How to put a switch on a power supply?

[mamba max1]

I have a server PS that I'd like to put an on/off switch on. Obviously, I have no idea of how to do this. The PS is rated for 42 amps and 540 watts. Excuse my near complete lack of know how regarding circuitry. Despite that, soldering is not an issue for me...even with very small things.

#1) what rating of switch do I need? (if it makes a difference I live in the US)

#2) where/how to I solder it up?

If I need to post pics, let me know.

Thanks!

[JAILBIRD]

I am in the process of converting a few server power supplies also. I don't know what PS you are using, but on mine there is a bank of small pins, some of which need to be jumped to activate the PS. I was planning on just puting the switch in the circuit between 2 of the pins. I will be using a standard SPST switch from Radio Shack. There is very low voltage on the pins.

[brijar]

I have converted a couple of server PSUs and neither of them had switches. I would have just put a switch on the jumper I made except the fan runs as soon as you plug it in. So what I did was open up the case and cut the black AC input wire right after the plug and put a switch I stole from a fried ATX power supply in line. Then I cut out a little square in the back of the PSU and wedged the switch in there such that it couldn't move once the case was put back together.
This would probably work fine for you.
http://www.radioshack.com/product/in...ductId=2062523
http://www.radioshack.com/product/in...ductId=2062485
Just find a switch that is rated for 125VAC and 10 amps or better. The circuit breaker on your house 125VAC is probably only 15a or 20a, so getting a switch rated higher than that would be pointless.

Good luck! Make sure it isn't plugged in when you're working on it lol.

[BrianG]

The rating of the switch to use depends on how you are doing it.

In JAILBIRD's case, he wants to use the "logic" method, which is the low voltage/current "enable" wire on many supplies. Simply using any SPST switch works here since you don't have to worry about current or voltage ratings. Larger/heavier switches can be used, but is just overkill.

The other method is what brijar describes, or what I call "power interrupter". As the name implies, the switch is placed inline of the input AC mains voltage, and so the ratings must be suitable. If the PS is the kind that uses 220/240v, make sure the switch can handle it. As he said, current ratings much beyond 15A is rather pointless, but keep in mind heavier/duty switches meant for heavier currents have better contacts and are less apt to pit from turn on spark (similar to how an ESC sparks when you hook up your batteries). Whatever you get, make sure it is rated for at least 50% more current than the PS uses. In the OP's 540w example, the input current is ~6A: ((540w/80% efficiency) / 120VAC. If using 220/240v mains, the current is even less at around 3A. For the former, use at least a 10A switch, for the latter, a 5A switch is fine.

FYI: Depending on availability, SPST (single pole single throw), DPST (double pole double throw), SPDT (single pole single throw), or DPDT (double pole double throw) can all work, but only SPST is needed. If using a DPxx type, parallel the connections for better current handling (double pole means there are two isolated/seperate SPxx switches in one package).