Convert monitor ccfl to led

[karmele]

Hi all experts,

I will try to explain clearly what I want to do and the doubts I have.
This is a Viewsonic monitor for years that have broken the lamps and finding no replacement we have decided to put LED strips.
We have the DC / DC controller bought in Aliexpress that as you know comes with four cables (VIN, GROUND, ON / OFF AND DIM) to solder on the monitor board.
I have seen many videos and I have the general idea of what to do but my doubt is that I can not find the right voltage to solder on the board the VIN cable. I only see 12V, 13V and 25V.

I explain what I have done so far:
VIN: I have soldered it to 25V in different places of the monitor board (I tested with 12 and 13V but they do not turn on the led) this connector board does not have the pin for VIN
GROUND: to pin ground on connector
ON / OFF: to pin ON / OFF of the connector that has 0.12V (is this enough voltage?)
DIM: to pin BRIGHT of the connector that has 3.28V

Well, what I have achieved is that I turn on the monitor that I have connected to the laptop, but the image I see is as if it had a lot of brightness but like fog, which means that the icons are not seen at all and what there is in the screen. I know I have not explained myself well and you will not understand me but it is difficult to explain.

So it is clear that somewhere I screwed up, either in the 25V of the VIN, either in the rest of voltages or maybe that as I read somewhere should have disconnected some mosfets and some capacitor on the board.
The help that I am asking for is that you tell me exactly where on the board I should solder the different wires of the regulator.
And this is where I ask for your help so you can guide me by giving me ideas and suggestions.
I send photos of the board on both sides, photos of the DC / DC controller, photo of the monitor model and also if you need I have the PDF of the monitor available.

Well, I thank all those experts who lend themselves to help.
Regards.

[budm]

Re: Convert monitor ccfl to led

Where exactly did you connected to the location that is 25V?
ON / OFF: to pin ON / OFF of the connector that has 0.12V (is this enough voltage?) The ENA per your picture (https://www.badcaps.net/forum/attach...3&d=1541690110) is shown as 5V (more likely 2 ~3V may work), 0.12V is not going work. Does that ON/OFF pin of that Viewsonic stay at 0.12V and does not change state when you turn the monitor on and off and have it connected to running PC?

[karmele]

Re: Convert monitor ccfl to led

There are two mosfet on the board on the right side. The one above is 25V, the one below is 13V. I connected it to the one above.
The ON/OFF pin is 0.12 in standby but once I click power it goes to 2.80V with de PC connected.
The DIM pin is 3.28V but once I turn on it goes to 1.28V
One more thing, I would like to show you the picture that I took from the screen for you to see how it looks, like foggy.
How can I post a picture? I can not find the way.

[R_J]

Re: Convert monitor ccfl to led

Post the pictures the same as you did in post #1 , Click on Go Advanced - Click on the PAPER CLIP (next to the happy face) and attach your pictures

[budm]

Re: Convert monitor ccfl to led

See attached picture for the VIN and GND connection to the LED driver board.

[karmele]

Re: Convert monitor ccfl to led

Thanks, I will try tomorrow morning. I hope it works.
I would like to add a couple of pictures for you guys to see how the screen monitor looks. Like I said before it seems like a foggy image.

Thanks again

[karmele]

Re: Convert monitor ccfl to led

See attached picture for the VIN and GND connection to the LED driver board.

Thanks a lot.

[karmele]

Re: Convert monitor ccfl to led

Post the pictures the same as you did in post #1 , Click on Go Advanced - Click on the PAPER CLIP (next to the happy face) and attach your pictures

Thanks a lot. I did it.

[budm]

Re: Convert monitor ccfl to led

Thanks, I will try tomorrow morning. I hope it works.
I would like to add a couple of pictures for you guys to see how the screen monitor looks. Like I said before it seems like a foggy image.

Thanks again

Did it look like that before you taken the LCD panel apart?
Are you able to dim the backlights level?

[karmele]

Re: Convert monitor ccfl to led

Did it look like that before you taken the LCD panel apart?
Are you able to dim the backlights level?

