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Samsung LE32R86BDX No Backlight

Troubleshooting TVs and Video Sources - Badcaps Forums - www.badcaps.net
Hi everyone,

I'm sorry for my bad english

This thread about a Samsung LE32R86BDX with a PSU BN44-00155A & an Inverter Board INV32N12A Drived by a SEM2006

I recovered this LCD with severals problems.

At first the TV was'nt turning on at all, no red light. I found the RM801 0.22 ohms resistor cut and after changing it

the red light going on and the TV turning on when touching the front panel......but there is no backlight at all (no flash & I don't know at this time if there is picture).

Measure on the PSU are the following :

5v -> 5v

12v -> 12v

13V -> 12.1V (??)

24v -> 24v

Measure on the Inverter Board :

Transformers Secondaries -> 1250/1275 ohms (expected 1250 ohms)

Little transformer T3 Primary and Secondary -> 36 ohms (expected 40 ohms)

Fuse F1 is OK (24v on the two pins)

So for the following tests I disconnect the Main Board and forced the PS_on to 5v and the same thing for BL O/F

I took the mesure on the pins of the SEM2006 IC:

Pin / Symbol / Measure

1 VREF 4.8v

2 SDT 0v

3 S/S 2.1v

4 HF 1.1v

5 DET 0v

6 ARC_P 0v

7 ARC_N 3.2v

8 FB 3.5v

9 ERO 0.5v

10 OVP 0v

11 PGND 0v

12 N1 0v

13 N2 0v

14 VCC 24v

15 UVLO 4.8v

16 EN 3.5v

17 FAIL 0.8v

18 SGND 0v

19 CT 2v

20 RT 2v

21 HRT 5v

22 BRT 1.5v

23 BCT 2v

24 BDIM 0v

When I was tooking measure around the pins 8 & 9 the Backlight start for a second, I thing I did a short circuit with my probe....

So I need some help there because I don't know how to interprate my results, I just understand that the two Channel MOSFET Driver output pins (N1 & N2) are low but I don't know why.

If you have and idea of what can I test know, it would be great

Thanks
Date: Jun 19, 2017   


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