Dummy load on SMPS

Thread Starter


Joined 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


Joined 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.