I was playing my twilight zone yesterday and after a few minutes of play I saw smoke coming up under my jet bumpers. I quickly turned the machine off thinking I might have a stuck coil. When I pulled up the playfield I was overwhelmed by some very toxic smelling smoke. I then unplugged the machine and opened up some windows to clear the smoke. Something was causing my 13VAC to short and for some reason no fuses blew. If there is a good side to this one, it was that I was playing the machine and acted fast, if a guest was playing or if this short had happened when no one was in my game room the results could have been catastrophic.

I opened up the machine thinking that it must be mis-fused somewhere. I checked everything including the main power fuse in the cabinet. Only one incorrect fuse was found, there was an 8amp fuse in F115 when there should have been a 3/4 amp fuse there. F115 is labeled as the switch matrix fuse.

The machine uses a rottendog CPU and power driver boards, has a pinsound sound card and a color DMD.

The blue and white wires from the transformer to J101 on the rottendog driver board are melted. I'm afraid my transformer might have also been damaged as the melting also damaged the wire from the exterior of the transformer to the plug between the transformer and the main harness to the backbox.

I've got some repair work to do, and will need to hunt down some parts. My biggest concern is what could have caused this and why didn't a fuse blow? F115 is labeled as a fuse for the switch matrix. Could it be the fuse that should have blown when this happened?

Anybody have any experience with this? Before getting my zone up and working again I want to make sure this can't happen again. And.... I will take very seriously the recommendation that anytime you get a new pin, to verify all the fuses.

I'm also putting a fire extinguisher in my game room.

Thanks in advance for the help,

Allen

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Thanks LTG, Other then smoke coming up from under the playfield, the game appeared to be playing correctly when I powered it down. I'm not sure anything else was damaged. When I searched the forum there was a post that mentioned a similar melted wire that might have been caused by a failure of one the rectifiers.

I'm really hoping I can figure out the root cause of this with a high degree of certainty. Does anybody know which fuse should have blown if the secondary 13VAC power from the transformer shorts?

Allen

Bump...

Wondering if anybody else has had their 13VAC wire in the harness and transformer melt without a fuse blowing?

Thanks very much! I was hoping I could reasonably blame the incorrect fuse for the issue. I do indeed have some work to do!