Re: Samsung LE40B750 backlight dies after a while
I´ll keep an eye out for a used, broken, cheap one but they are extremely rare now as they are very old already. Also it would have to be close by because the shipping fees alone would kill any chance to fix this economically....
Fusion_de
Member
Last Activity: 06-09-2022, 03:33 AM
Joined: 06-07-2022
Location: Rödermark
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Re: Samsung LE40B750 backlight dies after a while
Thanks for the suggestion. While it would be a good learning experience for sure I won´t put that time and money in a TV that is sold used for about 80€.
I´ll probably just deem it a "not worth to fix"....Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
Thanks for your concern. I did it just like you said. The CCFLs are fine (well at least as fine as they were before
).
I set the brightness to "0" now and it has been running "normally" for about an hour now. Obviously it´s not as bright as the sun now but it´s at least running.
If it really is the CCFLs, and it seems to be from what I can tell, repairing it wont really be an option. I checked and they are rare and hard to get and way to expensive for a 10+ year...Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
Ah. Ok. Understood. So you believe its the tubes themselves?Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
I´m sorry, what do you mean by "lower the panel"?Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
Some additional findings.
- The higher I set the backlight brightness, the quicker it dies. E.g. on "10" it takes maybe 5 seconds.
- The 4 transformers are making a slight buzzing sound when the backlight is on (not sure if this is normal?) and immediately stop when the backlight dies.
- Backlight won´t work only with the powerboard connected, i need all 3 boards hooked up for it to go on.Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
I removed the power board and did the measurements you suggested. Please see the measurements in my picture.
The transformers behave as you predicted, I couldn´t find any datasheet or something to suggest if these are the values they should have.
As to the high voltage caps, not sure on how to test them? My DMM isn´t really reporting anything for these. 0 Ohms and a minuscule capacity measurement on all of them.
All measurements were done with everything still in circuit. Not sure if...Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
I couldn´t figure out where the CCFL is getting its power from. Is it through those 2 ribbon cables too?Leave a comment:
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Re: Samsung LE40B750 backlight dies after a while
Hello Yokoono,
thanks for the suggestion, but as far as I´m aware it has none. I believe it is a CCFL?...Leave a comment:
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Samsung LE40B750 backlight dies after a while
Hello dear Badcaps gurus,
I was hoping someone could help me on my fault finding missing.
I saved an old, "broken" TV that my parents wanted to throw out from the recycler as I´m a strong believer in fixing stuff instead of throwing it out.
The patient is a Samsung LE40B750.
The symptom is "screen going dark after a while". The sound is still fine when it occurs.
Its not the signal source. First tests show its the backlight that dies. If I use a strong flashlight I can see the picture.
The... -
Re: New Members - please post your introductions here
Good morning. Glad I found this pool of knowledge here
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