Toshiba 40D1333B no back light.

[zomi]

Re: Toshiba 40D1333B no back light.

Interesting makes it even more of a bugger..

Seems that the leds fitted are of a low quality looking at home many are failing.
Coupled with the brickable main boards makes it even more of a minefield.
shocking for a toshiba set costing a premium for the name..

Ps. diodes gone on the inverter ?

[ReeceyBurger123]

Re: Toshiba 40D1333B no back light.

Interesting makes it even more of a bugger..

Seems that the leds fitted are of a low quality looking at home many are failing.
Coupled with the brickable main boards makes it even more of a minefield.
shocking for a toshiba set costing a premium for the name..

Ps. diodes gone on the inverter ?

Yeah I know just like the older inverters if it detects a change in the current eg bad bulb it wont fire, designed to fail basically. In some cases these inverters do fail but normally its a mix of bad led/diodes complete crap.

[zomi]

Re: Toshiba 40D1333B no back light.

Whats the easiest way to verify an inverter is good in these cases...

As you have

1. poor connections..
2. flaky/ blow led/diode.
3. inverter bad

And I take in that order...
awful awful desgin the way they have done it and how you get to the parts...

[tom66]

Re: Toshiba 40D1333B no back light.

It's not a Toshiba, it's a pile of Vestel garbage. Toshiba execs have taken their once good name and run it firmly into the ground. Sad.

[Dang]

Re: Toshiba 40D1333B no back light.

I've read somewhere that bad LEDs can be removed and then bridged to get the Tv working again, is that possible here?

[tom66]

Re: Toshiba 40D1333B no back light.

No - bridging LEDs will cause excessive power dissipation in the driver balancing circuit, leading to early failure. It may also cause dark/light patches to form.

[ReeceyBurger123]

Re: Toshiba 40D1333B no back light.

No - bridging LEDs will cause excessive power dissipation in the driver balancing circuit, leading to early failure. It may also cause dark/light patches to form.

I agree, and the drivers on these need the current to be perfect or it wont fire.

[zomi]

Re: Toshiba 40D1333B no back light.

Any easy way to test an inverter,where the backlight as failed. ?
to rule out the inverter ?

[Dang]

Re: Toshiba 40D1333B no back light.

OK, so what is the best course of action here? could something be put in place of the LED to help balance the current, a resistor maybe?

[thoma]

Re: Toshiba 40D1333B no back light.

http://cart100.com/Product/38462740332/

http://www.iccfl.com/product_info.ph...ducts_id=10314

regards thoma

[budm]

Re: Toshiba 40D1333B no back light.

You can use 3.3V 1W ZENER if the LED current is 100mA, it will run quite warm so try to get the body of the diode to make contact with the metal chassis of the LCD panel and use heat sink compound, also make sure to put it in reverse of the LED'S POLARITY.

[Dang]

Re: Toshiba 40D1333B no back light.

Thank you, worth a try and quite helpful.

[riget]

Re: Toshiba 40D1333B no back light.

I have a sneaking feeling this is a TV with the 24V going to the panel, and the LED driver is inside the panel.
That's how the AUO panels in the 40L1333DB sets do it, and they use a very similar arrangement of parts.

Hi, I've got a 40l1333db with the same sound but no picture problem, my power board is different to the one on this thread, I opened the screen and checked all led's work fine.
The lower left black connector is giving me, 3v, 5v, and 24v so all seems good
The connector for the led's is on the right a white block with just 2 wires to power the led's, when the tv is on this gives just 2v, can anyone see where on the psu the fault could be?

Thanks.

[tom66]

Re: Toshiba 40D1333B no back light.

When you say you "checked all LEDs work fine", do you mean you checked them with a multimeter/battery and made them all light up...
Or.... do you mean that you saw them all lit up (if so why are you checking the power supply LED voltage?)

[riget]

Re: Toshiba 40D1333B no back light.

Yes the fault is no backlight, the led's were checked separately.

[budm]

Re: Toshiba 40D1333B no back light.

Any good clear pictures of the whole bottom side of the board?

[riget]

Re: Toshiba 40D1333B no back light.

I'll take a pic tomorrow, thanks.

[riget]

Re: Toshiba 40D1333B no back light.

I'll attach some pics, the best my phone can do.

[Dang]

Re: Toshiba 40D1333B no back light.

Hi, I've got a 40l1333db with the same sound but no picture problem, my power board is different to the one on this thread, I opened the screen and checked all led's work fine.
The lower left black connector is giving me, 3v, 5v, and 24v so all seems good
The connector for the led's is on the right a white block with just 2 wires to power the led's, when the tv is on this gives just 2v, can anyone see where on the psu the fault could be?

Thanks.

As you have most probably already read, the PSU isn't the problem, at least not in my case, indeed this PSU has been used elsewhere now(a 50" Celcus) and has been working fine for a while now, my bet is a bad driver board or bad connections between the LED strips, some have actually soldered these together to cure the problem.

[riget]

Re: Toshiba 40D1333B no back light.

No mine is the psu, there is no driver board, the connector on the psu goes directly to the led's.