Temperature Abnormality; System Control - Sanyo PLC-XF45 Service Manual

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.
Each system operation as follows :
The temperature monitor -1:
------
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 maintained to normal temperature.
To shut down the projector urgent.
The CPU checks temperature of LCD panel periphery and inhalation air(IC5801). If each part tempera-
ture reaches to abnormal temperature, the CPU will turn off a projector, and will blink TEMPERATURE
WARNING indicator at intervals of 0.6 seconds. Cooling fans operate until temperature returns to nor-
Hot circuit
FUSE
F901
AC-INPUT
CHECK Fan
*
NOTE : TEMP. MONITOR LED OPERATION
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

========================
------------------------------------------------------------------
INTERLOCK SW
SW902
FANS
FANS
CHECK !
LAMP
REPLACE
WARNING
TEMP.
READY
LAMP
INDICATORS
NOTE : CPU OPERATION
CPU (IC801) performs an input check by the IIC-SDA
signal pin.
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.
mal. Indicator will stop blink, if temperature returns to normal. Trace the cause of the abnormalities-tem-
perature, and repair the projector.
The temperature monitor -2 :
------
Temperature check of lamps :
Temperature switches are arranged near the lamps. Temperature switches will operate, if temperature
reaches 85~90 degrees. When temperature switches have operated, lamp ballast units will be shut
down, then a projector will be turned off.
Note :
(1) Usually temperature monitor-2 will operate when other protection equipment did not operate with
trouble, so it is auxiliary protection equipment. When other protection equipment is rightly operat-
ing, this temperature monitor-2 rarely operates.
thought fault of other protection equipment.
(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 !
-38-
Troubleshooting
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If this temperature monitor-2 has operated it is
AC
Always
DC out
SWITCH
Switched
CPU IC801
and
I / O
EXPANDER
IC1831