Powering low voltage PS through isolated 120 is bad?

srarcade80

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Powering low voltage PS through isolated 120 is bad?

I just re-wired a midway cabinet (nba jam) which had one of those big brick transformers. Now the original way it was wired was AC comes in, gets filtered + fused, goes to switch, comes back down, goes into big coil, several 120s come out 1:1 isolated plus others to power coin door lamps and counter etc. On the 120 out, one drives monitor, other drives light fixture, last one drives low voltage supply. I did the same thing except i skipped the big midway transformer and ran into a small typical isolation transformer. What resulted was the game working for about 20 minutes and then blowing up the low voltage supply. Monitor was fine, light fixture was fine, no blown fuses.

Just trying to understand why the PS would die on isolated power? I skipped the midway transformer because i've had a few of them cause monitor chassis to smoke. (still not sure why, too much current? 3A)
 
Sounds like you might be overloading you new isolation transformer. You only need to run the monitor through the isolation transformer. Everything else (marquee, power supply, etc.) should be ran on straight 120 AC.

Edward
 
Overloading the transformer shouldn't destroy the power supply though...

Most chassis MUST be connected to an isolation transformer or they will be damaged. There is no such thing as too much current, it is drawn as needed. You could have a 1 million amp transformer and it would be fine to use.
 
Most chassis MUST be connected to an isolation transformer or they will be damaged. There is no such thing as too much current, it is drawn as needed. You could have a 1 million amp transformer and it would be fine to use.

Yes, I do know this. The reason i switched from the midway transformer to the standard small isolation transformer was because of the strange effects happening while powered by the midway one.

I'm going to re-wire it again, with only monitor power going through the isolation transformer this time.
 
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