A (very) Simple LCD Backlight Fix

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Intro: A (very) Simple LCD Backlight Fix

Fix any broken LCD backlight with an ordinary light bulb and a dead CRT monitor.

Broken LCD monitors basically come in three categories:
1) Cracked LCD panel, rendering the unit completely worthless
2) Backlight problem
3) Power supply problem

If it's a backlight or power supply problem, it can be fixed.
Usually, the problem stems from the high voltage inverter circuitry, either bad power transistors, capacitors, or thermal stress on the circuit board leading to broken solder joints.
But fixing these problems can often be a short term solution. The bulbs themselves have a limited lifespan, and the high voltage power supplies are prone to failure.
The panels themselves almost always outlive the backlights and high voltage power supplies.
The 17" Dell LCD monitor I found was no exception. When I first plugged it in, it would cycle power on and off continuously, with a notable burning smell. Further inspection revealed a fried power transistor. When i replaced it, the monitor stayed on, but the backlight would flicker on and off, then finally shut off after a few seconds..
The panel was good, but trying to fix the backlight with the proper parts wasn't really worth it.

But maybe I could still save it, or even make it better. After all, it's just a light. Lights should be user-replaceable things anyway.
I mean, a Lite-Brite was the cheapest toy, yet you could at least change the bulb.
So here's the result of my experiment, with help from an old CRT monitor:

Step 1: Go to Trash, Locate a CRT Monitor

Take a CRT monitor, remove the guts and dispose, keeping just the shell and monitor stand.

Install a light bulb socket about 1/2 way back. I used switching socket from an old lamp.
(for the bulb, I used a 60w-equivalent "daylight"/6500k CFL bulb. It has a blueish glow to it. )

Step 2: Cutout Back of LCD Monitor

For the LCD monitor, cutout the back and remove the metal shields/ PCB's behind the panel, allowing light to pass through it.
(This step varies a lot from brand to brand. Some brands will have ribbon connections on both the X and Y plane, while some just on the X plane. Fortunately, for my Dell monitor (which was actually a BenQ monitor), the ribbon connector was only on the X axis, so lifting it out of the way to allow light to pass through was easy, without requiring any extra wiring. )

For the panel light filters, there should be some diffusing paper/plastic behind the LCD, 3 sheets (one clear, one reflective, one translucent white), and then a large Plexiglass-like filter. I removed the Plexiglass and everything behind it, only keeping the 3 thin paper-like sheets behind the LCD. Shining a light behind the LCD resulted in an even white glow

Step 3: Mounting the LCD

4) Relocate the boards from the LCD panel to the CRT shell, mount LCD panel, and connect everything up. For mounting everything I drilled holes and used zip ties.

Step 4: Results

See my project page for more pictures.
http://www.ccs.neu.edu/home/bchafy/monitor/crtlcd.html

Conclusion

This LCD was saved from the trash.
And now if the light ever goes out, it's easy to change. Also, as a bonus, the monitor vents glow, partly illuminating the desk and keyboard at night. Shouldn't all monitors be made this way?
:-)

Notes

LCD Monitor is a Dell E172FP.

When the monitor is off and the light is on, the display is more transparent than black, sort of a light/mid gray.

There is some minor hot-spotting, but not very serious. Given the type of cheap hack this is, it is more than acceptable.

Obviously, the monitor is more bulky than it used to be, but very light. Almost half the weight of LCD monitor as it was before.
Bathroom scale says it weighs 7lbs. (original LCD weight was 13.25lbs)
Gettting rid of the LCD's metal frame, stand, and heavy plexiglass light filter was the major contributor to the weight reduction.
The CRT's shell and base are just plastic (with some springs).

The LCD frame was smaller than the CRT's. I just cut out some cardboard to fill in the gaps to block out the light for now. I know, it looks ugly. Later, I'll make a better looking frame.

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    66 Discussions

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    TailsL

    10 months ago

    cool idea,hard to find in 16/9 nowdays obviously,but now you can use cheap led bulbs!

