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Troubleshooting
Temperature abnormality
■ Temperature monitor operation
The temperature monitor system is provided to prevents damage of optical com-
ponents (the LCD panel and polarization film etc.) inside a projector from over-
heat. 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(IC301) checks the temperature and atmospheric pressure inside a pro-
jector. It checks a temperature using temperature sensors IC8811 and IC8851,
and it checks an atmospheric pressure using pressure sensor-IC886. The CPU
judges data from sensors and controls the air flow of the cooling fans so the tem-
perature inside the projector is maintained to normal temperature.
● To shut down the projector urgently.
The CPU checks temperature of LCD panel periphery (IC8851) and intake air
(IC8811). If each part temperature reaches abnormal temperature, The CPU will
turn off the projector, and will blink WARNING TEMP. indicator. Cooling fans oper-
ate until temperature returns to normal.
The temperature monitor -2 :
● Temperature check of lamps :
Thermal fuses (SW903, SW904 for Lamp1 and Lamp2, SW905, SW906 for
Lamp3 and Lamp4) are placed near the lamps. Thermal fuses will operate, if tem-
perature reaches 99ºC. When one of the thermal fuses becomes open, it cut off
the power supply to PFC1&2 boards, after that the projector will shut down, and
indicates the error on the projector with the LED indicators ( STAND-BY indicator
: On, other indicators: blinking).
■ Sensor's operation
The sensor's operation is as follows:
IC886 : For FAN control
IC8851 : Inside air temperature monitor (Panel)
IC8811 : Inside air temperature monitor (Room)
■ LED indicators
When the internal temp rises, the WARNING TEMP. indicator will start blinking.
When the temperature around the Lamp1, 2,3 or 4 rises abnormally , the
STABD-BY indicator is lighting and other indicators are blinking.
LX1750 Service Manual
020-000643-01 Rev.1 (01-2014)
-167-
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