Samsung 40F5500 red light blinking

[ovidiu.buzzi]

Hello to everyone on this forum.This is my first post on this forum and hope i will post well and not upset anyone.I have a 40 inch led smart tv samsung that have like 1 year of use very light use.it was ok before going to bed ,in the morning when i woke up the red light was blinking.I did open the tv it has a BN-4400645A power board.I look for the back light though the holes and is blinking not staying on which i was thinking is a power supply board.I don t see any bad caps the board looks like new .the voltages i did measure are.

1- 12,8
2- 2,98
3- 12,8
4- start from 20mV and goes up until 80mV and upper
5- 12,8
6- 2,98
7- 12,8
8,9,10- GND
11- 5,32
12- 5,32
13- 5,32
14- 3,33

My question is also on the upper side of schematics the voltage out of the 4 diodes it say 120V V_DRV and i get only 99 -100V.
Thank you and hope i did well my first post

[CapLeaker]

Re: Samsung 40F5500 red light blinking

Backlight LED's failed / failing. I am afraid you have to take the panel apart.

[ovidiu.buzzi]

Re: Samsung 40F5500 red light blinking

But is not turning on the TV even if i press the power button red light still blinking.I was thinking that it is possible to be backlight only if is turning on and you hear a sound or something but mine is alway blinking.I i disconnect the board from icon you can see though the hole how is blinking the backlight

[ovidiu.buzzi]

Re: Samsung 40F5500 red light blinking

So i am coming with updates......after a week of letting the tv on the table with all the boards disconnected i tried again to make some measurement but tv turned on and was working with no problem for 1 day after that the next day while watching it it started to reboot itself 3 or 4 time and didn't t power on life it did the first time and the stand by light is blinking with no reason without touch any remote or button.

[Moreno83]

Re: Samsung 40F5500 red light blinking

Hi ,

What you can do is turn on the tv. It will probably start with the blinking pattern. If so then take a heatgun/hairdryer and heat up the powersupply when the tv is blinking , see if it will turn on after a few minutes. If so then you have a problem on the powersupply.

[thoma]

Re: Samsung 40F5500 red light blinking

Disconnect cable between mainboard and Powersupply!
What happens?If you have backlight your mainboard is defect!
Disconnect cable mainboard T-Con
What happens?

[ovidiu.buzzi]

Re: Samsung 40F5500 red light blinking

Coming with updates Moreno83......you were right it was blinking i did use a hair dryer and after 30 40 seconds it did turned on by itself and works so that means is a power board problem........it means that is an imperfection on the board or is there any component that is bad like a bad cap that you can not see.do i have to heatgun the board??? thank you

[budm]

Re: Samsung 40F5500 red light blinking

It can be bad caps with high ESR. When cap is heated up the ESR will go down so the circuit will function again. BTW, bad cap can look normal.
Or can also be cold solder joints. I would resolder those transformers' legs and the legs of those devices mounted on the heatsinks.

[ovidiu.buzzi]

Re: Samsung 40F5500 red light blinking

ok so i did change all the caps on the output but no luck also resolver transformers and the devices mounted on the surface but still no luck and the stand by light still blinks......could that be the transformers since sometimes is working sometimes not???i don t know what else to check.....i know that is not the mother board

[budm]

Re: Samsung 40F5500 red light blinking

So when you heat up the board and it will function. So was that before the caps were changed or after the caps were changed?
And you did not change the caps in the primary side at all?

[budm]

Re: Samsung 40F5500 red light blinking

Btw, those Voltage readings in post 1, were they taken when the TV is working or not working?