Sony KDL-40EX725 Service Manual ▷ View online
KDL-40EX725 27
SECTION 4 - TROUBLESHOOTING
PROTECTION SHUTDOWN
Self Diagnosis
Supported model
The models in this manual contain a self-diagnostic function. If an
error occurs, the standby LED will automatically begin to flash. The
number of times the LED flashes translates to a probable source of
the problem.
A history of the errors is stored on the Self Check diagnostic page
A history of the errors is stored on the Self Check diagnostic page
as shown in
“Figure 4-3. Sample Self Check Diagnosis Page” on
page 32
. This page can be used to review the failure occurrence
data stored in memory to reveal past problems and how often these
problems occured. If there is more than one error, the standby LED
will identify the first of the problem areas. If the Self Check screen
displays a 0, no error has occurred.
STANDBY LED FLASH COUNT
Ambient Sensor/
(IR) Infrared Receiver
Picture Off /
Timer LED
Standby LED
Power LED
FIGURE 4-1. LED DISPLAY
2 times
5 times
LED ON 0.3 sec.
LED OFF 0.3 sec.
LED OFF 0.3 sec.
LED OFF
3 sec.
FIGURE 4-2. BLINK COUNT
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SECTION 4 - TROUBLESHOOTING
2X Blink - Main Power Error
A 2X protection mode blink pattern can be activated due one of the
following defects.
● Loss of REG12V (LVP)*
● Loss of -125V (Single Line)
● Excessive -125V Level (OVP)*
● Loss of Power-ON Signal
● Excessive PFC Voltage (OVP)
● Excessive PFC Temperature (OTP)
*Low Voltage Protection (LVP)
*Over Voltage Protection (OVP)
*Over Voltage Protection (OVP)
A loss or excessive condition of the REG12VDC secondary voltage
from the main power supply IC6351 will cause a 2X blink pattern on
the standby LED. The 12Vdc can be checked at CN6704/pin 16.
If the measurement is 0V or rises above 12Vdc (approaches 15V)
If the measurement is 0V or rises above 12Vdc (approaches 15V)
before the TV shuts down the Power Supply Board is defective.
If approximately 12Vdc is present and remains below 12Vdc before
If approximately 12Vdc is present and remains below 12Vdc before
shutdown then further troubleshooting is necessary to determine the
defective component.
After confirming proper REG12V levels, check the Negative LED
After confirming proper REG12V levels, check the Negative LED
Backlight supply levels. A loss or excessive condition of the negative
supply will cause a 2X blink failure. The voltage level can be checked
at CN6701/pins 1 & 3 before the TV shuts off. There will be 2 to 4
wires (Red & Blue) depending on the panel size. All individual wires
should be checked for proper voltage level. In normal operation the
voltage level will initially rise to approximately -175V and then should
regulate down to between 89V and 125V depending on the Backlight
adjustment in the User Menu. If one of the negative supplies is 0V
or rises above -175V before shut-off then the Power Supply Board is
defective, replace it to fix the problem.
A defective X-Reality processor on the Main Board or Switch circuit
A defective X-Reality processor on the Main Board or Switch circuit
on the Power Supply Board will cause a loss of the Power-ON signal
(2X). To determine which component is defective check the Power-
ON voltage level at CN6704/pin 1. In normal operation 3V should be
measured. If the 3V is present before shut-off then the Power Supply
Board is defective. If 0V is measured before shut-off then the Main
Board is defective.
Finally, there are PFC protection circuits on the Power Supply Board
Finally, there are PFC protection circuits on the Power Supply Board
that when activated will cause a 2X blink protection mode. The PFC
circuit is monitored for both over-voltage and over-temperature.
Therefore, if all the previously discussed circuits checkout okay,
there could still be a problem on the Power Supply Board in the PFC
circuit causing the 2X blink. Replacing the Power Supply Board will
fix the TV.
3X Blink- DC Regulator/Audio Error
The Audio error can occur due on of the following error conditions.
3X Blink- DC Regulator/Audio Error
The Audio error can occur due on of the following error conditions.
● Defective DC Regulator on Main Board
● Shorted or Damaged Speaker Connections
● Defective Audio Amplifier (Main Board)
● Loss of AU12V (Open F4200 on Main Board)
● Loss of AU12V (Open Fuse on Power Supply Board)
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SECTION 4 - TROUBLESHOOTING
The first thing to check when a 3X blink protection mode occurs is
the physical condition of the speakers and speaker connections. The
speakers should measure 8 ohms. Shorted speakers or connections
can cause a 3X blink protection mode.
If the speakers and connections check okay, then the defective
If the speakers and connections check okay, then the defective
component is on the Main Board. Either an open F4200, defective
DC Regulator, or defective Audio amplifier will cause a 3X blink
protection mode. In any of these cases, replace the Main Board to
fix this condition.
