Benchtop PSU not working properly

Discussion in 'The Projects Forum' started by FIT engineer, Aug 19, 2012.

  1. FIT engineer

    Thread Starter New Member

    Aug 19, 2012
    I recently started making my own benchtop power supply out of an ATX power supply I got off of ebay. I quickly took it apart, and grounded the green wire. The PSU stayed on, and I confirmed there were the proper voltages going to each lead by using my multimeter.

    Yesterday I ran into a problem. I cut ALL of the leads, grouped the grounds and power leads seperately isolating them using electrical tape and zip ties. I also combined the leads I wanted to use, and soldered the green wire to ground.

    Now, the PSU stays on for a split second, and then turns off. I confirmed this with a quick voltage spike from the leads when turned on, while quickly returing to 0V. Fan does the same thing.

    This is absolutely mind boggling to me because it seems I haven't changed anything, just reorganized wires. And now it wont stay on. Any ideas what could be wrong or where I could check?
  2. BMorse

    Senior Member

    Sep 26, 2009
    If you grouped all the same voltages together, that could be your problem, most ATX power supplies have multiple "rails" that these voltages could come from.... if you tied multiple rails together, then that could be your issue....