Samsung LE46B530P7WXXU confusing backlight

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Just checked again with the lead attached (testing from the solder points on the rear of the board) and I DO get 12.5v to the LD pins after all..

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Ok, another thing I've noticed: when the backlight is set to anything but full (10) there is a very slight buzzing noise which I think is coming from the top transformer. Also, having just made the backlight shut off, the top transformer is at 39 degrees (celcius) and the lower one is at 37 (I don't know if that is significant or not)

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Similarly the bottom two transformers (white tops - below the two large caps) the upper one gets significantly hotter than the lower..

[budm]

Re: Samsung LE46B530P7WXXU confusing backlight

Are you talking about the transformers on the power supply-inveter combo board?

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Yeah

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

I'm assuming the bottom two are transformers too - they look like them..

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Here... I can't find replacement parts for any of the the four transformers here... They're labelled as 'LP' on the board..

[budm]

Re: Samsung LE46B530P7WXXU confusing backlight

Those two components you have marked are the inductors for the PFC Voltage booster circuit to produce about 400VDC between the two legs of the main filter caps (two large caps rated @450VDC laying on the its side). If the PFC Voltage is not working you will not be getting the 400VDC on the caps.
I cannot read the P/N on the bar code sticker of the power supply board, bn44-??????, 00265b?

[budm]

Re: Samsung LE46B530P7WXXU confusing backlight

If it is BN44-00265B, then read these threads:
https://www.badcaps.net/forum/search...archid=5554766
https://www.badcaps.net/forum/showth...65B#post595019

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

budm - thanks again!!! I will be sure to check out those (also, I did try searching around myself, honestly, but thanks for finding that info for me).

I'll let you know how I get on tomrrow (it's 2am here)

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Is it normal that when testing the gold tabs/points along the balancer board... Will upload a pic, that the backlight shorts? Touching any point seems to force the backlight to instantly shut down? I thought perhaps this was a safety feature because there would be a very slight change in voltage but I started wondering if perhaps this was indicative of another problem?

The caps seem to be holding roughly the correct voltage when charged - will check again shortly and give you the readout.

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Here's a photo of the tabs I was trying to test...

[stedmund08]

Re: Samsung LE46B530P7WXXU confusing backlight

Any suggestions? ��

[budm]

Re: Samsung LE46B530P7WXXU confusing backlight

Not on those pad, those are Very high Voltage (2KV) pads.
You will have to look for the pads on the secondary side.
https://www.youtube.com/watch?v=oE6K4xBVweA
Your Balancer board is not exactly the same so tracing out the circuit will be required.