DESCRIPTION OF BLOCK DIAGRAM
1. Line Filter & Associated Circuit.6. Horizontal and Vertical Oscillation.
This is used for suppressing noise of power input lineThis circuit generates the horizontal pulse and the vertical
flowing into the monitor and/or some noise generated inpulse by taking the H and V sync signal.
this monitor flowing out through the power input line.This circuit consists of the STV9302(IC601) and the
That is to say, this circuit prevents interference betweenassociated circuit.
the monitor and other electric appliances.
7. D/D(DC to DC) Converter.
2. Degauss Circuit & Coil.This circuit supplies DC voltage to the horizontal deflection
The degauss circuit consists of the degaussing coil, theoutput circuit by increasing DC 50V which is the
PTC(Positive Temperature Coefficient) thermistor(TH901),secondary voltage of the SMPS in accordance with the
and the relay(RL901). This circuit eliminates abnormalinput horizontal sync signal.
color of the screen automatically by degaussing the
shadow mask in the CRT during turning on the power8. Side-Pincushion & Trapezoid Correction Cirucit.
switch. When you need to degauss in using the monitor,This circuit improves the side-pincushion and the
select DEGAUSS on the OSD menu.trapezoid distortion of the screen by mixing parabola and
saw-tooth wave to output of the horizontal deflection D/D
3. SMPS(Switching Mode Power Supply).converter which is used for the supply voltage(B + ) of the
This circuit is working of 90~264V AC(50/60Hz).deflection circuit.
The operation procedure is as follows:
1) AC input voltage is rectified and smoothed by the bridge9. Horizontal Deflection Output Circuit.
diodes (D900) and the capacitor (C908).This circuit makes the horizontal deflection by supplying
2) The rectified voltage(DC) is applied to the primary coilthe saw-tooth current to the horizontal deflection yoke.
of the transformer(T901).
3) The control IC(IC901) generates switching pulse to turn10. High Voltage Output & FBT(Flyback Transformer).
on and off the primary coil of the transformer (T901)The high voltage output circuit is used for generating pulse
repeatedly.to the primary coil of the FBT(Flyback Transformer
4) Depending on turn ratio of the transformer, thesecondary of the FBT and it is supplied to the anode,
secondary voltages appear at the secondary coils of thefocus, and screen voltage of the CRT.
transformer(T901).
5) These secondary voltages are rectified by each11. H-Linearity Correction Circuit.
diode(D941, D942, D951, D961, D971) and operate otherThis circuit corrects the horizontal linearity for each
circuit. (horizontal and vertical deflection, video amplifier,horizontal sync frequency.
...etc.)
12. Vertical Output Circuit.
4. X-ray Protection.This circuit takes the vertical ramp wave from the
If the high voltage of the FBT reaches up to 29kV (abnormalSTV6888(IC701) and performs the vertical deflection by
state), IC401(MICOM) pin 35 Sensing from FBT directly.supplying the saw-tooth current to the vertical deflection
Then MICOM control IC701 (Deflection controller) to stopyoke.
Horizontal drive pulse and stop Horizontal Deflection.
13. Dynamic Focus Output Circuit.
5. Micom(Microprocessor) Circuit.This circuit takes the horizontal and the vertical parabola
The operating procedure of Micom(Microprocessor) andwaves from the STV6888(IC701) and amplifies it to
its associated circuit is as follows:maintain constant focus on center and corners in the
1) H and V sync signal is supplied from the signal cable.screen.
2) The Micom(IC401) distinguishes polarity and
frequency of H and V sync.14. H& V Blanking and Brightness Control.
3) The Micom sets operating mode and offers theBlanking circuit eliminates retrace line by supplying
controlled data. (H-size, H-position, V-size, ... etc.)negative pulse to the G1 of the CRT. And Brightness
4) The controlled data of each mode is stored in itself.circuit is used for control of the screen brightness by
changing DC level of the G1.
5) User can adjust screen condition by each OSD
function. The data of the adjusted condition is stored
in EEPROM(IC402).
- 8 - |
ACEC
LG-GOLDSTAR
