EU55JS9000T black screen and sound good

[totof]

Hello.
I have this issue on my Samsung EU55JS9000T TV.
Backlight is good when the one connect box in not connected to the TV and I can launch the TCON screen test with the remote control.

But when I connect the one connect box the backlight immediatly turn off, the sound is OK (TNT source).
I dont know if the problem is from the one connect box or from the internal motherboard of the TV.
I open the one connect box (reference BN96-37087R) and all seems good, simply the Hawk-P CI is very hot after 5 minutes (~65 degres).

Is someone have experience for same issue for this TV and can help me ?

I see in the manual service the presence of a debug port but I don't know how to use it.

[Diah]

Re: EU55JS9000T black screen and sound good

the way to know,,,, turn on TV with out connect box... it should turn on BL ON and the screen displaying warning . so what do u have?? are there any display on screen ???

[totof]

Re: EU55JS9000T black screen and sound good

the way to know,,,, turn on TV with out connect box... it should turn on BL ON and the screen displaying warning . so what do u have?? are there any display on screen ???

I have not checked the BL_ON signal. When one connect box is not connected I have a message on screen that indicate box is not connected.

[Diah]

Re: EU55JS9000T black screen and sound good

I have not checked the BL_ON signal. When one connect box is not connected I have a message on screen that indicate box is not connected.

replace one connect box and its cable

[Davi.p]

Re: EU55JS9000T black screen and sound good

UE55JS9000....
check power supply outputs when you connect OCB

[totof]

Re: EU55JS9000T black screen and sound good

Thank you, I will check that but a have to open the TV.
To be continued ...

[lotas]

Re: EU55JS9000T black screen and sound good

The problem may also be in the connecting cable (frequent breakdowns).

[Diah]

Re: EU55JS9000T black screen and sound good

free of charge advice... if you are going to open the cover you will certainly killing the TV 100%
JS aerie need always repair person should wear in his / her arm hand GND band before touching any parts

[totof]

Re: EU55JS9000T black screen and sound good

I have tested with another connecting cable, same issue.

[totof]

Re: EU55JS9000T black screen and sound good

I have checked the BLU_ON_OFF signal and I have 4,7V when the One Connect box is connected. So it seems good.

[totof]

Re: EU55JS9000T black screen and sound good

I have continued the test:
When motherboard is disconnected (backlight is on):
VDRV = 52,9V
LED_VCC=12,7V
FAIL=0V

When motherboard connected and one connect box not connected (backlight if on):
VDRV = 56,4V
LED_VCC=12,7V
FAIL=0V
P_DIM1..16 = 0,81V
BLU_ON_OFF = 4,7V

When motherboard connected and one connect box connected (backlight if off):
VDRV = 59,5V
LED_VCC=12,7V
FAIL=0V
P_DIM1..16 = 0,36V
BLU_ON_OFF = 4,7V

So when one connect box is connected, the P_DIMx signals falls.

[Davi.p]

Re: EU55JS9000T black screen and sound good

those are not the right pins to measure, put some effort more...

[totof]

Re: EU55JS9000T black screen and sound good

those are not the right pins to measure, put some effort more...

Thank you for your answer but I agree more details to put effort on the right pins :-)

I'm not an expert.

[Davi.p]

Re: EU55JS9000T black screen and sound good

there are more pins on the connector that connects to the main board, test them all

[totof]

Re: EU55JS9000T black screen and sound good

there are more pins on the connector that connects to the main board, test them all

OK, I will do this.
All the signals P_DIM1..16 goes from TCON board and not from main board.

I'have tried to power one of the 16 LED strip with an external power (~30V) and it seems there is no picture, only sound is good.

[Davi.p]

Re: EU55JS9000T black screen and sound good

to test B.L. leds must use a resistor in series

[totof]

Re: EU55JS9000T black screen and sound good

New mesure on CN9003 signals :

When one connect box not connected (backlight if on):
OD_ON_OFF = 2,52V
BLU_ON_OFF = 4,7V
ANA_DIM = 3,45V
OD_LEVEL = 3,25V
P_DIM1..16 = 0,58V

When one connect box connected (backlight if off):
OD_ON_OFF = 3,28V
BLU_ON_OFF = 4,7V
ANA_DIM = 0,28V
OD_LEVEL = 2,2V
P_DIM1..16 = 0,04V

[Davi.p]

Re: EU55JS9000T black screen and sound good

can you photograph the table near the connector?

[totof]

Re: EU55JS9000T black screen and sound good

You can see photos on page 26 and 27 on pdf file on my initial post (samsung_unxxjs9000fxxx_uhd-tv_training.pdf)

[totof]

Re: EU55JS9000T black screen and sound good

I'am able to launch the tcon test screen but only when one connect box is not connected, it doesn't work if one connect box connected. For this test the screen goes from red, blue, green and white.
During the test the P_DIM1..16 signals show 3,14V on CN9003 connector (from tcon to backlight board). These signals are arourd 0,4V when one connect box is conected.

I try to find the default board : tcon, main board or one connect box.
I don't think it is an issue on backlight board or power board but I'm not 100% sure.