Sony TCON Schematic

TCON Troubleshooting and Replacement

Introduction

Sony will be announcing the availability of limited TCON replacement boards to service LCD panels beginning
with certain models going back to 2006. For many years technicians have been asking about the availability
of these components. In the relatively small percentage of units that experienced a failure of the TCON board,
replacement of the entire LCD panel was mandatory. This is not only costly from a warranty standpoint but it also
makes it near impossible to justify an out-of-warranty repair since the replacement LCD panel can easily cost 2/3
or more of the price of the entire television.

The reason why TCON assemblies have not been available in the past was due to the large amount of correction
data stored within NVM data points located on the board. Tolerance issues during the manufacture of the LCD
panels required white balance, gamma, and uniformity corrections to compensate for these inherent production
issues. There are other items for correct panel operation but the above mentioned items are the most critical.

Over the years, panel tolerances have improved dramatically and variances in uniformity have been reduced to the
point where a TCON loaded with average data results in a satisfactory picture when installed as a replacement on
a panel. Most Sony television models also have white balance data located on the video process board. Although
the TCON is loaded with data to properly white balance the panel, the ability to adjust white balance from the B
boards is present to compensate for shifts in white balancing due to panel aging and this mainly involves color
balance shifting of the fluorescent backlight lamps which tend to shift towards the magenta spectrum as they
age.

The main issue with previous LCD panel designs was the uniformity adjustment data. Due to variances across
the LCD panel it was impossible to achieve even white balance across the screen. For this reason, small zones
across and down the LCD panel required individual white balance compensation. Without this correction the
picture would have “blotches” of different color in sections of the screen. Better tolerances during manufacturing
have reduced the reliance on this uniformity data and allows for the replacement of TCON boards with satisfactory
results.

As mentioned in the beginning, not all LCD panels will have a TCON board available. This will mainly be
determined by availability of components from the LCD panel vendor along with decisions by Sony based on
sales quantity and failure history of the TCON assemblies. Most technicians have experienced the use of the LCD
panel replacement manual. This manual was created to proper identify the type of LCD panel installed in a unit
based on its serial number since some units changed to a different type of LCD panel during the manufacturing
production. The plan is to use this document to also provide TCON information and whether one is available and,
if available, which TCON is the proper replacement part for that particular panel.

LCD Panel Basics

LCD panels have steadily evolved over the last several years. New designs of the physical structure of the LCD
crystals have greatly improved the contrast ratio and viewing angle. Quicker response times and increased
refresh rates have helped to reduce the motion “smear” associated with LCD displays. Backlighting design
has also aided in producing a picture with color temperatures to make the images as true as possible. With all
these design improvements, one aspect of the LCD panel remains relatively the same: Processing of the video
signal.

Figure 1 illustrates a typical LCD panel and the associated video processing circuits as found in the WAX3
chassis. The various formats and resolutions of video signals are processed on the BU1 board. All video signals
exit the video processor in the native resolution of the LCD panel. In this design, the resolution is for a 1280 by
768 at 60HZ refresh rate panel. 48 horizontal lines are discarded to match up to the 720p resolution of the ATSC
specifications so the video will exit as 720p.

The LCD panel used in this model processes 8-bit RGB video data. Before the video information can be sent

to the TCON board it must be converted to a format that allows for practical and noise-free transmission. The

LCD PANEL

GATE

DRIVERS

SOURCE

DRIVERS

LVDS

TRAN SMITTER

BU

LVDS

REC EIVER

TCON

VIDEO

PROCESS

TIMIN G

CONTR OL

large number of parallel lines to transmit the 8-bit RGB data would need to be sent on differential lines for noise
reduction. This would require 48 lines just for the video. The TCON circuit also requires B+, ground connections,
a communications bus, sync, and a clocking line transmitted differentially so we can see that up to 100 lines
would be required. The practical way to transmit this information is to convert the parallel video data to a serial
stream and this is accomplished by the Low-Voltage Differential Signaling (LVDS) transmitter.

The LVDS transmitter contains a circuit to serialize the parallel data. The parallel video information along with
sync and clocking data are transmitted via twisted line pairs. Depending on the logic level, current is sent along
one or the other of the twisted pair of wires. The receiving end of the wires is loaded with a resistor (usually
around 100 to 120 ohms). The receiver detects the polarity of the voltage drop across the resistor to determine
the logic level. The current level swings in the wire are about 3ma with a voltage differential of around 350mv.
This allows for transmission of the video signal with minimal EMI.

