Samsung UN43NU6950BXZA no sound, no picture nor backlight.

[bdorset]

Disconnecting the cable that link the mainboard and power supply brings on the backlights. With PS and mainboard connected, when I press the power button the power_on/off 3.3V goes to power supply, The PS voltage goes up to 12.9V from 11.5V when that happens. Backlight does not come on. After about 10-15 seconds Power_on 3.3V drop to zero, power supply goes back into standby. I disconnect the panel same problem. The mainboard numbers are BN94-14106F
BN94-14106F, BN97-15621C, BN41-02662A. Any suggestions, any service information?

[budm]

Re: Samsung UN43NU6950BXZA no sound, no picture nor backlight.

How about the control Voltages on pins 2, 4, and 6 when main board is connected and not connected?
Seems to be main board issue since the power board self test is OK.

[bdorset]

Re: Samsung UN43NU6950BXZA no sound, no picture nor backlight.

With PS disconnected from mainboard:
Pin 2 =3.06V
Pin 4 =0V
Pin 6 =3.61V

With PS and mainboard connected and TV in on state
Pin 2 =0V
Pin 4 =3.38V
Pin 6 =0V

Voltages were measured on PS connector. NB that pin 4 on the PS is NC (not connected) to the rest of the circuit.

[nomoresonys]

Re: Samsung UN43NU6950BXZA no sound, no picture nor backlight.

As Bud suggested, looking like a mainboard issue.

[bdorset]

Re: Samsung UN43NU6950BXZA no sound, no picture nor backlight.

A closer look at the PS above show that the STB should be 7.6V and the ON= 12.35V. I measured STB=11.5V and ON=12.9V. Are those normal or it because the PS is not under full load because the TV is not coming on 100%?