Samsung UN40ES6100 no backlight

[dsc]

So I was handed this set that has audio, an image on screen but no backlight at all.
It has a BN44-00502A power board and I can't find any information about it at all.
Over all the board doesn't appear to have any damage, caps visually look fine.
I'm ready to start testing voltage and anything else I might need to but without any knowledge of what value should be at any point I am totally lost.
It doesn't help that I am a complete nube at this but I am adapt at figuring things out, got a whopping 3 sets fixed so far.
Any help, advice, encouragement or the next winning loto numbers would be greatly appreciated.

[budm]

Re: Samsung UN40ES6100 no backlight

Try looking at the TV in the dark room to see if you can see the backlights even flash on for seconds or not, if not then we need to find out if the main board is sending the BLU_ON on pin 6 and the PWM_DIM on pin 2 of the connector CNM803 or not.
You may also want to check the solder joints of the transformers'legs, the 3-pin of the power devices hwich are attached to the heatsinks.
If the command signal are there then we need to look at the LED connector to see what kind of DCV we have when you first turn on the TV (the meter must be in place when you turn on the TV since we want to see if the DCV does jump up and drop down or not).
Pictures provided by shopjimmy.

[dsc]

Re: Samsung UN40ES6100 no backlight

I did check for any backlights in a dark room, zilch.
What range should I be looking for on pin 6 and 2?
As always thank you budm!

[budm]

Re: Samsung UN40ES6100 no backlight

BLU_ON: <1VDC = Backlights OFF, >2~2.5VDC = Backlights ON
PWM_DIM: between 1~4.5VDC. <0.5V will cause the backlights to be off.

[freakaftr8]

Re: Samsung UN40ES6100 no backlight

Replace ic9101. Backlight controler IC. This is a known failure on this power supply. I've repaired a few already.

[dsc]

Re: Samsung UN40ES6100 no backlight

Thank you budm and freakaftr8.
I'm working on a set of reels for the day (in the golf biz) but when I get home I'll get back into the board.
freakaftr8, seeing as I would like to learn more of the electronics can you tell me how or what to test for on the IC 9101?

[freakaftr8]

Re: Samsung UN40ES6100 no backlight

Do just as budm suggested. This will tell you if power supply is giving the command to power up backlights or not. There are other tests along the way but this will give you a general idea of what's going on.

[thoma]

Re: Samsung UN40ES6100 no backlight



ftp://helpedia.com/pub/temp/datashee...itors/Samsung/

[dsc]

Re: Samsung UN40ES6100 no backlight

OK, pin #2 is at .437
pin #6 is at 4.94

[dsc]

Re: Samsung UN40ES6100 no backlight

Double checked the solder joints, all test/check out OK.
To be certain I am testing the right legs, #2 is clearly marked so I moved over two legs on the same row for #6.
I soldered a test lead on each to make it easier.
Would the IC 9101 cause the off reading?
I pulled the connection to force the backlight prior to asking for help with no results.

[budm]

Re: Samsung UN40ES6100 no backlight

If you pull out the cable between the main board and the power supply, plug into the AC outlet but the backlights are still not on, then you have bad IC as freakaftr8 as suggested, or possible LED problem.

[freakaftr8]

Re: Samsung UN40ES6100 no backlight

That's right I forgot to add that tidbit of info. This unit does have pull up resistors in the power supply so you can disconnect the cable between the main board and power supply and LEDs should light up if that IC is okay

[dsc]

Re: Samsung UN40ES6100 no backlight

My apologies, I should have mentioned that right off but as I often do I forgot to.
I greatly appreciate the help/advice.
This will be my first chip replacement. Might be old to the pro's but it is exciting to me.
Thoma, my device is not pulling up the links you provided, my apologies for not thanking you earlier.

[budm]

Re: Samsung UN40ES6100 no backlight

Un46es7500fxza fast track.
My post #2 'If the command signal are there then we need to look at the LED connector to see what kind of DCV we have when you first turn on the TV (the meter must be in place when you turn on the TV since we want to see if the DCV does jump up and drop down or not).'

[dsc]

Re: Samsung UN40ES6100 no backlight

OK so the part came untidy and I dropped it in.
Now when I go to power it up I get a flashing red light, once short and one long.
I tried to find a source for what the code means but fell short.
It is obvious I did something to it, any ideas?

[dsc]

Re: Samsung UN40ES6100 no backlight

Oh yeah, and there still isn't any backlight when I try to force it either.

[dsc]

Re: Samsung UN40ES6100 no backlight

Ok, so I checked the voltages again and they are all over the place, as in I can't get a steady reading.
Drops to .003 then rockets to 1.5+ sometimes as high as 5. on both pins 2 and 6.
All I did was install a new IC9101.
Any chance that someone knows where I can find a reference for the blinking code?
DSC

[dsc]

Re: Samsung UN40ES6100 no backlight

OK, another update.
I started checking all over the board and found a problem with the on board C9104 and C9114.
I now have 3.00 at pin #6 and 3.169 at pin #2
I no longer get the one short and one long flash, standard 5 flashes and it is back to being responsive but still no backlights.
The fast track is for a different board so I need to ask if the procedures will work with mine (BN44-00502a)

[dsc]

Re: Samsung UN40ES6100 no backlight

Ok, so I kind of simply jumped forward a bit and took the set apart.
I found that the left string of led's was fine but the right side had no less than 10 not functioning at all.
There is 56 on each side, I'd like to find the whole strip as a few were slightly dimer than the others on both sides.

[dsc]

Re: Samsung UN40ES6100 no backlight

Figures, Samsung no longer has the parts available.
They did give me the part number(s) for left and right string which I did find, at $121.
BN96-21460A is the left one BN96-21460A is the right side.
Next I'll see if Mouser can just get me the led's or try and source a scrap around here.
I'll put up a picture later of the string if anyone is interested.
DSC