> I checked all setting, nothing is muted. everything put at max volume.
> I tried to record anything to this laptop using two different
> microphones but nothing is recorded.
> probably the microphone jack is broken at this laptop. I still don't
> understand your method to test the jack. thanks
A Walkman, a transistor radio, a tape recorder, have a headphone output
jack. The signal on there, is a bit stronger than a microphone signal.
You can connect a Walkman to your computer, with a cable with male
connector on each end. The strong signal will serve as a means of
determining whether the jack works or not.
The reason a microphone may fail to work, is the MIC_PWR on the ring
contact, may not be the correct voltage. The sound chip may be used
to create a bias source, for electret microphones. Sometimes that isn't
strong enough, to make an electret microphone work. By using an audio
device, with a line level output, as a testing source, that is one way
to work around a possible microphone powering issue.
There are a number of different kinds of microphones.
1) Dynamic mic - that works like an ordinary speaker, but in reverse.
There is a magnet and a coil of wire. The moving wire generates a
tiny signal. Computer microphone inputs don't generally have
enough gain to work with them. No microphone bias or power is
2) Piezoelectric or ceramic microphone - is a material that generates
an electric signal, in response to sound pressure. Some of those
generate enough signal for the computer. No microphone bias or power
3) An electret microphone, has a simple amplifier in it. It needs a
small amount of current to work. Some computers have a 5V bias source
and a 2000 ohm series resistor, as a power source. Other computers use
a lower voltage. Electret microphones vary, as to how much voltage
they need from their power source.
Some mixer control panels, have a hidden "boost" check box, which increases
the gain of the microphone circuit. Sometimes that needs to be clicked,
to make the microphone work properly.
This is the kind of cable you'd use, to connect a Walkman or transistor
radio, to the computer microphone jack. I got a cable like this, with
my TV tuner card. http://www.radioshack.com/product/in...ductId=2102970