DESCRIPTION OF BLOCK DIAGRAM
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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 eliminates abnormal
color of the screen automatically by degaussing the
shadow mask in the CDT during turning on the power
switch. 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 diodes (D901~D904) and the capacitor
(C907).
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 primary coil of the transformer
(T901) repeatedly.
4) Depending on turn ratio of the transformer, the
secondary voltages appear at the secondary coils of
the transformer(T901).
5) These secondary voltages are rectified by each
diode(D902, D922~D924, D926)) and operate other
circuit. (horizontal and vertical deflection, video
amplifier, ...etc.)
4. X-ray Protection.
I
f the high voltage of the FBT reaches up to 29kV
(abnormal state), Q807 operates and IC401(MICOM) pin
11 come to low level. Then MICOM control IC701
(Deflection controller) to stop Horizontal drive pulse 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 signal 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).
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 TDA4856(IC701) and the
associated circuit.
7. Oscillating Circuit for D/D Converter.
This circuit generates the saw-tooth wave which has the
horizontal period by taking output of the TDA4856(IC701).
8. D/D(DC to DC) Converter.
This circuit supplies DC voltage to the horizontal
deflection output circuit by decreasing DC 160V which is
the secondary voltage of the SMPS in accordance with
the input horizontal sync signal.
9. Side-Pincushion & Trapezoid Correction Cirucit.
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.
10. Horizontal Deflection Output Circuit.
This circuit makes the horizontal deflection by supplying
the saw-tooth current to the horizontal deflection yoke.
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