MK3 blowing monitor fuse now...

8bitnintendo

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After must troubleshooting, I finally picked up a known tested working tube and chassis, now I stick it in my Mortal Kombat 3 cab and its blowing the chassis fuse... What is causing this???
 
What model monitor do you have in the cabinet? Are you hooked up to an isolation transformer? Certain models have to have an isolation transformer to run properly otherwise it can blow the fuse. I know MK 4 cabs don't have an iso in them, but I don't know if MK 3 cabs originally did or not.
 
Yep, sounds like you are running unisolated power to a chassis that requires it. If so, then not only is the fuse blowing, but your VR and some rectifying diodes are probably blown now, too....
 
The power going to the monitor is coming from the isolation transformer, it was turing on when I first got it, but ever since I started putting WG monitors in it I get nothing...
 
The power going to the monitor is coming from the isolation transformer, it was turing on when I first got it, but ever since I started putting WG monitors in it I get nothing...

What type monitor was in it before ?
What model WG are you trying to put in it ?

And just because power is coming from a "transformer" does not mean it is an "isolation transformer". ;)
Do a continuity check with your meter from the connector the monitor plugs into to the cord that plugs into the wall.
If there IS continuity, then it is NOT an isolation transformer.
 

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According to that diagram, the monitor is being connected directly to the AC power line (no isolation). You are probably using a monitor that needs an isolation transformer and it is now damaged.
 
just playing devil's advocate...

the diagram you guys posted has the 5.9V coin lamp feed, and the wire colors are the purple kind. that's the isolation transformer type that the Midway cabs came with.

if it was the regular AC block kind, it wouldn't have voltage for the coin lamps and the wires would just be black/white/green like the inside of an AC cord.

for what it's worth, I think MK3 came with K7000s and Polos, just like Killer Instinct did. they were made about the same time, if you consider the 1.0 units from 1994.

the switch from isos didn't take place until probably like Killer Instinct 2 that I know of for sure. by then I think they used U2000s and Polos, neither requiring isos.

what's the likelihood that the iso's wired up wrong like you say they sometimes come as, Ken? perhaps he's using the wrong power connector or something? K7000 didn't particularly have a real standard-ish AC connector.
 
The diagram was NOT posted by the person having the problem. I believe it was posted as an example of what may be in the cabinet...
 
That diagram came straight from the MK3 manual.

Which is all I can go by at the moment, five minutes with a multimeter would tell for sure.
 
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