LCD Samsung LE40B651 start loop

[cristi16707]

I have an issue with my Samsung LE40B651 LCD, and I need your help.
Few weeks ago, when I tryed to power on from stdy,I got it in totaly blank status: no stdy LED, no sound, no backlight. Thanks to your help indication (especialy budm and tom66) I was able to fix power supply board (BN44-00264A) by replacing of UM801S(STRW6252).
Now I have 5.3V, 13V on CNM802, CP815~390VDC,I get stdby LED, I can power on from sdtby, I get starting sound, I get backlight, but not any image. After around 5 seconds it reboot again, and again .. and so on. For more details about simptoms, please follow below video :
https://www.youtube.com/watch?v=ufYw...ature=youtu.be

If I pull out connector between power supply and main board, I get a stable backlight status.
If I pull out connector between main board and Tcon, the start-up loop is still there.

Could you give me some advices, please ? Can be a main board issue (BN40-00145A) ?

[budm]

Re: LCD Samsung LE40B651 start loop

It does sound like you have main board problem since you are getting the backlights when the cable between the main board and the power supply board is disconnected.
BTW, what happen if you disconnect the cable between the remote IR and the key panel button board?
Try heating the main board with hair dryer for a few minutes to see if the symptom changes.

[cristi16707]

Re: LCD Samsung LE40B651 start loop

I suppose you referred to cable from attached picture. When I disconnected, nothing happen, as the TV is in stdby, but cannot power on it.
I tried to heat the mainboard for a few minutes but not any change.
New idea ?

[budm]

Re: LCD Samsung LE40B651 start loop

I suppose you referred to cable from attached picture. When I disconnected, nothing happen, as the TV is in stdby, but cannot power on it.
I tried to heat the mainboard for a few minutes but not any change.
New idea ?

Forget to tell you to turn the TV on first then disconnect the cable, if it still does the same thing and heating the board does not make the difference, then just need to get the new working main board.

[cristi16707]

Re: LCD Samsung LE40B651 start loop

I disconnected IR cable, after power on, but still the same result.
Then I "cooked" the board but with not any result. I tried again to disconnect IR, but the same. It seems that I have bad lucky !
Are you sure that main board is issued ? Do you know some equivalent boards for BN40-00145A ?

[johnboy1313]

Re: LCD Samsung LE40B651 start loop

I disconnected IR cable, after power on, but still the same result.
Then I "cooked" the board but with not any result. I tried again to disconnect IR, but the same. It seems that I have bad lucky !
Are you sure that main board is issued ? Do you know some equivalent boards for BN40-00145A ?

BN40-0145A is the tuner part number. The main board should start with BN94. It looks like your board is actually BN94-02583U.

[cristi16707]

Re: LCD Samsung LE40B651 start loop

Yes, you are right. I attached tuner picture.
As not any new idea, I'm looking for such kind of board. I keep you post about result.
Thank you for your support !

[cristi16707]

Re: LCD Samsung LE40B651 start loop

After main board replacement TV works fine.
Many thanks to budm !

[budm]

Re: LCD Samsung LE40B651 start loop

Thanks for the follow-up on the repair.