Toshiba Satellite 1805 distorts music

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It started for no apparent reason (no system changes).

Any of the inputs that pass through the WAV input on the mixer is highly
distorted. These inputs can be from Winamp playing an mp3 or wav file,
or from Cool Edit playing a wav file.

An input from the CD player, which passes through the CD Audio input on
the mixer and is unaffected by the WAV gain, is much less distorted,
even though I drag it into Winamp's playlist to play it. If I lower
Winamp's gain to 67%, which also lowers the mixer's WAV gain, the
distortion disappears.

For test purposes, I use a sine wave, 1000 Hz, 0 dB, from a commercial
test CD as the cda file. I then used Cool Edit to generate an identical
signal, which I saved first as a 44.1 KHz, 16-bit, wav file, then
converted it to an mp3. All three were played via Winamp's playlist.
When the cda file is playing, it's coming directly from the CD (not an
hard drive copy).

An oscilloscope on the headphone jack shows the distorted outputs to be
clipped sine waves. If I lower Winamp's gain to 27%,the distortion
disappears. If I keep the Winamp or WAV gain at max and lower the Master
Volume gain, it merely attenuates the clipped signal without affecting
the degree of clipping.

I've reinstalled Winamp from its original self-extracting file; same

The mixer is the one Microsoft includes with WinME. I used Control
Panel\Add/Remove Programs\Windows Setup\Multimedia to remove and
reinstall it; same problem, although the program never asked me to use
the Recovery disc for a really fresh copy.

(As an odd aside, when I manually removed the two files I thought
controlled the mixer, voltrack.vxd and sndvol32.exe, I couldn't display
the mixer controls, but the files played the same way as before -
highly distorted mp3 and wav files.)

I deleted the soundcard's .inf driver; all three file types stilled
played as before - highly distorted mp3 and wav files.

I have a second Toshiba, Satellite 1405, configured the same way (except
Windows XP). All the Winamp v2.81 plugins in both computers are
configured the same. No signal processors. With the external volume
controls set at max, both computers put out 4V p-p; in the 1805, it's
highly clipped.

Seems like a hardware problem - something increasing the gain of an
amplifier follows the WAV gain on the mixer (or not attenuating its input).

Ali provides the sound section of the motherboard.

Any other ideas are greatly appreciated. If there are other NGs where
this post may be more appropriate, please let me know. (Correct my email



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