No backlight, with sound Samsung lcd LN46B640R3F

[budm]

Re: No backlight, with sound Samsung lcd LN46B640R3F

That long board is the balancer board, the inverter board is part of the power supply board.
By the way, you never see the lamps even flash on for seconds?

[sandersen]

Re: No backlight, with sound Samsung lcd LN46B640R3F

@budm the values I got were
Pin1 vcc 10.49VDC
Drive 1 0VDC .01 AC
Drive 2. 0VDC. .009 AC

My common was on gnd pin 4 I'm not sure if that was correct?

Also for the life of me I could not find C1804 I think it's the blue one near the fuse above the markings cy1811s.

[sandersen]

Re: No backlight, with sound Samsung lcd LN46B640R3F

@budm-No ever since the set went dark I can't see any flash at all. Turned it on by jumping the ps and sb in a dark room and saw nothing.

[sandersen]

Re: No backlight, with sound Samsung lcd LN46B640R3F

What voltages should I expect at drive 1 & 2?

[budm]

Re: No backlight, with sound Samsung lcd LN46B640R3F

It is not putting out right now, if it is working it will be high frequency AC.
On the connector CN1808 check the 12V on pin 1, and the LD pin 7/8 using the Ground pin 4/5 as the ground ref for the meter.

[sandersen]

Re: No backlight, with sound Samsung lcd LN46B640R3F

I'm assuming you meant cn1803 shown in the picture.
I measured pin 1 (12V) at 12.89VDC
Pin7 (LD) at 11.5VDC
Pin8 (LD) at 11.5VDC

[budm]

Re: No backlight, with sound Samsung lcd LN46B640R3F

OK, they are correct.
Need more thinking.
BTW, C1804 is the white cap on the left center of the board:
http://www.shopjimmy.com/media/catal...265B-TOP_1.jpg

[sandersen]

Re: No backlight, with sound Samsung lcd LN46B640R3F

What else could cause all the back lights to go out at the same time? Could some bad component cause all of them to go out?

[parsaservices]

Re: No backlight, with sound Samsung lcd LN46B640R3F

could be a bulb problem or bad contact? as i have been reading some topics by now and i seen topics that they went to reaplace the psu and still havent solved it.