Question Sound slowly fades away - very suspicious.

[Keskoo]

Hey! I've got this super weird audio issue with my laptop, looking for anyone insightful to help me uncover this mystery.

It is a Lenovo Legion 5P-15IMH05H (model 82AW0049CK) laptop, with 82AW WIN I510300H_RTX2060 mainboard. The issue initially appeared to be a faulty speaker connector on the mainboard as there was no sound coming off the built-in speakers even after those have been replaced. There was never any issue with sound playing through any sort of audio device connected via 3,5mm Jack. I have tried at least 4 different versions of audio drivers under both Windows 10 and 11 (have yet to try ubuntu). BIOS aswell as the chipset drivers and all the other drivers were kept up to date.

Then, after few months of using the laptop very sporadically, it suddenly, after being awaken from sleep, started playing sound from the built-in speakers. I've assumed there must have been some sort of a fix hidden in the windows updates, but after approximately a minute, the sound started fading away slowly, becoming quieter with more crackling until it gradually faded away completely. All sound via jack connected headphones was still completely fine. This happens regularly about once a week now, always immediately after I pick the laptop up from sleep, the sound is back for a minute, perfectly clear, until it slowly fades away again. There seems to be no way of recreating this on demand.

I do not care much about fixing the issue at this point, but I am extremely curious to know what might be causing such weird interaction, please help 😀.

Also if there is a better forum section to post this question in, please let me know so I can repost it. Didn't find any that was specifically audio related.

 

[Ralston18]

My immediate thought is that the "fade away" may be heat related.

Nothing specific per se (full disclosure) to base that thought on.

However, consider that all may initially be okay but heat causes something to expand and sound fades away.

And, to me anyway, "crackling" is a symptom of a loose connection. And heat/expansion tightens up such connections.

Try to experiment and test to determine if a loose connection is a potential culprit.

 

[Misgar]

If the output stages of the laptop's audio amplifier are coupled to the speaker via a high value electrolytic, e.g. 1000uF, the capacitor may be on its way out. You'd have to be proficient with a soldering iron to remove the capacitor(s) and an ESR meter would be handy to check if they're OK. Replacements should be around a dollar each.

 

[Keskoo]

My immediate thought is that the "fade away" may be heat related.

Nothing specific per se (full disclosure) to base that thought on.

However, consider that all may initially be okay but heat causes something to expand and sound fades away.

And, to me anyway, "crackling" is a symptom of a loose connection. And heat/expansion tightens up such connections.

Try to experiment and test to determine if a loose connection is a potential culprit.

Thanks for the reply. Seems like you are correct, the crackling starts at 58 °C or 136 °F, the sound is completely gone once it reaches 60°C or 140 °F (core temperatures), so I can only have the sound working for as long as it takes to reach those temperatures.

 

[Keskoo]

If the output stages of the laptop's audio amplifier are coupled to the speaker via a high value electrolytic, e.g. 1000uF, the capacitor may be on its way out. You'd have to be proficient with a soldering iron to remove the capacitor(s) and an ESR meter would be handy to check if they're OK. Replacements should be around a dollar each.

Thanks, since it is temperature related and sound disappears consistently around 140 °F core temp, can that be caused by a failing capacitator? Also what would happen once the capacitator is completely dead if it only affects speaker sound right now? I am capable of soldering and have access to good tools but I lack the understanding of how exactly a complex PCB works.

 

[Misgar]

If you have access to a can of freezer spray and a hair dryer, the usual fault finding process is to spray suspect components for a couple of seconds, then warm them up with the hair dryer.

I used this method to isolate a faulty integrated circuit in a HiFi CD player. The machine stopped playing the disc when this particular chip was cooled down.

If an electrolytic goes bad, it often becomes "leaky" with a relatively low resistance. Without an ESR meter, the best option is to replace any suspect components. If you see any brown liquid leaking out of a capacitor, replace it. Other signs are a bulging top.

However, your fault is probably in an integrated circuit and will be difficult to replace. An external USB speaker with integral DAC might be the only easy fix.