LG 776FM, FM776F-EA BLOCK DIAGRAM

BLOCK DIAGRAM

- 12 -

Input Voltage

100~240VAC

(50/60Hz)

Line

Filter

Degaussing Cir.

[ OSD Con trol ]

Power

Control

(IC901)

TILT

Control

Cir.

6.3V

15V

PROM

(IC402)

OSD IC

(IC301)

H Sync. sig .

V Sync. Sig.

C DATA(SDA)

C CLOCK(SCL)

VIDEO

Pre Amp.

(IC302)

Input

Signal

RGB

VIDEO

Main Amp.

(IC303)

CUT OFF Circuit

(IC304)

80V

Vertical Output

( IC601)

TDA4866J

H Defleciton

( Q706)

H-Linearity

Circuit.

Dynamic

Focus Cir.

- 120V

40V

15V

12V

MICOM

(IC401)

SCL / SDA

H/V Sync S ignal

PWM Control Signal

15V

50V

DY CDT

Heater ( 6.3V )

H/V Sync

Signal

Screen

H.V

R/G/B

Bias

R/G/B

Contrast

H Drive

B-Drive

B+

15V

BRIGHTNESS/CONTRAST

COLOR CURVE

H / V POSITION

H / V SIZE

SPCC

TRAPEZOID

PIN BALANCE

PARALLELOGRAM

TILT

TOP CORNER

BOTTOM CORNER

RECALL

DEGAUSSING

MOIRE

LANGUAGE

Audio Control

-Volume

-Treble

-Bass

-Balance

-Microphone

Audio Mute

850V

15V

6.3V

12V 80V

PURITY

Control

Cir.

15V

6.3V

Degaussing Coil

Dynomic Focus

Static Focus

TILT

Coil

PURITY

Coil

50V

80V

Auto Beam

Limit Circuit

DC/DC Converter

FBT

( T701 )

Regulation

Circuit

15V

SMPS

(T901)

Vertical Blanking,

Brightness Contorl

Circuit

X-RAY

Protection

Circuit

H/V Sync. Processor

( IC701 )

TDA4841

D/D

Feed Back

Energy Savi

Sound (15V)

Control Cir

Voltage

Feedback

REGULATOR

(Q1)

AUDIO IN

TO PC

l C

MIC

MIC OUT

AUDIO PRE-AMP

(IC1)

AUDIO MAIN-AMP

(IC2)

SPEAKER

DESCRIPTION OF BLOCK DIAGRAM

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1. SMPS(Switching Mode Power Supply)

When you turn on the power switch, the operating procedure is as follows:

1) The AC line voltage is rectified by the bridge diodes D900 and C908

2) The control IC(IC901) starts switching and generates switching pulses in the primary turns of the SMPS transformer (T901)

3) The switching pulses of the primary turns induce the secondary pulse of the transformer by the turn ratio. These pulses are rectified by each diode (D971,D961,D962,D951,D942, D941 and D901)

4) Each rectified DC voltage (80V, 50V, 15V, 6.3V, 5V and Audio(15V)) is supplied to the main circuit.

2. Over Voltage Protection Circuit

When the input voltage of IC901 Vin(pin 7) is more than Spec Voltage , all the secondary voltages of the SMPS transformer (T901) down to low value.

3. Display Power Management Circuit

1) Stand-by and Suspend mode. When no input of horizontal or vertical sync, Q972& Q952 are turned off.. then input power consumption is below 15 watts

2) OFF mode When no input of horizontal and vertical sync, Q942 is turned off and all the secondary voltages of the SMPS transformer (T901) down to low value. Then input power consumption is below 3 watts

4. X-ray Protection Circuit

If the high voltage of the FBT reaches up to 29KV IN an abnormal case, Q807 operates and IC401 pin 19 came to low level, then IC401 control IC701 to stop Horizontal drive pulse and stop Horizontal deflection.

5. Microprocessor Control Circuit.

1) Horizontal and Vertical sync signals are supplied to the

microprocessor (IC401).

2) Microprocessor(IC401) discriminates the operating

mode from the sync. polarity and resolution..

3) After microprocessor reads these adjusted mode data

stored at EEPROM, it controls operating mode data through IIC.

4) Users can control screen condition by the OSD, SET,

UP, DOWN, RIGHT and LEFT buttons.

6. D/D (DC to DC) Convert Circuit.

To obtain constant high voltage, this circuit supplies controlled DC voltage for FBT and Horizontal deflection circuit according to the horizontal sync frequency.

7. Horizontal and Vertical Sync Processor Circuit.

The horizontal and vertical sync processor IC (IC701) has a sync detector, a saw-tooth generator, and drive function. So output horizontal and vertical drive signal control screen distortions.

8. Horizontal linearity Circuit.

This circuit corrects the horizontal linearity for each horizontal sync frequency.

9. Horizontal drive and Output Circuit.

This circuit is a horizontal deflection amplifier for raster scan.

10. ABL Circuit.

This circuit limits the beam-current for the reliability of the CDT.

11. Vertical Output Circuit.

This circuit takes the vertical ramp wave from the TDA4841(IC701) and performs the vertical deflection by supplying the saw-tooth wave current to the vertical deflection yoke.

12. Blanking and Brightness Control Circuit.

Blanking circuit eliminates the retrace line by supplying a negative pulse wave to the G1 of the CDT. Brightness control circuit is used for control of the screen brightness by changing the DC level of the G1.

13. Video Processor Circuit.

Video processor circuit consists of the video drive output block. The video drive IC(IC302) receives the video signal from PC. The gain of each channel is controlled by the voltage of contrast pin. The cut-off circuit compensate different voltage of each channel between thecathode and the G1 of the CDT.

14. OSD (On-Screen-Display) Circuit.

This circuit displays on the screen information of the monitor's status.

15, Dynamic Focus Output Circuit.

This circuit takes the horizontal and the vertical parabola waves from the TDA4866(IC701) and amplifies it to maintain constant focus on center and corners in the screen.

16. Image Rotation (Tilt) Circuit.

This circuit corrects the tilt of the screen by supplying the image rotation signal to the tilt coil which is attached near the deflection yoke of the CRT

17. Earth Magnetic Correction(Purity) Circuit

This circuit corrects the convergence of screen by supplying the convergence signal to the Coil which is attached to the CRT near the deflection

18. Audio circuit

The sound circuit get to the audio gain with the preamp(IC1) and the main amp(IC2). The speaker maximum output is 3W. If adjust to volume in OSD menu, the MICOM control to IC1.