Mitsubishi Electric 1786FD2 Service Manual page 69

MEA 1786FD2 CRT Monitor Service Guide
3-3.What are the valid key functions for user:
There are Five keys on control panel. They are "i-key, "Left," "Right," "Enter," and
"Exit." The one, i-key, is for auto calibration function, the others are used for OSD
controlling. "Enter" for entering sub-menu of main menu, "Exit" for escaping to main menu
from sub-menu or leaving OSD menu, and "Left," "Right" for adjusting the bar value.
Except the OSD basic key functions, the user can only press "Right" for brightness
adjustment, or "Left" for contrast adjustment.
3-4.How to memorize the timing and adjusted data:
The EEPROM is 24C08, it has 1024 bytes memory size and communicates with MCU
by two wires of I 2 C bus, one wire is "SCL," the other is "SDA".
The MCU send clock and data to EEPROM to do "Write" function and send clock and
receive data from EEPROM to do "Read" function by these two wires.
We define three parts of storage area. One is for the storage of the factory preset data,
another is for saving user adjusted data, the other is for common settings area where stored
the data of the OSD color temperature settings, contrast and brightness value .
3-5.How to display the OSD menu:
The OSD IC is AP3114/AP315 which is developed by vender, it receives the data of the
OSD fonts and attribute what we want to display on the screen from the MCU by 2 wires of
communication, and exports OSD window data and PWM volume to the VIDEO circuit, the
block diagram is shown as below,
MCU(MTV112)
(1)Send data to
RAM for OSD
fonts or
attribute.
(2)Send data to
Control
registers
for PWM ouput
or OSD window
VSYNC
HSYNC
(H-BLANK,HBNK)
3-6.How to execute the auto alignment function:
The MCU MTV112 supports the UART function, it has 2 I/O serious ports, one is the
receiver, the other is the transmitter, they are connected with an interface to PC and PC can
execute alignment program by RS232 communication to send the formatted data to the MCU
for adjusting any adjustable parameters of the picture and saving the adjusted values into
OSD IC (AP3114)
SDA
Shift receiving
SCL
register and decoder.
Control RAM Fonts
register
s
PWM
output
generator
VCO circuit
Circuit Operation Theory
Output to
the VIDEO circu
ROUT
GOUT
BOUT
FBKGC
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