The LVDS receiver on the TCON board converts the serialized data back to parallel. This data is processed by
the timing control IC to allocate the RGB data into serial streams for processing by the LCD panel. The LCD
panel contains shift registers and drivers for all of the rows and columns of pixels on the panel. The drivers are
mounted on flexible circuit boards and bonded to the top and side of the panel. Without this arrangement the
TCON would require an IC and connectors to transmit on 4,560 lines!

All of this is accomplished by the TCON board. The term “TCON” is short for Timing Control. Other LCD panel
manufacturers may have a different name for this particular circuit but the term used by Sony will always be
TCON.

FIGURE 1

LCD PANEL VIDEO TIMING

Diagnosing a Failed TCON

DEFEC TIVE

DRI VE IC

DEFEC TIVE

TAB BON D

OR DRIVE IC

DEFEC TIVE

TAB BON D

OR DRIVE IC

In order for this concept to move forward successfully, it is important that the service industry be able to properly
identify the symptoms of TCON issues to avoid unnecessary service calls and repair costs. Accurate analysis of
TCON failures will reduce costs significantly (both in parts costs and time) when warranty repairs are involved
and will reduce the number of COD repairs that are lost.

A good approach when determining a TCON failure is a good understanding of which symptoms ARE NOT
caused by the TCON. Examples are as follows:

Video Process Failures: All video inputs received by the video process circuits are handled on a frame-by­frame basis. The video frames are converted and scaled to 8 or 10-bit RGB information. It is virtually impossible
for the video process circuits to cause a problem on a specific area of the screen. Failures on this board usually
appear as distortions, color level shifts, video level shifts or noise that involves the entire picture. The TCON can
generate symptoms that appear to be video process related but the video process circuits cannot produce the
symptoms of a failed TCON circuit.

LVDS Cable Failures: Although problems with the LVDS cable or connectors can generate symptoms of TCON
failures this usually tends to be intermittent and wiggling of the connectors will usually provoke a change in the
symptom on the screen. LVDS cables and connectors have become rather robust over the past few years and
most problems are caused by technicians who damage them and this is generally quite obvious upon close
examination.

LCD Panel Failures: Some LCD panel failures could possibly be mistaken for TCON issues. Other than damage
to the LCD glass, most panel failures are isolated to a particular area of the screen. Since the TCON disperses
the pixel data to groups of line and column drive IC’s situated on the outer edges of the panel, it is unlikely that
more than one of these IC’s would fail at the same time. Multiple columns of stuck on or stuck off pixels are,
therefore, more likely to be the fault of the TCON circuits. The same applies to a single row of lit or unlit pixels.
The TCON simply cannot cut out a single line of information. Figure 2 illustrates some typical symptoms of
failures that are caused by the LCD panel.

FIGURE 2

LCD PANEL FAILURES

TCON Failures

RELEASE TABS

Failures in the timing control circuits of the TCON can produce symptoms of absolutely no video or generate lines
and patterns that usually cover all or a substantial part of the screen. Determining if the TCON is the cause of a
“no video” condition is a bit more difficult since there are no indications on the screen to analyze.

Troubleshooting a “DEAD” TCON

Many of the Sony television models over the last few years will detect a TCON that has completely failed. The
communications data between the video process circuits and the TCON will cease to communicate if the TCON
fails completely. This will cause the television to shut down and display a diagnostics code indicating a failure of
the TCON. Not all chassis designs have this feature and it is not found on older models.

The typical scenario when this failure arises is for the technician to bring a video process board to the repair
location. It is usually safe to assume that the problem lies on the TCON board if the replacement video board
does not remedy the problem since it is highly unlikely that a replacement board with the same failure was
received.

One trick to check most TCONS for functionality is to loosen the LVDS connector at the TCON (as shown In
Figure 3) while the unit is turned on. Handle the LVDS connector with care and be certain to fully release the lock
tabs. Gently rock the cable in and out of the connector while observing the screen for any response. Depending
on the chassis, the symptoms of the screen may be gentle white flashes, intermittent colored lines, or a screen
full of random patterns. The idea at this point is to provoke some kind of response on the screen. TCON boards
that have failed will not usually generate any type of response on the screen.

