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Buzzing noise from Imac 27 inch

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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claudia_apc
Cadet
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304

Buzzing noise from Imac 27 inch

This was originally posted on APC forums on 9/8/2015


I am using a Back-UPS RS 1500 on my Imac 27 inch. It is connected all the time but when in battery mode there is a buzzing coming from my computer that unnerves me!! Any advice help appreciated I don't want to burn out my Mac!!!


Accepted Solutions
BillP
Administrator Administrator
Administrator
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304

Re: Buzzing noise from Imac 27 inch

This reply was originally posted by Bill on APC forums on 9/8/2015


Hi,

When the UPS goes on battery the sign wave changes to step approximated and this could be the cause of the power supply buzzing. Kbase FA158939 "Computers containing PFC (Power Factor Corrected) power supplies and their use Back-UPS and Smart-UPS SC with Step Approximated Sine waves." discusses this issue.

See Answer In Context

3 Replies 3
BillP
Administrator Administrator
Administrator
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0
305

Re: Buzzing noise from Imac 27 inch

This reply was originally posted by Bill on APC forums on 9/8/2015


Hi,

When the UPS goes on battery the sign wave changes to step approximated and this could be the cause of the power supply buzzing. Kbase FA158939 "Computers containing PFC (Power Factor Corrected) power supplies and their use Back-UPS and Smart-UPS SC with Step Approximated Sine waves." discusses this issue.

claudia_apc
Cadet
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304

Re: Buzzing noise from Imac 27 inch

This was originally posted on APC forums on 9/9/2015


Hi Bill

Thanks for replying, much appreciated! I don't really begin to understand the article I was forwarded to but it does seem to suggest that the buzzing will only occur for a limited period of time. My buzzing happens for the whole time the computer is attached to the UPS on battery mode! 

Am I damaging my Mac I wonder! I live in India where we have many power cuts so this is a major issue for me!

Claudia

BillP
Administrator Administrator
Administrator
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0
304

Re: Buzzing noise from Imac 27 inch

This reply was originally posted by Bill on APC forums on 9/9/2015


Hi,

It is unlikely but the sign wave could damage the power supply of a period of time. If you experience frequent power losses I suggest replacing the Back-UPS with a Smart-UPS SUA, SMC, or SMT model. Those UPS provide a pure sign wave while on battery.