How to Replace Your Laptop's Backlight

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Posted in TechnologyLaptop

Introduction: How to Replace Your Laptop's Backlight

About: Engineer making renewable energy products for African entrepreneurs.

Is your back light dim? Does it start up with a red tint? Does the back light eventually just give out OR do you hear a high pitch hum sound coming from your screen? Well, here's part two of the laptop disassembly and repair. We're now moving away from exploratory surgery and into healthy repair.

Warning

CCFL Tubes are small fluorescent bulbs. As such, they contain mercury. It is also likely that they are made with lead glass, which is very brittle and has a low melting point. Avoid shock and unnecessary stresses on the bulb including prolonged periods of high heat (soldering iron). Do not twist or bend your bulb and do not wrap wire around it.

Step 1: Parts and Supplies

You'll need everything you needed from part 1 to disassembly your machine. But you'll need the following too:

1. Replacement Bulb
2. High Temp Foil Tape (EMF Shielding)
3. Soldering Iron
4. Solder Wick
5. Wire Cutters

Step 2: Disassembly

If you haven't done so already -- take your screen apart!

Here's how to take apart the HP zv5000: https://www.instructables.com/id/E8M1EZJF3YWV61Q/?ALLSTEPS

Step 3: Desolder Old Bulb

Pull back the silicone end covers to expose the old CCFL's solder joints. Desolder using solder wick and remove the wire. My wire happened to have a nice through hole end.

Step 4: Solder New Bulb

If your old bulb had plastic rings on it, like mine, be sure to transfer those over to the new bulb. Then, solder on the bulb's wires. Do not apply heat for more than 4 seconds. Additionally, place the wire at the base of the connection. These bulbs are not directional - so there is no "+" and "-" side ;)

Step 5: Trim Bulb

My bulb came with long leads - trim these with wire cutters. Then, replace the silicone end caps.

Step 6: Place Bulb Into Reflector Assembly

Place the new bulb into the reflector assembly just as the old bulb was (in my case, wires pointing "up").

Step 7: Testing

Before going through the trouble of reassembly, reconnect your inverter and bulb and start up your machine. Does the bulb work? Allow it to stay on for a few minutes to make sure it doesn't overload the inverter (high pitched squealing). If everything is good -- continue forward. If the bulb does not light, check your solder joints and then check for connection issues. If that's good, check the bulb for cracks. Otherwise, there's a possibility you got a dead bulb.

Step 8: Attach Reflector Assembly to Glass

Behind the LCD and polarizing sheets - you'll find a pane of glass, about 1cm thick. The reflector assembly straddles this glass. So, what you need to do is clip the reflector assembly on to this glass AND do so in a way that won't break the bulb (that is, as even as possible).

In my case, I had an extra issue. The plastic trim was not removable without a lot of sensitive disassembly. Therefore, I couldn't directly attach my reflector assembly. So, I pulled up on the plastic case, attached the reflector about an inch away from the target and slid it over into place.

Step 9: Reassembly

Reassembly is reverse of assembly - however, be sure to replace any foil tape you may have removed. The tape I removed from my screen lost it's sticky backing during removal - so, I replaced it with new tape. If the mfr spent money to have it there to begin with, it's probably worth replacing (after all, we're saving hundreds of dollars doing this ourselves).

Take care as not to have any mystery screws left over.

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user

We have a be nice policy.
Please be positive and constructive.

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33 Comments

You make a good point about the "mystery screws". A good use for a digital camera is to take progressive photos as you disassemble, with a macro setting or lens if you have it. Then, should a question arise, you can refer to the photos for help. I like using a bowl for keeping my screws as I work. I'm looking for a small stainless steel bowl to use, and I plan to epoxy a large magnet to the bottom to make the screws stay put even if the bowl gets bumped. Thanks for posting this!

5 replies

Even better, use a muffin tin. There are 12 or so individual small bowls that are permanently attached. You can use them in order of disassembly and use the bits in the reverse order as you reassemble. A strip of masking tape along the one edge of each bowls makes a quick and simple labeling system. I learned this simple trick from an airplane mechanic I used to work with. As we took inspection panels and other parts off the planes, you just placed the screws and other fasteners in the bowls. Available at any Wal-Mart, Target or grocery store.

I use a egg box (carton?) for 24 eggs. I wrote the numbers from 1 to 24 in the bottom of the bowls. And sheet of paper in which I write the number of the bowl and What I out in it. Hm. Took a Picture of it, but can't seem to attach a picture with the mobile site.

Earlier I saw an instructable for a loose screws magnetic Altoids round can.

