Had the most bizarre assortment of problems with my Tempest cabaret that started over a year ago -- it would be sitting there in attract mode, and suddenly a game would start and the shooter would just continuously fire, get killed, then the screen would flip upside down for player 2 like it was installed in a cocktail unit! Self test showed a bad Math Box and BOTH Pokeys! 
I checked the obvious things back then, because it looked like a loose cable, but was busy with a lot of other things and let it slide.
Last week I was tired of having a 350-pound paperweight sitting in the corner of my office so I started searching for a fix and found this forum.
Saw the posts about the Tempest interconnect cable and cold solder joints, so I disconnected the cable, checked the pins, which looked clean, reconnected it and the game played OK! But about an hour later it started doing the play-by-itself thing again.
So last night I pulled the circuit boards and took them down to the shop. And holy crap, I couldn't believe it -- I've seen cold solder joints on hobbyist boards before but never on commercial assemblies. Check out the photo of pins 1 and 2 on the interconnect connector on the AUX pcb:
I was amazed! Used a solder wick to suck all the old solder out and resoldered all the pins. Put the assembly back in and fired it up, and it worked. Left it on for several hours and played a bunch of games, and it seems nice and solid!
I was seeing a little quivering of the video after it was on for a while, kind of a diagonal scaling (upper left and lower right were shrinking toward the center and back very quickly) -- Maybe some of those pots need to get swapped out -- or does that sound like a Big Blue issue? I think I'll get my scope out and put it on the power supply to see if anything funny is going on there.
I checked the obvious things back then, because it looked like a loose cable, but was busy with a lot of other things and let it slide.
Last week I was tired of having a 350-pound paperweight sitting in the corner of my office so I started searching for a fix and found this forum.
Saw the posts about the Tempest interconnect cable and cold solder joints, so I disconnected the cable, checked the pins, which looked clean, reconnected it and the game played OK! But about an hour later it started doing the play-by-itself thing again.
So last night I pulled the circuit boards and took them down to the shop. And holy crap, I couldn't believe it -- I've seen cold solder joints on hobbyist boards before but never on commercial assemblies. Check out the photo of pins 1 and 2 on the interconnect connector on the AUX pcb:
I was amazed! Used a solder wick to suck all the old solder out and resoldered all the pins. Put the assembly back in and fired it up, and it worked. Left it on for several hours and played a bunch of games, and it seems nice and solid!
I was seeing a little quivering of the video after it was on for a while, kind of a diagonal scaling (upper left and lower right were shrinking toward the center and back very quickly) -- Maybe some of those pots need to get swapped out -- or does that sound like a Big Blue issue? I think I'll get my scope out and put it on the power supply to see if anything funny is going on there.
