Re: No stereo sound

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Paul MR wrote:
The bottom-line is that the desktop computer plays only the right stereo channel.

<<snip>>

Some computer cases have provision for a microphone and a headphone jack
on the front of the computer. The computer case has a wiring harness that
goes to a 2x5 header block. There are a maximum of nine wires on the harness,
as one pin on the header is used for keying and is not present on the motherboard.
The minimum number of wires used on FP_AUDIO, would be five.

If you disconnect the front panel wiring, there would be nine pins sitting there.
There are a total of four pins, that are supposed to have two jumpers installed
on them, when the wiring harness is missing. If you forget to put the jumpers
back, when the FP_AUDIO header is not being used, then you lose audio on the
green connector on the back of the computer. In other words, the header provides
a continuity function, connecting the AC'97 audio chip, to the green connector
on the back of the computer. When the computer case wiring harness is installed,
it is the responsibility of the harness, to provide continuity, so that the
left and right channel are still available on the rear green connector.

The jumpers are mentioned here, on page 20.

http://www.formfactors.org/developer/specs/fpio_design_guideline.pdf

Occasionally, people who buy motherboards on Ebay, forget to put the
jumpers back, which were not provided by the previous owner. And that
is one way to lose one or both channels of the audio on the green
connector.

In terms of verifying jumpers and the like on the motherboard, it helps
to have the motherboard manual. It will usually have a small section
with a picture of the jumpers that should be on the FP_AUDIO header.

Paul
.

Relevant Pages

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    ... as one pin on the header is used for keying and is not present on the motherboard. ... There are a total of four pins, that are supposed to have two jumpers installed ... when the wiring harness is missing. ... a continuity function, connecting the AC'97 audio chip, to the green connector ...
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