Hi Guys,

Trying to track down an issue I am having with my Bally Star Trek which I can't seem to figure out.

The game boots up and starts a game on it's own and starts scoring like a few switches are activated and then stops.

When I go into switch test the #6 Credit Button is stuck on.

Switches 1 through 5 test good but after that #6 is showing it is stuck. I unplugged the connector that goes to the coin door but still stuck. I thought it might be the MPU so I replaced it with an Alltek MPU and the problem remained the same.
Testing switches I noted the solenoids for both slingshots fire, left and right bumpers fire. The bottom bumper, however, does not fire at all. I cleaned the switch (business card) but still nothing, contacts look clean visually. The bottom bumper does not fire in solenoid test so I either have a bad coil or transistor. In solenoid test, everything but the bottom bumper fires, I can also here the flipper relay click. I don't note any sound from the coin lockout door coil although I'm not sure I'm suppose too.

I looked for loose wires, diodes and caps and switches, but nothing.

Solenoid/Power Board test points
Tp1 5.1
Tp2 158.2
Tp3 5
Tp4 248
Tp5 14.7

Rectifier Board
Tp1 5.8
Tp2 247
Tp3 14.8
Tp4 6.8 AC
Tp5 45

Any ideas on what to look for would be greatly appreciated.

Game was working great for a few months with no issues until recently.

Tom.

That's what I was thinking. Unfortunately the schematics suck and they don't list every switch in the matrix in the manual.

Thanks I'll start with that.

Thanks.

This is what I love. The credit up button isn't listed on the switch matrix.

image_(resized).jpeg

Fixed the switch matrix issue. A bulb socket was touching the metal of a switch bracket.
Now I have to figure out why the bumper stopped working.