NEC PlasmaSync PX-42VM1G, Руководство по обслуживанию

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CIRCUIT DESCRIPTION
(2) Auto-picture function
When the auto-picture function is ON with an RGB input, the microcomputer picks up information about
the screen position from IC8701 through the MUSE bus (SKMUSE, SDMUSE, SBMUSE) and sets up
the screen position for IC8701 based on this information.
During the entry of RGB3 input, IC8701 generates an output of screen position data based on an input
toward the DE input terminal (Pin 36). Changeover for the calculation of screen position data is con-
ducted by PLOTHER1 output from the I/O extension IC of IC9503. IC9503 is controlled from the micro-
computer of IC9501 through the I2C bus of SCL and SDA.
(3) Last memory function
Various data of input mode, power ON/OFF condition, various setting values for user control, factory
adjustment values, etc., are stored in the external EEPROM (IC9502). During the entry of video input
and chrominance input, however, data of COLOR, TINT, and UCOL are stored in IC1011 in the VIDEO
PWB. During the entry of SECAM, data of R-Y, B-Y, and BELL are also stored in this IC1011.
(4) Fault detector block
The microcomputer performs fan stoppage, plasma display module alarming, and temperature sensor
detection.
1
Detection of fan stoppage
Two fans are mounted on the set main body. When a stop signal (“H”) from either fan is entered in
IC9704 and any one of the fans stops, the “L” signal is sent to the microcomputer of IC9501. When
any one of the fans stops, the potential at Pin 46 of the microcomputer is turned L and the LED
begins to flash in green. This is the power standby condition. The function of fan stoppage detection
can be made invalid by short-circuiting the section between TP9701 and TP9702 with a jumper
strap or the like.
2
Panel crack detection
If there is any error in the plasma display module (signal system), an alarm signal is sent from Pin
79 of the AD connector to Pin 48 of the microcomputer. When this terminal is maintained at the “L”
potential, the LED repeats the reciprocal lighting in red and green and a power standby condition is
assumed. To release the alarming condition, it is necessary to set the mains power of the main unit
at ON while the input changeover key is kept pressed at the set main body, and also to keep
pressing this input changeover key of the main unit for more than 2 seconds.
3
Temperature error detection
When the temperature sensor senses any abnormality in the power unit, an error signal input of the
temperature sensor is applied to the temperature sensor input terminal (Pin 99) of the microcom-
puter from Pin 10 of the PN connector. When the input terminal of the temperature sensor is turned
at the “L” potential, the LED begins to flash in red and a power standby condition is assumed.
(5) Remote control block
This system is made applicable to remote control. The infrared remote control light receiver block of
RV2101 is mounted on the LED PWB and its output from the LD connector is entered in IC9702. The
232C PWB is provided with an input terminal of wired remote control and its input from the RA connec-
tor is entered in IC9702. In IC9702, a signal of infrared remote control is generally selected and its input
is entered in Pin 95 of the microcomputer IC9501. When a wired remote control unit is connected, the
potential at Pin 1 of IC9702 is turned “L” and a signal of the wired remote control is selected.
(6) Control lock block
When S2001 is ON (pressed) in the 232C PWB, the potential at Pin 21 of the microcomputer IC9501 is
turned “H” and all keys other than the POWER key of the set main body become invalid.