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UPSes making buzzing noise on various PCs...

APC UPS for Home and Office Forum

Schneider Electric support forum for our APC offers including Home Office UPS, Surge Protectors, UTS, software and services and associated products designed to share knowledge, installation, and configuration.

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Malkor_apc
Ensign
Ensign
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6
217

UPSes making buzzing noise on various PCs...

This was originally posted on APC forums on 4/28/2009


This is something that bothers me, but whenever either of my UPSes kick into their self-test mode in which they slightly discharge the connected PC makes an annoying buzzing noise from its PSU. This also does the same on a SCPH-90001 PS2. Why is that and should I be concerned?


Accepted Solutions
BillP
Administrator Administrator
Administrator
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217

Re: UPSes making buzzing noise on various PCs...

This reply was originally posted by Angela on APC forums on 4/29/2009


yeah i agree, most likely it is not true RMS. usually it says it right on the actual voltmeter if it is.

See Answer In Context

6 Replies 6
Erasmus_apc
Sisko
Sisko
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217

Re: UPSes making buzzing noise on various PCs...

This was originally posted on APC forums on 4/28/2009


What UPS model are you working with, and do you have any specs on those power supplies?

BillP
Administrator Administrator
Administrator
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218

Re: UPSes making buzzing noise on various PCs...

This reply was originally posted by Angela on APC forums on 4/28/2009


[this thread|http://forums.apc.com/spaces/5/smart-ups-symmetra-lx-rm/forums/general/4711/symmetra-communications-...] may have some helpful info and is probably similar to what you are seeing. we can confirm once you provide the info Erasmus asked for.

Malkor_apc
Ensign
Ensign
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0
218

Re: UPSes making buzzing noise on various PCs...

This was originally posted on APC forums on 4/28/2009


Sony doesn't release schematics on the PlayStation 2, but the SCPH-9000x has an internal PSU that is at 32W. My desktop PC has a PC Power and Cooling Quad Silencer at 750 Watts. The PS2 is on an ES 350 while the computer is on an XS 1300.

My only other concern, and that I do realize multimeters are not reliable in testing AC voltages in stepped sine mode, is that why I only get an 80V readout as opposed to the XS 1300's 115?

BillP
Administrator Administrator
Administrator
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218

Re: UPSes making buzzing noise on various PCs...

This reply was originally posted by Angela on APC forums on 4/28/2009


if you are using a true RMS voltmeter, you should be reading 115v from a step approximated sine wave. if you use a non true RMS voltmeter, you will receive 80-88v.

[see this article for reference|http://nam-en.apc.com/cgi-bin/nam_en.cfg/php/enduser/std_adp.php?p_faqid=1493]

Malkor_apc
Ensign
Ensign
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0
217

Re: UPSes making buzzing noise on various PCs...

This was originally posted on APC forums on 4/29/2009


It's only a $7 meter so I don't think it's going to have RMS. I only got it for mainly DC metering (mainly alkaline batteries).

BillP
Administrator Administrator
Administrator
0 Likes
0
218

Re: UPSes making buzzing noise on various PCs...

This reply was originally posted by Angela on APC forums on 4/29/2009


yeah i agree, most likely it is not true RMS. usually it says it right on the actual voltmeter if it is.