Buzzing Sound coming from transformers

[ITSYSTEMSALBANIA]

Hi all

I repaired an dell psu model H280P-01 which was dead i replaced some 10v capacitors and the power supply its fixed but when i power on the psu i hear a buzzing sound coming from this two transformers.Is this sound normal or not.Thank you.

[ReeceyBurger123]

Re: Buzzing Sound coming from transformers

How loud is the buzzing is it abnormally loud ?
Normally the ac switching frequency noise that passes through the transformers is slightly audible but shouldn't be too loud. If its very loud it could indicate a short on the secondary side of the psu.

[R_J]

Re: Buzzing Sound coming from transformers

Yes they make noise, some louder than others, a loose winding or core lamination can even sound louder. If the supplies are working I would say they are ok and normal.

[ben7]

Re: Buzzing Sound coming from transformers

Might want to check the capacitors in the PFC circuit (if it has one), it might be 120 or 100Hz noise you hear. It might also be normal no-load (or light load) oscillations.

-Ben

[ITSYSTEMSALBANIA]

Re: Buzzing Sound coming from transformers

The psu makes the buzzing sound when no load is connected when i conect a load the buzzing sound stops.Thank you all for your replies.

[ben7]

Re: Buzzing Sound coming from transformers

The psu makes the buzzing sound when no load is connected when i conect a load the buzzing sound stops.Thank you all for your replies.

Yep it's because of the very light (almost none) load. The power supply does provide a slight load for it's internal circuitry, but that's only a few watts at most.

It basically ends up skipping pulses, hence you get a sound that humans can hear.

You can add some minimum-load resistors if it bothers you.

-Ben