Another helpful procedure is to rapidly heat and/or cool the TCON with hot air devices or circuit coolant and
watch for patterns to appear on the screen.

EXAMPLES OF REACTIONS WHEN LVDS

CABLE IS PARTIALLY REMOVED

FIGURE 3

LVDS CONNECTOR

Figure 4 illustrates 2 examples of a loss of control data to the drive IC’s. In the first example, an entire group of

DEFECTIVE

TCON DATA

OUTPUT

DEFECTIVE

TCON OR LOOSE

TCON TO PANEL

CONNECTING

CABLE

column drivers has lost the data stream for red. The second example involves the complete loss of drive data
for all RGB information to the right side of the screen. This is sometimes caused by the flat cable connecting the
TCON to the LCD panel coming loose. The area of missing video can be dark or completely white depending on
the panel design.

FIGURE 4

EXAMPLES OF TCON FAILURE SYMPTOMS

The remaining illustrations show other TCON failures that have been encountered in the field. The idea is to get
a grasp of the concept of TCON induced failures to avoid unnecessary parts replacement.

SYMETRICAL PATTERN

OUTPUT FAILURE OF MULTIPLE DRIVERS

CORRUPTED UNIFORMITY ADJUSTMENT DATA

TCON Replacement

REMOVE WIRE

HARNESS FROM

THIS RETAINER

REMOVE 6 MACHINE

SCREWS SECURING

POWER SUPPLY SUB-

C

H

ASSIS AND SWING

DOWNWARD

UNPLUG

CN6600

REMOVE

GROUND CLAMP

SCREW AND

UNPLUG LVDS

CONNECTOR

In many instances, replacement of the TCON board will be relatively straightforward. In some cases, other
boards may have to be loosened or removed to allow access to the mounting screws and clearance to remove
the TCON. The issue of most concern is keeping track of the heat transfer pads, standoffs and insulators. The
TCON is heavily shielded and it is easy to have one or more of these components accidentally fall out of the
assembly when removing.

TCON assemblies that use multiple heat transfer pads must be removed slowly and every attempt must be made
to keep the shield and circuit board together as they are removed from the unit. Check for any service bulletins
pertaining to the model and panel design that contain the subject line of “TCON heat transfer pad locations” for
pictures to show the proper location of these components.

In this example, the removal of the TCON board from a KDL40XBR6 is demonstrated. It serves as an excellent
example since it requires the partial removal of the power supply board along with containing 6 heat transfer
pads, 3 insulating pads, and 5 insulated standoff pads.

Referring to Figure 5, unplug the LVDS connector from the TCON. Remove the screw from the LVDS cable
ground strap so the cable can be moved away. Unplug CN6600 from the inverter board and remove the harness
from the retainer as shown. Remove the 6 black machine screws securing the g board sub-chassis to the panel.
Pull the top of the G board towards you and downward to allow access to the bottom screws securing the
TCON.

FIGURE 5

TCON REMOVAL PREPARATION

Referring to Figure 6, carefully un-peel the conductive tape from the top bracket taking care not to tear them.

CAREFULLY PEEL THE

ADHESIVE FOIL SHIELDS

FROM THE TOP

BRACKET. REMOVE TOP

BRACKET.

TOP BRACKET

SECURED WITH 12

SILVER MACHINE

SCREWS

Leave the tape attached to the TCON shield. Remove the top bracket covering the gate and source driver
components. This will allow access to the upper flat cable connectors.

FIGURE 6

TCON REMOVAL PREPARATION (STEP 2)

As illustrated in Figure 7, carefully lift the locking tabs securing the flat cables. Leave the flat cables attached to

CAREFULLY LIFT THE

LOCK CONNECTORS

AND REMOVE THE FLAT

CABLES. REMOVE THE

EIGHT SILVER MACHINE

SCREWS SECURING THE

TCON ASSEMBLY

the TCON. Remove the 8 silver machine screws securing the TCON and shield assembly. The TCON board has
an insulating pad between it and the LCD panel that will cause the board to stick. Not much effort is required to
release it. The goal at this point is to remove the board and shield together so as to avoid dropping heat transfer
pads and insulators located between the front of the board and the shield.

