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View Full Version : PSU loop/bypass?



chetspartan
11-04-2005, 01:46 PM
Hey all, first post here. (Found this great community from a link to TribalOverkill's project log, wow is all I can say about that one.)
I'm liking the vibe here a lot so far, very friendly people.

Bread and butter of the question is how can I hardwire/bypass a PSU to put out power to a few case fans for a project outside of a PC. I read somewhere else awhile ago it's just a matter of connecting 2 wires on the 24pin(?) to create the loop/circuit. Anyone have the specifics or a link with instructions/diagrams for me? Thanks

Ok her is why I need it, tell me if you see any problems with my idea.

My sister has in wall cabinet/shelving for her audio/visual gear under a subbed(sp?) in wall nook for her TV (sweet Samsung 42" DLP). Her, the ex-husband and their builder didn't think about all the heat the components would produce (main culprit is the Yamaha 7.1 receiver) so she has to keep the door open to the cabinet when it's all on. They burnt out a cable box already due to this. There is a nice overhang/lip where the cabinet/shelving sticks out and above the baseboard near the floor and the TV nook is directly above the cabinet in a corner next to the adjacent wall, this TV also is on a lazy susan/slideout tray of sorts so you can pull it out and turn it to face the room. What I'm thinking of doing is cutting a spot for 2 120mm fans in the overhang at the bottom for intake (covered with a custom fan grill so her daughters don't lose any digits) and 2 more 120mm fans at the top of the cabinet in the back to exhaust up into the nook, which has ample room behind the TV and on top to let the air pass out into the room. The receive has an auxillary AC outlet which the PSU would plug into and turn on with the receiver.

Would my idea of bypass wiring the PSU then hooking up all the fans work for this?

Thanks again.

slaveofconvention
11-04-2005, 04:53 PM
You have to connect the green wire to any black wire, if memory serves. But it's supposed to be a momentary contact - leaving it permanently connected may not work properly. Use a super-cheap spst momentary pushbutton switch. The other thing you MIGHT have to do, depending on the power supply, is make sure there's a constant drain on one of the rails (I think it's the 5v) as some PSUs wont work properly without there appearing to be something connected...

chetspartan
11-04-2005, 06:16 PM
Thanks slaveofconvention for the suggestions.

I found the original text where I read about this:

http://answers.google.com/answers/threadview?id=52126

and if you scroll down there's an example:
http://www.gideontech.com/guides/psu_powerup/

Also something that may be of benefit to this community as well.

This is also good for case modders like myself, who may want to be
able to test the case mods before installing them, or before acquiring
a motherboard.

I plan to wire up a plug that will fit into the PSON pin and the
adjacent ground so that I'll have the ability to run my case mods
(currently some cold cathode lighting, a lit temp/fan speed/voltage
display, etc..).