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System Control
NOTE : Temperature monitor operation
===
The temperature monitor system is provided to prevents damage of optical components (the LCD panel and polarization
film etc.) inside a projector from overheat. Two protection systems are provided.
The temperature monitor -1:
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I
To control the air-flow of the cooling fans.
The CPU checks the temperature and atmospheric pressure inside a projector. It checks a temperature using temperature
sensor-IC5801 and it checks an atmospheric pressure using pressure sensor-IC886.
CPU judges data from sensors and controls the air flow of the cooling fans so the temperature inside the projector is main-
tained to normal temperature.
I
To shut down the projector urgent.
The CPU checks temperature of LCD panel periphery and inhalation air(IC5801). If each part temperature reaches to
abnormal temperature, the CPU will turn off a projector, and will blink TEMPERATURE WARNING indicator at inter-
vals of 0.6 seconds. Cooling fans operate until temperature returns to normal. Indicator will stop blink, if temperature
returns to normal. Trace the cause of the abnormalities-temperature, and repair the projector.
Hot circuit
FUSE
F901
AC-INPUT
CHECK Fan
*
NOTE : TEMP. MONITOR LED OPERATION
I The red LED indicates temperature monitor operation as follows:
LED off:
Normal temperature.
LED flashes in 0.6 second interval:
Abnormality temperature.
Doesn't the temperature warn-
ing indicator (red) blink?
The projector is turned off when
the temperature around the LCD
panel reaches 46 - 48 degrees.
And a temperature warning indi-
cator blinks.
TEMPERATURE ABNORMALITY -1
========================
Each system operation as follows :
INTERLOCK SW
SW902
Refer to page 32
FANS
FANS
CHECK !
LAMP
REPLACE
WARNING
TEMP.
READY
LAMP
INDICATORS
NOTE : CPU OPERATION
I CPU (IC801) performs an input check by the IIC-SDA
signal pin.
I When it has detected abnormal condition, CPU turns off
the projector compulsorily. Cooling fans operate until
temperature returns to normal. Moreover, a projector
cannot be turned on during this period.
The temperature monitor -2 :
------
I Temperature check of lamps.
Temperature switches (SW 903~904) are arranged near the two lamps. Temperature switches will oper-
ate, if temperature reaches 90~100 degrees. When temperature switches have operated, lamp ballast units
will be shut down, then a projector will be turned off.
I Note;
(1) If other protection equipments ( The function of fan operation check, The function of voltage check "Power-failure"
and Temperature monitor 1 ) are rightly operating, the lamp does not become an unusual temperature. So, the tempera-
ture monitor 2 rarely operates. However, when those protection equipments do not operate with fault, the temperature
monitor 2 operates and the broken protection equipment is covered. If this temperature monitor 2 operates, it is thought
fault of other protection equipments. Also trace the cause of fault of other protection equipments with the cause of an
unusual temperature.
(2) The CPU does not check operation of temperature switches. Therefore, when temperature switches have operated
and a projector has shut down, TEMPERATURE-WARNING indicator does not blink.
ASS'Y POWER
DC out
16V /9V /6.25V /-6V
POWER
CONTROL
FAN
ON/OFF
CONTROL
I / O
EXPANDER
SUB POWER
CHECK !
-30-
Troubleshooting
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AC
Always
DC out
SWITCH
Switched
CPU IC801
and
I / O
EXPANDER
IC1831
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