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.

Comments

[conundrum2142]

Hi, maybe this could help folks.
Seasonal LED lighting strips originally sold as a silver coloured (in actual fact Cu/Al) wire with SMD LEDs encased in resin about every 4".
This works brilliantly for older laptop screens, etc.
Won't be as good as the original but adequate for most functions.
The trick is to use multiple pieces and put them offset so that the overall voltage is within range of what most laptops expect to supply (ie 3.3V <500mA) and use resistors to get the required balance.

I've also been known to use household lighting bi-pin lamps as well.
These have several advantages not least being a lot more efficient and often available in sales.
12V as well so can be used as is, with minimal modifications and a little experimentation to get the required light geometry post filtering.

[igregory67]

This would be great for building a cheap MAME arcade cabinet... dead LCD's are easily found for super cheap... and you'd have lots of room behind it to mount your light source.

One day, when I get the time, I'm going to try this:)

[RoelV5]

One thing to be very careful with is the tube in the CRT. If one does not know how to disarm it properly, it can implode then explode. Very dangerous. There is a proper way to "air a CRT", but you have to know how to do it.

[TailsL]

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

[Lima79]

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.

[TimS4]

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

Incandescent is the best.

[daved8]

you can buy "warm" cfl bulbs

[RedIrishman]

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.

[tagh]

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

[Shomen]

Brilliant!

[74LS374]

I likes this idea... simple and cheap...

[RetroPlayer]

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::

[mr monoply33]

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.

[mr monoply33]

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.

[outbackshaq]

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

[gana_anaq2]

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 :)

[Timofte Andrei]

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

[cyberraxx]

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.

[nessimmax]

very nice : )

[motogen]

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