SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

[syaoran123]

Hi there, my first thread here.

Have a SAMSUNG LA40N81BDX that behaves in the following sequence:

1. Power button is pressed
2. Clicks on like normal, blue light near samsung logo turns on, backlight flickers on
4. 5 seconds later, back light turns on while coloured vertical lines progressively fill the black screen. The lines are solid.
5. 10 seconds later, another click is heard and everything is switched off.
6. Repeats

I have deduced it to be the main board, rather than the screen/t-con board due to the fact it is switching off and having no response to the remote. Have already changed the EEPROM and already tried heating up the processors with a heat gun.

Anybody else have this sort of experience? I want to try repair the board to component level because they are expensive/hard to find.

[ReeceyBurger123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

So heating the Mb has no effect but heating the Tcon does ?

[syaoran123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

Only heated the MB processors underneath the metal shield/heatsink which had no effect. Havent touched the T-con. Can it really cause the TV to turn off?

Edit: actually it responds to the remote power button only. No menu displays appear.

[ReeceyBurger123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

That would be the Mb Id say normally two 1000uf caps under the cpu heatsink that cause the set to crash after heat up but normally heating that area causes it to fault out.

[syaoran123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

I heated it while the heatsink was on actually. But i will remove the heat sink later today to see if i can find any 1000uf caps.

[Diah]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

before it shut down press power on RC and let it go in standby mode, then from this STY mode go direct to service menu.. when it switched to service menu.. press source for signal... and keep it so to see how long it will stay on.

[ReeceyBurger123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

before it shut down press power on RC and let it go in standby mode, then from this STY mode go direct to service menu.. when it switched to service menu.. press source for signal... and keep it so to see how long it will stay on.

What does this exactly do ? I have a Samsung here does nothing when you do that ?

[Diah]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

his Tv turn on, only had bad screen then turn off after few seconds. from stand by to go service menu, if it show menu list normal then eeprom data corrupted . can easy to recover them next step.. if there no menu.. then go forward to other inspection on main boards.

[syaoran123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

No service menu. Just tried it

[Moreno83]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

Does this tv also have the extra board above the mainboard?

[syaoran123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

No extra board

[Moreno83]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

Ok , as Reecey said. Try to heat the mainboard. I have a similar model with the same mainboard but has a extra board.
My tv also had lines when the board cooled down but when i heat it the lines go away.

So try to heat the board for a longer period of time and see if it stays on. The problem is most likely bad capacitors.

[syaoran123]

Re: SAMSUNG LA40N81BDX coloured vertical lines appear then switches off

So I removed the heatsink and this is what i see. Which part do you think is faulty?