Samsunt TV power supply

[xfox]

Hello folks, got broken TV, burned fuse on PS board, new fuse burned out, found two failed mosfets, replaced, replaced fuse, checked voltage and instead of 13V in jumping from 9v to 15v (on mainboard connector), checked all tiodes and capacitors.... please help to find a problem

[budm]

Re: Samsunt TV power supply

1) What is the TV model number?
2) " checked voltage and instead of 13V in jumping from 9v to 15v (on mainboard connector)" Are you saying when the TV is plug in but power switch is not activated, the A13V is 9V then when power switch is activated, it jumps up to 15V? If you look at the label by the diode DM854C, in stand by mode the A13V will be 8V, when it is on it will be about 13V.
3) If you run the power supply board without the cable to the main board connected, what Voltage do you have between the two legs of the main filter cap. 380 ~ 400V?
4) 3) If you run the power supply board without the cable to the main board connected. Do the backlights come on and stay on.
Notes: power supply board is P/N BN44 -00807A

[xfox]

Re: Samsunt TV power supply

TV model is UN55MU6290F, before plug in main board, I just plugged-in power supply, so just power, nothing else, and voltage is going up and down with motherboard disconnected, standby 5v also has fluctuations, on voltage on main capacitors 380v to 405v

[budm]

Re: Samsunt TV power supply

1) when you perform the power supply board self test (not connected to main board) and the LED connector still in place, do the backlights also flashing on and off?
2) "standby 5v also has fluctuations" What standby 5V? This power supply does not use 5V standby, when in standby, the A13 is 9V.
3) Please verify that your meter's batteries is not low which will cause the Voltage reading to be higher that what the reading should be.

[xfox]

Re: Samsunt TV power supply

Hmmm, thank you for advice, connected backlight, and somehow got 12.8v stable, connected, TV back to life

[budm]

Re: Samsunt TV power supply

Inspect both ends of the cable that goes between Power supply board and Main board to see if there is any sign of over heat, loose pins.