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ViewSonic Corporation
E771-4
4
Operation Theory
This is a fully digital controlled multi-sync color monitorthat is compliant with DDC1/2B Plug and Play VESA
standard and offers the following main features.
4-1 Main Features
1. Simplifieddesign with minimum components.
2. The NOVATEK NT68P61AU processor-- that has PC bus controlled geometric correction, contrast and
brightness-- offers the functions for: (a) Contrast, (b) Brightness, (c) H-size, (d) H-position, (e) V-size, (f)
V-position, (g) Pincushion, and (h) Trapezoid.
In addition, it also offers more functions as: (a) Sync. processor, ИР and O/P, (b) Mute, (c) Power saving
- Suspend & Stand-By, (d) Power saving override, (e) DDC1/2B, (f) PC Bus for auto-alignmentthrough
signal cable (g) CS1 switching for linearity and size compensation.
3. Stores up to 14 factory preset modes and offers 7 user modes. There are 16 function icons in OSD. They
are controlled by Б) v ^ [2] keys оп front panel.
4. Powerful PHILIPS TDA4856 and
TDA4866 present the following useful functions: (a) Pincushion, (b)
Trapezoid, (c) V-Position, (d) V-Size, (е) Vertical's "С" and "S" correction -- factory adjust, (f) Pincushion's
V. position correction, (g) Corner correction -- factory adjust, (h) Pincushion unbalance correction --
factory adjust, (i) Parallelogram distortion -- factory adjust, (1) Moire cancellation -- factory adjust, (К) X-
ray protection, and (1) Full horizontal and vertical auto sync capability.
5. Software controlled auto shut off function activated if fH < = 29 kHz and fH > = 73 kHz.
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. Full range AC input and simplified line filter design.
4-2 Microcontrol Section
1. This monitor uses NOVATEK NT68P61AU CPU. It contains a 6502 8-bit CPU core, 256 bytes of RAM
used as working RAM and stack area, 24k bytes of OTP ROM, 14-channel 8 bit PWM D/A converter, 2-
channel A/D converters for key detection saving I/O pins, internal H. sync and V. sync signals processor
providing mode detection, and an РС bus interface. When H/V sync through D-Sub signal cable enter pin
41 and pin 42, the CPU performs frequency / polarity detection and calculate and send to H/V sync OUT.
Then CPU reads the data from 1703 and transfer to device 4856 and some DAC in CPU, above operation
takes about 500 ms.
2. There allows 14 factory preset modes and 7 user modes. There are 8 functions, Contrast, Brightness, H.
Size, H. Position, V. Size, V. Position, Pincushion, and Trapezoid, all controlled by OSD icon which can
be adjusted by user.
3. The pin 25 and pin 26 are used for ATE function. When CPU receives C6 as slave address, it will operate
in ATE mode which is used for auto-alignment. After alignment the data will be stored in 1703.
4. The user control parameters are selected by OSD icons, through [] у А [2] keys, they are detected Бу
sensing the voltage through R710, R740, R711, R743, R741, R742 to pin 14 and 15 of 1701.
4-3 Deflection Section
1. PC -- autosync deflection controller is TDA4856.
2. The TDA4856 is a high performance and efficient solution for autosync monitors. All functions are
controllable by PC bus. SDA and SCL signals come from microprocessor feed to pin 19 and pin 18 to
control all functions.
Confidential - Do Not Copy
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