I've got some odd issues going on with my Back to the Future. I'm thinking I have some sort of issue with the power supply board. Here is what has been going on.

1. The machine won't always turn on. The lights come on but there is no score display and no sound. Sometimes the vuk will lock on. If I unplug the connectors on the power supply board and plug them back in it will usually turn on and everything will be fine.

2. Now the bumpers and slingshots will not fire. In diagnostic mode they won't fire either. Some of the flashers listed under the coil test are no longer working either. The right sling did fire once this morning then very weakly after that. Now they won't fire at all.

3. The machine will randomly reset. When that happens it will usually be playable. But every once in a while it will totally lock up and the display and sound will go out like when I try to turn it on.

It all seems related to the power supply. I'm going to have some time later today to look into it more. But if anyone has any thoughts I'd love to hear them!

I'm gonna take a look and check voltage right now. I just checked the machine before jumping on here and in diagnostics during the coil test for the slings, if I hold the start button they will both fire after a while, albeit very weakly.

A little update here before I have to go mow the lawn.

I fiddled with the CN1 connector on the Power Supply Board and everything is working now. I am wondering if I need to replace the connectors. Both the male and female for CN1 area little toasty. However I think there may be something else going on. I measured the voltages on the CN1 connector on pin 10, 11, and 12 and got 4, 6 and 2 respectively. It looks like 10 and 11 should both be 9 and pin 12 should be the ground. Not sure what to make of that.

Thank you for all the advice so far terryb. It is much appreciated!

The numbers I gave earlier were what I was getting in AC mode. The DMM I have automatically switches between AC and DC. Not sure what to make of the numbers then.

I just got done monitoring the 5 volt test point. I did get it to fluctuate by turning off the game, then unplugging and plugging back in the CN1 connector. When the game would operate fine it was at 5. But when it would turn on and be locked up it was between 0-2.

So it appears this may be the issue. My only other concern now is the readings I was get on pins 10, 11, and 12 on the CN1 connector. But it does look like the CN1 connector could be the culprit.

Thanks again for all the help terryb. I'm going to order the connector replacement kit for the CN1 and report back with my results.

I think I am also going to order a new capacitor for the C7 on the Power Supply. It looks like mine leaked at some point. There isn't any damage but I think it should be replaced. Odd thing though. In looking at the capacitor in the manual it says it is a 100 uf 25v, the one on my board is 100 uf 16v. I need to do some more digging, but it appears the one on my board is the wrong one.

I replace the female end of the CN1 last night to see if that was the issue. Since doing that I've had no issues! I'm still going to replace the CN1 on the Power Supply Board and that capacitor when I get a chance.

Thanks again for the help terryb!