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Posted by jcole on December 20, 2007, 3:40 pm
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I have a Vaio R505EL laptop I purchased new several years ago. I got
it mainly because at the time it was a system that would work cleanly
with a firewire connection to a Sony miniDV camcorder I had, allowing
me to import digital video and edit it natively using Adobe Premiere.
The builtin memory stick reader was also handy. Until recently this
computer has always served me well, and I do still use it occasionally
to edit digital video. The laptop is running Windows XP Home SP2.
A few months back I became aware that when using a VoIP softphone on
the laptop the person on the other end was hearing a loud hum when I
spoke. I started doing some tests to try and isolate the problem and
have determined that...
It's not the builtin sound card (Yamaha AC-XG WDM Audio device.) I
typically use external speakers/mic and/or a headset plugged into the
laptop sound card, but also have problems when using a USB Plantronics
DSP-400 headset (nothing plugged into sound card).
When using the laptop sound card interface the hum goes away when I
unplug the AC power adapter. There is a hum when using the USB headset
without the laptop power adapter plugged in, but the hum is MUCH worse
when the power adapter is plugged in.
I took the laptop to a Circuit City and borrowed a power adapter from
a Sony floor model. Same problem, so it would appear I do not have a
bad power adapter.
I have tried this with and without the docking station, and with and
without other USB and ethernet connections. No difference.
Audio playback is fine under all circunstances.
II'm thinking it likely there could be a problem in the laptop
circuitry somwhere, but perhaps it could be a driver problem? I did
install Windows Media Player v10 hoping that might straighten things
out, but it didn't.
If anyone has run into this type of problem and/or has any ideas on
what else I might try to debug could you please post (or shoot me an e-
mail)?
TIA for any assiatance. ...jcole
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