User's Manual

3
This controller provides sync processing, which can accept separate input signals, a very short settling
time after mode change for protection of external power components has been taken into account.
The TDA4841 provides extensive functions like a flexible B+ controller block of H-deflection and a
geometry control with facilities, leading to excellent picture quality, this device also can directly drive the
vertical deflection output stage, the line driver stage, the E/W output stage and all controls are tracked
with the incoming frequencies, picture can be adjusted along horizontal direction by OSD H-shift control,
the horizontal size, east/west, trapezoid corrections are obtained by varying the supply voltage of H-
deflection circuit via buck converter, five capacitors plus power MOSFET switches and DC controlled
linearity coil are designed for optimal screen linearity.
VERTICAL DEFLECTION:
The majority of vertical deflection function is integrated by two ICs: TDA4841 and TDA8172.
The TDA4841 takes care of sync polarity correction, automatic catching and holding of the vertical
oscillator, generation of saw-tooth drive current for vertical output and vertical s-correction, and
generation of a correct V-blanking pulse for video blanking during vertical retrace lines.
The TDA8172 is a DC-coupled vertical deflection booster with differential input signals is suitable for
color monitor. The output stage has thermal and soar protection, and high linear saw-tooth signal
amplification to obtain the required vertical deflection current.
EHT GENERATOR
The IC UC3843AN is used as a controller to generate required extra high voltage for CRT, the
transformer(LOT) transfers the voltage to required anode voltage and rest tertiary output voltage.
The adjustable focus (G3) and screen (G2) voltages are internally derived from the anode voltage, other
secondary windings are used to generate the voltages for G1, also provides dynamic focus on G4 to get a
good focus performance. (G4 is also adjustable).
For safety reasons, x-ray protection circuit is included, that UC3843AN will feed fold the EHT generator
if the anode voltage exceeds a certain value (27—29.5kV), this circuit is also used for over beam current
protection, it will feed fold the EHT in case the total beam current can not exceeds a certain value.
C. VIDEO AMPLIFIER
VIDEO AMPLIFIER:
The video circuit mainly consists of Light Frame IC TDA4823, pre-amplifier TDA4886A, post amplifier
LM2435T and DC restoration circuit and OSD IC Novatek 68275-00031 the video DC level and gain at
cathode are controlled via I2C bus & software.
The red, green and blue video signals are amplified by pre-amplifier and post-amplifier, then AC couple
to CRT cathodes via DC restoration circuits, three cut-off adjustments are provided to set the video black
level at cathode for all three guns, three individual gain adjustments are also provided to adjust the white
balance, both cut-off and gain controls are digital control via micro-controller.
A spot-killer circuit is also added to prevent the CRT damage due to spot burn out when the set is
switched off.
D. H / V CONVERGENCE CONTROL (only for 107P4)