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Old 07-29-2012, 11:32 AM   #10
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Join Date: Jul 2007
City & State: East Coast, USA
Line Voltage: 220-221
I'm a: Professional Tech
Posts: 4,145
Default Re: Need tips in fixing APC 1500VA UPS having buzzing noise

Correct. Surge protectors on INPUT to UPS, not on output.

Having them on output side can also present a load/short to the UPS which it tries to compensate for by boosting output. A vicious circle.

I think the unit is fine and just gone a little noisy. You could replace them and the problem will remain. Because the noise is load variable, I would be scoping the output for spikes or looking further back in the circuit.

Try a paper towel roll as a "stethoscope" to pinpoint the noise. Try moving components with a wood or plastic tool to see if they're just resonating from the switching circuit. It's why PSUs have that glue/caulk around coils and caps.

They make noise when making power. Nature of the beast.


PS: I'm now seasick from watching that video....

Some folks have -NO- camera skills...
veritas odium parit

Last edited by Toasty; 07-29-2012 at 11:35 AM..
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