LG OLED55C9PSA Owner's Manual page 13

Generated Sound
• Cracking noise A cracking noise that occurs when watching or
turning off the TV is generated by plastic thermal contraction due
to temperature and humidity. This noise is common for products
where thermal deformation is required.
• Electrical circuit humming/panel buzzing A low level noise is
generated from a high-speed switching circuit, which supplies a
large amount of current to operate a product. It varies depending
upon the product. This generated sound does not affect the
performance and reliability of the product.
• Make sure to wring any excess water or cleaner from
the cloth.
• Do not spray water or cleaner directly onto the TV screen.
• Make sure to spray just enough of water or cleaner onto a
dry cloth to wipe the screen.
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