Sanyo PLV-Z4 Service Manual page 77

● Description of Fan control circuit
Fan control circuit
The Fan drive power supplies "FAN1", "FAN2", "FAN3" and "FAN4" are generated from "S16V_F". Each power
supply drives fans as follow;
FAN1 ....FN901 for power and ballast exhaust
FAN2 ....FN902 for lamp cooling
FAN3 ....FN903 for lamp exhaust
FAN4 ....FN904 and FN905 for intake and panel cooling
The fan spinning speed is controlled by "FAN_CONT1", "FAN_CONT2", "FAN_CONT3" and "FAN_CONT4" from
pins 15, 14, 13 and 12 of IC7841(DAC).
Power failure protection of Fan
The alarm output signals(PWM signals) from the fans are connected to IC4401(Color Manager) and IC4401 moni-
tors the fan spinning speed for safety.
When an abnormality occurs on any one of the fans, for example the fan spinning speed is lower than the specified
speed, IC301 shuts down the projector. If a fan connector is not connected firmly, IC301 also shuts down the pro-
jector.
Temperature sensor for Fan control
TempA - TH902 around the intake fan "FN904"and "FN905" for outer temperature of the projector
TempB - IC8841(above the lamp) on the Main board for optical parts
TempC - TH901 on the polarized glass (IN-B) for panel and polarized glass temperature
The temperature sensors measure surrounding temperature and sends data to IC301. IC301 controls the proper
fan spinning speed based upon these temperature data. Also, when a temperature rises over a specified value,
IC301 judges that there is abnormal internal temperature and turns off the projector.
FAN SPEED [rpm]
(Max. FAN Spinning Speed)
(Min. FAN Spinning Speed)
(Min. Setting Temperature)
FAN SPEED [rpm]
(Min. Setting Temperature)
(Max. Setting Temperature)
Temperature vs Fan spinning speed
Lamp mode = NORMAL/ECO
(Max. Setting Temperature)
(Shutdown Setting Temperature)
Lamp mode = AUTO
(Shutdown Setting Temperature)
TEMPERATURE [ºC]
(Max. Lamp Power)
The fan spinning speed is controlled
(Min. Lamp Power) with the temperature and the lamp
power.
TEMPERATURE [ºC]
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Chassis Block Diagrams