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Equipment Repairs => LCD TV forum => Topic started by: Turnip on December 11, 2015,11:19:07

Title: Toshiba 40L1333DB - No backlight.
Post by: Turnip on December 11, 2015,11:19:07

Hi Folks,

Had one in today, where sound was OK but no LED backlight.

Set uses 17IPS20 with Vestel VES4000VNDS-03 screen.

Noted 125v on two wire feed to screen, but not even a glimmer of light.

CCFLs used to last years, but this set is just over two years old, Gather this problem is common, where unbroken screens may soon be available on Ebay, If Council tip folks don't bust 'em first.

Just a matter of sorting some LEDs - Chris.

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: jordan on December 11, 2015,12:24:30

40L1333DB

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: Turnip on December 11, 2015,13:29:53

Hi Jordan,

Thanks,

Problem -  LED Backlight, where replacement diodes are currently unavailable, even from Vestel,

Vestel is usually nifty with schematics, even if they don't include screen options, Gather they used  several different screens on this set but never bothered mention differences.

Just have to try sort suitable LEDs - Chris.

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: downunder on December 12, 2015,03:39:03

Hi Chris,

A little bit of light reading for you. Probably won't help. 125V sounds about right, maybe edge lit. Usually one has to bite the bullet and crack open the panel for a shufti.

Bruce

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: Turnip on December 12, 2015,07:28:31

Hi Bruce, and thanks.

Wasn't going to crack it open, but gift from customer so had a shufti. 5 strips of 9 Leds all in series.

Found one Led S/C and another O/C with burn marks. Leds are 3.4mm square and strips marked

VES390UNDC-01 also LG Innotec 39FHD-C Rev 0.2  Now to try find some diodes or wait around for a

screen smash - Thanks again - Chris.

Later - Checked Ebay and got a strip, not the right one so will have to swap Leds and hopefully not damage many - Gather heat strip from underside and tweezer Leds off.

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: downunder on December 12, 2015,19:46:12

Hi Chris,

Indeed there seems to be a myriad variety of LEDs used, specifically designer to make techo's blood boil.

Yep, heat the underside and old LED slides off easily. Ever trying to be helpful, Bruce

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: old tvman on December 15, 2015,05:33:51

Check the small connectors that join the led strips in the middle,very common for poor connertions I always fit links to them ,if that does'nt cure the problem apply a dc supply to the strips  to determine which strip is faulty.
davy

Title: Re: Toshiba 40L1333DB - No backlight.
Post by: Turnip on December 15, 2015,11:34:33

Hi Davy, and thanks.

This set doesn't have middle connectors, just a supply strip at the top with 5 plugs for the vertical Led strips of 9.

Made it easy to discover which Leds were duff using a current controlled P/S at about 25v, max current set to 200 m/a though realise nearly half an amp is the biz normally.

Getting to like Led backlights, as could be an earner, but not yet met a duff 'top and bottom' jobby, as repair could be testing - CCFLs were bad enough, and broke with a puff at a wrong move.

Got one in to sort tomorrow - Technika LCD19-220 with a duff bottom tube - Unusual, as usually the top tubes corrode at the ends first - Chris.

Later - Technika tube had died of old age, thought sort from scrap to discover Sammy LTM190M2-L31 screens come in at least three versions and can't swap the bits as they won't fit. All fun.