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Old 09-22-2012, 01:11 AM   #20
Join Date: Jul 2006
City & State: southern california
Posts: 28
Default Re: Need tips in fixing APC 1500VA UPS having buzzing noise

Attached is a clip of the sound that comes from the 22uF, 150V bipolar yellow capacitor when charging the batteries/online.

At 45s into the recording, I turn off the line power - notice how the noise goes away completely when it's running off batteries in the 1000VA (the one which was running when I recorded the noise). It returns/increases when I connect a heavy load to the UPS output.

I am sure you will agree this is very different from the gentle hum of a transformer?

If this is a characteristic sound of APC UPS when the batteries are dying, I would like to know if there's a battery I can buy, from say Walmart or Home Depot etc just to see if a new battery makes the noise go away.
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