FIGURE 7

RELEASING THE FLAT CABLES

If successful, both components should stay together as illustrated in Figure 8. Note the spacers mounted on the

TRY TO KEEP TCON
BOARD AND SHIELD

ASSEMBLY TOGETHER

WHEN REMOVING

OBSERVE FOR AN Y

INSULATING PADS

STUC K TO THE CHASSIS

AND NOTE THE

LOCATION

back side of the board. These will need to be transferred to the replacement board. In Figure 9, the insulating
pad can be observed sticking to the chassis.

FIGURE 8

TCON REMOVAL

FIGURE 9

INSULATING PAD STUCK TO CHASSIS

Referring to Figure 10, the assembly is laid with the shield down on the work surface. Lift the circuit board upward

HEAT

TRANSFER

PADS

INSULATING

PADS

slowly while observing the location of the heat transfer and insulating pads. In most cases the heat transfer pads
will remain attached to their appropriate IC’s and the insulating pads will be stuck to the shield. If anything falls
off, use the illustration to return them to their proper position. Transfer all heat and insulating pads along with the
flat cables to the replacement board.

FIGURE 10

SEPARATE TCON FROM SHIELD

Once the components have been transferred to the front of the circuit board, attach the shield and flip the

SPACER

PADS

CONDUCTIVE

SPACER

assembly over as shown in Figure 11.

Transfer any spacers or insulation pads to the replacement board.

FIGURE 11

TRANSFER SPACERS AND PADS

TEMPORARILY

SECURE TCON

TO SHIELD

WITH

ELECTR ICAL

TAPE

Temporarily secure the TCON board to the shield with electrical tape as shown in Figure 12. This helps in
preventing movement of the circuit board while installing the assembly back onto the LCD panel.

Once the TCON assembly is secured to the panel, insert and lock the flat cables. Plug in all connectors and
secure the G board sub-chassis. Don’t forget about the wire harness that was removed from its retainer.

FIGURE 12

USING ELECTRICAL TAPE TO SECURE TCON TO SHIELD

TCON Part numbers

The following pages contain part numbers for the TCON boards currently available. Please note that some
models use more than one panel type and this is distinguished by the serial number of the unit. If the model is
not listed here, the TCON is not available.

R

R

A

R

R

A

R

R

A

R

R

A

2008 US MODELS

KDL-26M4000

Serial Range

US: 4,000,001 - 4,200,000

PART NUMBE

1-802-613-11 LCD PANEL (26INCH WXGA TFT)
1-857-072-11 (TCON) CONTROL MT BOARD

Serial Range

US: 4,200,001 - 4,400,000

PART NUMBE

1-802-754-11 LCD PANEL (26INCH WXGA TFT)

N

KDL-26M4000 (RED)

Serial Range

US: 4,420,001 - 4,425,000

PART NUMBE

1-802-613-11 LCD PANEL (26INCH WXGA TFT)
1-857-072-11 (TCON) CONTROL MT BOARD

Serial Range

US: 4,425,001 - 4,500,000

PART NUMBE

1-802-754-11 LCD PANEL (26INCH WXGA TFT)

N

DESCRIPTION

DESCRIPTION

NA

DESCRIPTION

DESCRIPTION

NA

KDL-26M4000 (TAN)

Serial Range

US: 4,410,001 - 4,415,000

PART NUMBE

1-802-613-11 LCD PANEL (26INCH WXGA TFT)
1-857-072-11 (TCON) CONTROL MT BOARD

Serial Range

US: 4,415,001 - 4,420,000

PART NUMBE

1-802-754-11 LCD PANEL (26INCH WXGA TFT)

N

DESCRIPTION

DESCRIPTION

NA

KDL-26M4000 (WHITE)

Serial Range

US: 4,400,001 - 4,405,000

PART NUMBE

1-802-613-11 LCD PANEL (26INCH WXGA TFT)
1-857-072-11 (TCON) CONTROL MT BOARD

Serial Range

US: 4,405,001 - 4,410,000

PART NUMBE

1-802-754-11 LCD PANEL (26INCH WXGA TFT)

N

DESCRIPTION

DESCRIPTION

NA