Williams Hot Shot - not quite a pinball but WPC based

[swamprat96]

I think the fact that this thing is a basketball game and not a pinball is throwing me. My tiny mind is struggling to understand the latest issue

As the title says this thing is all Williams WPC boards driving a very simple basket ball game. Thers only one solenoid on the whole game! And that's what I'm having trouble with. I've never seen the game going so I could be making incorrect assumptions.

Anyway the solenoid will not fire under test mode. It fires if I ground the coil and if I ground the Tip102 behind the Tip36 (Q78). Both transistors test ok on the board (yeh I know not bulletproof). I was starting to think the pre driver 2n5401 or the ic in front could be the issue. But-

The Solenoid they use is actually a Flipper coil. So the hold winding is fired via Q76 - and thats not working either. Again it will hold if I ground the coil and if I ground the Tip102 before the Tip36 (Q76).

So i'm thinking the 74LS374 chip that drives both perhaps? Never had to change one in a williams before.

Please check my logic and any suggestions welcome

PS No corrosion(my first thought), reseated the ribbon cable and associated connectors

[swamprat96]

OK this thing is haunted It is now completely working- and whilst that might sound good I did nothing to it. I lowered the playfield and noticed a whole string of controlled lights came back on that had been out. I then tried the solenoid and away it went

I'm now suspecting the old BR2 issue or caps or both. Possibly still CPU I guess but I can't see anything obvious

[Pinball Fixers]

I have seen one of these machine, but not for may years now...

Your pinball thinking is correct with the machine, so repairing it shouldn't be too much of a problem.

At this point I'd be checking the wiring, as you said then when you lowered the playfield down it started working - so check for shorts, wires that have had the insulation worn through, connectors, etc...

It may be the bridges and caps as you have said, but BR2 and its associated cap is more of a resetting problem than a non-working coil problem...