Power Supply Output Voltage Error


Newly Enlightened
Apr 8, 2021
Hello, folks
I bought a LED driver:
input: AC100-240V
Output: DC30-57v / 600mA (constant)

I connected it to a led strip, they flashed several times then switched off (i suspect they died, so i check the LED Driver Failure Detection Analysis), then took the multimeter and measured the Output voltage, and it was around 74V, but failed.

I suspect this is what killed the leds. My question is: am I missing something ? This power supply is supposed to output max 57V. Why does it show 74?

Is the power supply faulty? Or did I measure it wrong? Thank you in advance.


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Nov 3, 2009
Ottawa Ont. Canada
I believe that the 30-57v dc output applies to under load, but not sure what is normal upper limit under no load; probably should not go up to 74v though so might be defective. I could try it on a couple I have around but may not be definitive answer.

What are specs for the LED strip, is it (nominally) around 48v? It must be pretty substantial.

Are you sure the LEDs are damaged? Is there another driver you can test with even one with lower current, but similar output voltage range?

If the driver is not doing anything bad, getting hot, smoke etc. you could test it with a resistor load if you have it. Two 33 ohm 10W (or so) resistors in series should give around 39-40v if it is working OK; not for too long as they will get hot.