Toshiba 50l1350u dead backlights

[adam3303]

What would cause all the back lights to go bad all at once on this tv. Have good voltage from power board to leds. I have removed the back light strips and all fail to light using micrometer diode test. All positive connections on strips fail continuity test also. Lamp holder is a 6637L-0021A and led strips are 6916L-1272A, 1273A, 1276A & 1241A. I believe that replacing these will fix the tv, but just curious why all would fail at once. Any help is appreciated.

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Hello i am haveing the same problem Adam my Tv was working fine but now the backlight its not working i can see the picture but its really dark any help please ?

[Andrew F. Ali]

Re: Toshiba 50l1350u dead backlights

Look for cold solder joints and cracks on the backlight system. Perhaps a loose connection is preventing power to it.

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Look for cold solder joints and cracks on the backlight system. Perhaps a loose connection is preventing power to it.

Hello Andrew thank you for your answer where can I locate the Backlight on this TV since I can only see the main board T-con board and power supply is it underneath of the lcd glass ? one other question those this tv have an invert board combine with an other board or backlight combine with an other board ? Thank you so much .

[CapLeaker]

Re: Toshiba 50l1350u dead backlights

Before you are all game and tear into the panel, how about you turn the TV on and probe the BLon pin against chassis GND. This way you know if the main board is turning on the backlight first place. Then probe the L1 pin pair and the L2 pin pair. See what that gives first.

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Hello CapLeaKer I got the tv open how can I probe the BLon pin against the Chassis ? if you can give me an idea where is the BLon pin and the L1 and the L2 pin on what board would I be working on thank you a lot ! witch one its the BLon pin ?

[CapLeaker]

Re: Toshiba 50l1350u dead backlights

Everything is on the power supply. There are 2 connectors, one big one and a small one. Next to it there should be little chart that explains what pin has what function. Put the DMM into DC put the black probe to chassis GND or to a GND pin and the positive lead to the BLon pin. On the L1 and L2 pair, that is the backlight. There can be a 100V DC depending on size. Of course the TV has to be on.

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

I open up this tv and notice 6 lapms but 0nly 3 of them are working so I took two wires from a good one and test one of the bad one and it came on so now I know all the lamps that are not working are good and look careful at the led lamp board there is no cracks so seems like I have a failed power supply do any body know if this power supply its fixable ? is it the capasitors or diodes ? any help thank you!!

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Everything is on the power supply. There are 2 connectors, one big one and a small one. Next to it there should be little chart that explains what pin has what function. Put the DMM into DC put the black probe to chassis GND or to a GND pin and the positive lead to the BLon pin. On the L1 and L2 pair, that is the backlight. There can be a 100V DC depending on size. Of course the TV has to be on.

I open up this tv and notice 6 lapms but 0nly 3 of them are working so I took two wires from a good one and test one of the bad one and it came on so now I know all the lamps that are not working are good and look careful at the led lamp board there is no cracks so seems like I have a failed power supply do any body know if this power supply its fixable ? is it the capasitors or diodes ? any help thank you!!

[Andrew F. Ali]

Re: Toshiba 50l1350u dead backlights

Looks like supply to the LEDs is not working. I would just go ahead and change the Power board.

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Thank you!

[CapLeaker]

Re: Toshiba 50l1350u dead backlights

I open up this tv and notice 6 lapms but 0nly 3 of them are working so I took two wires from a good one and test one of the bad one and it came on so now I know all the lamps that are not working are good and look careful at the led lamp board there is no cracks so seems like I have a failed power supply do any body know if this power supply its fixable ? is it the capasitors or diodes ? any help thank you!!

Read my post 7 again

[Andrew F. Ali]

Re: Toshiba 50l1350u dead backlights

Yes. Please revisit the CapLeaker Post #7. What voltages are you getting??

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Hello I know what is my problem with this tv I have a bad lamp basically half of this lamp its good the other half its bad the way I found out I connect a wire from the + to the - pin in the middle of the lamp and all lamp came on except the rest of the lamp so now I need to order the part 6916L-1276A thanks for your help !!

[Bossgt08]

Re: Toshiba 50l1350u dead backlights

Read my post 7 again

Hello I have this model# Samsung

pn42c450b1dxza i am haveing the same problem with this model ! i have a black screen no picture at all i have sound even if its dark in the room any Help thannk you? i am haveing a problem with ! i have a black screen no picture at all but I have sound I replace the T-con board but that didn't fix my problem thank you![/QUOTE]

[Andrew F. Ali]

Re: Toshiba 50l1350u dead backlights

With the back cover carefully removed check to see if the backlights are OFF. Most likely they are. Where are the supply wires for the backlights coming off? The power board or another board. Check the voltage on the BL-ON pin. Perhaps you should open a separate post with your TV Model No. You would get quicker responses.

[Andrew F. Ali]

Re: Toshiba 50l1350u dead backlights

That should be a separate 'thread' not post....Thanks

[s22nik]

Re: Toshiba 50l1350u dead backlights

this is what i have does these voltages seem right?

MY BOARD
--------

L2- =1.01V
L2+ =79.8V
L1- =14.88V
L1+ =79.8V

PWM =0.229V
5.1V =5.129V
BL_On/Off =3.236V
Power_TV =3.291V
AC_Detect =3.502V
5.1V =5.128V
GND =0.001V
12V_LNB =0.001V
GND =0.002V
12v_AUD =12.49V
GND =0.001V
GND =0.001V
12VDC =12.48V
12VDC =12.48V
12VDC =12.48V

NEW BOARD
---------

L2- =1.188V
L2+ =77.2V
L1- =12.82V
L1+ =77.2V

PWM =0.229V
5.1V =5.165V
BL_On/Off =3.235V
Power_TV =3.291V
AC_Detect =3.530V
5.1V =5.165V
GND =0.001V
12V_LNB =0.013V
GND =0.002V
12v_AUD =12.56V
GND =0.002V
GND =0.002V
12VDC =12.55V
12VDC =12.55V
12VDC =12.55V

[tvsteve2]

Re: Toshiba 50l1350u dead backlights

Bossgt08 Your Samsung isn't a LED TV it is a PLASMA TV a completely different technology!