A defect on the Power Supply Board can cause a 3X blink protection
A defect on the Power Supply Board can cause a 3X blink protection
mode and shut-off. Check the AU12V level at CN6704/pin 14. If 0V is
measure before shut-off the Power Supply Board is defective.
4X Blink – Balancer Error
The 4X error code is only used on models incorporating local dimming
4X Blink – Balancer Error
The 4X error code is only used on models incorporating local dimming
LED backlighting. If a failure occurs on the LD board the TV will shut
down and display this diagnostic code. Models using conventional
non-local dimming LED backlighting do not utilize this error code.
5X Blink - TCON Error
The 5X blink protection mode indicates a communications error
5X Blink - TCON Error
The 5X blink protection mode indicates a communications error
between the TCON Board and the X-Reality microprocessor on the
Main Board. If the TCON is available for replacement, replace the
TCON. If the TCON is not available, the LCD panel must be replaced
since the TCON circuit is part of the LCD panel assembly. In rare
cases a loose or defective LVDS cable could also be the cause.
6X Blink - Backlight System Failure
NOTE: All models will make two attempts to power up before a 6X is
NOTE: All models will make two attempts to power up before a 6X is
activated. The SONY logo (Backlight) may or may not display on the
screen. However, the splash tones will be heard two times. After the
second attempt the TV will turn off and the standby LED will blink a
6X protection mode. (Note: The splash tone may not be heard if it is
turned off or the volume is set to minimum.)
If a 6X blink pattern is activated then a defect has occurred in one of
If a 6X blink pattern is activated then a defect has occurred in one of
the following areas.
● Defective Panel LED(s)
● Defective Power Supply
When troubleshooting a 6X backlight system failure it is key to notice
if the backlights illuminate before the TV shuts off. The following
list shows the possible backlight status and blink pattern and the
possible failed components.
1) Momentary Backlight and 6X
1) Momentary Backlight and 6X
a) Defective LED(s) (LCD Panel Assb.)
2) No Backlight and 6X
a) Replace Power Supply
In most cases, if the Sony logo (Backlight) momentarily illuminates
and the TV shuts off and a 6X is activated than one or more of the
backlight LEDs are defective. The LCD Panel assembly panel must
be replaced for a defective LED. However, before replacing the LCD
panel assembly check for a complete loss of the Negative Backlight
(-89V to -125V) power supply. The -89V to -125V power supply can
be checked at CN6702/pins 1 & 3.
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SECTION 4 - TROUBLESHOOTING
If there is no backlight before the TV shuts off and activates a 6X,
than check the Backlight ON signal from the TV microprocessor and
the Positive (+145V) Backlight power supply from the Power Supply
Board. The BL-ON signal can be checked at CN6704/pin 5 and the
+145V at CN6701/pins 1 & 3.
If the Backlight-ON signal is okay and the Positive Power supply
If the Backlight-ON signal is okay and the Positive Power supply
is missing then the Power Supply Board is defective. However, if
the Backlight-ON is missing then the X-Reality Microprocessor is
defective and the Main Board must be replaced to repair the problem.
7X Blink - Temperature Failure
These models do not display a temperature warning OSD dialogue
7X Blink - Temperature Failure
These models do not display a temperature warning OSD dialogue
box before shutting off and going into a 7X standby LED blink pattern.
The main objective when a 7X blink pattern occurs is to determine
which of the following possible defects is causing the excessive
temperature condition indication.
● Excessive Ambient Room Temperature
● Dust or Debris Blocking the TV Ventilation Apertures
● Defective Temperature Sensor or X-Reality Microprocessor
(Main Board)
The first step is to notice how long it takes the TV to shut off and
trigger a 7X blink protection mode.
If the TV has an actual excessive temperature condition it will
If the TV has an actual excessive temperature condition it will
take a considerable period of time to shut off and indicate a 7X
blink protection mode. This is because it will take time for the TV
components to heat up and for the temperature sensor to detect the
excessive temperature and shut the TV off.
If the TV takes a considerable period of time to shut-off check the
following items:
● The TV should not be located too close to any heating
devices.
● The TV should have at least 4 inches of clearance around
the sides & rear, and 11 inches of clearance over the top to
ensure adequate ventilation.
● Check that all vented areas on the TV are clear of all dust
and debris.
● If the TV shuts off immediately after Power-ON then one
of the following components has failed (Not an Actual
Excessive Temperature Condition).
● X-Reality Microprocessor (Main Board)
● Temperature Sensor (Main Board)
In either case the Main Board must be replaced to fix the
problem.
8X Blink – Not listed in Self Check
8X blink code is mainly used during TV software development. Look
8X blink code is mainly used during TV software development. Look
in TV’s service SELF CHECK for error code history and notice at the
bottom of the list WDT (Watch Dog Timer) error codes, in particular
notice 103 HOST_WDT.
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