Paul Patience, P.Eng, PMP, LEED AP
After 3 years with my Sony
WegaKF42WE620, I found the screen looked splotchy in some areas.
After extensive reading in the various forums, I found many people talking about
their various problems.
Some had blue, yellow, pink, or whatever blobs on their screen. Some had what
looked like fingerprint smudges on their screen. Others had squiggles and lines.
Some of these problems are due to the LCD matrices growing images within their
matrix, but many of the problems seem to be due to the fact that dust is
actually collecting on the optical elements.
The LCD Projection TV's have an inherent problem with dust getting into the
The first approach to these problems
is to ensure that the optical elements are free of dust.
In order to do this, a disassembly of the optical driver assembly is necessary.
To perform this work, I highly recommend that you have patience and careful
repair practices to ensure that you do not damage your TV set.
The following procedure is not for the faint of heart and applies to a Sony Wega
KF 42WE620. Many similar Projection LCD TV's will follow the same procedure.
Disclaimer and Limitation of Liability
By entering this site, you hold this site and
it's affiliates not legally responsible for any damages due to advice given
here. This site and it's affiliates takes no responsibility for consequences of
any actions that arise from advice given. Any opinion is given with information
provided by you and can not be taken as absolute. This site and the information
and materials contained therein are provided "as is". All repairs should be
undertaken by a competent and qualified technician. By using this site, you
understand and agree that all advice given and followed are at your own risk and
do not hold this site or it's affiliates responsible for any damages. This site
makes no representations or warranties of any kind regarding this site or its
operation, contents, information, advice, or materials.
If your TV no longer works or something is wrong after attempting
the following, DO NOT CONTACT ME.
I am not in the business of TV repair, there are people that get paid
for that work.
If you are having trouble understanding what is written below or a
procedure I have described,
then you should not attempt this repair
It is VERY EASY to break these components as they are very delicate and
not meant to be serviced by the average consumer.
0) UNPLUG THE TV. DO NOT ATTEMPT THIS WORK WITH THE TV
PLUGGED INTO A POWER OUTLET.
1) Remove the back lower panel.
2) Remove the front lower panel below the screen area. There are 3 pressure fit
snaps that hold this panel in place as well as 2 thumb screws from the back of
the TV on either side.
The pressure fit snaps are VERY snug and you need to get your hand
behind the cover to unsnap them without breaking or unduly bending the
Make sure you keep the front cover coming straight out and not twisting
3) Remove the lamp from the front of the TV and disconnect the power light
circuit card in the front as shown below.
4) Remove the fan and large metal plate from the
back of the set and slide out the electronics section as pictured below.
5) To remove the optical assembly, the large black item as shown below, there
are 3 screws that can be seen from the back that are down 3 channels of the
assembly. You will need an extra long philips screwdriver to get to these.
Disconnect the fan connectors and front lamp cover switch connector as
shown disconnected below.
6) After pulling out the Optical Assembly, remove the fan on
top, pictured below.
7) To clean this fan unit, I cut a diagonal off the
end of a ball point pen housing and inserted it into the vacuum as shown
in the image below. The image above is the cleaned unit and the image
below is the dust after about 1 year since the last time I cleaned this
unit. Our house is very clean but you can see that the unit still
collects a lot of dust.
8) After removing the lamp fan, also remove the angled
plastic top plate above the LCD matrix assembly and the plastic form on
top of the optical assembly, this is in the center of the top of the
unit as pictured below.
9) The next step is the most delicate, DO NOT FORCE ANYTHING.
10) The 3 ribbon cables in the top centre of the optical assembly
connect the 3 red/green/blue LCD matrix units. You can see these ribbons
in the picture below.
To disconnect the ribbon cable you must turn up the small brown wings
sticking out from under the cable at the connector.
Use a very fine small screwdriver to bring one of the flaps of the brown
ribbon holders up. This will release the ribbon and allow it to be
easily removed from the socket.
Disconnect all 3 ribbon cables.
11) To remove the LCD matrix, prism and lens assembly,
you must remove the 4 black screws from the front of the unit as well as
4 larger silver screws next to the black screws.
The picture below shows the unit removed with arrows on one side showing
the back of the holes where you have to remove the screws.
Do not remove the silver screws holding 2 straight metal plates around
the front of the large round lense unit.
