Description Of Block Diagram - LG Flatron T710P Service Manual

1. Line Filter & Associated Circuit.
This is used for suppressing noise of power input line
flowing into the monitor and/or some noise generated in
this monitor flowing out through the power input line.
That is to say,this circuit prevents interference between
the monitor and other electric appliances.
2. Degauss Circuit & Coil
The degauss circuit consists of the degaussing coil,the
PTC(Positive Temperature Coefficient) thermistor
(TH901), and the relay(RL901).This circuit eliminated
abnormal color of the screen automatically by
degaussing the shadow mask in the CRT during turning
on the powerswitch.When you need to degauss in using
the monitor, select DEGAUSS on the OSD menu.
3. SMPS(Switching Mode Power Supply).
This circuit is working of 90~264V AC(50/60Hz)
The operation procedure is as follows:
1)AC input voltage is rectified and smoothed by the
bridge diode(D900) and the capacitor(C908).
2)The rectified voltage(DC) is applied to the primary coil
of the transformer(T901).
3)The control IC(IC901) generates switching pulse to
turn on and off the power control FET(Q901) the
primary coil of the transformer(T901) is turned on and
off repeatedly by Q901.
4)Depending on turn ratio of the transformer, the
secondary voltage appear at the secondary coils of the
transformer(T901).
5)These secondary voltages are rectified by each
diode(D941,D942,D951,D961,D962, D971) and operate
other circuit.(horizontal and vertical deflection,video
amplifier,...etc.)
4. X-ray Protection
If the high voltage of the FBT reaches up to
29kV(abnormal state), IC401(MICOM) pin 35 sensing
from FBT directly.
Then MICOM control IC701 (Deflection Controller) to
stop horizontal drive pulses and stop horizontal
deflection.
5. MICOM(Microprocessor) Circuit.
The operating procedure of MICOM(Microprocessor)
and its associated circuit is as follows:
1)H and V sync signa is supplied from the signal cable.
2)The Micom(IC401) distinguishes polarity and
frequency of H and V sync.
3)The Micom sets operating mode and offers the
controlled data.(H-size,H-position,V-size,...etc)
4)The controlled data of each mode is stored in itself.
5) User can adjust screen condition by each OSD
function. The data of the adjusted condition is stored in
EEPROM(IC402).

DESCRIPTION OF BLOCK DIAGRAM

6. Horizontal and Vertical Oscillation.
This circuit generates the horizontal pulse and the
vertical pulse by taking the H and V sync signal.
This circuit consists of the TDA4866(IC601) and the
associated circuit.
7. D/D (DC to DC) Converter.
This circuit supplies DC voltage to the horizontal
deflection output circuit by increasing DC50V which is
the secondary voltage of the SMPS in accordance with
the input horizontal sync signal.
8.Side-Pincushion & Trapezoid Correction Circuit.
This circuit improves the side-pincushion and the
trapezoid distortion of the screen by mixing parabola
and saw-tooth wave to output of the horizontal
deflection D/D converter which is used for the supply
voltage(B+) of the deflection circuit.
9. Horizontal Deflection Output Circuit.
This circuit makes the horizontal deflection by supplying
the saw-tooth current to the horizontal deflection yoke.
10.High Voltage Output & FBT(Flyback Transformer).
The high voltage output circuit is used for generating
pulse to the primary coil of
Transformer secondary of the FBT and it is supplied to
the anode, focus, and screen voltage of the CRT.
11.H-Linearity Correction Circuit.
This circuit corrects the horizontal linearity for each
horizontal sync frequency.
12.Vertical Output Circuit.
This circuit takes the vertical ramp wave from the
TDA4841(IC701) and performs the vertical deflection by
supplying the saw-tooth current to the vertical deflection
yoke.
13.Dynamic Focus Output Circuit.
This circuit takes the horizontal and vertical parabola
waves from the TDA4841(IC701) and amplifiers it to
maintain constant focus on center and corners in the
screen.
14.H&V Blanking and Brightness Control.
Blanking circuit eliminates retrace line by supplying
negative pulse to G1 of CRT.And Brightness control
uses the IIC line , changes the cut-off DC Level.
15.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.
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the FBT(Flyback