I have a Toshiba 40l1333b with a backlight problem.

Problem:
The backlights don't light up.

Screen: Lta400hm23
LED Driver board: Ssl400 0d5a- Rev 1.0
Back light LED Strip connector board: SSL400_WP01 REV:0.0

Firstly I replaced the driver board, but that didn't fix the problem.

with the replacement driver board connected, I tested the led strips with an LED tester and all the leds light up.

I tested the leds using test points VOUT and IS (which are on the led driver board).

Also i have checked the continuity from the led driver board to the led strips, and continuity is OK.
I think there is a fault with the led driver board. I have attached two photos of the led driver board. The photo with just black test shows what the voltages should be at various points (i found these voltages from a photo I found on a forum). The second photo ( with the green text) show the results of testing the replacement driver board.

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Any clues which component on the led driver board in faulty?
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Update: I replaced the SN358 op-amp with with a LM358, but it made no difference.


Here is a number of photos with varying test results
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correct voltages on SSL400_05DA
http://testing.dfear.co.uk/toshiba_40l1333b/151120-IMG_20151120_221823.v2-1.black text.png

results of testing original SSL400_05DA (from the tv)
http://testing.dfear.co.uk/toshiba_....black text.original board - test results.png

results of testing replacement SSL400_05DA
http://testing.dfear.co.uk/toshiba_...ack text.replacement board - test results.png

results of testing SN358, TR10E and CN001 - original SSL400_05DA
http://testing.dfear.co.uk/toshiba_40l1333b/original - ic results.png

results of testing SN358, TR10E and CN001 - replacement SSL400_05DA
http://testing.dfear.co.uk/toshiba_40l1333b/replacement - ic results.png

 

Looks as if your not getting an enable signal from your main board

 

Looks as if your not getting an enable signal from your main board

I have checked the pinmap on the board and I think I may have recorded some voltages in the wrong place for CN001. If pin 5, which is NC is not present then I definitely have messed up.

I have amended the results and have re-uploaded the following photos:
http://testing.dfear.co.uk/toshiba_40l1333b/original - ic results.png
http://testing.dfear.co.uk/toshiba_40l1333b/replacement - ic results.png

Having checked the amended results, I think I do have the enable signal from the main board, as I have 3.242 or 3.245 V on pin 12 which is ENA.

Is the the voltage on pin 12 (ENA) correct?

 

I have fixed the backlight problem on this TV.

The problem was the crappy connectors that connect the led strip pairs together.

Solution:
I have soldered solid copper wire jumpers between the pairs of led strips. Only one connection was faulty but I put copper jumper wires between all of the led strip pairs, on both the positive and negative connections.

FYI:
The voltage on the LED tester (after the repair), when putting the probes on the IS and V_OUT test points on SSL400_05DA, was 124V.

 

Mark as SOLVED

 

FYI:
I used the solid copper wire from 1.0mm2 twin and earth electrical cable to make the jumper links.


https://obrazki.elektroda.pl/7825770300_1541702334.jpg