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    Lima79

    2 years ago

    hello, i am new on this great site so i am not sure where to post this one
    anyway. Is there anyway to make a power supply for LCD monitor backlight
    just recently my good old LG monitor 20inch just gave up the problem is
    with the "IT-007 EBJ56945505 inverter transformer "its available on
    eBay.com but sadly its not available on Indian e-commerce sites anyway
    the transformer gets too hot and as a result the backlight turns off,
    when i add a fan on the transformer it works like a charms but there is
    no space on the back cover of the monitor, so hoping that i could find some help on the net but to my surprise there is non. If instructables could give me some idea than i would greatly honored. Sorry for my English. Thank you.

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    TimS4

    4 years ago on Step 4

    and this shows just how TERRIBLE CFL bulbs are - way **WAY** too much green.

    Incandescent is the best.

    1 reply
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    RedIrishman

    3 years ago on Introduction

    This is so ghetto. lol No offense. Great idea! I guess you could use any box with heat ventilation to keep the bulb cool and not light up the whole room.

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    tagh

    3 years ago on Step 4

    Cool fix. Now to find a widescreen CRT...

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    Shomen

    4 years ago

    Brilliant!

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    RetroPlayer

    7 years ago on Introduction

    I don't mean to be a spolisport, but... why? The whole point of an LCD monitor is that it is thin and saves on desk space. You just made it as big as a CRT monitor, out of a CRT monitor. Why not just use the CRT monitor instead?

    ::Blank Stare::

    2 replies

    One functioning screen is better than two dead ones. CCFL bulbs bought from a reputable place can cost upwards of $70. I'm going to try to wire an LED array to get a screen of mine working. If that doesn't work, I may do this. SO MUCH potential in a dead screen.

    Edit:
    The new bulb will cost about $10, $70 was the LED substitute for the cold florescent, but I still wouldn't install one. I don't even like taking them out. I ended up buying a foot of white LEDs from a novelty lighting site for about $8 and it works great. Right now I'm powering the back-light separately with an un-used plug from my computer's power unit.

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    outbackshaq

    7 years ago on Introduction

    I wonder what would happen if you had a plexiglass panel and drilled holes on the edges. then in those holes you place superbright white leds, then on one side of the panel you put a tinfoil sheet. would that make an even light? because the leds arnt facing the screen. you could also sand down the frotn of the panel to make it less clear

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    gana_anaq2

    8 years ago on Step 4

    Great idea ! For a better illumination try to use fluorescent bulbs ( the old ones like tubes) and in front of them put a laminating foil unheated. This is a mate surface and it will make the light to distribute uniformly. The led solution is not good because the led is omnidirectional, and you will see the spot where the led is.
    For an estetic look try try to put 12mm fluorescent bulbs ( like in emergency light {EXIT} ) inside the original case, and the inverter for that lamps put it with wire in a separatly box :)

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    Timofte Andrei

    8 years ago on Step 4

    put a mirror inside the crt-case ;) oh...and use an AC variator for the bulb ;) if you wanna change the luminosity ;)

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    cyberraxx

    8 years ago on Introduction

    Nice one. I May be able to get hold of an LCD with dead back light. I wasn't too sure about how to go about reviving it. May try using supa-bright LEDS for back light and some sort of diffuser.

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    motogen

    8 years ago on Introduction

    i only have the sme thing as same as the finish one aove,but when i turned on the power seems like nothings happened,i know there somethin i didnt door something wrong i did please advice thanks

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    motogen

    8 years ago on Introduction

    please tell me what to do im really having a hard time working on this and i  still cant get it right,ive been doin this for 3 dys now and still im ariving at the same situation

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    motogen

    8 years ago on Introduction

    im doing the sme project as you did right now,i have 3 thin paper like  pastics 2 are identical and one with a border,should i leave them and taking out only the fiter like  glass and a white one?when im done working on it i have no display,the power is  on and it has a indicator telling the monitor i turned on,is there anything you cn advise thanks

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    motogen

    8 years ago on Introduction

    i do the same thing as you did,i have a power my  screen goes white as same as the photos  on yours but i still dont have a display,everytime i turn it on,all i have is a white glowing screen,i havent connected the cpu yet,any second opinion if  there's something wrong on what i did,i have no display please reply thanks