Microphone or line in won't work


I recently purchased a Dell inspiron 630M notebook with Windows XP home edition.  When I first got it, the onboard microphone worked fine, I tested it by recording my voice using windows sound recorder.  That worked fine.

The next time I tried doing it a few months, I could barely hear myself, when I tapped the actual microphone locations, only dull bumps could be registered.  Now when I try to do the same, nothing is audible, nothing registers on the 'wave' screen in windows sound recorder.  Similarly, I can't record anything from line in.

I know I have done something.  Yes I have checked the microphone volume and yes its fine - done that about 50 times.  When I 'test' the hardware using the 'sounds and audio devices' properties dialog box accessible from control panel, the process indicates that it has failed.

In past months I have hooked up various micropones to the external microphone input and tried them, and they were really faint.  I even used an amplifier to increase the volume, and whilst it could be heard, there was heaps of noise, sounded awful.

A couple of times I plugged in my speakers into that external microphone input socket by mistake, but I can't imagine this would do anything.

I uninstalled the only device in my device manager that appears to be my sound card - 'SigmaTel high definition audio codec' under 'Sound, video and game controllers' and then rebooted to automatically reinstall it.  No improvement.

I tried going into setup when I start up and seeing if there is any settings in there that might be worth changing, can't see anything.

The annoying this is that this happened with my last dell laptop :(

If you can provide a solution to this problem, you are a genius.

Who is Participating?
fredshovelConnect With a Mentor Commented:
There's a bit more info here:http://forums.us.dell.com/supportforums/board/message?board.id=insp_audio&message.id=24909

2. Run Dell Diagnostics audio test. If that fails then it is a hardware problem which would need to be fixed by Dell, or you could get an external soundcard. To run diagnostics restart, and as soon as it starts to boot up hold down f12. Select 'diagnostic' from the boot menu. It will run some tests for a couple of minutes before the diagnostic comes up. When it does select 'custom', then the audio test. This will test your audio system independently of windows and drivers. If this test fails then forget about all the other stuff.

3. In Services (Start/Control Panel/Administrative Tools/Services) check that Windows Audio is enabled, set to automatic, and running.

4. In Device Manager (Start/Control Panel/Administrative Tools/Computer Management/System Tools/Device Manager/System Devices) check that 'Plug and Play Software Device Enumerator' is installed and running. It will be listed alphabetically if there.
If not , then you need to reinstall it.

5. Go to Start/Run and type in sndvol32.exe to make sure the system mixer is installed and running. The audio drivers won't stay installed without this application being installed and running correctly.
jamietonerConnect With a Mentor Commented:
First i would suggest testing outside the os either in knoppix (www.knoppix.org), or in the dell diagnostics. To get to the dell diagnostics press f12 that will bring up a boot options menu choose either diags or utility partition(if the utility partition has been deleted you will need to boot to the resource cd that shipped with the system). It will first run a quick test on the system then it will ask you to press a key to boot to the utility partition, once in the utility partition choose custom test then click the plus next to audio and run the record test, if it fails the motherboard will need to be replaced (integrated sound). If it pases then either the OS or a driver is causing the issue. Next i would remove the sigmatel software from add/remove programs this will remove the driver also and then reinstall the latest version from dell's website (support.dell.com). If removing and updating the driver still doesnt help see what other audio programs are installed possible one could be causing the issue.
Matt PessolanoCommented:
I had the same exact issue with my dell 630M.  Turned out it was the actual motherboard.  It was a long and tiring process of elimination.  But it solved the problem
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Is your soundcard correctly selected?  G to Start/Control Panel/Sounds and Audio Devices -- click on the Audio Tab

...continued: -- click on the Audio Tab -- there is a selection for playback and recording. Your soundcard should be selected for recording as well as playback.  Make sure that a USB camera or something is not selected as a recording device -- choose your soundcard.
Get a warranty replacement for your PC, it is busted.
pmccar06Author Commented:

What do you do about the motherboard issue?

If it was an issue with the motherboard it would need to be replaced
GinEricConnect With a Mentor Commented:
For starters, you never put an amp [amplifier] on a line in or mic in!  If the microphone works on a real amplifier, then your sound card or chip is the problem.

If the laptop wasn't blown out to begin with, you probably fixed it [blew it out entirely] by putting an output from an amp to an input on a computer.

