PSU dismantling - what do I need to be aware of?

[artoodeeto]

Subject line says it all - I want to take my PSU apart and custom mount the innards & fan, but I know just enough about them that their capacitors can hold quite a charge. Since I don't really want that charge transferring to me, what sort of precautions should I take before dismantling it? It's a Thermaltake Toughpower 650W w/modular cables. thanks!!

[Technochicken]

Most PSU's will probably have a circuit to bleed the charge from high capacity capacitors while they are not being used, but just in case, you should probably discharge them before handling the innards. This can be done by simply connecting the two leads with a screwdriver, but I have read that that can possibly dangerous. What I do is connect the two leads to a high wattage resistor, and let it sit for about a minute.

[artoodeeto]

thanks! now to go find a high-watt resistor (all I have right now are 1-ohm). Radio Shack, here I come....

[Technochicken]

Just for a reference, the one I use is a 5k ohm, 75 watt one made by Ohmite. This is probably overkill, but I have it, so why not. Something in the area of 10-25 watts, and 5k ohms or more should do just fine for the large capacitors in the PSU.

[slaveofconvention]

I've also heard of the following method, but can't personally vouch for it - turn on the pc, or a pc with the PSU connected to it, and enter the bios to prevent it loading into windows or your OS of choice, then pull the power cable out of the back of the PSU without turning it off at the wall, the PSU or the PC - apparently this causes the caps to drain themselves into the PC (harmlessly)

[nevermind1534]

^That's what I do. It works very well. Otherwise, most PSUs will be drained after around 30 seconds to a minute, especially if the mobo is plugged into it.

[artoodeeto]

I've also heard of the following method, but can't personally vouch for it - turn on the pc, or a pc with the PSU connected to it, and enter the bios to prevent it loading into windows or your OS of choice, then pull the power cable out of the back of the PSU without turning it off at the wall, the PSU or the PC - apparently this causes the caps to drain themselves into the PC (harmlessly)

that actually makes perfect sense - since the computer doesn't exactly have any kind of sensor to tell it when you've yanked the wall power.
I've had the PSU disconnected from the wall (and the master switch turned off) but still plugged into the motherboard since yesterday morning. I take it then it should be totally drained now? Or do I need leave it connected to the m/b, flip the master power switch back on (without plugging it in to the wall) and wait a few minutes?
I'm very interested to see how much of the PSU's weight is its case and how much is the PCB/heatsinks and other innards...

[nevermind1534]

The way you have it right now should be fine, especially if it's a name brand PSU.

[artoodeeto]

sweet. If you don't hear from me within a few days, either I've zapped myself or the PSU. :P
I figure even if I decide it's not worth the effort to dismantle (depends mostly on internal space in the case), from looking at a similar thermaltake PSU taken apart, it looks like all the "hardwired" cords just plug into a PCB board, which is good news for me - I'm not using the hardwired 6 pin PCI-E cable. Be nice to get it out of there.

[mofo]

I call dibs on the sandcrawler... :whistler:

Space prohibiting, the psu naked in the assembly bay could provide a nice backdrop to the droids scattered about. It would still look great even behind a thin plastic sheet.

[artoodeeto]

I call dibs on the sandcrawler... :whistler:

Space prohibiting, the psu naked in the assembly bay could provide a nice backdrop to the droids scattered about. It would still look great even behind a thin plastic sheet.

LOL sure ya do :D

that's a great idea re: psu location, I'll have to see if I can incorporate that somehow. The major limiting factor with ideas like that is the top of the model needs to be completely removeable, and in order to have a minimum number of plugs to unhook before removing the top (currently 2 plugs: fans and lights), all the computer equipement has to be on the base. If I just stuck the PSU (sans outer case) into the main loading bay, I wouldn't be able to physically reach in and hook up the plugs. hmm...I'll have to think on this one...you're givin' me some good ideas! +rep for that! :P

[artoodeeto]

ok....got it mostly dismantled...but...how do I get the plug and main switch detached from the metal case? Am I right in thinking that I need to desolder them from their wires and pull them out from the outside, or is there some trick I'm missing that would allow me to detach the plastic collars from the outsides of each and pull the remaining parts through to the inside of the PSU?
http://i597.photobucket.com/albums/tt53/artoodeeto/crawler%20update/10--02-23DSC_0002.jpg
http://i597.photobucket.com/albums/tt53/artoodeeto/crawler%20update/10--02-23DSC_0001.jpg

and double ARG! It seems that some of the wires really are hardwired, which means without snipping cables, I can't remove the extra 8-pin PCI-E cord (my GTX 285 uses two modular 6-pin cords). although I suppose I could try desoldering them...maybe I'll do that. I don't want to permanently damage it, I doubt I'll ever need that cord, but I always think what if....
http://i597.photobucket.com/albums/tt53/artoodeeto/crawler%20update/10--02-23DSC_0004.jpg

It's only still in the case because of the plug and main switch; all the screws holding it in are removed...
http://i597.photobucket.com/albums/tt53/artoodeeto/crawler%20update/10--02-23DSC_0003.jpg

[x88x]

Follow the leads from the plug and switch to where they meet the circuit board. It's likely that there's a plug there that you can pull out, and get everything out of the case without having to desolder anything. The switch will be a pain to get out of the hole though. On the topic of desoldering, if you don't plan to use the 8-pin PCIe connection, but want to have it semi-available just in case, I would recommend cutting the wire off about 2-3" away from the PCB; that way you still have a workable length to solder it back on if you decided you want to later, but you get it out of the way.

[artoodeeto]

Yeah, I forgot to mention that I followed the leads to a couple of plugs on the PCB. I tugged with no result, and I can't tell if they're soldered in or not. I think I'll try gently tugging with a pair of plyers, and if that doesn't work, then I'll consider cable snipping. I think I want to extend their length anyway so I can orient them wherever is most convenient, as opposed to being forced to keep them in their current orientation. I probably will just snip the PCI-E cable. There's other cables soldered in the same place, so I don't want to risk screwing up their connections, and I have no problem re-soldering it back on if I ever do need it.
Thanks!!

Oh...here's another question. :D would it be a bad idea to mount the fan above the PSU blowing air away from it? on the face of it, it would seem like a bad thing, but when I put my hand over the intake side of my 120mm case fan, it feels noticeably cooler...but I don't know that the PSU fan would suck enough air through the heatsinks to be effective.

[x88x]

Check the plugs for clips that might be holding them in place, kinda like the clips on floppy-power-connectors.

For the fan, it doesn't matter so much which direction it's going, as long as you have good airflow going over the heatsinks.

[artoodeeto]

My warranty is SO void now LOL...but actually it was probably expired anyway.
I got it dismantled. I ended up snipping a short length of wire (my solder gun wouldn't melt whatever solder they used) that attached the power switch to the main power plug so I could pull the switch and plug out of the case, but you were right, the other wires were just clipped onto the PCB. It took some work to get them off, but I prevailed.
Now I gotta solder longer wires to the switch and power plug so I can locate them wherever I need to, and I need to do some internal redesign in my case to accomodate the changes.... fun!

[artoodeeto]

Yet another question - I know that it's possible to paint circuit boards, although I don't know the particulars. I think they need to be coated with something before painting? Is it possible to do this with the power supply PCB's and all the various capacitors and coils on it, or does the (I'm assuming) high current level make that a bad idea? And do I assume correctly that I should at least avoid painting the heatsinks on the PCB? Thanks!

[x88x]

Yes, you should not paint the heatsinks...unless you can find a metalic paint with a high conductivity rating, that might be ok. As for everything else, as long as the paint is not conductive, and is rated ok for high temps, it should be fine.