Temperature Abnormality - Sanyo PLC-XF70 Service Manual

Troubleshooting

Temperature Abnormality

temperature monitor operation
The temperature monitor system is provided to prevents
damage of optical components (the LCD panel and po-
larization film etc.) inside a projector from overheat.
Two protection systems are provided. Each system op-
eration 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 sensors IC541 and IC8811, and it
checks an atmospheric pressure using pressure sen-
sor-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
IC886
PRESSURE SENSOR
TH901
TEMP. SENSOR
IC2541
TEMP. SENSOR
IC8801
TEMP. SENSOR
AC
INPUT
FUSE MAINS
SW
NOTE : SENSORS OPERATION
■ The sensor's operation is as follows:
IC886 : For FAN control
TH901 : Abnormal temperature detection
IC2541 : Inside air temperature monitor
IC8801 : Abnormal temperature detection and
for FAN control
Temperature sensors location can be seen on
"protections"( page-8).
POWER
FAIL
R/C
IC801
CPU
RESET KEY
IC_RESET_CPU
POWER(DC)
POWER
NOISE
FILTER
The temperature
switch is operated?
If the temperature
around FET reaches 85
degrees, a PFC circuit
will be shut down.
(TH901) and intake air (IC8811). If each part tempera-
ture reaches abnormal temperature, the CPU will turn
off the projector, and will blink WARNING TEMP. in-
dicator at intervals of 0.5 seconds. Cooling fans oper-
ate until temperature returns to normal. Indicator will
stop blink, if temperature returns to normal.
the temperature monitor -2 :
● temperature check of lamps :
Temperature switches (SW903, SW904) are placed
near the lamps. Temperature switches will operate,
if temperature reaches 90 ºC. When temperature
switches become open, they cut off 1VA line, the
power failure "PF_TH" signal become Low, and then
the CPU will shut down the projector, and the LAMP
indicator is lighting and other indicators are blinking.
IC5801
IO
IC1881
Check FAN
POWER
circuits.
FAIL
DA
CONVERTER
FAN
CONTROL
FAN
CONTROL
PF_PFC3/4
SWITCHING
POWER
SUPPLY
PRIMARY CIRCUIT
The temperature switch is
operated?
When the temperature
around a lamp driver reach-
es 85 degrees, the lamp bal-
last will be shut down and
a lamp error signal changes
from L to H.
-131-
BLAST_SW3/4
INDICATORS
LAMP3/4 12VA
LAMP COVER SW
FAN SW903/904
THERMAL SW
PF_ Check the
FANS
temperature
12V
switches.
FAN
PF_TH
P.F.C. BALLAST
1/2 1/2
LAMP-1/2
LED indicators
When the internal temp
error, the WARNING TEMP.
indicator will be blinking.
When the temperature rises
a b n o r m a l l y a r o u n d t h e
lamps1 or 2, the LAMP indi-
cator is lighting and other
indicators are blinking.
SW902