powersupply modding and 3rd wire (case related)

[terramir]

I'm putting a computer inside an old amplifier case, the catch is since I'm cramming a rad, pump etc, and other stuff in there I will not have much room for anything else, including the power supply. So I figure that I could remove the power supply from it's casing and mount it on the inside of the plastic front. easy enough to do, but the power supply has the 3rd wire mounted to a screw that holds the PCB to the power supplies case, which means the 3rd wire is connected to the case via the case of the power supply.

Now the question is should I run a wire from the 3rd wire also to the metal case in order to ensure everything is safe, and the fuse get's triggered in case the case get's electrified for some reason?

let me know

terramir

[mcw]

Now the question is should I run a wire from the 3rd wire also to the metal case in order to ensure everything is safe, and the fuse get's triggered in case the case get's electrified for some reason?

 

I'm going to guess you're talking about the ground wire (generally green or green w/stripe)... If you plan to mount the power supply to a plastic area, then you really don't have any proper place to ground it out... If you gutted the amplifier, it should have already had a ground zone on there (for the internal power supply that the amp used), you might be able to use that same mount post... otherwise, create your own.

 

Make sure you use a thicker wire than it already had, though.. if you do happen to have a ground issue, that wire needs to be thick enough to carry the excess - especially if it's going to be extended.

[paulktreg]

A word of caution.

 

How are you going to cool the power supply. Most are optimized for airflow directly down onto the printed circuit board and require a cooling fan. Lower end power supplies get hot quickly.

 

The power supply 0V rail is connected to earth (ground) inside the power supply usually via the printed circuit board mounting screws, via stand-offs to the power supply case. The metal case of the power supply is also part of the EMI sheilding which in turn means the PC enclosure is connected to the 0V rail for the same reason. EMI may not be a problem but the switched mode power supply, especially the cheaper ones, is a very effective transmitter.

 

You may be better using one of the fanless power supplies but you'll still need to get some air over it and be limited to 350~400W.

 

What power supply are you using?

[terramir]

I'm going to guess you're talking about the ground wire (generally green or green w/stripe)... If you plan to mount the power supply to a plastic area, then you really don't have any proper place to ground it out... If you gutted the amplifier, it should have already had a ground zone on there (for the internal power supply that the amp used), you might be able to use that same mount post... otherwise, create your own.

 

Make sure you use a thicker wire than it already had, though.. if you do happen to have a ground issue, that wire needs to be thick enough to carry the excess - especially if it's going to be extended.

Yeah I thought about doubling up because if there's a big leak the green and yellow wire is what's gonna save my butt

it will trip the fuse in no time flat, well in theory it should

terramir

[mcw]

What are the system specs (and what kind of power supply - brand/model/wattage)? Just make sure you have some type of protection around the power supply (as mentioned)... In the rare instance that there's an arc or something, you don't want that jumping off and melting plastic (which may be a fire hazard in itself).

[terramir]

A word of caution.

 

How are you going to cool the power supply. Most are optimized for airflow directly down onto the printed circuit board and require a cooling fan. Lower end power supplies get hot quickly.

 

The power supply 0V rail is connected to earth (ground) inside the power supply usually via the printed circuit board mounting screws, via stand-offs to the power supply case. The metal case of the power supply is also part of the EMI sheilding which in turn means the PC enclosure is connected to the 0V rail for the same reason. EMI may not be a problem but the switched mode power supply, especially the cheaper ones, is a very effective transmitter.

 

You may be better using one of the fanless power supplies but you'll still need to get some air over it and be limited to 350~400W.

 

What power supply are you using?

It's a cheap 450 W PSU and I will be directing airflow 1/2 of a 120mm fan onto the pcb and the heatsinks, as for shielding would a plastic compartment with aluminum tape do? and it will be grounded onto the case in some fashion I thought about other power supplies, but the catch is that this computer will be using about 200W currently and well about 400 + watts of the 450 in the long run, considering pump dvd burner, and currently an E4300 @3ghz and well later on probabaly some quadcore @ 4Ghz.