Electronic – Why does the PSU die everytime I test with multimeter

high voltagemultimeterpower supplyvoltage measurement

I've set up my PSU to use as a "lab power supply", I'm trying to obtain 12 Volts at 14 amps. I have the red, orange, yellow, black wires separated, and connected the green wire to ground to keep the PSU on.

That being said I feel that the problem is not necessarily with those first few steps. Every time I connect my multimeter between all the black and red, or black and yellow wires the entire PSU shuts off and won't restart until I touch the power wires to a grounding source (Some plates of metal I have).

I'm trying to figure out how I can test the connection with my multimeter without shutting off the entire PSU.

Best Answer

A multimeter set to measure current (an ammeter) looks like a short circuit, or just a wire. When you connect your multimeter to the PSU, you are overloading it by presenting it with such a low resistance that it can not provide enough current to maintain its designed output voltage, so the protection circuits kick in and turn it off. Were it not for those protection circuits, a fuse in your meter would blow, or some wires would get hot and melt, or something similarly bad would happen.

More likely what you want to do is set your meter to measure voltage. In this mode, the meter looks like an open circuit, as if it's not there at all. Or, if you are interesting in measuring the current being supplied to a load, put the meter in series with the load, not in parallel with it.