EU55JS9000T black screen and sound good

[totof]

Re: EU55JS9000T black screen and sound good

The fan was a little dusty and I cleaned it, it still worked.

Whether the OCB is connected or not I measure 12V on pins 25 and 26 of CN201

[Davi.p]

Re: EU55JS9000T black screen and sound good

Whether the OCB is connected or not I have 12V on the fuse at the input of the tcon.

This changes things..

because the TV was too old for him

that man is ridiculous..

He tried another cable and another box but same result. But the technician didn't really know if his cable and his box were really functional

so this does not change things..

Carefully if possibile, safe, test the connector for the ocb on the main board to find the 12v feed pins, then connect a protected 12v test psu to the ocb to see if it goes into protection..

[nomoresonys]

Re: EU55JS9000T black screen and sound good

Check up on the fan in your ocb, make sure it's clean and functioning properly.

[totof]

Re: EU55JS9000T black screen and sound good

Thank you Davi.p
Whether the OCB is connected or not I have 12V on the fuse at the input of the tcon.

Before bringing me his TV, my colleague went to an approved Samsung repair center but the technician didn't really look because the TV was too old for him. He tried another cable and another box but same result. But the technician didn't really know if his cable and his box were really functional.

[Davi.p]

Re: EU55JS9000T black screen and sound good

OCB has a short circuit that disables the screen (12v off> tcon off) that disables the dim signal to the led driver board (backlight off).. since you are not a technician you have to get a replacement ocb.. 12v on MB maybe remains on because of a protection circuit at valley of the screen switcher mosfet..

[totof]

Re: EU55JS9000T black screen and sound good

The connector pin of power board

[Davi.p]

Re: EU55JS9000T black screen and sound good

you must show the tables of the main power board, the orange one..

[totof]

Re: EU55JS9000T black screen and sound good

I make the tcon test with a service RC (it's a RC bought by my colleague, the tv is his).
Some photos of the tv during the test.
A photo of the one connect cable.

[Davi.p]

Re: EU55JS9000T black screen and sound good

i don't like downloading big files.. can you report connector signals? how do you make the screen test? Standard RC or service RC? can you post a photo of the OCB cable? especially the connector.. are you sure the replacing ocb cable is good?

[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.

[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)

[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

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

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

[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

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

[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

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

[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.

[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.