Panasonic Viera TC-P42S1, Technical Manual

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Panel MPU SOS Detect
• Protection circuits are incorporated in the unit to prevent the failure of a single circuit
or component from creating catastrophic damage.
• A shutdown condition occurs when there is an over voltage, a short or a drop in any
of the voltage lines. Also the shutdown circuit is triggered when the fans are drawing
more current than normal.
• Normally the CPU of the D board and the CPU of the A board detect when a
shutdown condition has been triggered.
• When an abnormality has occurred, the unit’s protection circuit operates and the TV
is reset to the standby mode. At this time, the defective block can be identified by the
number of blinks of the POWER LED on the front of the unit.
• The Panel MPU IC9003 of the A board (Located on the D board on previous
generations) detects conditions that make the power LED blinks1, 2, 3, 4, 5, 6, 7, 8,
or 9 times.
• The Main MPU IC1100 of the A board detects conditions that make the power LED
blinks 10, 11, 12, and 13 times.
• The number of times that the POWER LED blinks indicates the areas where a
problem is suspected.
• 1 Blink SOS: Communication error with IC9003.
• 2 Blinks SOS: Pin 62 of the CPU IC9003 monitors the 15V line. During normal
operation pin 62 is kept high. If the 15V line is missing or shorted, a low is provided to
pin 62. As a result, the unit shuts down and the power LED blinks 2 times.
• 3 Blinks SOS: IC9805 is a 3.3V regulator located on the D board. Its output is
monitored by IC9003. If the 3.3V is not present at pin 61, the CPU (IC9003) shuts
down the unit. The power LED blinks 3 times.
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