P.c. Power Supply 12v Line "hum"

Hi I’m using an old external PSU to supply 12V. to a mini-amplifier. The PSU is causing an annoying hum. Are PC power supplies prone to this? If I use a “switchable” power supply, no problem. I’d rather deal with this at the source, so is there any sort of filter I can use to “clean up”the 12 volt line. Obliged for any help here.

 

Normally the feedback is due to poor or nonexistent grounding in the power supply. Some are not designed to prevent the "hum".

 

Probably not. You can check your facility grounds to make sure you wall outlet is properly wired and grounded. A decent AC Outlet Tester can do that.

But it is more likely the hum is caused by a loose coil or transformer winding or transformer plate vibrating and there is not likely you can do anything about that. If you can see the offending winding or plate, applying some hot glue or epoxy might help but those fixes, if they work, tend to be temporary.

The good news is, such noise is usually harmless and the supply can last for years. The question becomes, can you put up with it that long?

 

Are you sure this is PC power supply?

 

Sound more like a notebook AC/DC power block.

 

not notebook, its an old pc power supply

 

It is really odd you say it is a PC power supply but also an "external" power supply. I've been around and working on computers since before IBM released the first PC and can't recall ever, any that came with external power supplies. So you have peaked curiosities. Do you know the brand and model of the original PC this came with? Any part numbers on this power supply.

My comments about the hum, coil and transformer windings and plates remain the same. Again, just curious now about the PSU.

 

Sorry for the confusion. Insofar as I took it out of the PC, it then became, for me, "external"

 

Ah, okay. That clears that up. Thanks.

 

I'm going to take the easy way out & just use a normal "switchable" PSU. Good forum, good information thank you all for your help

 

Well, it may be the easy way out but it is not the wrong way out.