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
D901 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 are induced the
secondary turns of the transformer by the turn ratio.
These pulses are rectified by each diode (D971,D961,
D951, D931, D941 ,D991)
4) Each rectified DC voltage (120V, 50V, 15V, 80V, 6.3V,12V and 5V) is supplied to the main circuit.
2. Over Voltage Protection Circuit
When the input voltage of IC901 Vin(pin 4) is more than
22.5V(typical), 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, Q951 and
Q952 are turned off.
Then input power consumption is below 15 watts
2) OFF mode
When no input of horizontal and vertical sync,
Then input power consumption is below 5 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 41 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, LEFT, and Audio and Audio Mute buttons.
6. D/D 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
TDA9112(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 the cathode
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 TDA9112(IC701) and amplifies it to
maintain constant focus on center and comers in the
screen.
17. 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.
18. Earth Margnetic Correction(Purity) Circuit
This circuit corrects the convergence of screen by
suppling the convergence signal to the coil which is
attached to the CRT near the deflection.