Bally 742-A blowing fuse

[newkid3]

  Hello all,  I have very little experience with Electro mechanical slot machines. I have a Bally
742-A that is blowing the 50v 3 amp fuse. I have done some troubleshooting. I pulled the hopper and reels out of the machine. I also unplugged both door plugs. Then I plugged the machine in and pushed the door switch in just to make sure everything was connected. I then unplugged the machine and checked the fuse and it was still good. So then I hooked up the top door plug and plugged the machine in pushed the door switch. Checked fuse and it was still good. So then I plugged the bottom door plug in and did the same test. It blew the fuse. It seemed like it did not blow the fuse until I pushed the door switch in. It sounded like the counter clicked when I pushed the door switch in. Then when I checked the fuse it was blown.
 So I put everything back in the machine and connected the top door connector but left the bottom connector unplugged. I plugged the machine in and pushed the door switch and the fuse did not blow. So it has to be something on that bottom connector.
 Is there a manual and schematics out there for this machine?
 Would anyone know what I should check for a short from the bottom door connector?
I checked for a short between the cabinet and all of the wires in that plug on both sides of connector but did not find a wire that showed a short. I just thought of something I did not have the door switch pushed in when I was testing the connector wires for a short.
 I would really appreciate any help you could give me. Thanks

[newkid3]

  I did do some more testing today. If I plug the machine in with everything in it and everything hooked up but the door open the fuse does not blow. As soon as I push the door switch in the counter clicks over one number and the fuse blows. So it was 84033 before i pushed the door switch in. When I pushed the door switch it went to 84034 and the fuse blew.
 Does anyone know what is tied into the door switch that could be shorted out? Wish I had a schematic for this machine.

    Thanks

[jimliner]

Is it the coin in, coin out or drop meter that goes up by one number?

My guess is the "in" meter.

Jim

[newkid3]

 Jim, it has a sticker on it that says CASH BOX.

    Thanks

[jimliner]

Ok, that switch is on the door along with the coin in switch. 

I would look for obvious sign of shorting at the switch.  Usually the door switch has heat shrink on connections.  Also look at wires to and from meter.  You could disconnect the drop (cash box)  meter and see it fuse is ok when switch is closed. 
        I added a drop switch to a door.  The wires can be routed behind a plate.  That's where they were cut and taped.  If fuse doesn't blow with bottom door molex disconnected, you may want to check at switch on door.

[newkid3]

  Jim, I think you might be correct on the switches on the door. I was just looking at some pics I took of the inside of the door and I see two suspect areas just from looking at the pics.
Both switches has the heat shrink pushed down the wire on at least one wire. If you look close on the second pic of the switch at the bottom left hand side of door it looks like it is pushed back and twisted some also.
 I wont be able to look at the machine until a little later today but I hope I will find the issue there.
I am thinking the switch is shorted out to the cabinet ground and that is why the meter steps up one and then the fuse blows.
 I will report back with my results.

     Thanks

[newkid3]

  Well it was not a switch. The pictures were deceiving. The switch connections are pretty far away from metal. I will get the shrink tube back on all of them like it should be though.
 I disconnected all of the wires off of the meter marked CASH BOX and put a wire nut on the two orange wires to make sure they were still connected. I then put a wire nut on the other wire just to protect it. After doing this the fuse does not blow. I put the hopper back in and everything on the machine works and plays as it should.
 When the meter was hooked up it did seem to operate before it blew the fuse each time. So would it be the meter is shorting out internally? Do you know if this could be fixed?
 What are my options short of just leaving it unhooked?

   Thanks

[jimliner]

Replace meter.   They come up for sale from time to time.    Here and on eBay.    If I have a spare I will pm you.   

[newkid3]

 I don't guess it would hurt anything to leave it not hooked up if I decided to would it?

[jimliner]

Nothing wrong with no meters.  Usually meters were pulled out when machines were sold to public.  (At least that's what I was told.)

I am kind of a traditionalist, and put meters back in when possible.   

[wolftalk]

742A-326 is "horseshoe scramble" made for binion's casino.  The schematic would be w-1046-685 and will be extremely difficult to find.

the glass, reel tapes, reel wiper wiring, payout counter wiring and slotted reel index discs appear to be unique to the machine, but the rest of the internals should be very similar to any 742A.   You can poke around in https://bingo.cdyn.com/slots/ for paperwork and manuals.

if your meter is popping fuses, the metal case can be removed so you can see the coil inside - look for folded over metal tabs which you unfold and slide off the case.  Assuming it's not just the coil lugs shorting to the case where they go through the holes, the coil itself is probably bad and you'd be looking for another 50V "tab" meter.

I can probably scrounge meters from the pacific pinball museum warehouse if you can't find any.

meter are most interesting if you have "coin in" and "coin out" so you can see the actual payback of the game and compare it to the statistical payback which can be calculated using the frequency of the symbols on the tapes and the payout table.