Troubleshooting - Sony KDL70XBR7 Training Manual

Troubleshooting

Unlike other model designs that utilize stand-alone inverters and balancer
boards, this model does not generate the familiar 13X protection shutdown
when a lamp failure occurs. The balancer circuits normally signal an open
lamp condition and this is detected by the BE Micro located on the FBU
board.
In this circuit design, the open lamp detection line is monitored by the left
inverter board. This line is incorporated into the same detection circuit as
that used for a failure of one or both of the inverter circuits. If one or more
of the backlight lamps fails to light or one or both of the inverters fails to
start for various reasons the unit will shut down and generate a 6X error
code.
This error detection configuration can generate a 6X diagnostic code for a
variety of reasons and can be caused by any one or more of the following
circuits.
• LCD Panel (defective lamp)
• Balancer board (extremely rare)
• One or both of the G9 boards
• G8 board (low probability)
• F2 board
• FBU board (low probability)
• Inverter board (both failing at the same time is unlikely)
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Chapter 4 - Inverter and Backlight Troubleshooting
Due to several circuits responsible for generating the high voltage for the
backlights it will be necessary to bring the following boards to the repair
location if a 6X error is occurring:
• G9 board
• Left inverter board
• Right inverter board
The left and right G9 boards are identical and since it is unlikely that both
have failed, only one should be brought. Once these components are
brought to the location the troubleshooting flowchart found in Figure 4-2
will aid in determining what is likely causing the 6X shutdown. Use the
procedures in the troubleshooting flowchart to isolate the cause rather
than trying boards one at a time. Shot-gunning of the repair components
is the most common cause of secondary problems being introduced into
the television being serviced.
Note that the G8 and F2 boards along with the LCD panel can cause
this symptom. The G8 and F2 boards could cause this failure but are not
the likely cause and bringing a replacement LCD panel on the first trip
(especially a very expensive 70") is not practical. If, for some reason, the
components brought to the location are not the cause, the flowchart will
at least be able to diagnose the correct part to be brought on the second
trip. As usual, always check the Authorized Service website to see if there
is any new information regarding the symptom for the problem you are
going to repair.
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