Dead power supply making "whining" sound

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Hello,

I have a dead 5V power supply from a Linksys router. It is making a
very high pitch "whining" sound. I opened up the unit and noticed one
of the caps is deformed (the top of the cap is more rounded). What
could cause this high pitch sound? Is it the cap or other component?

Mike McWhinney

 

[Arfa Daily]

Hello,

I have a dead 5V power supply from a Linksys router. It is making a
very high pitch "whining" sound. I opened up the unit and noticed one
of the caps is deformed (the top of the cap is more rounded). What
could cause this high pitch sound? Is it the cap or other component?

Mike McWhinney

The problem will be the cap. If you had an ESR meter to check it with, you
would find that the reading was away out of the window. Replace the cap with
a high quality low ESR type, specced for use in switch mode power supplies,
and with a 105 deg temperature rating. It is worth also replacing any others
that are near to anything that gets hot. If there's not too many in there,
just replace them all. They're cheap enough. Word of caution. Be careful
running the supply with its case off. The primary side of a switcher is VERY
dangerous ...

Arfa

 

[Pooh Bear]

Hello,

I have a dead 5V power supply from a Linksys router. It is making a
very high pitch "whining" sound. I opened up the unit and noticed one
of the caps is deformed (the top of the cap is more rounded). What
could cause this high pitch sound? Is it the cap or other component?

Probably mostly the transformer core. That's not the problem though. You need to
replace that cap first. Make sure you use a low esr type designed for switchers.

Graham