Line In is -10 dB, generally, that means it's a signal less than 1 Volt.  Specifically, it's defined as 1 ma [milliampere] over a specific Voltage [usually 1 Volt].  A ten watt amplifier is generally about 30 times the voltage and the amperage is limited only by the fuse rating; so like 5 Amp can, and will, flow into that baby fragile input on you Line In.  And a Mic In is usually -60 dB, which means it's less than 1/10,000th of 1 ma, down in nanoamps somewhere!  Unless you use a 60 Volt Neumann, in which case you get a lot more Volts and Amps.

If you're going to use a device in front of a computer input, know what you're doing first, and try to get a micromixer, that will match the Line In and Mic In between the microphone, or whatever you're using, and the computer input.

They're cheap, RadioShack still has one, I believe, for about $50.00

Any musical instrument store should have one, and the salesmen there should definitely know how to hook it up and tell you also how not to hook things up.

And yes, such voltages can feed right through to the motherboard and burn her up.
Right click on the speaker Icon on the desktop, open volume control, then in Master volume, click properties, then in the nest screen, click recording radio button, OK, and NOW you see the recording volume.  Make sure the line in and microphone are all the way to the top, and check microphone to select it.   How ridiculously buried this control is.

If this does not solve the problem, remove all sound drivers from the device manager, and let them reinstall.  If this does not solve the problem, try a BIOS upgrade for the laptop.  If still no luck, buy something else than a dell, they make really crummy motherboards lately.
<I even used an amplifier to increase the volume, and whilst it could be heard, there was heaps of noise, sounded awful.>

With reference to GinEric's comment <For starters, you never put an amp [amplifier] on a line in or mic in!>
He may have meant a mixer (which is an amplifier, albeit a pre-amplifier) -- he may be using 'amplifier' as a GinEric
term. Geddit?) If it was a power amp -- fair comment.
<Line In is -10 dB, generally, that means it's (expecting) a signal less than 1 Volt.>  -10db is in fact consideribly less that 1V RMS; it's around 316 millivolts. A line level input should be able to accommodate a signal from around 100mv to 2V RMS.

Hey pmccar06,
I didn't get any feedback on this: <Make sure that a USB camera or something is not selected as a recording device -- choose your soundcard.> see original post for how to do this.

You may have discounted this but it's worth a test. Because most USB cameras have microphones in them, and if it (or anything else) is selected as your recording device your mic in won't work. Might not be the answer but worth a test.

...and if you happened to have a USB camera selected -- and connected -- (not saying you did) and you connected your microphone and tapped it, you would still hear the tapping, but through the camera's mic not the one in your mic in -- <only dull bumps could be registered>.

Once again, might not be the answer but  worth a test.
pmccar06Author Commented:

I checked that audio tab about fifty times prior to posting this message.  For both playback and record 'SigmaTel Audio' is listed as the default device, and always has been to my knowledge.  I am aware that you do not stick an amplfied signal into a microphone input, but I was getting desperate to figure if the input was even functioning - it confirmed that there was something wrong.  This problem was present long before I did that.

Thanks to all that have posted, I have emailed Dell and awaiting a reply, and will award points to the person whose suggestion was most valuable.

Pmccar06 have you tryed it outside windows yet? If you test the mic in either knoppix or the diagnostics it will usually give a good indication if its a hardware or software issue.
GinEricConnect With a Mentor Commented:
Now I've got to review all my NAB Standards, but I was thinking along the lines of matched impedance; so if you put 600 ma over 600 Ohms, IR gives you 1 Volt.
The basis of the definition of whatever dB or dBu that happens to be.  I actually think I meant -10dB as well for Line In.  I haven't looked at the 128 and more inputs and outputs in my studio for years; maybe it's time I did so.

I have been too busy, like the poster, trying to get the real sound levels out of computers!

But I still think the best way is a little mixer, a RadioShack one, that has real levels.  If they don't match what the computer is showing, then there is no doubt about it, the computer is the one that is wrong.

If nothing worked, you're probably back to the motherboard drivers.  Dell is currently notorius for installing all their own proprietary drivers, and basically trying to erase the ones that come with the Asus motherboards they have built for them [Asus board, just with a Dell model number on it, you can usually cross-reference these to the real Asus model number].

Dell is a monster to restore.  It wants to stay XP Home, and it doesn't want any new devices or stuff that Dell can sell you yet another computer for, instead of a simple upgrade or add some better software.  I think they're totally going down the wrong track here, and they would do well to consider what happened to Gateway for trying this, as well as many others.

You also never stated what the sound chip was; is it a RealTek?  If so, you need the real RealTek drivers, the ones that normally come with the motherboard, whatever it is that's in that laptop.

You can bet somebody else made the motherboard, not Dell.  Maybe IBM or Sony, Toshiba, whatever.  But if you go and get Everest and install and run it, you should find out what motherboard Dell is actually using.

