Overheat Protection - Sanyo PLC-XF31N Service Manual

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 Red-LCD panel periphery (IC2541) and
inhalation air(IC5801). If each part temperature reaches to abnormal temper-
ature(IC2541 ; 47degrees / IC5801 ; 42degrees),
the CPU will turn off a projector, and will blink TEMPERATURE WARN-
ING indicator at intervals of 0.6 seconds. Cooling fans operate until tempera-
ture returns to normal. Indicator will stop blink, if temperature returns to nor-
mal. Trace the cause of an unusual temperature, and repair the projector.
(Refer to the item of " temperature abnormality" of troubleshooting.)
"SW903" Temperature "SW903" Temperature
switch for Lamp-2. switch for Lamp-2.
It operates at 100˚C It operates at 100˚C
Temperature sensors
location

Overheat Protection

D7/E7
PRESSURE PRESSURE
Sensor Sensor
IC886 IC886
Temperature Temperature
Sensor Sensor
IC2541 IC2541
Temperature Temperature
Sensor Sensor
IC5801 IC5801
--
The temperature monitor system --
----- The temperature monitor -2 : -----
Temperature check of lamps.
Temperature switches (SW 903~904) are arranged near the two lamps.
Temperature switches will operate, if temperature reaches 90~100 degrees.
SW904 (Lamp-1)-----
SW903 (Lamp-2)-----
When temperature switches have operated, lamp ballast units will be shut
down, then a projector will be turned off.
Note;
(1) If other protection equipments ( The function of fan operation check, The func-
tion of voltage check "Power-failure" and Temperature monitor 1 ) are rightly
operating, the lamp does not become an unusual temperature. So, the temperature
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.
(Refer to the item of " temperature abnormality" of troubleshooting.)
(2) The CPU does not check operation of temperature switches. Therefore, when
temperature switches have operated and a projector has shut down, TEMPERA-
TURE-WARNING indicator does not blink.
-5-
It operates at 90 degrees.
It operates at 100 degrees.
"SW904" Temperature "SW904" Temperature
switch for Lamp-1. switch for Lamp-1.
It operates at 90˚C It operates at 80˚C
D7/E7