NO Backlight

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NO Backlight

Postposted on Sat Aug 21, 2010 8:35 am

I have a samsung 40" lcd LE-40R73BDX,
turns on ok but very faded picture even though settings are on dynamic, would a master reset or a replacement of power caps do the job or is this my backlight gone?
any advice appreciated.
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Sat Aug 21, 2010 8:52 am

chrisdot wrote:I have a samsung 40" lcd LE-40R73BDX,
turns on ok but very faded picture even though settings are on dynamic, would a master reset or a replacement of power caps do the job or is this my backlight gone?
any advice appreciated.


You should have a black screen with virtually no distinguishable picture unless you hold a flashlight to the display if you blacklight has died. Without a picture of the screen, it is difficult to advise you on this.
Disclaimer: I over-analyze everything, so try not to be offended if I over-analyze something you wrote.
Shining Arcanine
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Re: SAMSUNG DARK SCREEN

Postposted on Sat Aug 21, 2010 8:58 am

yeah i can distiguish picture and sound is fine but its a struggle to do so, think theres no backlight workin, is there any way to check this or sort it out without new panel?
would it be a waste of time resoldering the back of the inverters?
chrisdot
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NO Backlight

Postposted on Sat Aug 21, 2010 2:36 pm

no backlight on samsung le40R73bdx, was wondering where loose connections or dry joints would be so that i can touch them up and hopefully recover my tv...sat night is so boring without **** tv that im gonna take a load of pills!!!!
help someone!!
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Sat Aug 21, 2010 2:58 pm

chrisdot wrote:yeah i can distiguish picture and sound is fine but its a struggle to do so, think theres no backlight workin, is there any way to check this or sort it out without new panel?
would it be a waste of time resoldering the back of the inverters?


The way to check it is see if holding a flashlight a short distance from the screen and shining it onto the screen makes the area on which you shine it more visible than the area where you are not shining it. If it is the backlight, then you should see an improvement. If that is the case, I probably should refer you to someone else, as modifying hardware is outside my area of expertise, but I can tell you that it should be possible based off guides I have read for LCD computer monitors.

http://lmgtfy.com/?q=replacing+lcd+backlight

I might be able to be more helpful if you took a picture of the screen with a digital camera (with no flash) and uploaded it so I could get some kind of idea of what you are seeing. Someone else who knows more in this area probably could be even more helpful than I could be with this provided you can post a picture.
Disclaimer: I over-analyze everything, so try not to be offended if I over-analyze something you wrote.
Shining Arcanine
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Re: SAMSUNG DARK SCREEN

Postposted on Sun Aug 22, 2010 2:00 am

that link just shows how to replace backlight i could do that without help i just dont want to have to buy a backlight because the manufacturers would only want to sell a panel and thats out of the question, what i ewas really after is how to find why its not working and try to fix it myself as cheap as possible, i have a sharp 46" with smashed screen and sharp wanna charge me 700 quid when a new tv is 599.

is there anywhere i can check for bad connections or dry solder joints and touch them up......sod it im gonna do that today anyway and report back as ive nuthin to lose.
chrisdot
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 4:05 am

gonna try strippin it and resolderin all the joints on all boards prob try inverters first. will report how i get on
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Sun Aug 22, 2010 4:57 am

ok i resoldered the joints on both inverters with no joy same result when i shine a light on screen i can see images clearer, so any ideas?
chrisdot
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 4:58 am

ok stripped and resoldered all joints onm both inverters and no joy still same result, shine a light on screen and it can be seen.any ideas?
chrisdot
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 6:43 am

i'd be interested to know how you end up but, wow, i don't know anything beyond the manual for that TV.
Matter is merely energy condensed to a slow vibration, we are all one consciousness experiencing itself subjectively, there is no such thing as death, life is only a dream, and we are the imagination of ourselves... back to you with the weather, Bob!
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 6:50 am

no warranty it was a customers tv from tech guys and currys were gonna skip it, i got over 30 tellys workin and soldecept this un!!!!
chrisdot
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 8:40 am

go for gold... let us know how it turns out. Is it a matter of simly reheating the original solder on any cracked joints or do you need to remove it and re-solder?
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Re: SAMSUNG DARK SCREEN

Postposted on Sun Aug 22, 2010 11:20 am

Sounds like your backlight burned out. Why not replace it?
SpotTheCat
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 1:06 pm

Basically u keep a damp sponge close have some solder and i like tinned flux as it precleans tip before wiping it on sponge.
i pre wiped all joints with a fibrepen before to clear any flux left from factory, then just put a tiny amount on tip and touch the joint as soon as it melts (u can feel it first then see it), then take solder iron off in a sorta rhythmic motion and you should have a nice shiny joint.
some of the factory soldering was ridiculous obviously the solder bath operative likes his smoke and food and pish breaks.
but it still didnt work so i stripped panel down to check if the ccfl's were still all ok and they were, so im guessin new inverters and caps for power supply to prevent it happening again.
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Sun Aug 22, 2010 1:08 pm

SpotTheCat wrote:Sounds like your backlight burned out. Why not replace it?

surely the inverters would have a shorter lifespan than ccfl's i dunno!!!

would there be a way of testing that safely at home?

where would i get one and how much roughly would it be ? any links to good uk parts sites?

it was a brand new tv as well still has store stickers on it!!!! panasonics were the worst though cant remember how many panels i had to fit to those, suppose it was only 1 model all thier others were quite good.
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Sun Aug 22, 2010 4:24 pm

Read the troubleshooting, maintenance, etc. sections of the manual.
SpotTheCat
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Re: NO Backlight

Postposted on Sun Aug 22, 2010 4:34 pm

I merged your threads, please keep everything in this thread.
SpotTheCat
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Re: NO Backlight

Postposted on Mon Aug 23, 2010 2:08 pm

SpotTheCat wrote:I merged your threads, please keep everything in this thread.

will do spot the cat.
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Tue Aug 24, 2010 2:52 am

chrisdot wrote:
SpotTheCat wrote:Sounds like your backlight burned out. Why not replace it?

surely the inverters would have a shorter lifespan than ccfl's i dunno!!!

No guarantees. A CCFL that was incorrectly sealed, or manufactured with an inadequate supply of mercury or inert gas, would crash and burn pretty quick.
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Re: NO Backlight

Postposted on Tue Aug 24, 2010 3:15 am

gonna do the psu power checks today make sure its regulaying properly and i may have a guy close with a ccfl unit so heres hopin.

Fitted 4 1000uf 164 105 oC capacitors on psu still no backlight

dont forget polarity peeps they all dont go in the same way!!!!!

so its either backlight burnt out or inverter personally i think its inverter but havent checked voltages going to it yet will report back....
chrisdot
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Re: SAMSUNG DARK SCREEN

Postposted on Thu Aug 26, 2010 4:52 pm

chrisdot wrote:ok i resoldered the joints on both inverters with no joy same result when i shine a light on screen i can see images clearer, so any ideas?


I did not see your responses until now. What you are saying seems to indicate to me that the CCFL backlight in the panel is dead. You will need to replace it if you want to repair the TV.
Disclaimer: I over-analyze everything, so try not to be offended if I over-analyze something you wrote.
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