Samsung LN46B650T1F mo backlight red led on

[ivtec]

Hi guys i picked up today this Samsung LCD LN46B650T1F no backlight and red led on,
so far what tested,the 2 big caps side by side each 168v,the bridge rect has 79v
all fuses Diodes and other componets that i could check seem ok,
i don't have the supposed 5v,13v,5.1v, volts at CN801 going to main board.
I checked a couple SBRF'S in the circuit that seemed suspected,i took them out and they seem OK ? not sure,i sent a pic of the Scheme i made measured with diode function,are these OK?.
Also there is a SM Q-50P04 that i circled on the other side close to the SBRF's
that seems to be bad? it measures OL between all legs?
do you know anything about this TV? can you share some of your knowledge,
Also the other side of the board where Inverter transformers are is kinda dark ?thanks

[dick_barton]

Re: Samsung LN46B650T1F mo backlight red led on

What's the board number BN44-2xxxx

[budm]

Re: Samsung LN46B650T1F mo backlight red led on

BN44-00265B, see schematic attached.
Pictures provided by shopjimmy.

[ivtec]

Re: Samsung LN46B650T1F mo backlight red led on

What's the board number BN44-2xxxx

Thanks dick_barton; BN44-00265B

[ivtec]

Re: Samsung LN46B650T1F mo backlight red led on

BN44-00265B, see schematic attached.
Pictures provided by shopjimmy.

Thanks a bunch budm,apreciate.

[dick_barton]

Re: Samsung LN46B650T1F mo backlight red led on

Can you list your voltages as given on CN801 using pin number, name and voltage since you must have a voltage to light the red led.
eg
Pin 1, Power On/Off, xxx
Pin 2, H_Sync, xxx
Pin 3, STBY5.3, xxxx
etc since it helps not to have to keep looking up the names on the schematic.

The SM Q-50P04 is a P channel Mosfet. With your meter in diode mode you should be able to check the diode across the Drain - Source pin.

[ivtec]

Re: Samsung LN46B650T1F mo backlight red led on

Hi guys i have good news,i have a whole pile of electronic boards in a big box, it's so much stuff that i don't know what i have,as i was checking through the boards to check if i had a SM Mosfet, i was surprised and perplexed when i stumble on an exact same power supply for this tv also have the Main board and Tcon board,i must have picked these boards from a Samsung same tv broken screen,i even did not try to figure out the issue of the original power board just put in the one i had found and powered tv and tv came right up ,tv runs like a champ and have some spare parts,thanks

[dick_barton]

Re: Samsung LN46B650T1F mo backlight red led on

That was a stroke of luck.