A problem started occurring on my Meteor a couple of nights ago that I've not encountered before and I'm looking for some guidance.
I restored this machine 6 months / ~200 games ago and I haven't had the glass off, playfield up, or the backbox open since March till Thursday night when I noticed this behavior.
Meteor has 6 switches that will spot (drop) a drop target in the METEOR bank if the corresponding switch lamp is lit:
Upper Rollover Button
Middle Rollover Button
Lower Rollover Button
Stand-Up Target
Left Return Lane
Right Return Lane
The problem is with the Left Return Lane. When the SPOT TARGET light is off, the switch registers correctly and awards 500 points. When the SPOT TARGET light is on, the switch still registers 500 points and does NOT drop one of the METEOR drop targets. The Right Return Lane, along with all of the others besides the Left Return Lane, operate normally with the correct points (500 with the SPOT TARGET lamp off) and dropping a METEOR target if the lamp is lit (and awarding 2000 points).
Here's what's wrong: If the Right Return Lane SPOT TARGET lamp is lit, and the Left Return Lane SPOT TARGET lamp is NOT lit, and you roll over the Left Return Lane switch, a METEOR target will drop, the score awarded is 2000, and the right SPOT TARGET lamp turns off.
Here's a sort of Truth Table of the what's happening on my Meteor with the red indicating incorrect behavior:
Return Lane Truth Table (resized).jpg
So mechanically, everything seems to work so I'm not suspecting any wiring or connector issues. Which leaves some sort of logic problem. Not sure where to start?
The MPU is a one-year old Alltek, and I've tried clearing the memory. I do have the original MPU that has some reset issues I haven't fixed yet. It does boot once in a while all the way to attract mode, so I'm thinking of maybe trying that to see if the problem replicates. If it does replicate, then at least I know the issue isn't with the Alltek board.
Thanks in advance for any advice....