Author Topic: Panasonic TX-L42E5B Backlight issue ?  (Read 181 times)

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Turnip

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Panasonic TX-L42E5B Backlight issue ?
« on: November 16, 2018,07:55:41 »
Hi folks,

Have one which works perfectly for hours then cuts to S/by with a 1 / 1 error code. Turn it on again and it's OK for hours.

Checked the six strings, all read 55v on the tester. Wonder if might be an inverter issue ?  Chris.

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Panasonic TX-L42E5B Backlight issue ?
« on: November 16, 2018,07:55:41 »

downunder

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Re: Panasonic TX-L42E5B Backlight issue ?
« Reply #1 on: November 17, 2018,06:08:29 »

Hi Chris,

Error code 1 is a backlight SOS in these. You could try reducing the backlight level in the menu. See if that helps.

55V per string doesn't quite ring true. You'd expect perhaps 12 LEDs per string on a 42". If 3V LEDs are used that's 36V per string. If 6V LEDs are used that's 72V per string. Even if each string had a series/parallel configuration, it still doesn't gel.

While the tester is a useful tool, I think it sometimes tells porkies. From the outside, it will still light a strip even if it has a shorted or open
LEDs whereas in actual TV operation, that would be enough to trigger an error. Because of this, I disembowel about 6 panels a week, to find that although the tester lights a string, one or two LEDs may be out.

BRUCE

Turnip

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Re: Panasonic TX-L42E5B Backlight issue ?
« Reply #2 on: November 17, 2018,10:28:40 »
Hi Bruce, thanks for the heads up.

Guess screen Leds as you say, as it's an LG screen, famed for failure. Checked the strings with the set working and got much the same equal voltages so thought might be an inverter issue. Not yet got down to the strings, but on Ebay they appear to be rectangular 6v where already I have a pile of Leds from China.

Feel six a week nifty as can only suss two max as have rubber band issues with genuine audio.

Chap came by with a Linn Sondek LP12 where his motor was duff.

Not into audio myself, but noted his genuine player is worth thousands on Ebay, even though seemingly crap and a bit heavy.

Not one to cast, as an MP3 chap with dubious ears.

Sorted a new motor at a horrible price, and chap currently happy.

Just hope he doesn't check speed with mains, as frequency is a bit suspect

Mulja tv repair portal

Re: Panasonic TX-L42E5B Backlight issue ?
« Reply #2 on: November 17, 2018,10:28:40 »

Turnip

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Re: Panasonic TX-L42E5B Backlight issue ?
« Reply #3 on: December 09, 2018,11:10:28 »
Hi folks,

Think mention - Replaced the Led driver board and all seems OK after a few days. Tend to suspect chip SW5516QFN as it feeds and controls the 6 individual strings.

Its a well known SMD chip but Ebay doesn't yet stock them - Chris.

Turnip

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Re: Panasonic TX-L42E5B Backlight issue ?
« Reply #4 on: December 10, 2018,12:00:24 »
Hi folks,

Disaster. After several perfect days it popped off again. Screen off where 6920L-0001C strip seems to work perfectly - Merde.

Thought go Ebay China as half the price of UK stock. Guess might suss the old strip at some point as have plenty of the diodes.

Just a matter of knowing which one or ones might be duff.

Guess will be peeved if the Pana goes 1/1 after new strip fitted - Suspect just life - Chris

 

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