Copyright 2009 by Morris Rosenthal -All Rights Reserved
contact info
The printable eBook version of The Laptop Repair Workbook is
now available for download anywhere in the world.
I always pull the battery before I work on any laptop or notebook. The last
thing you need is for your Dell to power up while you're taking it apart.
I'm taking apart this Dell Latitude for the sake of illustrating an example,
but it's not something you normally want to undertake without first
troubleshooting the screen failure. The first challenge for getting into
the Dell and checking connections replacing the screen or backlight is to
find the screws. Like all laptops I've seen lately, the Latitude has four
screws hidden under rubber pads at the corners of the screen.
Some would-be home laptop repair techs give up because they can't get the
rubber pads out. In some instances, as with this Dell, you really need to
dig something fairly sharp and stiff into the cavity to get under the plug.
I used a jewelers screwdriver in this case. Once you remove the rubber bumpers,
you'll expose a regular Philips head screw. Some laptop manufacturers put
a little glue on there to keep the screw from loosening, in this case Dell
didn't, they probably figured it's hard enough just to get the rubber out.
Don't rush into tearing the screen apart without
troubleshooting the video problem first.
Once the screws securing the plastic bezel are removed, you still have to
unsnap it from the body of the lid. If you've never worked on the particular
notebook model before, you don't know where the plastic latching tabs are,
so it's a bit nerve wracking. You can see the main locking tab holding the
screen bezel on this Dell Latitude about halfway down the side of the bezel.
The circuitry to the right of the LCD is the inverter that provides the high
voltage for the backlight.
Sometimes you can locate hidden tabs with a thin screwdriver, sometimes I
just keep a steady force on the bezel and pry. When you locate the sticking
point, if should release if you push in on the bezel at that point to free
it from the notebook lid. Here I'm lifting the whole bezel off our Dell laptop,
exposing the inverter circuit to the right (you can also see it above), which
is a standard placement. The only function the bezel serves is as a cover,
removing the screws doesn't free up any of the components.
The LCD screen is secured to the back of the Dell laptop lid with four screws.
The light grey metal structure you can see on the front isn't actually part
of the LCD screen, we'll be removing it later. It houses the backlight and
the reflector, keeping the whole assembly together as one unit. This Latitude
LCD assembly is a much more modular design than the Toshiba we disassembled
in the last page.
Once the screws are removed, I stood the LCD assembly on the keyboard while
removing the connectors. The first connector I removed was the simple ribbon
cable which delivers the digital video signals (addressing for the LCD matrix)
to the Latitude screen. It's a simple push together connector that I removed
by grasping it right at the connector and gently pulling it out.
Here I'm removing the inverter connector. The inverter circuit powers the
backlight in our Dell, a CCFL (Cold Cathode Fluorescent Lamp), which requires
a high voltage to strike a plasma. CCFL tubes actually have better life
expectancy than the inverters, so most techs will try replacing the inverter
before fooling around with removing the backlight. I illustrate removing
the inverter board from a Toshiba Satellite here.
You can find replacements on the aftermarket fairly easily for most models.
Now we get to removing the grey metal structure that secures the actual LCD
screen to the backlight assembly. The design used a dozen little metal tabs
that are bent into depressions in the white plastic holder, and which are
easily opened with a small screwdriver. Dell also saw fit to tape the units
together on the top and bottom. I just undid the tape on the top and left
it on the bottom as a hinge.The LCD screen from this Dell Latitude utilizes
a nice translucent light panel, in addition to the backlight, The purpose
of the light panel is to spread the light from the backlight equally behind
the LCD for even backlighting.
The CCFL backlight itself is secured over the top of the LCD screen in a
channel with a thin strip of copper tape. The tape is reusable, at least
it held up through this extraction and replacement. Dell really seems to
have a tape thing going on with this Latitude:-) Once the CCFL backlight
is exposed, you can pull back the little rubber insulators on the ends and
unsolder it. Yup, the tube is actually touch soldered to the inverter leads
on either end. Below I show the exposed backlight on a black background.
Assembly is simply the opposite of disassembly.
The printable eBook version of The Laptop Repair Workbook is
now available for download anywhere in the world.