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[SOLVED] Board making sound on power up

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rvspr

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Hi

I have an issue on EVM board.

One board is making sound on power up..

As it is a socketed board,i removed the processor and checked it,there is no sound.but on placing the processor it is making sound..

The board is fine(no short r low resistance in any voltage rails)

Then i isolated a inductor in 5V rail,no sound.The inductor I had isolated is an inductor in buck converter like shown below.

MOSFET_buck.jpg


What will be reason/cause for this sound

1.Is the inductor gone bad?

2.any other device in the power rail is causing the problem?

or any other thing that can cause this kind of issues.Kindly Share the ideas to solve this issue.

Thanks

Rajan
 

Hi;
Is your coil shielded one?
Sometimes, shielding ferrites have some cracks and glues (connection coil and ferrite) is broken in that case it may cause some "hiss" noise.
Try to replace coil.

Goodluck
 
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    rvspr

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what kind of sound are you talking about? is it a humm? if yes, you might have a faulty inductor.
 
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    rvspr

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How are you powering the board ?
Check if your external supply has a programmable current limit or maybe it isn't powerful enough to drive the required load.
 
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    rvspr

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Hey you guys are right..:)Thanks
The inductor had gone bad...

With that I have some questions
1.What may be the reason for the failure of inductors?
2.With that problematic inductor,i found fast switching of transistor (ie) the freq is ~720Khz instead of 350Khz..Any reason?
3.If the transistor have some problem ,will it cause such effects?

Thanks
 

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