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KDL-55BX520
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53
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1.25 MB
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Service Manual
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Device
TV
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kdl-55bx520.pdf
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Sony KDL-55BX520 Service Manual ▷ View online

KDL-55BX520 28
SECTION 4 - TROUBLESHOOTING
2X Blink - Main Power Error
A loss of REG12V from the power supply triggers this protect 
event. This symptom is usually remedied by replacing the power 
supply board. If the error continues after the power supply board 
is replaced, suspect excessive loading which is causing the power 
supply to shut down. This is usually caused by a failure of the Inverter 
circuits. Unplug the Inverter and turn the TV back on. If a 6X error is 
displayed, the inverter (or LCD Panel) must be replaced.
3X Blink- DC Regulator/Audio Error
The REG 5V and D3.3V source originating on the Main Board is 
monitored for low-voltage conditions by the CPU. A failure causing a 
3X shutdown would require replacing the Main Board.
5X Blink - TCON Error
A communications error with the timing control circuits (TCON) has 
occurred. 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
If the Inverter circuits fails to generate high voltage or one or more 
of the backlight lamps fails to light, the television will shut down 
and display this diagnostics error. Observing for the presence of 
backlighting is crucial in determining which component is likely at 
fault.
If the backlights turn on before the 6X shutdown occurs, it is safe 
to assume that the inverter circuits are functioning and one of the 
lamps failed to ignite. Replacing the LCD Panel is necessary. If 
the backlights never turn on before the 6X shutdown, the inverter 
has failed. If the inverter is available for replacement, replace the 
Inverter. If the inverter is not available, replace the LCD Panel.
7X Blink - Temperature Failure
A digital thermometer IC located on the main board provides a 
temperature reading of the chassis and LCD Panel. If the temperature 
exceeds a pre-determined point the TV will shut down. If this problem 
occurs immediately at turn-on, the temperature sensing IC has failed 
and replacing the main board is required. If this occurs after the TV 
has been running for a while, check for ventilation issues that could 
cause the TV to run hotter than normal.
KDL-55BX520 29
SECTION 4 - TROUBLESHOOTING
DIAGNOSTIC CODE DESCRIPTIONS
The Diagnotic Table provides an overview of the number of times the Standby LED blinks and the possible location. To access the Triage 
documents for the models listed in this manual, login into the Sony Authorized Servicer Portal at 
www.sony.com/asp
.
Diagnostic Item
Diagnostic Item
Description
Number of times 
Standby LED blinks
Possible Location
MAIN_POWER
Main Power Over Voltage Protection
2
G17 Board
BALANCER
Panel Balancer Error
4
NOT USED
PANEL
TCON Error
5
LCD Panel
BACKLITE
Backlight Error
6
LCD Panel
G17 Board
TEMP_ERR
Temperature Error
7
A Board
Ventilation
DC_ALERT AUD_PORT
DC Alert 
Audio Error Detection
A Board
3
FIGURE 4-3.  DIAGNOSTIC TABLE
NOTE: To provide information to customers regarding how to use their TV features or FAQs, refer the customer to the Sony esupport webstie 
at 
http://esupport.sony.com/.
KDL-55BX520 30
SECTION 4 - TROUBLESHOOTING
VIEWING THE SELF CHECK DIAGNOSTIC HISTORY
It is possible to bring up past occurrences of a failure for confirmation on the Self Check diagnostic history screen. This feature is useful for 
failures which are intermittent or when the customer is not sure what is causing the television to shut down. 
1.  TV must be in standby mode (Power off).
2.  Press the following buttons on the Remote Commander within a second of each other: 
 
DISPLAY   
 Channel  5  
 Volume  -  
  POWER
 
   
 
 
 
 
          * NOTE: This differs from accessing Service Adjustments Mode (Volume +)
Back
<<
002 MAIN_POWE
001
 001 indicates an error was detected
003 AUD_PORT
000
 000 indicates no error was detected
003 DC_ALERT
000
004 BALANCER
000
005 TCON_ERR
000
005 HFR_ERR
000
005 P_ID_ERR
000
005 PANEL_POWE
000
006 BACKLITE
000
007 TEMP_ERR
000
000131 00010 00131
[Menu] Exit
Panel Operation Time by Hour (max 99999)
Boot Count (max 99999)
Total Operation Time by Hour (max 99999)
SELF CHECK
KDL-55BX520 31
SECTION 4 - TROUBLESHOOTING
CLEARING THE SELF CHECK DIAGNOSTIC LIST
Since the diagnostic results displayed on the screen are not 
automatically cleared, always check the self-diagnostic history after 
you have completed the repairs to be sure you have cleared the 
result display to “0”.
1.  To clear the Error history and Error count: Press the 
Channel  8  
 Channel  0 .
2.  To clear the Panel operation time: Press the Channel 
7  
 Channel  0 .
EXITING THE SELF CHECK DIAGNOSTIC SCREEN
1.  To exit the Self Diagnostic Self Check screen, turn off 
the power to the TV by pressing the POWER button on 
the remote or the POWER button on the TV.
TEST POINTS
“Power and Control Block Diagram” on page 36
 contains the 
board-to-board connector and pin information to identify voltages, 
signal and control lines for troubleshooting purposes. All critical 
voltages and control signals are easily accessed at the power supply 
board. Use this drawing in conjunction with the previously discussed 
troubleshooting  techniques  and  flowcharts  available  in 
Section 
5 - Flow Charts and Diagrams on page 32 
for testing operating 
voltages and control signals.
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