Laptop Deals
Computer Repair
The Laptop Repair Workbook
Starting Your Own PC Business
Questions? Comments?
Copyright 2008 by Morris Rosenthal
All Rights Reserved
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Copyright 2008 by Morris Rosenthal -All Rights Reserved
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The printable eBook version of The Laptop Repair Workbook is
now available for download anywhere in the world.
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Before you start working on any laptop or notebook computer, remove the battery.
It's just too easy to accidentally power up a laptop when you're working
on it, and that could easily spell disaster, even if you don't panic. The
first part of the puzzle when you repair a laptop screen is to determine
what the failure is. We aren't going to do that here, because there's actually
nothing wrong with this Toshiba notebook, I'm just using it for example.
The second step, once you know what you're trying to fix, is to find the
screws to take apart the cover, which houses the LCD and inverter.
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Most Toshiba laptops use four screws to secure the plastic bezel, two at
the top and two on the hinges.The top screws are hidden under some rubber
bumpers, you really need to dig a screwdriver with an edge on it into the
side to compress them enough to get them out. The screws below the LCD on
the hinges are under rectangular paste ins that I needed a jewelers screwdriver
to pry up.
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In all cases, the screws securing the plastic bezel around the laptop screen
had some variety of loc-tite on the threads, and need a good deal of force
to remove. It's critical to pick a screwdriver that matches well so you don't
end up stripping the head.
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Once the screws are removed, we gain access to the LCD with it's backlight
and inverter by prying open the plastic shell. It takes a sharp screwdriver
to get it started unless you know exactly where to push in the snap-together
injection molding. The funny thing about notebook computers is that they
are actually incredibly tough, I've never broken one while working on it,
even when I didn't have a clue how it was put together. Once you pop a couple
of the snaps, you can sight down the crack and see where the others are,
which makes it a lot easier.
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I don't have any particular order for doing this, so I started with removing
the backlight from the top of the LCD. The backlight is secured to the LCD
by two small screws that do require a jewelers Phillips to remove. Laptop
LCD backlights are actually florescent bulbs, with CCFL (Cold Cathode Fluorescent
Lamp) being a favored technology. The average life for a laptop backlight
is on the order of 30,000 hours, or more than three years of 24 hour a day
use. When the backlight in a laptop flickers or fails, it's more likely the
inverter than the CCFL tube.
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Here we have the backlight removed from the top edge of the Toshiba screen
(the LCD is actually manufactured by Sharp). It's a pretty simple design,
one wire goes to each end of the tube, just like a regular florescent tube,
and the inverter produces the high voltage, high frequency energy required
to strike a plasma and keep it lit. This isn't terribly efficient, and newer
laptop computers employ LCDs that don't require a backlight, which helps
a great deal with battery life. The CCFL tube is tacked to the wire at each
end with solder since it's not really intended to be disposable.The inverter
that drives the backlight is a much more frequent cause of failure than the
CCFL tube. The inverters are sold as modules, frequently remanufactured,
for between $60 and $80 for most laptop models that employ them.
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It can be very frustrating to get a lemon version of a laptop that goes through
inverters, particularly when the warranty expires. Removal and installation
of the backlight inverter is actually pretty simple once the shell is open.
Two screws hold this Toshiba inverter to the case, and there are also plastic
guide pins for aligning it. Two plug in connectors, one for the LCD backlight
(below, left) and one for the inverter control (below), complete the installation
or removal. The final picture in the series is really just a reminder not
to forget the LCD ground when you reinstall the LCD in the shell.
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