No, before taking the panel apart it looked OK.
Yes, I wired the DIM to 3.5V and I am able to dim the bright and contrast but no much. There is a slight difference from 0 to 100.
I tried what you proposed me yesterday and it keeps being the same, no changes.
Someone has proposed to me to lower the tension with a resistance of 10 ohms and 5 watts. He told me that that brightness could be due to the high voltage in VIN (25V).

I will keep you posted.
Regards.

[budm]

Re: Convert monitor ccfl to led

No, before taking the panel apart it looked OK.
Yes, I wired the DIM to 3.5V and I am able to dim the bright and contrast but no much. There is a slight difference from 0 to 100.
I tried what you proposed me yesterday and it keeps being the same, no changes.
Someone has proposed to me to lower the tension with a resistance of 10 ohms and 5 watts. He told me that that brightness could be due to the high voltage in VIN (25V).

I will keep you posted.
Regards.

Are you 100% sure that you put all filter, polarizer sheets for the LCD back together correctly, backlights will not cause that faded pictures to like that on the screen, it can also be due to bad Gamma Voltages.

[karmele]

Re: Convert monitor ccfl to led

Are you 100% sure that you put all filter, polarizer sheets for the LCD back together correctly, backlights will not cause that faded pictures to like that on the screen, it can also be due to bad Gamma Voltages.

I have disassembled and assembled everything again and everything remains the same.
I have observed a strange thing that has puzzled me. Measuring the input and output voltages to the inverter of the LEDs, I see that through the VIN wire enter 21V and 21V get out, so far so good. Now, I measure what goes into the monitor by means of the four wires (two pairs red and white) positive and negative, and I get positive 21 V and 15V negative , the same in the two pairs. Look at the photos of the inverter so you can clarify what wires I'm talking about.

I have a basic knowledge about electronics but, can you tell me why the negative gives 15 V positive? Is this OK?

[R_J]

Re: Convert monitor ccfl to led

Full +21 volts is applied to the + of the led's. The negative side of the led is controlled to vary the current/brightness, in this case 15 volts above ground (difference is 6 volts to the led's)
I agree with budm, check the diffuser sheets, they need to be installed in the right order and the right direction.

[karmele]

Re: Convert monitor ccfl to led

So, I undertand it is OK? Can you explain to me with more details? I thought it could have something to do with my problem.

Thanks a lot.

[R_J]

Re: Convert monitor ccfl to led

What would you like explained? The diffuser,polarizer and prism sheets behind the panel MUST be in the correct order and the correct direction, they are NOT just sheets of plastic.
There are usually 2 or more sheets
Did you keep all of them in order when you removed the lcd from the panel.
Maybe this will help explain https://pid.samsungdisplay.com/en/le.../lcd-structure

[karmele]

Re: Convert monitor ccfl to led

Are you 100% sure that you put all filter, polarizer sheets for the LCD back together correctly, backlights will not cause that faded pictures to like that on the screen, it can also be due to bad Gamma Voltages.

Hi again,
Yes, I have disassembled and assembled everything again and everything remains the same.

Thanks.

[karmele]

Re: Convert monitor ccfl to led

What would you like explained? The diffuser,polarizer and prism sheets behind the panel MUST be in the correct order and the correct direction, they are NOT just sheets of plastic.
There are usually 2 or more sheets
Did you keep all of them in order when you removed the lcd from the panel.
Maybe this will help explain https://pid.samsungdisplay.com/en/le.../lcd-structure

Hi,
I was not asking you for details about the order of the sheets, but about the leds inverter voltages.

Thanks for your help.

[budm]

Re: Convert monitor ccfl to led

You need to look up the spec sheet of that LED driver IC, the spec sheet will usually gives application circuit which is most likely to match what you have on your board.

[karmele]

Re: Convert monitor ccfl to led

You need to look up the spec sheet of that LED driver IC, the spec sheet will usually gives application circuit which is most likely to match what you have on your board.

Hi again and thanks for helping me,

Well, the IC is DF6113 I attached a picture. Please can you guide me about reading the spec sheet? I do not have the knowledge to do it.

Thanks again.

[stj]

Re: Convert monitor ccfl to led

which way are you pointing the leds??
they should face towards the center of the panel - not forward.