issue that I am sure lives on the S&T. When two switches are hit in play, background sounds are silenced until they are brought back by a kicker being set off. All ROMs are freshly reprogrammed, all PIAs are working, as is the CPU (externally verified) and all chips reset back into their sockets properly. A cap kit was also performed by a previous owner (and looks OK). The switches work and score and this behavior preexisted on the stock -35MPU and continue with the AlltekSystems model. As this isn’t a switch error, I am trying to figure out which sound input line is failing here - all voices work, with a mysterious “Period Completed!” In the launch lane (strikes me as an error, too).
The 4049 IC tests good in my IC tester, all gates reporting in OK, and I am working to verify the 75LS155 demux. I'm wondering if one half of the demux is dead, and half still working, but I don't have any spares to prove this so I will order a few for fun.
Since I cannot know by inference what sound/voice is triggered by switch 35 in play (that left outlane) I can't know what line is shot in advance of just poking around and working every permutation. I have the same issue with switch 12, which is the rollover in the launch lane - the one that yells "Period Completed!" - what would it normally say?
I have a video of all this in demonstration, as well as a video of the switch matrix test (for the non-believers) and foolishly posted this to a FB group first, here:
That link, if you can load it, will show you the videos I made, as I can't export them here yet (they're on my phone). The "advice" I got there was staggeringly useless, but well, it was an attempt to find someone with the experience (plenty of people with heart there, to be sure, including the ones trying to help).
Any ideas on how I can run this down?demux (resized).jpg