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Getting 230v pumps to turn on with comp

Discussion in 'Overclocking & Cooling' started by ted34, 12 May 2006.

  1. ted34

    Wise Guy

    Joined: 5 Jul 2005

    Posts: 1,734

    Location: Edinburgh

    Just gone over to water and got an eheim 1250 which is 230v. Theres a couple of items you can buy such as critcool relay but this uses a pci slot which i dont have spare.

    Took a trip down to a certain high street retailor and got what i needed. Came out at under £4 but this is cheaper than normal as flatmate works there (suppose to be about £6)

    The pumps run with 3A fuses so to be safe i bought items above 3A so fuse will blow before relay etc.

    3core mains flex (i went for 6A) - length: however long you need it to be
    3 5A terminal blocks
    1 5A 12Vdc DPDT minature relay (product code on pack: N41AW)
    1 16A rocker switch (product code on pack: GU56) - 16A is a bit excessive but was all that they had in stock above 3A
    Some 7mm heatshrink
    Molex plug (if you dont have a spare one)

    The rocker switch isnt needed but it allows you to bypass the relay and turn pump on without comp. I wanted this for changing the water and checking etc

    First thing is the relay:

    There are 8 contacts on them each labelled. Starting at the near left in the picture is contact 1:
    4 8 12 r1
    - - - -
    - - - -
    1 5 9 r2

    Numbers 1 & 4 are of no use to us as they make contact with contacts 9 & 12 when the relay is OFF. Numbers 5 & 8 make contact with contacts 9 & 12 when the relay is ON. which is what we need.

    Strip the sheathing back on the 3 core wire. Slide some heatshrink on so you can cover the contact after. Solder the blue / black (neutral) wire to contact 5 and the brown / red (live) contact to contact 8. I also soldered 2 3inch long pieces of wire onto each contact. These are wired in parallel and go upto the switch.

    Next is the bit for the pump. Instead of attaching the pump directly to the relay (which would make it harder to remove for future upgrades) i soldered on 2 3inch length of wires to contacts 9 and 12. Make sure here that you keep contact 9 neutral and contact 12 live. Also to contacts 9 and 12 solder 2 lengths of wire that attach to the other side of the rocker switch.

    At this stage contact 1 and 4 should have nothing attached, contacts 5 and 8 should have the neutral and live input from the length of 3core mains flex, and contacts 9 and 12 should have corresponding neutral and live outputs. The rocker switch is connected across contacts 5&8 and 9&12. Once this is like this push the heat shrink over the contacts and heat it so it shrinks (this will stop any exposed wires).

    Next is to attach the pump to the 2 3inch wires coming out of 9 & 12. This is done by using the terminal blocks. One each for the neutral, live and earth wire. The earth wire (green/yellow) attaches directly to the earth wire in the 3 core mains flex (bypasses the switch).

    Now all that is left to do is hook up the 12v supply that will turn the relay on. The 12v supply is the yellow and black wire in any molex plug on the psu. I used a 3pin to 4pin fan convertor for this. Cut the 3pin end of leaving just the two wires. Solder one of these to r1 and the other to r2 (doesnt matter which).

    Finished product should look like this (sorry for bad photos):

    End wiring:
    5 into socket / plug neutral
    8 into socket / plug live
    9 into pump neutral
    12 into pump live
    r1 and r2 into 12v supply

    5 connected to swicth neutral 1
    8 connected to switch live 1
    9 connected to switch neutral 2
    12 connected to switch live 2

    edit: Make sure you dont leave the earth wire out
  2. lay-z-boy


    Joined: 27 Sep 2004

    Posts: 9,231

    Location: Nantwich

    nice guide, should help some n00bs out.

    my only gripe would be that most modern watercoolers will end up with a ddc, 50z or d5.
  3. ted34

    Wise Guy

    Joined: 5 Jul 2005

    Posts: 1,734

    Location: Edinburgh

    I know - most people seem to go for those pumps but eheim are easy to get spares for from fish shops. Was going to go for the citicool relay but as i dont have any spare pci slots it wasnt an option. I think dangerden make a relay that doesnt need a pci slot but it was out of stock when making order