EMP-9000/8000
2-38Revision:A SEIKO EPSON
2.14.2. Safety Switch
This is the thermal switch for overheat protection installed on the lamp outer housing. If over-
heat condition is caused by the contamination of the exhaust fan, normally the thermistors
(PBS/LAMP) temporarily shuts off the supply of ballast power to protect it from overheat. The
safety switch is installed, considering the thermistors trouble in overheat condition.
Figure2-39 Safety switch
To the safety switch the cable with fasten tab is connected from interlock switch. When the
temperature increase to certain degrees, every regulating operations of the power supply unit
are stopped. (AC power is shut off and this switch runs once, you can not start up the power,
before the temperature decrease to certain degrees.) In this case, you must also consider the
thermistor trouble or the Main board Assy unit trouble.
2.14.3. Thermistor and temperature sensor operation
CPU on the Main board Assy unit detects the temperature (resistance) with three thermistors
and five temperature sensors in each 100ms. Five of temperature sensors are placed on the
Main board Assy Unit and detect the temperature of major circuit. three of thermistors are
placed in the main body and mainly detect the temperature of optical block area.
CPU judge the following state according to the measurment result then change the fan opera-
tion or shut down the power.
Thermistor controll
Thermistor Fan Slow
Medium-
low
Medium-
high
High Warning Shut down
LAMP Exhaust 65 70 75 80 83
85
over 1minutes
PBS Exhaust 63 67 70 73 76
78
over 1minutes
LV Exhaust 50 53 55
AT 57
Temperature sensor controll
Temperature
sensor
Fan Slow
Medium-
low
Medium-
high
High Warning Shut down
Arround PW364 Intake/
Exhaust
57 60 63 66 68
AT 70
Arround LM2202 Intake/
Exhaust
57 60 63 6 68
AT 70
Arround AD9483 Intake/
Exhaust
57 60 63 66 68
AT 70
Arround TA1270 Intake/
Exhaust
53 56 59 62 63
AT 65
Arround LH Intake/
Exhaust
57 60 63 66 68
ATL70
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