Thread: Rewiring 5V AC Adapter To Molex Connector

  1. #1
    Registered /usr
    Join Date
    Aug 2001
    Newport, South Wales, UK

    Question Rewiring 5V AC Adapter To Molex Connector


    After much drama messing about with an external dual RAID SATA box for my 2.5" hard drives (basically I bricked it doing what the manufacturer told me to do), I have now settled on a rather dapper box that is metal but has no RAID processor inside it (I guess I'll have to let the computer do the honours). The only thing is that it's designed to be fitted into a 3.5" bay, not used externally. It has a single SATA power connector on it.

    I have just taken receipt of a 5V DC (max 3A) power supply. It had one of those 5.5mm barrel connectors on it. I also have one of these. My intention is to supply 5V through the Molex end (connecting two of the four pins) to provide external power for the hard drives (2.5" drives only use 5V).

    However, I seem to have come across a conundrum:- I hacked off the barrel connector and stripped the DC cable back to find... 3 wires.

    There's a thick white one in the middle (I'm guessing that's the +5V, it's supposed to be centre positive), and two thinner ones (one black, one white). Are they both ground? If so, is there a reason for this?

    I think the best way to achieve this is to get some female pins, solder the big white one and one or both of the others into two pins and then connect them to the Molex end, then tape the whole thing up. Or if both the thin ones are ground, make two pins out of them and connect the 12V ground as well, just to be on the safe side.

    Yes, I know I could get a dual voltage adapter and get the full Molex, but needing only 5V gets me a smaller brick.

  2. #2
    Registered User
    Join Date
    Dec 2006
    That sounds very strange for a DC adaptor. Do you have a multimeter to measure voltages across them?

    I am GUESSING the either the white or black is earth ground, and the other DC ground (one of them shouldn't carry any current in normal circumstances). But it doesn't make sense to have a thicker 5V than ground, because current in them will be equal.

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