Dummy load on SMPS

Discussion in 'General Electronics Chat' started by mikec, Nov 9, 2008.

  1. mikec

    Thread Starter Member

    Nov 4, 2008
    Hi Guys

    I have an smps from my plasma TV that is tripping its voltage protection. ie it is killing the chopper signal to the main transformer upon startup. A scope on the output of the transistor shows a nice square wave for a split second at turn on, then the signal disappears.

    If I unplug all of the connectors that come off the supply, the supply will not power on as expected.

    Any thoughts on how best to build a dummy load perhaps with an LED on each of the output voltage rails to make sure that the problem is on the supply and not external to the supply. I am currently thinking of some big fat resistors at the moment.

    Mike C
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Usually one of the regulated outputs is monitored and fed back. Some fraction of the output capability is the necessary load. After that, it's all a guess about which output and what load will keep your switcher running.