After removing all 8 screws, the unit can slide out. Tuck the ribbons
down before sliding the unit out from the main optical assembly.
12) The next task is to clean both sides of the 3 LCD
matrix units as well as the 3 prism faces. The picture below is
unfortunately not in focus but shows the areas that need to be cleaned.
Do not try to remove the LCD Matrix units held on by 3 screws each.
You will misalign your TV convergence!
mounting on the steel plate that connects to the prism plate is very
delicate with plastic connectors at the corners.
I almost broke one of them trying to take the LCD matrix off. I
recommend taking a cue tip and using a needle nose pliers, pull off some
of the cotton swab to make the cue tip thin enough to get between the
matrix and the prism. Be careful not to leave any cotton strands behind.
You can use a clean cotton t-shirt to clean off the exposed side of the
LCD matrix units as well as the rounded lense cover.
DO NOT USE ANY SOLVENTS OR CLEANERS ON THE LENSES or LCD's. There are
coatings that can be easily removed with any type of cleaner.
13) Remove the top circuit board from the main optical
assembly, there were 3 screws.
14) Remove the flat black plastic cover on top of the main optical
assembly unit. The picture below shows the circuit board and cover
removed from the main optical assembly.
15) The next step is also a very delicate procedure
and must be done with care. The 3 light focusing lenses and 3 colour
filters still in the main optical assembly must be cleaned.
Referring to the picture below, the white arrows show 3 small screws
holding each colour filter in place. I recommend proceeding with only 1
at a time so that you do not get them mixed up when replacing them.
Remove the small screw at the top of the filter and remove the VERY
delicate filter unit. Clean both sides with a piece of cotton and set it
The Green filter has an extra filter behind it that must also be removed
and cleaned. The yellow arrow below shows the screw and bracket holding
that filter in place.
16) After cleaning a filter and before replacing it,
use a piece of cotton cloth and clean the round light focusing lense
behind the filter as shown by the blue arrow in the picture above.
A more close up, albeit out of focus, picture of this area is shown
17) The green arrow in the picture above points to the
light tunnel that the lamp bolts against. You should clean this VERY
well. I use high grade 100% alcohol to clean this face, not rubbing
alcohol as that is mostly water and will not properly clean. I noticed
there seemed to be quite a film built up on this face. Anything left
behind will be BURNED onto the glass so I highly recommend that this
face be VERY clean with absolutely NO fingerprints or anything else left
18) There is another fan on the bottom of the main
optical assembly that should be cleaned as best possible.
This fan blows air through the LCD matrix and filter area as shown by
the white arrow in the picture above.
A close up of the fan is shown below. You will be able to see this in
the cavity behind the blue filter shown on the right above.
19) After cleaning and vacuuming the unit, replace the
LCD matrix, prism and lense unit, reconnect the ribbon cables, reinstall
the flat black plastic cover.
20) Reinstall the top circuit board as well as the lamp fan and slide
the unit back in place. Don't forget to feed the front power light
connector back through the front hole.
21) Screw the main optical assembly back onto the TV frame with the 3
screws. You will notice in the picture above step 12 that you can see
these 3 screws still attached to the matrix/prism/lense unit.
22) Reconnect the lamp fan electrical connectors, and the front lamp
safety switch connector. Put the cable harness back in the holders and
23) Reconnect the front power light connector and slide the unit back in
24) Re-install the main lamp in the front and replace the protector
25) Snap the front cover back on and tighten the rear thumb screws.
26) Push the electronic assembly back in place in the TV and replace the
PC style fan and metal support plate in the back of the TV.
27) Now turn on your set before you put on the back
cover to make sure that your TV works. Hopefully you will not have
broken anything or forgotten to reconnect anything and your picture will
now look as good as new.
28) If all is well, replace the back cover, sit back and enjoy. If not,
time for you to troubleshoot and figure out what you missed.
If you really want to mess with your TV, here
is a Service Manual for a similar model, the KF42WE610.
I do not know what all the settings do so this is a user beware warning.
Make sure to record all of your settings before making any changes.
For other manuals, try this
If your TV no longer works or something is wrong, DO NOT CONTACT
I am not in the business of TV repair, there are people that get
paid for that work.
If you are having trouble understanding what is written above or a
procedure I have described,
then you should not have attempted this