Monday, January 04, 2016

PANASONIC TX-42AR400 Service mode and led blinking codes – LCD Television repair

Category: Lcd Television repair  

Contents of this article 

  • How to enter to service mode 
  • Led blinking code 
  • LCD panel test procedure 



PANASONIC TX-42AR400

Service Mode
How to enter into Service Mode
After exchange parts, check and adjust the contents of adjustment mode.
While pressing [VOLUME ( - )] button of the main unit, press [INFO] button of the remote control three times within 2 seconds.
Key command
[1] button...Main items Selection in forward direction
[2] button...Main items Selection in reverse direction
[3] button...Sub items Selection in forward direction
[4] button...Sub items Selection in reverse direction
[VOL] button...Value of sub items change in forward direction ( + ), in reverse direction ( - )
How to exit
Switch off the power with the [POWER] button on the main unit or the [POWER] button on the remote control.
Display of SOS History
SOS History (Number of LED blinking) indication.
From left side; Last SOS, before Last, three occurrence before, 2nd occurrence after shipment, 1st occurrence after shipment.
This indication except 2nd and 1st occurrence after shipment will be cleared by [Self-check indication and forced to factory shipment setting].
Exit
1. Disconnect the AC cord from wall outlet.
Hotel Mode
Access command to the Hotel mode setup menu. In order to display the Hotel mode setup menu: While pressing [VOLUME (-)] button of the main unit, press [AV] button of the remote control three times within 2 seconds.
To exit the Hotel mode setup menu Disconnect AC power cord from wall outlet.
Troubleshooting Guide
Use the self-check function to test the unit.
1. Checking the IIC bus lines
2. Power LED Blinking timing
Check of the IIC bus lines
How to access
Self-check indication only
Produce TV reception screen, and while pressing [VOLUME ( - )] button on the main unit, press [OK] button on the remote control for more than 3 seconds.
Self-check indication and forced to factory shipment setting
Produce TV reception screen, and while pressing [VOLUME ( - )] button on the main unit, press [MENU] button on the remote control for more than 3 seconds.
Exit
Disconnect the AC cord from wall outlet.
Power LED Blinking
When an abnormality occurs, the protection circuit will operate and reset the unit to stand by mode. During this time, the
defective block can be identified by the number of blinking times of the Power LED on the front panel of the unit as follow:
R_LED Blink
Factor
Name
1
SOS from PANEL inverter
BL_SOS
3
TCON power down
TV_SOS
9
SOS from audio AMP
SOUND_SOS

LCD Panel test mode
Purpose:
To find the possible failure point where in LCD Panel or Printed Circuit Board when the abnormal picture is displayed.
How to Enter:
While pressing [VOLUME ( - )] button of the main unit, press [OPTION] button of the remote control three times within 2
seconds.
How to Exit:
Disconnect AC plug from wall outlet.
How to confirm:
If the abnormal picture is displayed, go into LCD Panel test mode to display the several test patterns.
And then, judge by the following method.
Still abnormal picture is displayed: The cause must be in LCD Panel.
Normal picture is displayed: The cause must be in A board.
Remarks:
The test pattern is created by the circuit in LCD Panel.
In LCD Panel test mode, this test pattern is displayed unaffected by signal processing for RF or input signal.
If the normal picture is displayed, LCD Panel must be okay and the cause of failure must be in A board.
Voltage chart of A-board
Set A-Board to a dummy set and check the satisfaction with the specified voltage as following table.
Power Supply Name
Measurement Point
Specification (V)
SUB1.2V
TP8004
1.14 - 1.26
SUB3.3V
TP8003
3.19 - 3.46
SUB5V
TP8002
4.92 - 5.25
STB5V
TP8009
5.3 ± 0.3
PNL12V
TP4300
11.5 - 12.5