Tv led backlight

Hornnumb22

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I am converting a ccfl tv over to led backlight and have installed 6 strips of 10 leds. So if it takes 30v per strip, what kinda of amps should it be pulling? I can adjust the led driver board but don’t won’t to overdrive them. Thanks
 

Lynx_Arc

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I am converting a ccfl tv over to led backlight and have installed 6 strips of 10 leds. So if it takes 30v per strip, what kinda of amps should it be pulling? I can adjust the led driver board but don’t won’t to overdrive them. Thanks

It depends on the LEDs themselves as they vary from 5050 to 2835 etc and from single color to RGB
 

snakebite

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hopefully your strips have proper lenses.
they are rather specific to the leds and distance to screen.
otherwise you will have bright and dark spots.
i would have kept the ccfl unless they were bad and a shop like ccflwarehouse did not stock them.
 

Dave_H

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At bare minimum you will need to get the LED tint ("chromaticity") right, have very even/correct light dispersion, and the right levels. Looks like there's a whole lot more to it than it may seem. My own work experience is limited to second sourcing white LEDs for backlighting a small keyboard. LCD displays are more critical

How do you control brightness of the strips? If it's using PWM there could be flicker issues.

What are specs of the LED strips? How large is the LCD screen? Must be an older TV.

Some online research could help...even Wikipedia has something:

https://en.wikipedia.org/wiki/LED-backlit_LCD

https://en.wikipedia.org/wiki/Backlight

A friend has a piece of expensive test equipment about two decades old, which lost its LCD display CCFL backlight. He complained about the smell of "magic smoke" being let out, probably the backlight power converter. I was going to help him with LED replacement but he's decided to send it off for repair.

.
Dave
 

Lynx_Arc

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Another problem is dimming the screen, as you likely won't have direct control via the TV settings to adjust the brightness if it does anything it may either dim too fast or not much at all. It may be an idea to drill a hole somewhere in the back and install a control to manually adjust the brightness of the LEDs.
 

Dave_H

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Looks like the OP started a discussion then disappeared...

Question is not whether it can be done, but whether the exercise provides a good (enough) result.

Using 10 inch strips that sounds like a not very large screen (maybe 15"). I would think reasonable current for small SMT white LEDs for this purpose would be 20-60mA.

I am also wondering how OP would power multiple strips from a single driver. Connecting them in parallel to a constant- current driver may not end up with equal current distribution. Perhaps OP can confirm that these are indeed LEDswired in series, and any additional circuitry on the strips. It sounds a bit unusual, usually strips have LEDs all wired in parallel (3-5v), or a series-parallel combination for 12v, with dropping resistors if designed for constant-voltage drive.


Dave
 

Lynx_Arc

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The problem with powering them isn't hard to solve as you can buy power supplies to suffice it is how much you want to spend that is the problem. The big problem is likely the CCFLs are powered by a higher voltage such that you cannot easily convert it to power an LED strip and if you were able to do that then the backlight control in the TV may make for a problem if you can adjust the backlight through the TV firmware then it could affect the LED lighting if run off the same (converted) power supply you could end up turning it down a little and have it literally black out and be unable to see the screen at all to turn it up. If you add a dedicated power supply for the LED strip you likely would have to consider turning it on/off manually as there may not be anyway to get power from the TV circuitry that goes on/off with it other than perhaps installing a relay somehow. In other words there is no easy seamless opgrade option you will have to work around it somehow.
 

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