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Non-working LCD screens can often be found cheap or free. I started doing this originally because I needed multiple screens for schoolwork but didn't want to fork out the money for a brand new one. The key to getting a suitable one for this Instructable is to get one where the screen itself is not broken. This Instructable will describe how to replace the CCFL (Cold Cathode Fluorescent Lamp) backlights with LED strips. The advantage to using these instead of single LEDs is that the LED strips can be purchased cheaply on Ebay and the monitor can be completely reassembled because the LED strips take up less space than the original CCFL backlights. This means that externally the modified screen will look just like a stock screen.
From my experience, these non-working screens usually have problems with either the power supplies or the inverters for the backlights. Often times, these problems are easily fixed by replacing bad capacitors, but occasionally the problems are different. I managed to accumulate several screens with problems with the inverters I was unable to diagnose with a reasonable amount of effort, so I decided to replace the backlights with LEDs, thereby cutting out the faulty inverter circuit.
DISCLAIMER: This instructable involves opening and modifying electrical devices and handling bulbs that contain mercury. Be sure you are comfortable doing this before attempting this Instructable and be sure to always disconnect power before working. I cannot be held responsible for anything that comes about from attempting to replicate this Instructable. Attempt it solely at your own risk.
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Signing UpStep 1Tools and Parts
To complete this project, I used the following tools and parts.
Tools:
Soldering Iron
Screwdrivers
Wire Strippers
Solder
Parts:
Self Adhesive Surface Mount LED Strip
Wire
Electrical Tape
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You will have to either unplug the monitor to turn off the backlight or you can wire a MOSFET up as a switch to control it. The way I did this was to use the wire to the LED that turns green when the monitor is on as the control signal to the gate of the MOSFET. This makes it so that the backlight is controlled by the single LED on the front panel. If you are not familiar with electronics though, I would not recommend this as it varies for each monitor.
i have 3 15" monitors i may try this with, either this or they get repurposed into something else, what, i dont know.
Where did you get the self-adhesive, cut-to-fit LEDs!?!?! And how much you got & what you paid for it?
I've never seen stuff for sale anywhere. and have many other uses for that kind of LED stock in my lab. Please tell us where you got it from!!!
"I bought mine from eBay. Specifically, I bought these: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=200388725627&ssPageName=STRK:MEWNX:IT
It is actually only 150 warm white surface mount LEDs on an 8 foot strip, not 300 like the ad says later. The 8 foot strip was enough to do two 17 inch monitors and one 20 inch television and have between 1 and 2 feet leftover. I know that you can get twice the length for not much more money. If I had to do it again, I would probably get the longer strip and get them in cool white to try to get a better color and brightness. Just make sure that they are narrow enough to fit into your CCFL holder."
BTW, the ad has been corrected. It now reads 150 LEDs on an 8ft strip. I wonder if you can get 300 LEDs in an 8ft strip...? that would rock. I'd do my laptop right now if I could get 300s.
Thanks for the info! And good job!
Regards
Too bad you trashed it.
The inverter board and main board are separate .
They connect with wire cable.
The main board supply power (DC12V)and one channel control signal to inverter board by wire cable.
The control signal can controllable inverter board let CCFL bright or dark and inverter board respond signal to main board by control signal channel.
I mean that main board must have respond signal from inverter board.
If main board can not receive the respond signal then main board not working.
Have some way can bypass the signal let main board working without respond signal.
First, does all of the main board not work or just the power to the inverters? If the main board continues to work enough to produce power and turn on the screen without the backlights, I would try taking power from a different place than the inverter power.
Second, if the main board does not work at all, do the boards work if you leave the broken inverter in place with the CCFL's disconnected? The backlight won't come on, but does the screen still show signs of displaying a picture when you shine a very bright flashlight directly onto it? If it does, I would try leaving the broken inverter in place and just not connected to anything but the main board. You just have to find a source for your LEDs then. The original inverter output is NOT suitable for powering LEDs.
The last thing I would try, which may completely ruin your screen if done incorrectly, would be to find out what the signal back from the inverter board to the main board is and try to replicate it.
I hope this helps and I'm sorry I can't answer your question more exactly, but I have never seen this problem before.
If he does what you've suggested and it doesn't work, he may just need to "Jumper" the circuit at the motherboard.
Best bet might be to start out with a schematic diagram of the unit in question. You can generally find it on-line by google searching for the model number and manufacturer's name Or just head to their website and look in the Support area. Sometimes if you call them and ask where you can find this information, they will bend over backwards to help you find it.
my laptop's screen works but I was wondering if the brightness could still be changed. I know very little when it comes to the individual components, but I still want to fix a laptop I found at a thrift store for word processing, maybe some PSX 7 GBA emulation...
Laptops are very proprietary and run at strange voltages. Just look at what it takes to charge them. Most are 19 Volts and about 6 Amps-ish (mines a little older and this is what it takes to charge and run mine. I can't even use the adapter from my other laptop to run this beast! It's just too weak at 70W) and it takes 110W.
All I'm saying is knowing is half the battle. But if you don't mind risking it, try it! You may just get lucky!
Plus I bet the battery will last a lot longer with LEDs and not that inverter eating up battery time and wasting most of that juice as heat!
Let us all know how you're doing on it and if you're successful or if you get stuck and need some suggestions!
Good Luck!!!!
but the inverter board connect with main board . Have some signal contact each other.?
My question is when the inverter remove then main board can not contact inverter signal so the main board not working .
Have some way can by pass the signal? thanks
Did you ground the inverter somehow? I imagine it could be quite dangerous otherwise because of the high voltage.
And do you know certain ways to find the 12V power supply in step 6? I know that every monitor is different and I didn't look into one yet, but I already saw some circuit boards and I'm not sure if I could find a point to get special voltages from, at most the grounding maybe.
I took voltages from where power originally went to the inverters. Since those ribbon cables are no longer needed, I used the wires that I needed and removed the rest. The only bad thing about this is that in some monitors, these do not turn off when the monitor is turned off. I am working on a modification for monitors where a switched line cannot be found.