SAMSUNG MODEL UE40D5520

[engineer1234]

I have a Samsung Model UE40D5520, when you power it up the TV comes on and shows the Logo then after a couple of seconds it switches off then back on again, it continually does this.

I have checked the BN44-00422B power supply and I cannot see any obvious capacitor problem, can anyone please give me some guidance, I see plenty on this fault on the internet but I cannot see a cure.

Any help would be greatly appreciated 

[fix2003]

try heating the processor chip. possible tin whisker has been reported with these sets

The idea is to heat the chip to such a temperature to evaporate the tin whiskers but to avoid reflowing the IC connections.

[downunder]

Unplug the main board from the power supply and power the set on at the mains. If all is ok apart from the main board, the set will power on and display backlights for as long as it is left on. If it does, then the main board is faulty.                      Bruce

[engineer1234]

Fix2003 thank you for your reply, I tried what you suggested but the TV still has the same problem
 

[engineer1234]

Downunder thank you for you reply, if I unplug the power supply from the main board the backlights all stop on, when I plug it back in again, they come on when the screen shows " smart TV ", then go out when this disappears from the screen.

Can you suggest a fix for this board or is it a case of replacing it?

[downunder]

OK, so the main board is the culprit, but it is not very repair-friendly. Can only suggest what fix2003 suggested. If you don't have a heat gun or don't
feel comfortable with this, you could remove the main board and pop it in your kitchen oven, preheated to 180 deg, for 10 min. Works for LG main boards which suffer from the same problem, but the outcome is not guaranteed on Samsung main boards. Worth a shot though.           Bruce

[kennyc]

Have you disconnected the cable to the Tcon or the screen from the main board if there is not a Tcon board?

[sinclairtv]

Check the cable between the boards. This commonly has carbon coating on it.

[zomikula]

Band nand on the main baord
you can pick up replacment nands on ebay for about £20
If u can solder do that..

[engineer1234]

zomikula - Thank you for your reply I have tried all other suggestions although helpful none has worked, can you be more specific on what you mean, I am an electrical engineer, I have searched for this part on e-bay but come up blank, also where is this part located on the motherboard and if I do replace it is there anything else I need to do?

[zomikula]

search for 'samsung nand 40d5520'