Studio XPS 1645 No Sound From Speakers

Try running the audio tests in Dell Diagnostics. To run Dell Diagnostics

1. Restart the computer and tap the f12 key as soon as it starts to boot up .
2. Select 'Diagnostic' from the boot menu. The computer will run its pre-boot assessment tests (PSA) before Dell Diagnostics starts. During the PSA you will hear some tones through the system speaker but this does not adequately test the audio hardware. Dell Diagnostics plays an instrumental piece of music complete with drums, so if you only hear some tones then you have only run the PSA.
3. Dell Diagnostics should open after the PSA tests, or you should see an option to open it. If you have ever reformatted your entire hard drive then Dell Diagnostics will no longer be there as an option. In that case run it from the Drivers and Utilities (Resource) CD if you have one.
4. Select 'Custom', then the audio tests. (At this point - after you have opened Dell Diagnostic custom - if you can't find the option to select the audio tests that is a symptom of a failed audio chip.)
5. The tests will run. Alternate between using headphones and listening to speakers in case only one signal path is working.

If you have this combination of symptoms:

    * Speakers don't work and are not muted or deselected
    * Headphone jack does work
    * Reinstalling audio driver does not help
    * Audio test in Dell Diagnostics passes
    * On models with 2 headphone jacks, one may be "checked" in the control panel as if in use
    * Sometimes but not always, a very gentle wiggle of a plug in the jack will get it to resume normal functioning, at least temporarily.


That combination of symptoms means that the sense pin is not working for some reason. There is a sensing pin in the jack (Sense_A pin) that is used to detect the presence of plugs. Failure of the sense pin results in the computer behaving like there is always a plug in the jack. The software switch that should route audio to the speakers does not get triggered.


There are 3 ways to confirm that you have a failed sense pin:

1. Check for the combination of symptoms that I listed. If you have all of them then it is pretty certain you have the failed sense pin. Note that when you run the audio tests in Dell Diagnostics you should hear audio through the speakers. That is the opposite result from what one would expect. There is a complicated reason for this behavior which I can post if interested. If you do not hear the audio through the speakers during the tests then there is some other hardware problem.

2. Replace the headphone jack. If that fixes the problem that confirms that you had a failed sense pin.

3. Restore the laptop to its original factory configuration. This is called PC Restore in XP and Factory Image Restore in Vista. If the speakers still don't work after PC/Factory Image Restore and you have the combination of symptoms listed above, that is a definite confirmation of a failed sense pin.

The only way to repair a jack with a failed sense pin is to replace it.

Jim,

Thanks so much for the detailed reply.  I will run the Diagnostices as you suggest, but I'm almost sure I have a bad sense pin based on the symptoms.

Yes, please explain for me why you would hear audio through the speakers during the diagnostics if a bad pin prevents it otherwise.

Also, what's involved with changing out a headphone jack?  Is it something the average person can do?  Since the machine is under warranty, I'll contact Dell once I run the Diagnostics.

Changing the jack on most models requires replacing the motherboard. Some models have a jack daughter board that can be switched out. I don't know if your model has that or not. If you find out please let me know.

The switching software runs in Windows -- it is this software that is not functioning and thereby blocking the audio signal from the speakers. Dell Diagnostics runs in DOS and is designed to  eliminate Windows software (OS and drivers) from affecting the hardware during the tests. So the switching software is removed from the signal path, allowing the signal to pass through. The audio tests in Dell Diagnostics "pass" and correctly affirm that there is a software problem, but it cannot know that the software is not functioning because of the bad hardware. Because the bad pin only affects the switching software it is not relevant during the tests.

I have this happen sometimes, my computer has no sound and I need to reboot.  When it happens any program that tries to make sound freezes.  I wonder if it is related?  I had my motherboard replaced and it did not fix it.  I also did a reformat and it did not help.

