First: Nothing wrong with that. It supplies all the same voltages. I think the pinout is identical. I own Pinbot and recently owned a Comet. I've been meaning to scan my pinbot manual, the one on IPDB is horrendous. Do you just need the transformer secondaries and colors of the wires? What info do you need specifically? Either way, if it boots up and is working and doesn't blow fuses, I think you're fine.

Second: The connector on the PSU is correct. All connectors on pinballs are keyed, meaning certain male pins are removed on each connector and little plastic plugs are inserted into the female connect to make sure you line it up right and so you don't plug it into something you are not supposed to. You see how that white connector has to pins cut off? that corresponds to the missing wires on the connector, you are in good shape (although that header looks a little burnt/toasty and probably needs to be replaced).

third: What do you mean by manually touch the playfield contact together? You mean the contact switch for the right slingshot? If that is happening, you may have a GI line or a bulb touching or near the sling switches. You'll have to lift up the PF and examine. Pushing in on the switch may cause it to touch a bulb socket.

GI lines get warm if you aren't using LEDs. Decent current draw going on with a bunch of bulbs...

For the sling, that resides in the special solenoid section on the mpu (the 6 TIP122/102's next to thee relay). It is not cpu controlled, so you may have a burnt out TIP102 if that sling shorted out on the GI line. You'll have to manually ground the tabs on each one to test them out and see if they all fire. Just take an alligator clip, clip it to the tab, and touch a gnd point in the bakbox momentarily. If it fires, the issue is with the line to the switch or the coil is blown out. It isn't likely the coil is bad if you can manually move it though. When coils go, the sleeve usually melts too and makes it hard to move the plunger.

Correct, those 6 transistors. The theory behind it is that if they were computer controlled, they wouldn't react fast enough. The problem with it is that they can latch and stick on and burn up because they aren't computer controlled. they usually burn up when they fail, but not always. You can test them easily if you have a multimeter, or you can manually active them by doing the alligator clip method I wrote about above.

There are 6 special solenoid drivers. In Comet, the 2 slings, and the 3 pop bumpers use them. Q77 needs to be replaced, TIP102. That will fix your bad sling. But before you do that, inspect that sling and the switch and wires carefully. If the transistor blew, something shorted it out, you don't want it to blow out again.

Q85 is not used in this game, so it will not activate anything. Technically, if you don't have a TIP102 or TIP122 (try to always use TIP102s), you can take the one out of Q85 and put in in Q77's place.

Ratshack sells TIP102's

Not really, ops did that all the time. If the part it working an unused, nothing technically wrong with it. Just always better to get the new 10 cent part if you can. I do this sometimes to confirm suspicions prior to ordering certain parts sometimes, especially more expensive parts, otherwise you're wasting money.

My advice would be not to try and restore it yourself, unless someone makes an overlay or a new repro comes out. That was a freakin' painful restore. I saw Vids and was like "I can do this" and 100 hrs later I understood how good guys like Vid are at it and ended up with an OK restore... A better than nothing, but not great 6/10 job. Great learning experience though, and that was the intention.

You got a scan and someone that can print an overlay?

You can use SYS9 or SYS11 PSUs. Even a damaged PSU is an easy fix though. Large traces on those boards. May be cheaper to send it out for repair then to get a replacement that will also need new caps and whatnot. Post some pictures when you get a chance.

Yes, the relay cubes can fail.

You desolder the lugs on it and replace it like any other component. But they don't fail that often. The relay on the PSU controls whether the flashers or coils are operating, so if you have one working all the time, but not the other, the relay could be bad. A TIP driver on the MPU controls the relay, whether flashers or coils are selected. So it may not be the relay, it could be the selector transistor on the MPU.

BTW, I've seen much worse PSUs and got them working fine. No need for a new one here. Go easy on the solder flux (don't use it on PCB boards). BTW, you'll wanna replace the large +5v cap on there along with any other older electrolytic ones. May as well drop the Zener diodes down to 91v if you have the original displays while you're at it.

Check the voltage at the coil itself. If it has voltage, suspect the switches for the sling, possibly a broken wire. I'd check continuity first on the switch (make sure it is registering closed), then buzz back to the MPU where it connects..

Awesome you didn't give up on this. Just re-read this. Looks like you've got a PITA on your hands.

Probably a light bulb socket touching one of the metal brackets on one of the kickers. Carefully inspect those areas.

The coils always have power on them, so that isn't going to help you. The MPU just controls which signal paths get set to ground.

I'd lift up the playfield on the flimsy sys9 prop (be careful, I used to bungie strap the sys9 PFs to a hook in my ceiling cause I didn't trust those shit props they have), and turn it on so you can see which coil is buzzing. Then turn it off right away so it doesn't burn up a coil. Let us know what you find.

You can order caps from Mouser, but it can be time-consuming to put together a cart and find all the right/close enough values. If you aren't familiar with caps or ordering caps though, I'd wait for the kit so you don't get the wrong stuff and blow it up.

Check for + voltage on the coil.

Small resistance between the two tabs on the coil = good. It should be good to go as long as it can move manually.

Next, check what Grumpy said to find out if that transistor is shorted or not. With game OFF, if ohm probe between ground and that tab reads 0 ohms, it is no good. Else, the next test is to make sure the coil is getting power.

Done that myself a while back before I got the desoldering gun.