I’m working on a Williams Space Shuttle, (System9). After spending way too much time and effort I’ve got the game playing fine—with the exception of an annoying problem at startup—the ball server solenoid ALWAYS fires once when the game is powered up. Otherwise the solenoid works as it should during game play. According to the owner, the machine, has ALWAYS behaved this way.
I’ve researched this issue online, but can’t seem to find anything definitive about the cause or the solution --everything from loose wires on the coin door to stuck switches. The Williams troubleshooting guide mentions this problem and offers four possible remedies: (1) coil TIP output transistor, (2) solenoid diode, (3) pre-drive transistor, (4) the QUAD AND chip (7408).
The TIP transistor is fine (new), the diode is fine,(new) and my assumption is that the drive transistor is fine (have not pulled it to check) because the solenoid works fine during game play. On the long shot that the 7408 has a single gate that has failed, I’ve ordered a new 7408IC.
Should the 7408 not solve the problem, can anyone offer some potential area(s) to look? I’ve done all the obvious things (re-seated chips, connectors, etc) but at this point I’m running out of ideas. Attached is a snip of the schematic. U57 is the gate, TIP122 is drive, SOL2 is the ball server. Any insight would be greatly appreciated. I’m a klutz.