Distorted soubnd on LG Smart TV 42LW5500-ZE

Miguel Giménez

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Apr 29, 2021, 7:19:13 AM4/29/21

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Good morning

I own a LG 42LW5500-ZE Smart TV about ten years old. It worked OK until
about two weeks ago, when the sound quality started to degrade and has
worsened from day to day. It sounds as a mix of saturation, crossover
distortion, box resonation and loudspeaker cone broken. I will open the
set this weekend, but before I would like to know if anybody has any
experience with this.

The sound make me remember class AB discrete amplifiers, when the bias
was not properly adjusted and the transition of one leg to the other was
not smooth, but the TV amplifier looks a class D one (NTP-7400L).

TIA

--
Saludos
Miguel Giménez

Peter W.

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Apr 29, 2021, 7:34:13 AM4/29/21

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I have no idea of the environment around the TV, but it could be as simple as something crawling into the speaker and causing havoc, or the speaker itself self-destructing. Something hatching out inside would account for the slow degradation. It is springtime. after all! Be careful when opening....

Peter Wieck
Melrose Park, PA

ohg...@gmail.com

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Apr 29, 2021, 10:52:20 AM4/29/21

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Bad speakers. LG made their own and they were crap. Even if you find some on ebay, they're just as old and likely to sound like garbage. Just add a cheap soundbar or powered computer speakers/sub. Even a crappy soundbar will sound a lot better than the LG did when it was new. The rest of the TV is well made.

Michael Trew

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Apr 29, 2021, 1:04:49 PM4/29/21

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I second that. I've never heard a slim flat screen TV with good
sound... typically ranges from acceptable to very poor, and gets worse
with time. That's one upside to my old console TV. The CRT isn't a
great picture, but the speakers are nice. Even a cheap Walmart
sound-bar will help you, or hook the audio-out into an external stereo
if you have one laying around.

Miguel Giménez

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Apr 30, 2021, 5:44:59 AM4/30/21

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Thank you to all posters. Do LG sound bars have also crappy loudpseakers?

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Saludos
Miguel Giménez

ohg...@gmail.com

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Apr 30, 2021, 10:28:23 AM4/30/21

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Well, yeah. But they're still far better than the ones the TVs have. Flat TVs have special needs, and the speakers are necessarily very thin and are all plastic, including the frames (generally). Even a cheap soundbar will have drivers that are physically much larger than those in the TV and not limited by the constraints of a thin TV cabinet, so they make much more sound with much less effort.

Jeroni Paul

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May 1, 2021, 10:08:39 PM5/1/21

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Hi Miguel, I hope you are all well.

As others said this sounds like a problem with the speakers. The coil is glued to the plastic membrane and is now loose from one side.
I have had luck fixing some of these speakers. Depending on the speaker construction it may be easier to pull the magnet or separate the membrane from the frame. Either way once you get access to the coil you can glue it back, I use two component adhesive. Make sure you glue it exactly at the original position. Once dry glue the magnet/membrane back, the magnet may need centering, for that I apply an audio signal while the glue is not dry and center it for a loud and clear sound.

Miguel Giménez

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May 4, 2021, 8:54:03 AM5/4/21

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Thank you, Jeroni. Glad to hear from you again, after
es.ciencia.electronica near defunction.

--
Saludos
Miguel Giménez