Temperature Abnormality - Eiki LC-XT4U Service Manual

●

Temperature Abnormality

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 pro-
vided. 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 sen-
sor-IC5801 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 temperature inside the pro-
jector is maintained to normal temperature.
■ To shut down the projector urgent.
The CPU checks temperature of LCD panel periphery(PTH901) and
inhalation air(IC5801). If each part temperature reaches to abnor-
mal temperature, the CPU will turn off the projector, and will blink
WARNING TEMP. indicator at intervals of 0.5 seconds. Cooling
fans operate until temperature returns to normal. Indicator will stop
blink, if temperature returns to normal.
POWER
BUFFER
FAIL
IC886
PRESSURE SENSOR
PTH901
TEMP. SENSOR
IC2541
TEMP. SENSOR
IC5801
TEMP. SENSOR
R/C
RESET KEY
AC
INPUT
FUSE MAINS
SW
NOTE : SENSORS OPERATION
■ The sensor's operation is as follows:
IC886 : For FAN control
PTH901 : Abnormal temperature detection
IC2541 : Inside air temperature monitor
IC5801 : Abnormal temperature detection
and for FAN control
Temperature sensors location can be seen
on "protections"( page-7).
I/O EXPANDER
IC801
122
CPU
123
IIC
UNIT_SUB POWER
AC
SENSOR
ASS'Y
POWER
NOISE
FILTER
PRIMARY CIRCUIT
The temperature
switch is operated?
If the temperature
around FET reaches
85 degrees, a PFC
circuit will be shut
down.
------ The temperature monitor -2 : ----------------------------------
■ Temperature check of lamps :
Temperature switches are arranged near the lamps.
Temperature switches will operate, if temperature reaches 110
degrees. When temperature switches become open, they cut off
12V_PFC line, the power failure "PF_TH" signal become Low,
and then the CPU will shut down the projector, and b
READY and WARNING TEMP. indicators will start flash-
ing.
IC1801
BLAST_SW1/2/3/4
BLAST_ERR1/2/3/4
LAMP1/2/3/4
POWER
FAIL
DC-DC
CONVERTER
FAN
CONTROL
FAN
CONTROL
PF_PFC1/2/3/4
SWITCHING
POWER
SUPPLY
The temperature switch
is operated?
When the temperature
around a lamp driver
reaches 85 degrees, the
lamp ballast will be shut
down and a lamp error
signal changes from L to
H.
- 63 -
Troubleshooting
INDICATORS
12VA
Check FAN
circuits.
LAMP COVER SW
FAN
SW903/904/905/906
THERMAL SW
PF_
FANS
12V
FAN
P.F.C. BALLAST
1/2/3/4 1/2/3/4
LAMP_1/2/3/4
WARNING TEMP. indica-
tor (red) blink?
The projector is turned off
when the temperature
around the LCD panel
reaches abnormal temper-
ature. And a WARNING
TEMP. indicator blinks.
oth of
SW902
Check the
temperature
switches.
PF_TH