5 year old topic, but still relevant!
I have similar issues with the audio out jack on 640m win WinXP.
- When using line out to stereo system for a long time (say 5 hours min.), the audio out jack stops giving sound! No crash, no disabled devices, just no sound. When unplugging the line out from the audio out jack, sound works normally over the computer speakers (which are excellent, but that's another topic 😄 ). Very odd issue. It does seem to fix itsself after some time (at least half an hour), but is very annoying.
So far I tried:
- reinstalling sigmatel drivers, with and without deinstalling old drivers, with versions dedicated to dell, not dedicated to dell, oldest releases, newest releases. The whole works
My 640m used to have a different motherboard on which this was not an issue!!!!! Swapping motherboards resulted in glitchy keyboard, non functional mousepad and this obscure error. It might be a result from the motherboard not functioning 100%, but since no errors are given by the system, it seems more likely that it is a safety measure as described above by IXIST.
Any feedback or help is much appreciated!
The problem I have with the safety theory is that if it is a hardware safety device it would happen with every 640m motherboard, and if it is a software feature then it is related to the audio driver (if it were an XP feature every XP laptop would have it). If you are using the Sigmatel R171789 (188.8.131.5215), that driver is used on 40 different Dell laptop models. They would all have the feature and it would be a known issue by now. I don't know the answer but my feeling is that there was a bad batch of motherboards.
Thank you for answering!
Your suggestion could very well be true, since my other motherboard worked fine (until I destroyed it by spilling a drink on the keyboard :-S).
Do you think I could solder out the audio out connector from my old motherboard to fix the problem? Or is the faulty switch embedded in a chip somewhere?
I don't know where the switch is. The audio chip is on the motherboard, and the jacks are soldered to the motherboard. The audio out jack has mechanical contacts plus impedance sensing circuitry that can get messed up.
Replacing the jack could be tricky. It could be simpler to get a usb audio adapter -- they only cost a few bucks at places like Amazon.
I believe the 640m motherboard is the same as the E1405 model, so while you are researching maybe there is something you can find out about it.
I did a little shopping research and apparently a second hand motherboard is around $10.... Hardly worth tinkerling with my old board or buying an external device. As my current motherboard also had a faulty connection for keys and mousepad, I took the easy road and ordered the motherboard.
Still odd that some motherboards have this particular issues, while others don't. I'm just hoping my replacement board is from a good batch 🙂
Thanks for your help and information!