I am trying to troubleshoot two recent issues with my Alien Star game.

1) The top ("a") segments of the Player 1 and Player 2 score displays are not lit up. At first I thought it was the displays, but apparently some issues will appear in both displays since they share the same circuitry. All the connectors to the displays are straight and clean. Also, I don't see any obvious problems on the control board but I'm not sure what/where I should be checking. I have the schematics and I'm pretty handy, but the electronics look a little complicated, so I'm looking for some guidance with this issue.

2) I have an intermittent problem with the ball return. It suddenly stopped working and when I finally got around to investigating, it started to work again after fiddling with the outhole coil. After playing several games, the return stopped working and that's when I realized the issue is with the coil which opens to allow the ball to advance to the shooting position. Mechanically it appears to be closing the contacts when the ball hits the wire, but the coil doesn't move. I tested the resistance of the coil which is 15.6 ohms, which is also the the same reading as the outhole coil which is working properly. Not sure what to do next.

Ball return (resized).JPG

Control board (resized).JPG

Display (resized).JPG

The issue does not stay with the display when P1 and P3 are switched.

I'm not sure about the nomenclature of the ball return coils, but if I start the game with the two balls sitting in the outhole, that coil activates and pushes the first ball and then the second ball towards the second coil. The second coil does not activate to allow the first ball to the shooter. If I then take the second ball and drop it back into the outhole, that coil sends it back up the ramp but the second coil doesn't activate and the two balls remain behind that coil. Also, once the second ball is pushed behind the first ball, the sound stops and the playfield lights go out as if the game is over, although the display stays lit and P1 score is blinking "00" and ball-in-play display is "1", as if waiting for ball to be played. I'm not sure how to test the coils aside from the basic resistance test with power off. Frustrating, since the return was working fine a few days ago.

Balls in return (resized).JPG

- So, the connectors at Z19 appear to be solid (see pics), so I'm guessing I should start by replacing that and see what happens.(?)

- When the balls are in the trough, the leaf contacts of the switch are closed and when I check for continuity at the wires coming from the switch I get a reading of 3 ohms. This is consistent with the reading I get on the outhole switch which is working properly. As I noted earlier, as soon as the trough switch closes the sound stops and playfield lights go out, and the only way I can restart the machine is to turn the power off and on.

Thanks for the guidance, zacaj! To be honest I've never had to work on the electronics/circuitry of a pinball machine, so I'm figuring it out as I go along. I've had the machine for 20+ years and have only had to perform routine maintenance (bulb and bumper replacement, etc).

Z19-1 (resized).JPG

Z19-2 (resized).JPG

The display issue just started, never happened in the past. I didn't even notice the chipped board edge until you pointed it out. However, that would explain the unusual red wire which you can see in the photo. It appears that the board corner chipped and was subsequently repaired by soldering the thin red wire to splice the affected circuit. The soldering looks to be solid, so don't think that would be the cause of the issue. I'll try to check schematic to see what that red wire circuit does.

As of right now, the trough switch closes when the first ball hits the trough. The trigger wire and leaf contacts are "adjustable", so I'm not sure if that's supposed to be correct or whether the switch is supposed to be closed only when the second ball hits the trough.

Is there any way to test an IC while still on the circuit board to determine if it is the problem? Or should I just replace the IC since it MAY be the problem and see if that's the solution?

Thanks zacaj. That's a little above my expertise so I may check locally for assistance. Would like to solve that ball return problem, since I can live with the display issue for now.