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Chapter 3 - Troubleshooting
CTV-68 16
Protection Shutdown
Critical voltages and circuit operations are monitored by the CPU on the
BAL board. If a fault is detected the unit will be forced to shut down by the
CPU. The monitored circuit in which the fault occurred will cause the CPU
to flash the standby LED in groups of repeating sequences. The number
of blinks in these groups identifies which voltage or circuit caused the
protection event.
Not all of the available protect codes are used. Models that are LED
backlit do not use the 4-blink balancer error as this circuit is found in
models that are backlit with fluorescent lamps. The following list contains
the protect circuits and diagnostics codes used in the EX700 models. The
troubleshooting flowchart in Figure 3-5 provides guidance in locating the
possible component causing the shutdown.
2X: A loss of REG12V from the power supply triggers this protect event.
The causes range from a failure of the REG12V line, power supply failure,
power supply shutdown, or a problem with the detection circuit on the BAL
board.
If a failure occurs on the power supply board that causes a loss of the
REG12V line, the standby LED will not light when power is applied to the
television. After about 10 seconds, the standby LED will light briefly and
begin blinking in groups of 2.
3X: The REG 5V and D3.3V source originating on the BAL board is
monitored for low-voltage conditions by CPU IC5000. A failure causing a
3X shutdown would require replacement of the BAL board.
5X: A communications error with the timing control circuits has occurred.
Since both of these circuits are located on the TCON board, replacement
of the board should remedy the problem. In rare cases a loose or defective
LVDS cable could be the cause. If the TCON board is not available as a
separate part, the entire LCD panel must be replaced.
6X: If the inverter circuits fail 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.
7X: A digital thermometer IC located on the BAL board provides a
temperature reading of the chassis and LCD panel. If the temperature
exceeds a pre-determined point the unit will shut down. If this problem
occurs immediately at turn-on, the temperature sensing IC has failed and
replacement of the BAL board is required. If this occurs after the unit has
been running for a while, check for ventilation issues that could cause the
unit to run hotter than normal.