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Planning Modding a PSU to have a power switch

Discussion in 'Modding' started by Impatience, 28 May 2014.

  1. Impatience

    Impatience Active Member

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    I have a SFX PSU which doesn't have a power switch on it. It's a CiT 300w.. Think a BeQuiet SFX without the switch on the rear next to the plug socket. :thumb: Thanks to phinix, i've now got a latching vandal switch and I was thinking of modding the PSU to turn on and off via that vandal switch.

    Now, here's the fun part.. As I dont have a clue about how PSU's are normally routed cable-wise to the power switches, I dont know if this is:
    A - Possible
    B - Wise/A clever thing to do :hehe:
    I'd rather not have a computer melt or set on fire.. Especially as it'll be in a custom wood case! :worried:

    I know that there's a setting in the BIOS that lets the computer power on when power is restored.. So I was thinking of using the modded PSU switch as the power on button and then use the Windows shutdown and then the button (after) as the power off/disconnect.

    Is this safe/possible to do?
     
  2. woof82

    woof82 New Member

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    I think the power switches are wired directly onto the incoming mains supply, basically between the PSU's socket and the rest of the internals.

    A: If you pull it apart and can find a lead connecting to the socket you can cut it and solder in a switch.

    B: Large capacitors in the PSU might hold charge and could give you a shock. Shorting out the mains supply accidentally (badly soldered connections, leaving un-insulated wires) would be dangerous. Using a switch that isn't rated to at least 240V 2A AC (240V*2A=480W, assuming 80% eff gives 384W rating) could result in a fire / short / shock. If you're having the switch a long way from the socket you're increasing the risks.

    I'm just not sure why you'd opt to do this rather than just using a simple push switch wired on to the motherboard's power switch pins. They're low voltage (5V I think) therefore safer. If you wanted to kill all the power you could just turn the power off at the wall. You could even wire a switch into the power lead between the wall socket and the PC if you knew what you were doing. You can get mains rotary switches or something that you could put a nice face plate on or something.

    Result: Possible, not entirely safe.
     
  3. blackerthanblack

    blackerthanblack Active Member

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    As already said, this is mains so if you were to embark on this you would need a few things:

    Need to be clear about what you are doing (plan)
    Any equipment needst to be rated correctly - you need to know the switch is right for the job (I would say 240V 5A as long as you don't have a powerhouse of a PC). Any cable used need to be rated right. Any joints or solder needs appropriate protection (they may be inside the case, but don't bank on always remembering to avoid touching them when you are routing around on some other problem.

    There are some other similar solutions out there - mainly cases which have the PSU at the front - where the mains is taken from the back (normal socket) to the front (PSU) by an extension cable. It may be worth sourcing a cable like this so you can splice the cable to go through the switch?

    The above assumes a level of competancy in joining/soldering and protecting joints.
     
  4. Impatience

    Impatience Active Member

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    Hmm.. This seems like it's above my level of skill.
    well, my faith in my skills..
    I was hoping that the switch was connected in a slightly less (potentially) dangerous way.. But since the current physically goes through it.. I dont trust myself for that! :hehe:
    I guess i'll have to get a mobo switch after all! :thumb: Now, what to use that latch switch for.. :dremel:
     

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