Electronics rookie trying to convert broken LED display into skylight

Thread Starter

psamaac

Joined Mar 12, 2020
6
Hi all
New here! I am looking to convert my broken LED display into a skylight, something like DIY Perks youtube videos. I was able to disassemble the display and get the lens layers and broken panel off. But i am unable to figure out exactly how to bypass the signal detection stage of the monitor itself so as to avoid it from hitting standby mode. Being a PC monitor, it tends to go into standby if there is no signal detected through any of its inputs (HDMI and VGA). The youtube video i referenced used a laptop screen which had a PWM and LED_EN point on the PCB which he connected to the power supply using a couple of 180 Ohm resistors. In another video he used a TV with the fresnel lenses on but the LEDs he used were stick on type strip LED. What i was hoping to do is use the existing circuit and power supply and just bypass the signal detection so the lights stay on. Is there a way to do it or is it just an exercise in futility? Another video i came across was from Marcus Fuller where he uses an old TV, but only removed the TV circuit board and bypassed the circuit tricking the mainboard. Something similar is what i hope to achieve. Any help i can get is much appreciated.

The monitor I am using is a Viewsonic VX2776 SMHD. Attaching an image of the circuit board though i understand that just looking at the image of the board may not be enough to solve this.
IMG20200313055507.jpg
Just wanted to say i am very new to electronics and only have a basic understanding in hobbyist or enthusiast electronics and electrical work.

~Regards
Sam
 

bug13

Joined Feb 13, 2012
1,838
First thing first, LCD back light driver can generate HIGH VOLTAGE, so BE CAREFUL.

I would recommend you get someone who knows electronics to do it for you. But if you insist to do it yourself, here is what I would to:
  1. Identify the booster converter, usually close to a inductor.
  2. Look up the datasheet of the boost converter
  3. Identify the enable/disable pin.
  4. Pull this pin high or low according to the datasheet with an appreciate resistor.
 

Thread Starter

psamaac

Joined Mar 12, 2020
6
First thing first, LCD back light driver can generate HIGH VOLTAGE, so BE CAREFUL.

I would recommend you get someone who knows electronics to do it for you. But if you insist to do it yourself, here is what I would to:
  1. Identify the booster converter, usually close to a inductor.
  2. Look up the datasheet of the boost converter
  3. Identify the enable/disable pin.
  4. Pull this pin high or low according to the datasheet with an appreciate resistor.
Thank you bug13 for the help. I am looking at the circuit board but there aren't any traditional looking inductors on the board. If you are talking about the power supply itself, then it is just a brick style supply similar to the one's you'd find in a laptop, rated for 19V 2.1A. So basically all the power that is going into the circuit is ~19V DC. So unlike conventional monitors that have a power supply unit built in doing all the conversions and powered from the mains this one takes it from an external power brick. This may be due to the fact that the form factor is really slim and the design did not allow room for an internal power converter.
 

bug13

Joined Feb 13, 2012
1,838
Thank you bug13 for the help. I am looking at the circuit board but there aren't any traditional looking inductors on the board. If you are talking about the power supply itself, then it is just a brick style supply similar to the one's you'd find in a laptop, rated for 19V 2.1A. So basically all the power that is going into the circuit is ~19V DC. So unlike conventional monitors that have a power supply unit built in doing all the conversions and powered from the mains this one takes it from an external power brick. This may be due to the fact that the form factor is really slim and the design did not allow room for an internal power converter.
There are two I can see from your picture. One with marking 330, another smaller one with marking 2R2, they are both inductors. Look up tho two IC next to those inductors.
 

Thread Starter

psamaac

Joined Mar 12, 2020
6
There are two I can see from your picture. One with marking 330, another smaller one with marking 2R2, they are both inductors. Look up tho two IC next to those inductors.
Sorry i was looking for the coil style inductors here, although i had a feeling the 330 and 2R2 had something to do with it. Checking now, will update you in a bit.
 

Thread Starter

psamaac

Joined Mar 12, 2020
6
Hi bug, Tried looking for the boost converter but i can't find it. Only IC close to the 330 inductor is a Winbond marked 25x41clnig 1725. Cant find any data sheet for it, just came close to understanding that it has got something to do with power control. May be i should give up because this obviously needs more technical skill than what i thought i could accomplish with.
Although would you know of any alternative ways of lighting the LEDs directly without using this main board at all. or would that only complicate things further?
 

Thread Starter

psamaac

Joined Mar 12, 2020
6
The MOSFET next to the 330 inductor reads BA5N10, The datasheet is available for this but i cant figure if this is what would sort me out. There is a component near the 2R2 inductor that is marked NA7JA but not sure what that is. IMG20200313074543.jpgIMG20200313074611.jpgIMG20200313074625.jpgIMG20200313074633.jpgIMG20200313074646.jpg
 

bug13

Joined Feb 13, 2012
1,838
There might be a separate connector/cable that are for back light only. Can use a meter to measure the voltage (You need to be careful, you really should get someone know what to do to help you on this), if it’s very high, that’s your back light power.

The chip next to that connector is most likely a booster.

But if you can’t find the datasheet, then you may need to reverse engineer it to find out the control pin.

if you need to reverse engineer it, it may be too difficult to convert the HOW-TO in a post or two.
 

Thread Starter

psamaac

Joined Mar 12, 2020
6
There might be a separate connector/cable that are for back light only. Can use a meter to measure the voltage (You need to be careful, you really should get someone know what to do to help you on this), if it’s very high, that’s your back light power.

The chip next to that connector is most likely a booster.

But if you can’t find the datasheet, then you may need to reverse engineer it to find out the control pin.

if you need to reverse engineer it, it may be too difficult to convert the HOW-TO in a post or two.
Thank you again for your reply. The chip right next to the power connector is marked APA2604C which according to the data sheet is the audio power driver for the speakers.
I'll try to see if i can get some help on this. I am not really savvy at this and do not wish to keep pestering you either. Someone physically examining this would be easier i suppose.
Thanks again though! much appreciate your help! :)
 
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