AT&T DSL modem, get rid of high pitch noise?

John Doe wrote in news:4e93c62c$0$19608$c3e8da3 $ snipped-for-privacy@news.astraweb.com:

A piece of switching power supply working at an audible frequency. Get a piece of tubing to act as a stethoscope, and move that around the components, to find out what produces the sound. Probably one of the coils involved. Then try to decrease the sound(glue or wax covering it?).

Yes definitely the SMPS. It will run that way for years. The sudden appearance of that noise, though, can indicate pending failure, as something may have gone out of tolerance. The sealing method mentioned earlier may solve the issue if it is a mechanical ringing of the coil.

I haved a network hub that suddenly started singing years ago after a long power disruption, and that unit still running with no problems.

Not everyone can hear that high a pitch sometimes, and I can identify with the OP hearing the squeal. I often hear CRT horizontal squeal and it can be very irritating indeed. Of course no one else in the room can hear it. The extended hearing range is an asset when I am diagnosing PSU in the PCs I service. I can hear the PSU loading down or oscillating prior to failure.

- Tim -

Move it to another location and use a longer cat-5 ethernet cable to connect it up.

My DSL modem is currently in the utility room connected to garage, approx 4 ft from Demarc on outside wall. From there a use cat-5 enet cable/jacks/patch cables to connect to other rooms in house.

You can also replace the 12volt wall wart with a real switching power supply. (All sorts of nifty switching power supplies are available for a song in the garage sales these days.)

I've got my DSL modem powered via a 12v dc Belkin Battery backup that came from a former Universe install. :-)