Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

[jczarniak]

Hi,
Got now Samsung LE40B652
Backlight is on only for few seconds after switching TV on.
Power supply:
BN44-00264A
Checked the voltage on the two filter/PFC 450V/82uF caps:
Fluctuating between 382-402V when TV is ON
Standby: 332-346V
Not sure if that's what I should expect for this power supply.
PFC chip?
Read online something about backlight transformers also.
From your experience what it could be, please?
Thanks a lot for any support.
Regards.

[tvtimmy]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

Most likely bad transformer. Compare resistance readings from each one. Odd reading one is bad.
It also could be a bad bulb. Use a florescent bulb and touch the transformers on left and right sides when powering up the set. Bulb should light up a bit.

[jczarniak]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

Most likely bad transformer. Compare resistance readings from each one. Odd reading one is bad.
It also could be a bad bulb. Use a florescent bulb and touch the transformers on left and right sides when powering up the set. Bulb should light up a bit.

Checked the transformers.
Got same readings on all of them, about 1530-1540 Ohm.

[tvtimmy]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

Check capacitor CI892.

[jczarniak]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

Check capacitor CI892.

Very interested.
I'll check that this evening and I'll let you know.
Thank you very much.

[jczarniak]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

Check capacitor CI892.

Done, replaced.
Still same

Two filter caps 82uF/450V also replaced
Still the same.

What else can I check?

[tvtimmy]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

You may have a bulb that is going bad. You can check the small blue disk capacitors by the transformers.

[vinceroger69]

Re: Samsung LE40B652, Backlight is on only for few seconds after switching TV on.

https://www.badcaps.net/forum/showth...er+testing+cfl
https://www.badcaps.net/forum/showth...x+dx-40l261a12