Sanyo PLV-55WHD1 Service Manual page 93

● Description of System controls
Communication between Main board and Digital board
IC801(TV CPU) and IC5500(DTV processor & scan converter) are communicated with UART data. The service data
is memorized in IC836(EEPROM).
Power supply lines
When the PTV is connected to outlet with AC power cord, S5V line from T641(Converter Transformer) is supplied for
standby circuit, including IC801(TV CPU). IC801 is waiting for POWER key input or remote control signal.
When the PTV is turned on, the "POWER_ON" signal (Power ON:H) from pin 76 of IC801 is sent to PC642(photo-
coupler), and then the switching power supply circuit, including IC651(Switching regulator controller), T651
(Converter Transformer), starts operation.
The "DEV_SW" signal (ON:H) from pin 70 of IC801 and "PANEL_SW" signal (ON:H) from pin 71 of IC801 are also
sent to the power supply circuits.
Thermal switch
The thermal switch (SW902) is above the lamp to prevent the internal abnormal temperature rising. If the internal
temperature reaches near 95°C, the switch will be opened and LAMP_SW signal will be cut off.
Note; The thermal switch is not reset to normal automatically even if the internal temperature becomes normal,
so in this case you have to reset it manually.
Lamp cover switch
If the lamp cover is not fixed securely, lamp cover switch(SW1861) will be open, and LAMP_SW signal will be cut off.
Temperature sensor
There are the temperature sensors inside of the PTV to prevent the internal temperature rising abnormally and to
control the cooling fans. (refer to P.90 "Fan control stage" for detail)
- Temp. sensor-A IC8861 (around the intake fan "FN906") on the Key board
- Temp. sensor-B IC8811 (above the lamp) on the Main board
- Temp. sensor-C IC8801 (above the prism block) on the Main board
The temperature sensors monitor the surrounding temperature and send data to IC801 via the IIC bus. IC801 con-
trols the proper fan spinning speed based upon these temperature data.
If the internal temperature rising abnormally to the threshold level, TV CPU shuts down the PTV after cooling.
Power failure protection of secondary power circuit
The PTV provides the protection circuits to prevent the secondary failure when the power failure, fans failure or tem-
perature failure occurs. The power failure detection lines are connected to the power supplies and fans. When a fail-
ure occurs, IC801 receives the power failure detection signals "P_FAIL" and "P_FAIL_PNL" through the power fail-
ure detection lines and the "POWER_ON" signal (Power OFF:L) is supplied to stop the power supply operation.
Fan control circuit
The fan driving power supplies "FAN1", "FAN2", "FAN3" and "FAN4" drive the fans as follows;
FAN1 ....FN905 for power and ballast exhaust and FN906 for intake
FAN2 ....FN901 for lamp cooling
FAN3 ....FN903 and FN904 for LCD panel cooling
FAN4 ....FN902 for PBS cooling
The fan spinning speed is controlled by "FAN_CONT1", "FAN_CONT2", "FAN_CONT3" and "FAN_CONT4" from pins
4, 5, 6 and 7 of IC1801(D/A).
Power failure protection of Fan
When a fan abnormality occurs, the fan lock signal becomes to "H". "FAN_ERROR" signal (Error: L) is sent to pin 18
of IC801 via Q7898. If a fan connector is not connected firmly, the power failure protection will be operated.
Screen size option
R801 and R802 connected to pin 3 of IC801 are the option resistors for the screen size.
L: 65 inch, H: 55 inch
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Chassis Block Diagrams