Switching power supply through isolation transformer or not?

DaveyPocket

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Switching power supply through isolation transformer or not?

I've been thinking. Is it a good idea to connect a switching power supply to an isolation transformer or go directly into the wall? I've seen some set-ups where the isolation transformer is connected directly to wall supply. The test rig I built has both the monitor and switching power supply going into an isolation transformer. Is there a bad thing to doing this? Does it really matter which I connect it to?
 
It is preferrable to parallel the switcher, iso, and marquee light. However, many manufacturers in the Jamma era pulled power to the switcher off of the isolated monitor power lines (iso output) and there was never any ill effect. Most ops did this as well when they were rewiring some classic era cab to Jamma.
 
Never connect anything but the monitor to the iso. They are generally designed to power ONLY a monitor, by connecting additional things to it you risk overloading it and causing a fire.
 
^^^What he said.^^^^

The isolation xfmr is rated for a specific current on the secondary. You exceed this by connecting more than a monitor to it and it'll burn up.

Yea, I've seen it done incorrectly in conversions too, but I always changed it to the way it should be.
 
An isolation transformer isn't rated for near enough current to run the switching power supplies. They'll run as hot as a skillet even after being on a short time. It's risking some serious damage by setting the plastic and paper they are made with on fire.

Also, you MUST be careful when wiring up those supplies as there are different kinds with different wiring requirements!!!!

I had one here that had a label on it that you MUST NOT connect the chassis of it to field ground. That means you don't hook a ground wire to the screws holding the power supply in place. Normally you DO this with these power supplies, but not with that particular one...

Also, switchers REQUIRE you to wire them correctly or you risk popping fuses and/or tripping GFCI outlets. Even worse, you could trip breakers. If you reverse neutral and hot you can run into all kinds of issues, including floating grounds with 60+ volts on them. This can and will fry things such as the video ground traces on your game board.
 
I've been thinking. Is it a good idea to connect a switching power supply to an isolation transformer or go directly into the wall? I've seen some set-ups where the isolation transformer is connected directly to wall supply. The test rig I built has both the monitor and switching power supply going into an isolation transformer. Is there a bad thing to doing this? Does it really matter which I connect it to?

Can you post a pic of how your test rig is connected to supply and transformer plz.
 
The isolation transformer I have is a Hammond 185G230 (Datasheet: http://www.hammondmfg.com/pdf/5c0022-23.pdf)

This isolation transformer has dual primary and secondary coils. I have it configured two use both coils in parallel. By doing this, according to the data sheet, I get 1.52A on the secondary coil. At the time I built this I assumed it would be enough for a monitor and a game with a light load running through a switching power supply connected to the ISO. I am very cautious of things catching fire and whenever I have used my test rig I always checked the switching power supply and transformer for overheating, melting, etc... none of that has happened so far which is good. I didn't put any fuses or type of breaking mechanism on this... which I should definitely go back and do (I built this in a hurry to test a few things out). I also do not have a line filter, should I install one of those as well? I'm a little new to AC and high power circuitry so I appreciate everyone's advice they gave me earlier.

Also how can I tell the difference between hot and neutral on a switching power supply and ISO? I might have them backwards... The switching power supply doesn't really indicate which connection is hot/neutral. Does it matter for the ISO?

One of the pictures in this post shows a brown extension cord type socket, the switching power supply and monitor both connect into that.
 

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So are we also saying Arcadeshops power supply conversion instructions are incorrect and every one that has connected their switcher to the monitor lines have created a fire hazard and should change immediately? Has anyone actually had a problem? or is this just a bunch of crap.
 
Bob Roberts has an excellent write-up of AC power wiring:

http://homearcade.org/BBBB/acwiring.html

Thanks for the link KenLayton, definitely a good reference.

So are we also saying Arcadeshops power supply conversion instructions are incorrect and every one that has connected their switcher to the monitor lines have created a fire hazard and should change immediately? Has anyone actually had a problem? or is this just a bunch of crap.

I was thinking the same thing. If the ISO is able to pump out enough amps to support both the monitor and a game board that's not too power hungry, I don't see what could go wrong.
 
How many of you who are questioning us more knowledgeable people are capable of working out if the iso is capable of safely running both the monitor and power supply? My bet is none.

Do it properly and play it safe. Don't be a cowboy.
 
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