12v 30a power supply now reading 22v?

I set my new power supply with the adjustment screw a couple of weeks ago to be outputting a perfect 12v. Now it's all of a sudden reading 22ish and the lowest I can turn it is to 21v.

Any ideas how this could happen? It's a new 12v 30amp PS from lulzbot.

Thanks in advance for any tips!

Anybody? I did fry a regulator on my mega by accidentally getting the polarity mixed up on an end stop. However, got a new mega 2560 and ramps seems ok. Could something like that have increased the voltage of the PS?

Any ideas?

Did you check the voltage from the power supply? I don't understand how the regulator on the mega could have any effect on the supply voltage unless you are not measuring it from the supply itself...

Yeah I'm measuring from the terminals. Here's a couple pics.

Any ideas?

Hi,
If it is not very old it would be worth returning to the manufactures. It sounds like the voltage sense circuit may be damaged. This can happen if the PSU is accidentaly disconnected when powered on and live. The load dissappears and the voltage rises rapidly damaging the sense circuitry. Its the same mechanism that frys the sense resistor on the stepper boards.

If you feel confident and have a circuit diagram (would not recommend without) you could check this yourself but take extreme care as switch mode PSU's can have very high voltages inside and mains potential is obviously present and lethal.

It seems that your source is DC while your multimeter is set for AC. Have you tried measuring it on DC setting?

Quote
miso
It seems that your source is DC while your multimeter is set for AC. Have you tried measuring it on DC setting?

I noticed that too, and it begs the question...is that 21v of AC ripple? Coz that's huge!

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Waitaki 3D Printer

You guys are right. I'm on glue. Sorry and thanks!!

I have to say that Lulzbot was willing to send me another one. A testament to their great service!

Thanks again guys!

so whats it at now.?

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Switching it back to DC I was able to set it back to 12v. I heard 12.2v is better than 12v. So I put it at12.2.

i do know the more the better, i want to try 14v some day if i ever get a power supply like that.

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[mike-mack.blogspot.com]