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Old 07-29-2012, 01:52 PM   #11
vsmGuy
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Join Date: Jul 2006
City & State: southern california
Posts: 28
Default Re: Need tips in fixing APC 1500VA UPS having buzzing noise

Quote:
Originally Posted by Toasty View Post
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.
Things like this make me say "ignorance is a bliss". All the while I had been buying surge protectors and I have only one power tap I got at Walmart. Now I either need to remove the protection PCBs from the strips I have or buy new taps

Quote:
Originally Posted by Toasty View Post
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.
I was afraid something like this might be up, but read on (I don't want to put in $50 in parts + a weekend of my time behind a lost cause)

Quote:
Originally Posted by Toasty View Post
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.
I gave it a closer look today - the EPCOS is surely making th noise - I touched it with a plastic rod and I could feel it vibrating. I touched the other components around the region with it and could feel nothing.

Surely this confirms the source of the noise once for all?

Quote:
Originally Posted by Toasty View Post
PS: I'm now seasick from watching that video....

Some folks have -NO- camera skills...
Actually I PM'ed the guy for his feedback, so we should see him on this thread
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