Wolfrick It's easy to make a quick sketch of the equipment your are disassembling too. It is a technical's usual practice to make sure things will go the right places again... I've learned it from a friend who's a CASIO technician, and show this to a Japanese teacher from CASIO JAPAN... The guy never thought it could work so well... Warmest Regards dudaott

Good job on your instruct. Thank You. Now to pull apart my Toshiba. This should be fun.

user

Heh! I like your Chinese soldering iron. Tai hao.

1 reply

Ni Hao!

That's the instructables iron ;) It's a Hakko something or other - I think it's a Japanese company/brand but very well may be manufactured in china :p

Your profile says mechatronics student.... what school? Any sweet robots?

I did this one on a Dell 5150 with a 15" UXGA screen. It can be very very tricky to get that reflector back into place because you've got the lamp in there and don't want to break it. Meanwhile, you need to slip it around the thick (quarter inch) glass behind the LCD so that the light shoots up through the glass. The lamp has high voltage so you want to make sure there are no exposed wires. Those silicone rubber end caps might be torn after you get the thing apart. Bottom line, it can be challenging and you need good eyes and careful fingers to get it all back together just right. I felt lucky to have been successful. I got my LCD out and on the back it said "DO NOT TOUCH WHITE TAPE --- SENSITIVE AREA." Unfortunately, I had touched that tape when I flipped the LCD over to the back. Fortunately, it does not seem to have been damaged. Look up CCFL (cold cathode fluorescent lamp) to find a supplier. You should not need to spend more than $15 + $7 shipping. But I would strongly recommend ordering new end caps and wire to make the job easier and safer. You'll still save at least $100 in labor.

1 reply

Good tip.  The LCD doesn't seem to be damaged because if you took off the white tape, there is a thin ribbon cable there.  This cable contains millions of tiny wires (3 per pixel) and at one point, right before it goes into the LCD, becomes so packed the wires seem to come together into a rectangle (they're indistinguishable).  They don't want these to break or short.  However, if you're careful, I found this cable can survive quite a bit of bang. =P (I took apart one of those LCDs completely).
By the way, it's a diffusion panel, made of mostly plastic, not glass. xD
Ryan

so thats what makes the screen all bright. but wouldnt a bulb make the lighting uneven (im not questioning ur method im Q'n the designers of lap top)

4 replies

Fluorescent tubes are used for a few reason.... Here's 3: 1. Cost 2. Energy Requirements 3. Uniform Output So, by having low energy requirements, you save on battery power and can use a smaller pack - which saves on cost in that area. The bulb itself is cheap, but the inverter is a little more expensive. Fluorescent tubes have a pretty uniform light output - so I'm not sure why you'd think it is uneven. Perhaps you're thinking it to be more like an incandescent?

How do they dim the bulb? cause with a standard florescent bulb you cant just lower the voltage right?

the bulb never dims....the LCD matrix does all the work.

Opps didnt read #8 so the glass diffuses the light evenly i thought they just like had a a bulb going across the screen and that would make it uneven (i have 6 hour jet lag at the moment so im not thinking strait JSYK)

I also have a Dell 17" Monitor built by the Benq for Dell The inverters in these monitors are always failing because of a design flaw, or rather cheap out. There are 4 transistors that are really hard to get that fail because they are not on a heatsink and wear quickly. Anyhow I decided that it was not worth fixing the inverter and instead found a couple of old point of sale touch screen machines. (486 mi-cos yuk) they had a really nice modular inverter that sported just 5 pins kinda like a square chuck of black epoxy with pins sticking out. these things are great it is too bad they don't use them today anymore but then again they are manufactured in Canada so go figure. if you happen across any of these old point of sale machines it is worth digging out the inverter module because you never know when you are gonna need 1500 volts... Now the monitor is brighter then ever and it did not cost me anything to fix it.

1 reply
user

i replaced one with different transistors it worked and won't go again (better transistors)

i Got Myself an Old laptop With a Broken Screen, I Opened the Screen And Took Out the Backlight And the Inverter, Coincidentally I had another Old laptop,That Was A Similar Model,It had the Same Inverter And Cable,So I Tested the CCFL tube from the laptop with the broken screen and it worked,The Inverter+CCFL Worked Like a charm,Now I am Making Myself a lamp,I got that thing to run off of a 9V Battery,And a 13V Power source.

Before buying your replacement light,measure it!I found there are big differences in what they say the size is and what it really is.Example inspiron 1200 is said to have a 15 inch when its really 11.5!The light sellers even have it on their sites as 15 so double check!