Changing the jack on most models requires replacing the motherboard. Some models have a jack daughter board that can be switched out. I don't know if your model has that or not. If you find out please let me know.   The switching software runs in Windows -- it is this software that is not functioning and thereby blocking the audio signal from the speakers. Dell Diagnostics runs in DOS and is designed to  eliminate Windows software (OS and drivers) from affecting the hardware during the tests. So the switching software is removed from the signal path, allowing the signal to pass through. The audio tests in Dell Diagnostics "pass" and correctly affirm that there is a software problem, but it cannot know that the software is not functioning because of the bad hardware. Because the bad pin only affects the switching software it is not relevant during the tests.

Jim,

OK, I ran diagnostics and confimed that it is indeed a bad jack.  The Dell Diagnostic was able to play music through the speakers.  It also runs a Jack Test and shows that there seems to be something "plugged in" to one of the headphone jacks even when it's not.  There is also an IDT sound utility inlcuded with my system and this too shows that one headphone is constatly "connected."

I had somewhat of a hard time convincing Dell Tech Support that the jack was the issue.  They insisted the speakers were bad and wanted to replace them.  When I pointed out what the diagnostics indicated, they finally agreed.  They confirmed that there is a separate daughter board for the microphone and headphone jacks in my XPS 1645, but said they must replace the motherboard as well for comptibility reasons (although I don't understand why).  So, they will send a Tech out to replace the daughter board, motherboard, and the speakers under warranty.

Any suggestions on what I should show or mention to the Tech when he arrives?  Thanks again.

Nolag, your problem does not seem to be related to the issue that we are discussing about the sense pin in the headphone jack.

I had somewhat of a hard time convincing Dell Tech Support that the jack was the issue.

Dell has always been under-informed about the jack problem imo. In the past it frequently took restoring back to factory configuration just to convince them it was not a software problem, much less getting them to understand about the sense pin.

I can't think of anything to tell the tech. Out of curiosity I would ask why the daughter board and the motherboard are not compatible. Thanks for finding out that the XPS 1645 does have a daughter board. I will make a note of that.

Yeah, I guess not.  Figured I would see though.  What is a daughter board anyways?  (just curious what else they messed up with my comp)

I used the term daughter board to mean a circuit card with jacks on it. The daughter board plugs into the motherboard instead of the jacks being mounted directly on the motherboard.

Dell has always been under-informed about the jack problem imo. In the past it frequently took restoring back to factory configuration just to convince them it was not a software problem, much less getting them to understand about the sense pin. I can't think of anything to tell the tech. Out of curiosity I would ask why the daughter board and the motherboard are not compatible. Thanks for finding out that the XPS 1645 does have a daughter board. I will make a note of that.

Jim,

Just to let you know, my XPS 1645 has been repaired.  Replacing the daughter board solved the problem.

The field tech, who thankfully had a clue, did not see the wisdom in replacing the motherboard and speakers when everything pointed to a failed sense pin in the headphone jack.  He said that when Dell agrees it's a hardware issue, they usually will replace all related components to be sure the issue is resolved and to avoid another field call.  But in my case, just replacing the daughter board was the prudent thing to do and that there should be no "compatibiliy" issues with the original motherboard and new daughter board.  And there wasn't.  Upon reboot, the speakers sprang back to life.

As an fyi, my particular daughter board contains both headphone jacks, the mic jack, and two USB ports.  Repair took less than 15 minutes.

Thanks again for your help.  I appreciate it.

Thank you for the feedback. I have updated my notes accordingly.

Hello how can I get the board(the daughter board)? I think mine has the same problem just happening a couple of days ago.

Thanks! I found it for my XPS 1645 it is F138F.

Hello how can I get the board(the daughter board)?

If you are not under warranty, see the list of models with replaceable circuit boards in the Headphone Jack FAQ. For most models with replaceable boards, I gave an address where you can get it from the parts-people. Also try ebay. If under warranty contact tech support.