Service manual

4.1 Power supply (DC/DC Converter):
4.1.1 IC251 MP1583 is a switching regulator controller that uses PWM method. That can be used for DC to
DC conversion for step-down. It converts a 12V DC into regulated and stable output voltage of 5V.
4.1.2 Regulator:
IC253 function is to convert a 5V into regulated and stable O/P 3.3V.
D252, D253 are 3.3V convert 2.5V.
4.2 DDC data select:
4.2.1 IC601(AT24C02) saves D-SUB DDC data.
4.2.2 IC602(AT24C02) saves DVI, DDC data.
4.3 MCU
The MTV312M micro-controller is an 8051 CPU core embedded device especially tailored for CRT/LCD Monitor
application. It includes an 8051 CPU core, 1024-byte SRAM, 14 built-in PWM DACs, VESA DDC interface,
4-channel A/D converter, and a 64K-byte internal program Flash-ROM.
The MCU controls the keyboard signal and audio signal.
4.4 Scalar
The MST9131A is a high performance, and fully intergrated graphics processing IC solution for LCD monitors
with resolutions up to SXGA. It is configured with an integrated triple-ADC/PLL, a high quality scaling engine,
an on-screen display controller, a built-in output clock generator, an integrated DVI receiver, and LVDS display
interface. To further reduce system costs, the MST9131A also integrates intelligent power management control
capability for green-mode requirements and spread-spectrum support for EMI management.
The analog input (CN602) signal and DVI-D input(CN601) signal are designed to be connected directly to scalar
IC, The MST9131A built-in LVDS transmitter, is designed to be connected directly to panel.
4.5 Audio processor
IC802(PT2313L) is a four-channel digital control audio processor utilizing CMOS Technology. Volume, Bass,
Treble and Balance, Front/Rear Fader Processor are incorporated into a single chip. Loudness function and
Selectable input gain are also provided to build a highly effective electronic Audio processor having the highest
performance and reliability with the least external components. All functions are programmable using the I
2
C
Bus.
Volume signal through IC802 pin34(right) pin25(left) into audio amplifier.
4.6 Audio amplifier
IC803(TDA1517) is an integrated class-B dual output amplifier, It contains two identical amplifier differential
input stages. The gain of each amplifier is fixed at 20dB.
Pins 1 and 9 are right and left channel inputs respectively. Pins 4 and 6 are right and left channel outputs which
connect to two 4OHM speakers.
Pin 8 is the mute/stand-by.
4. Circuit Description
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ViewSonic Corporation Confidential
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Do Not Copy VG910s/b