Hi!
I've been restoring my id4 and now I've got an issue with the VUK. I'll try to explain it. The VUK fires and sends the ball back to the playfield, as it should, after entering the VUK from the alien head or the virus hole. But, sometimes the VUK keeps firing like three times after the ball has been delivered back to the pf. Everything seem to work except this. So, I've checked all switches in the switch test and the VUK switch is not active. Also it's not stuck since I've looked it over and adjusted it. The only strange thing I can see is that switch 45, in the metal subway from the virus hole to the VUK does not have a diode on it. It's the same on a spare pf I've got as well as for another guy who have the same problem. I wonder what can be wrong here.. Do the subway switches share the same diode for some reason or why is it left out? any ideas?

Thanks

Hm, not really at the VUK itself but the ball can reach the VUK by two entrances. The first has an opto that opens the alien head, next a normal switch when the ball has landed in the head, next another normal switch in the subway to the VUK. The other entrance is a drop hole in the pf, the "virus hole". There it's just one switch in a subway to the VUK. The VUK itself has a normal micro switch with a ring on its arm that gets pressed down when the ball is there and should be shot out.

The switches I mentioned above are all on the same column, including the opto that opens the head.

I've heard that the opto giving a false reading could cause some strange behavior but not sure how in this case.

Let's say the VUK has "presence" on the opto and if the head is open it knows it should fire after the subway switch has been triggered. But if it does not (since it was a false reading and no ball is there) it will fire anyway thinking the through switch might be bad. Kinda like a ball search.

I must test this a bit more but I think it happens during multiball when a lot is going on like lots of vibrations and two balls can pass the opto at almost the same time and maybe pass as one reading etc. Maybe this confuses the VUK. Now I'm just brainstorming and I'm no expert.

Also, why isn't there a diode on one of the subway switches?

/andy

After playing it some more it seems something's fishy with the alien opto the through switches and the VUK switch. It's not really anything wrong but sometimes the opto will lock the ball even though it doesn't make it down the hole. After that strange things happens but seem to go away after the next ball is locked...

Just to follow up (and hopefully help someone else), I noticed the switch #52 that indicates if the head is open or closed was not triggered by the actuator arm on the shaft from the left head half. When I aligned it so it closed the switch when the head is open it now seem to work properly. Still need to give it a few more plays but from the three plays I made to test it it works now. If not check if the switch works at all and make sure it's closed when head is open and vice versa.