[WESTSIDESC]

im at work trying to make a videoconference thing work but theyre using these laptops that seem to hum only when they are plugged in and sound fine when they arent. however, they need to be plugged in to last, but the amount of hum is unacceptable. The laptop is the sony pcgr505gl and it has a power supply with only a 2 prong plug, no ground. is there anything i can do to make the hum stop? open the computer and attach a ground wire to the metal desk? anything?

thanks

rj

 

[D-EJ915]

You mean fan buzz or speaker hum? If it's the Fan then it's probably just on the "performance" setting and you should be able to go somewhere and turn it down to a "battery life" setting which will truncate your power but quiet it, most likely.

 

[Hammerstein]

Try replacing the AC adapter brick and line, because it might be that. In my case, I find that mine makes an annoying hum sometimes (and it probably means its failing, too!).

 

[bigshot]

If your wall sockets are fairly recent, the screw in the middle of the faceplate should be grounded. Attach a wire to that and try touching it to exposed metal. See if that helps.

See ya
Steve

 

[ken36]

Great thread. This is the way I'm learning to better understand. Thanks.

 

[Nospam]

The problem may not necessarily be with the laptop.

I had a cheap set of computer speakers that would hum very loudly when connected to my iBook. Tried it running the laptop off the battery, as well as 2 different brand power adapters (in 3 different outlets around the apartment).

Tested it in a different building, and the hum was gone. I'm guessing there's something going on with the wiring in my apartment???

In the end, I upgraded my speakers and the problem went away

 

[Snake]

Quote:

Originally Posted by Nospam The problem may not necessarily be with the laptop. I had a cheap set of computer speakers that would hum very loudly when connected to my iBook. Tried it running the laptop off the battery, as well as 2 different brand power adapters (in 3 different outlets around the apartment). Tested it in a different building, and the hum was gone. I'm guessing there's something going on with the wiring in my apartment??? In the end, I upgraded my speakers and the problem went away

With really cheap computer speakers they use a plastic chassis with minimal, or no, electronic shielding. Since the circuit is an audio amplifier stage it will pick up any stray electromagnetic interference in the preamp stage and amplify the signal to sound like a "hum". Motors, solenoids, dimmers with poor RF damping, poorly shielded switching power supplies, AC line noise - even dimmed incandescent light bulbs can emit an RF signal that the amp stage will pick up as stray.

If your speakers hummed like mad in your apartment home a common cause is poor shielding on electrical or CATV, or the very most likely candidate is a fluorescent fixture pretty much operating anywhere within, say, a 50 foot radius. A fluorescent, with the ballast and operating principles, is pretty much the world's largest RF hum generator. In office buildings the interference is so bad you can't pick up anything in the low megahertz range and down, like AM. The fluorescent fixtures completely wipe any signal off the map.