Bought a power supply kit (#1 inside the cab) from Big Daddy's and I have no idea how these should be wired. Can I safely assume that I can match up the wiring with the 90 degree prong in the lower left corner and the ground in the upper right?

Thanks,

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Thanks!

Oh, they are marked - the "~" symbol is for the alternating current from the transformer and it also has marks for the corresponding "+" "-" for the rectified DC coming out.

I'm sure glad this wasn't the first machine I got because I would have never made it through this project.

Thanks. Will do.

Yeah I didn't know that. I assumed this part was metal to metal. Thanks.

I only did the solenoids (24v) rectifier and that already has fixed a couple of startup issues. I had a solenoid lock on at startup and the scoreboard was flickering (not like the slamtilt but just sort of random - I did the slamtilt mod right away) but now no lockups and a solid set of 0's. Oh, and no blown fuses

No wonder tho, the old ones were rusted and corroded, not to mention they were 31 years old.

I started at the power supply in the head and then rebuilt the acid damaged MPU, but I'm thinking I probably should have started at the cab power supply. Oh well. I guess I wanted to get the hard stuff out of the way. I have a few weeks to rebuild the electronics while my clear coat cures.

Damn, I did a boneheaded move, I had the playfield board disconnected. I forgot. It didn't actually fix anything, accept now the voltage is 30 rather than 20. The other ones look like hell but test in the correct range.

I've kind of been putting off what I think is the root of this machine's problem while I take care of all the obvious upgrades. The wiring from the coin door had apparently been pinched in the door and the wires had shorted and melted together. I pulled them apart and individually wrapped them in electrical tape.. I'm no good at reading the schematics but I have a hunch that it's possible that it fried an IC on the MPU (all fuses check out). I'm thinking Z11 (it's the only one related to push buttons that I see) and possibly others. I don't have a logic probe but does any of that sound feasible?

The machine only powers up the general illumination, scoreboard, and the shooter lane eject coil locks on. Nothing else.

Thanks for the help guys!

I uploaded a video to my YT so you can see exactly how it starts. I have the driver board out ATM since one of the coils is locking on. Should I put it in and maybe pull the fuse to the coils?

I replaced a resistor and zener diode on A2 and all of the test points check out with correct values so I think that is good. I also replaced the caps in A1. Connectors all "look" good and I checked the one that goes from A2 to the MPU and that was good. The MPU had minor acid damage and I replaced all of those parts and it didn't change anything.

Video link:

Here's a pic of the shorted wires:

coin.jpg

I should say that startup isn't much different with the driver board plugged in.

It's funny, I bought it from a guy that said he tried for a couple weeks to get it going but when I looked in the door I saw the burnt wires still stuck together. I didn't say anything but I followed the wires right to a burnt out fuse. I thought it was going to be an easy fix!

Actually when I just put the driver board back in and turned it on I had the same coil lock on but also one of the kickers is firing like it's doing a ball search. Balls are in the trough.

I think I found a problem.

ic.jpg

Okay, thanks guys.

Yeah I don't get a response from any of the buttons on the coin door. But thanks I'll follow what you mentioned.

It's hard to tell from the pic but it's bulged on the side and the top where it's also cracked open a little. Fortunately I have one. I'll replace it tonight and go from there.

Thanks, I needed to hear that about now I have two weeks of my free time into the playfield so far. My 12yo daughter placed all of the components for the acid repair herself and I didn't double check her work. I really want to see this thing fire up, she'll be very proud. It just might really spark her interest in electronics.

Well guys I'm getting a little closer. Now the coin lockout coil is energizing (it hadn't been). The scoring displays still show 0's, flicker a little and then strobe. The next step in a proper startup would be credit display. The sound board doesn't boot up (maybe it does?) but I do get "sounds" occasionally.

I'm going to finish upgrading the power supplies and add the ground mods and hopefully come across a bad connector or shorted wire and then I'll go back to diagnosing the boards. I am throwing around the idea of getting an all-in-one board (all the boards have had work done to them over the years) But I'd hate to get one and still have problems because of wiring and connectors. I don't know if I can rule that out until it finally fires up.

That chip was really hard to remove! But I think I did my best solder job yet on the new one. I just hope I don't have to replace more of them.