There has been a large amount of chatter on Techlore about Sony
convergence ic problems. Luckily Most Sony projection tv's no matter
what model you have should be similar to my explanation below, Since
Sony rarely fully re-engineers a tv what I am about to say will apply
to most Sony projection TV's. A service manual is generally not needed
to perform the repair.
WARNING! If you don't have any electronic
experience this is not for you, I assume no liability for any harm that
may come to you or your tv. Perform this procedure totally at your own
risk. High Voltages exist in your tv and on the boards I am going to
talk about, and can have high voltages on them even after the tv is
unplugged.
What has happened to your tv:
What has normally happened is that the convergence output driver ic's
either one or both of them has shorted. Causing your picture to be
un-converged, The Symptom of your failure can take on many different
looks, so one explanation of what the failure looks like will not be
adequate. It will be basically one or more (red,Green,Blue) crt's are
not aligned correctly, and colored shifted, and distorted picture of
some kind will be seen. Auto focus will not fixit and may even make it
worse. When these ic's short, they can cause one or more pico fuse to
blow. Allot of people ignore this part of the repair and get
themselves into trouble. Please listen to my warning, and make sure
you check these fuses!
About the boards:The
two boards we will be working with are the "D" and "G" boards. They
will have a big "D" or "G" stamped into them. On most models the "D"
board will be to the center left of you when looking from the back.
The "G" board will usually be to the left of the "D" board and
standing vertically. When removing the board make a mental note of
where all the plugs go. The Flyback (the big gray transformer near the
back) has a fat red wire coming out of it. To remove this wire push
down and twist on the distribution block side. Don't try to remove it
from the flyback side, you can damage the flyback. There is a focus
wire going upto the focus block as well, pull the wire straight out of
the focus block side. But if you have enough room to work behind your
television you can leave the red and focus wires in the tv, just flip
the board over at the television after removal.
The Parts:The
parts you will need are two ic's that are referred to as STK ic's. This
is in reference to the first three letters of the part number. You
will also need some pico fuses. The pico fuses are little yellow fuses
that look like resistors. When they blow, they will show no physical
sign of failure. The amperage rating will be printed on the fuse. For
example a 5 amp fuse will have the number 5000 on it. A 3.15 amp fuse
will have the number 3150 on it. You will need to use an ohm meter to
test these fuses.
If your set uses either STK392-110, or STK392-120, you should replace
them with a higher wattage part; either the STK392-150 or STK392-180.
Since this is a very prolific problem, there are allot of companies
that make cheap bad ic's that can be purchased usually for around $6.00
- These replacement ic's are BAD, they will FAIL on you again. I have
had allot of experience with this problem, please listen to my warning!
Only get a set that is from a reputable manufacturer. If your ic part
number is something other than the ones I mentioned above, ONLY use the
EXACT same part number for replacement. The part number is boldly
printed on the part.
The Location of the parts;
The stk ic's are on the "D" board, attached to large heat sinks, When
looking from the back you can see the heat sinks but the part's
themselves will be pointing away from you and hard to see without
removing the board, or using a mirror to look at the part numbers. The
fuses are generally located under the fins of the heat sinks. There are
several of them and vary by model. On the "G" board there will be two
yellow pico fuses near the connector going to "D" board. These fuses
provide power to the stk ic's you must check these as well.
The Repair:
When replacing the STKs make sure you use heat sink compound on the
back of the ic's before installing them. Also as a rule of thumb, screw
or clamp the ic's down to their heat sinks before you solder the pins.
Replace any blown pico fuses and re- install your boards. When you turn
your set on it may still be out of convergence due to many factors. Try
pressing the auto focus button on front of your set. If this does not
work, you will need to do a convergence. Please see my article "Sony
Convergence Procedure" to complete this part.
Possible Problems after the repair;Many
things can happen during your repair, the most common problem and one
that even I - an experienced tech still have problems with are not
plugging in all the wires. This will cause various strange problems. So
if the set acts differently than It did before. First suspect that you
have missed a wire. Don't assume that you got all the wires in. it is
extremely easy to miss one. I have had people and techs tell me "I am
sure I plugged in all the wires" but when I investigate a little
further we find that wire that was hidden behind something else and
once we plug it, all will be well. Another issue you need to be aware
of is if you are in convergence mode and you cannot move one of the
colors in either vertical or horizontal directions. Re-check you pico
fuses and solder. 99% of these problems are due to either shorted pins
or a missed pico fuse.