8-1
SECTION VIII VERTICAL DEFLECTION CIRCUIT
The basic configulation is the same as TV of N4SS chassis. Size and linearity are adjusted by sending data to IC302 (TA8859AP)
through I
2
C-Bus line.
Unlike ordinary TV, the adjusting data are stored in memory; 4 sets for RGB mode besides for TV. In RGB mode only, user
control can be adjusted, and in addition, 3 sets of user adjusting data are memorized.
Ver centering circuit which is adjustable by remote control, is added as well. And in RGB mode, user can control size and picture
position.
1. OUTLINE
As can be seen from the block diagram, the sync circuit and
the V trigger circuit are contained in ICH08 (LA7860), and
the sawtooth generation circuit and amplifier (V drive circuit)
contained in IC302 (TA8859AP). The output circuit and
pump-up circuit circuits are included in IC301 (TA8427K).
ICH08 LA7860
SYNC
CIRCUIT
V. TRIGGER
IC302 TA8859AP
SAM TOOTH
WAVE GAIN
CIRCUIT
AMP
LOGIC
CIRCUIT
IC301 TA8427K
PUMP-UP
CIRCUIT
OUTPUT
Microcomputer
CENTERING
CIRCUIT
DEFLECTION
YOKE
Fig. 1 Block diagram of V deflection circuit
1-1 Theory of Operation
The purpose of the V output circuit is to provide a sawtooth
wave signal with good linearity in V period to the deflection
yoke.
When a switch S is opened, an electric charge charged up to
a reference voltage VP discharges in an constant current rate,
and a reference sawtooth voltage generates at point . This
voltage is applied to (+) input (non-inverted input) of an
differential amplifier, A. As the amplification factor of A is
sufficiently high, a deflection current flows so that the
voltage V2 at point becomes equal to the voltage at point
.
Fig. 2
S: Switch
Differential
amplifier
VP
a
R1 C2
R2
C2
R3
V2
c
A
L
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