How to Replace Your Laptop's Backlight

by trebuchet03 in Circuits > Computers

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How to Replace Your Laptop's Backlight

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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.

Parts and Supplies

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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

Disassembly

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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

Desolder Old Bulb

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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.

Solder New Bulb

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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 ;)

Trim Bulb

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

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").

Testing

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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.

Attach Reflector Assembly to Glass

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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.

Reassembly

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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.