You can play with all the drivers just about forever, but until the levels match real levels, it's all just guessing.  I have no lack of real meters here, so I can check that .707 out and in match reality.  .707 is the maximum energy transfer point for all audio; zero noise, zero distortion, maximum signal.  Almost always no computer matches these inputs and outputs, and I haven't seen software that does yet either.

Computers don't have a standard, which is why there are so many problems.  They do actually have amplifiers in them, they have to for speakers and headphones.  Nominally some Op Amp at the output, sometimes at the input, and SAD and DAC chips in between for Serial Analogue to Digital conversion and Digital to Analogue conversion.  No, you can't play a flat out digital signal, it must be converted to analogue.  And if the final stage amplifier, usually an Operational Amplifier, is not biased or fed properly, you get the wrong volume.  This is part of what the drivers are supposed to do.  Also, some Summing Amplifiers that can take a digital signal, and by summing its pulses, produce and equivalent of the analogue wave form.  Anywhere along the line, if any signal is off, then the results will be off.  The circuitry is very technical, but it all revolves around control of the amplification and without standards all controls are pretty much "unpredictible."

Generally, and again, if any sensor, such as software, shows a seeming analogue wave form or presence, then something else between that point and the input or output, or both, is wrong.  Only a sensor that can show the absolute input and the absolute output is reliable.  The op amp out could be blown and software that picks off the wave before the very output will not show it as blown.

And the output is fed back to such sensors through a common resistor, that's all, so it doens't burn its own circuitry up.  Normally, that resistor is in the megohms, sometimes higher, which restricts the current to nanoamperes.  What ancient history is coming up on just who makes what chips these days, but you can bet that RCA, Motorola, and Marconi are at the end of the trail for nearly all semiconductors.

If you can get Everest and start to identify what's in the laptop, maybe we can find out what the real problem is.  There are just too many thousands of possibilities in the million of transistor circuits in any computer to say with certainty that it is either the hardware or software just yet.  It almost sounds as if you somehow shorted out a tristate buffer when you plugged one of those microphones in, which would mean, actually, a bad microphone [one that wasn't properly grounded or one whose configuration and impedance didn't match the input?]

The reason it sounds like such is because the level died over time.  The speakers are a load, and unless they have some high bias, or the input requires an earth ground, they shouldn't be able to burn out an input.  On the other hand, some microphones are not so nice, especially if they have a static rug charge on them and will take out a CMOS tristate input the instant they make contact.  Sometimes, they will do this a little more slowly, over time, as they overheat and burn up either the feedback or right through the input stage, especially if that input stage is not high impedance, sometimes regardless, since static discharges can easily get up into the tens of thousands of volts and highter.  And CMOS and others can't take that beating for long.

I think you're trying to troubleshoot a real hardware problem with a software approach.  You should eliminate one or the other first, and it will be easier to eliminate the hardware by narrowing it down to what you see in and what you see out, preferably on a real meter of some kind.  Even a near dead signal will pass through to a good mixer, which can boost any signal up millions of times [output].  If there's any signal left, you'll see it on a real meter in a real mixer.  As for the input, if you don't see it in any software meters on the computer, you can pretty much bet that either the input is blown, or, the driver is not working.  But if you do see it, and have no output, then it's something on the output chain.  Lastly, if you don't see it on input or output or in the machine, it's most likely the driver; unless the whole circuit is bad.

It's tedious, but it's the way to find out if it's time to get a new laptop or not.
pmccar06Author Commented:
Hi all

A big thankyou to all for your help.

Dell got me to run the diagnostics CD, which indicated that there was no microphone connected to the PC.  Upon learning this, Dell immediately dispatched a motherboard to a local contractor who installed it yesterday.  Before the contractor left, I got him to wait around whilst I tried to record some sound using Windows Sound Record, result: zip/nothing.  The contractor thinks it is the microphone hardware as this is seperate to the motherboard.

I have split the points amongst several of you the fairest way I can think.

GinEric, you technical discussion on mics, sound levels, amps and so forth was enlightening to say the least.  I appreciate the effort you put into your explanation, this will be a good reference for me in future when recording audion in digital form using a PC.

Jamietoner, I did have a look at knoppix but the foreign language spooked me.

Fredshovel your comments were aligned closely with what Dell had to say, thanks.

Thanks for all your help, I appreciate it.

Cheers Phil

<Fredshovel your comments were aligned closely with what Dell had to say, thanks.> That's probably because I pasted it from a Dell forum -- but glad everything is working.

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