Can we omit reflective paper?

[capwizard]

Can we omit reflective paper on LED panel?

This series of Samsung TV (Un32H5203) LED strips are total garbage. We need to change all the LED stripes but I don't want to spend money so I just use the LED Stripes from another TV set. I tried to cut holes to match with LED positions that's a lot of works. I have an idea! can we just use white paint to reflect the lights?

[gabiz_ro]

Re: Can we omit reflective paper?

Better some "hollow punch" to make holes in reflective paper.
Or diy some metal pipe sharp on edge and make holes easy.

[capwizard]

Re: Can we omit reflective paper?

Thank you, my friend, I did try but it is not working good so I will try to do is use the heater pipe and stamp on it.

[capwizard]

Re: Can we omit reflective paper?

(1) I took out LED stripes from this TV.

(2,3) it is a 50in TV with long stripes with my specially customized tool, no problem even leds have glue on them.

(4) so I just use half of them and shorted the connectors for return current.

(5) tested with my Antique LED Tester.

(6,7) tested with TV power supply. The connectors to the LEDs are being burnt. so, I just jumped wires to the backside of PCB.

[budm]

Re: Can we omit reflective paper?

https://www.badcaps.net/forum/attach...0&d=1551719016
Poor contact resistance, better off solder the wires to the board directly, or replace the male/female connectors.

https://www.badcaps.net/forum/attach...8&d=1551719016
So that is about 2.75 Vf per LED at 11mA.

[capwizard]

Re: Can we omit reflective paper?

https://www.badcaps.net/forum/attach...0&d=1551719016
Poor contact resistance, better off solder the wires to the board directly, or replace the male/female connectors.

https://www.badcaps.net/forum/attach...8&d=1551719016
So that is about 2.75 Vf per LED at 11mA.

(1) The TV has 24 LEDs but I put 28 LEDs then I found out, LEDs will have had a blinking problem.
So I just bypass 4 of leds

(2) I try to make an EXT adapter to my antique LED tester easier for me to use the same meter as an external meter then I will let you know.

[capwizard]

Re: Can we omit reflective paper?

https://www.badcaps.net/forum/attach...8&d=1551719016
So that is about 2.75 Vf per LED at 11mA.

Yes, One thing I always wanted to do was that I wanted to know how the voltage and current of a real TV drive the led panel. I put a switch to my antique LED tester so I can put the voltage and current meter for external use. The total is 24 leds. Voltage and current divide by 24 will be each one.

(4) shows 77.3v at 310ma. 77.3v/24=3.22v
at 310ma for each led.

[budm]

Re: Can we omit reflective paper?

https://www.badcaps.net/forum/attach...8&d=1551719016
So that is about 2.75 Vf per LED at 11mA.

Yes, One thing I always wanted to do was that I wanted to know how the voltage and current of a real TV drive the led panel. I put a switch to my antique LED tester so I can put the voltage and current meter for external use. The total is 24 leds. Voltage and current divide by 24 will be each one.

(4) shows 77.3v at 310ma. 77.3v/24=3.22v
at 310ma for each led.

3.22V forward Voltage at 300mA is about right, if you look at the graph of Vf VS If you can see it is about what you expect to get.
Example: Vf VS If chart for single LED rated at 240mA

[capwizard]

Re: Can we omit reflective paper?

From the data, we can see that manufacturers are overdrive the leds cause a lot of problems

Now we go back to the topic: Can we omit reflective paper replace it with white paint?

the answer is...Why not! The result is amazingly good with no white highlights, no spots. Why don’t you try it yourself next time? Don't forget to use high gloss paint.

[gabiz_ro]

Re: Can we omit reflective paper?

Some strips are bonded or in contact with metal ,using at heatsink.
There is double side adhesive in some cases and affect thermal transfer,with one layer of paint this is worse.
Protect area where strips will be mounted with something like scotch tape and after paint dry remove it so strips will be in contact with metal.

No dark area where are those bypassed leds?
Better search for schematic or datasheet of driver IC and adjust OVP protection to allow higher voltage so all leds will light fine.

Test with image is not so relevant, better check with white screen to see spots or dark area or any other problems with backlight.

[capwizard]

Re: Can we omit reflective paper?

very good questions.
(1) I thought about that too, LED strips need to touch with the metal sheet to dispatch heat which are the major causes the failures of the LED stripes. This is my first time using this method. I am thinking that there is still much room for improvement.

(2) not perfect but still acceptable. Pic ( 2)

(3) Because of the lack of documentation, so far I only have one model that I can do it to adjust led driver's voltage.