On 12/08/2019 22:30, wrote:
Steve Walker wrote:
Brilliant! (literally ;-) ) Thanks for posting this, all I need
now is a dead TV.

The last one I threw away had a failed backlight, so not much use for this!

In the video it is noted that it is the diffuser and fresnel lens
in the screen is more use than a backlight (he replaces a backlight
that is inconvenient to power with a fairly generic LED strip).

Not all screens are edge lit though. Many of the ones I have
seen/repaired[1] have a backlight consisting of strips of LEDs mounted
on long thin PCBs, that point at the back of the screen panel, and are
arranged in a number of rows down the screen. These screens have lots of
diffusion layers, but not always a fresnel one.

[1] Individual LEDs failing, often stopping the backlight PSU from
starting, leading to no backlight. You can identify the failed strip by
powering it up from a few cascaded PP3s. Sometimes the failed LED looks
obvious due to heat damage around it. Desoldering the chip may restore
operation, although IME, once they have started failing, others will
soon follow. The strips are usually pricey enough to make repair non
economic if you need to replace more than one.


--
Cheers,

John.

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