Samsung LN55B650T1FXZA no backlight

[alfredomfr1]

TV have sound but no backlight.
I can see image in the dark with a flashlight.
If disconnect the main board - PSU cable nothing happen.
LD: 12.35v
FB1 and FB2: 0v

[budm]

Re: Samsung LN55B650T1FXZA no backlight

1) Did you find out if you have BL-ON signal to turn on the backlights circuit or not?
2) Do you have about 380~390vdc between the + and - legs of either one of the two main filter caps?
3) The fuse in the middle of the board which is for the inverter circuit is good?
4) Did you see the backlights even come on for seconds if you at the screen in the dark room?
5) the white rectangular cap with 2h684K has the correct capacitance?
LD Voltage is find, >11V = good, <10V = bad
FB1 and FB2 are very low AC feedback Voltage, they are not present at this point because the backlights are not on.
I cannot read the power supply board P/N, it looks like BN44- 00???

[alfredomfr1]

Re: Samsung LN55B650T1FXZA no backlight

Inv-On: 5.1v
Main Caps: 386v
Fuse: Ok
Backlight never come
Cap 2H684K: 9.5nf ?????
Power Supply model: BN44-00268A

[budm]

Re: Samsung LN55B650T1FXZA no backlight

684K = 0.68uF 10% tolerance
Did you remove it and measure it off the board?

[alfredomfr1]

Re: Samsung LN55B650T1FXZA no backlight

I measured outside

[dick_barton]

Re: Samsung LN55B650T1FXZA no backlight

If that reading is correct then it's faulty and you need to replace it. Plenty on Ebay.

[budm]

Re: Samsung LN55B650T1FXZA no backlight

I measured outside

Well, you found the cause of the problem.
BTW, do you see any bulging on the sides of that cap?

[alfredomfr1]

Re: Samsung LN55B650T1FXZA no backlight

No bulging on the sides of the capacitor.
I will order a new one and let you guys know what happen
Thanks for the help

[alfredomfr1]

Re: Samsung LN55B650T1FXZA no backlight

Capacitor Replaced: TV working good again
Thanks budm and D Barton

[vinceroger69]

Re: Samsung LN55B650T1FXZA no backlight

Thanks for the update glad the capacitor fixed the issue.

[jones]

Re: Samsung LN55B650T1FXZA no backlight

same model, same problem, same bad cap 0.684n

[jones]

Re: Samsung LN55B650T1FXZA no backlight

video of it https://www.youtube.com/watch?v=ibnj4DMVtGE