High pitched sound coming from enclosure circuit

[kirov89]

Hello.

I have this here circuit from an IDE HDD enclosure. I'm looking to use only the power supply part of it. As in, I don't need the IDE/USB part of the circuit.

It works fine though I can hear a high pitched sound coming from it (like an electric squealing) when plugged in and turned on. This occurs both with and without load.

Here are pictures of the circuit:
top - **broken link removed**
bottom - **broken link removed**

I'm wondering whether this is something to worry about. I myself don't think it's normal as I can hear it from 2-3 meters away.

The power adapter this circuit is using is this - **broken link removed**

Any help appreciated. Thanks!

 

[Sceadwian]

There is no power supply per say in the enclosure, it's just a regulator. The sound you're hearing is probably from the crappy load regulation of the actual power supply, you're using causing the inductor or a cap or two to sing because of the bad initial regulation, it's not good, but it's not instant failure either, the input caps to the circuit (enclosure regulator) probably need to be dramatically larger, that alone may solve the problem.

 

[Diver300]

I think that the inductor is one of these:-

https://www.farnell.com/datasheets/69763.pdf

(It might be one size smaller, but it is certainly that type)

I have had quite a lot of trouble with those. Either the core cracks, or windings short. Either way, the effective inductance is reduced by a lot, and the inductor saturates too quickly for the rest of the circuit to turn off. You get a lot of output ripple and often an audible squeaking.

I haven't been able to test that type of inductor except by substitution, as I don't have and inductance meter or a multimeter that reads ohms to a low enough level.

 

[creakndale]

I recently had a working PC power supply start squealing and decided to troubleshoot it. I found one open electrolytic capacitor and one out of spec. capacitor. Both capacitors physically looked fine (no bulging or leaking). Replace both of them, the squealing stopped and the power supply still works

creakndale