onboard sound problem: right channel is muted

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BUGS

Anyone have this problem with the onboard sound for an asus a7v8x? I
tried different speakers and headphones and the output is clearly
muted for the right channel. I uninstalled and reinstalled the
soundmax drivers, did a system restore and still having problems.

thanks in advance.
 
Anyone have this problem with the onboard sound for an asus a7v8x? I
tried different speakers and headphones and the output is clearly
muted for the right channel. I uninstalled and reinstalled the
soundmax drivers, did a system restore and still having problems.

thanks in advance.

Make sure there are two jumpers on the FP_AUDIO1 header. It is
a 2x5 header, with one pin missing for keying purposes. The jumpers
should look like this.

o o
o o
o<->o
o
o<->o

HTH,
Paul
 
Ok, I checked that and it was OK. However, i narrowed down the
problem. when "Line In" is muted, sound comes out both channels fine.
However, when I do not mute "Line In", the right channel output
becomes muted.
 
Ok, I checked that and it was OK. However, i narrowed down the
problem. when "Line In" is muted, sound comes out both channels fine.
However, when I do not mute "Line In", the right channel output
becomes muted.

I take it that some kind of "playthrough" thing is selected as
well ? I.e. There has to be some kind of path from the Line_In
to Line_Out in the hardware, in order for the state of the
Line_In to have an effect on the Line_Out. It could be that
disabling Line_In or disabling playthrough has the same effect.

It sounds like the basic problem is, some DC is leaking into the
Line_In signal. All the signals on a sound chip are AC coupled,
so no DC from an external device can touch the sound chip pins.
The sound chip inputs are DC biased by the chip, typically to
mid rail (i.e. 1.65V for a 3.3V chip). An AC sound signal, when
AC coupled to the pin, wiggles the voltage above or below the
1.65V bias level. If one of the AC coupling capacitors goes
bad, this can potentially rail the input, and if that signal
goes to the mixer inside the chip, the summation of the railed
signal plus an ordinary sound, will yield silence. (Of course,
you'd need a source of DC plugged into Line-in, in order to
complete this scenario.)

If you have a voltmeter, you could compare the voltage on pins
23 and 24. If you just want it to work, then it is likely
time to exercise the warranty and RMA the board. (A work around
would be to use the white AUX-in 1x4 connector on the surface
of the motherboard, as a line input. Then, leave the Line-in
function permanently disabled.)

It could also be an internal fault inside the ALC650.

The ALC650 design package is here, if you want to see how
the sound chip is hooked up. Download alc650_data5.zip
from this page:

http://www.realtek.com.tw/downloads...5&famid=All&series=8&Spec=True&refdesign=True

HTH,
Paul
 
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