TV Samsung UN75NU6900FXZA

[alfredomfr1]

LEDs TV work with the Power to Main Board cable disconnected.
If the cable is connected red light no present, STBY pin oscillating.
I replaced the Main Board 2 times with same result.
Now the weird thing: With the TV connected and the LEDs lighting up , I connect back the cable to the Main Board, the TV turns off but the red LED light up and you can turn ON and OFF the TV working perfectly until you disconnect the power.
When you disconnect the Power the TV return to the previous situation.

[Diah]

LEDs TV work with the Power to Main Board cable disconnected.
If the cable is connected red light no present, STBY pin oscillating.
I replaced the Main Board 2 times with same result.
Now the weird thing: With the TV connected and the LEDs lighting up , I connect back the cable to the Main Board, the TV turns off but the red LED light up and you can turn ON and OFF the TV working perfectly until you disconnect the power.
When you disconnect the Power the TV return to the previous situation.

you are just tricking the T-CON protection section on MB to remain ON.
in other words.. don't do this again... go down to the panel buffer boards you will have on each side at the middle U ribbon cable disconnect one a time and turn on normally see if the TV start

[alfredomfr1]

I've done this before, with any combination, the same result, the red LED off, TV can't power ON, Stby fluctuating between 3v and 7v, Main Capacitor 164v, same result with 3 main boards

[Diah]

I've done this before, with any combination, the same result, the red LED off, TV can't power ON, Stby fluctuating between 3v and 7v, Main Capacitor 164v, same result with 3 main boards

in this case then yours PSU in questions... disconnect MB from it,,, and disconnect the BL from it too and plug in wall measure the V on the socket at any pins of A13V

[Diah]

blown cap !

[lotas]

No, it's the thermal paste that got in...

[Diah]

No, it's the thermal paste that got in...

lol my eyes still strong... the cap in red circular are in question,, no pasta on it

[lotas]

Yes, just like the others...
This is when thermal paste was applied to the transistors, those that are attached to the radiators, and the capacitors were stained with it.

[Diah]

Yes, just like the others...

let say you are correct... then why they put thermal paste on them... its unusual at Samsung.... mean this caps are under load and heat.

[nomoresonys]

Looks like someone was just a slob and wiped the excess paste all over everything.

[nomoresonys]

Ok, so lets follow suggestions, isn't that why you come? Do as suggested in post # 4, report results here.

[R_J]

never mind

[alfredomfr1]

No, is a light effect, cap is ok

[R_J]

No, is a light effect, cap is ok

That is NOT the caps I am talking about

[alfredomfr1]

I will do the #4 advice tomorrow, thanks for all your effort, see you guys tomorrow.

[alfredomfr1]

MB and BL disconnected
CNM802
1- 0.9v
2- 3.3v
3, 5, 7, 9- 12.85v
4- 3.3v
6- 3v
8- 4.5v

CH1- 301v
CH2- 0
CH3- 301v
CH4- 0
CH5- 0
CH6- 301v

Main Capacitors- 396v

DM851C
leg 1- 150v
leg 2- 0v
leg 3- 158v

DM852C
leg 1- 158v
leg 2- 302v
leg 3- 150v

[Diah]

MB and BL disconnected
CNM802
1- 0.9v
2- 3.3v
3, 5, 7, 9- 12.85v
4- 3.3v
6- 3v
8- 4.5v

check again you may missed with pins NO.

[alfredomfr1]

pin 10, 11 and 12 are GND

[Diah]

pin 10, 11 and 12 are GND

man.. i remarked yours error with red color... pin 8 are Power_ON is it really 12.85V ?

[nomoresonys]

802, 3,5,7,9 are the A13, so they look ok. 8 was 4.5 Diah.