Table of Contents
Advertisement
Circuit Description
4. AUDIO
OUTPUT
4-1 (AN5265)-Monaural
model
The audio signal output from pin 50 of ICI 01 is inputted to
pin 2 of IC1101 and passes through the pre - amplifier
circuit and the drive circuit into the audio amplifier. The
audio amplifier is the SEPP (Single- Ended Push Pull)
type and the output from pin 8 drives the speaker directly.
4-2 (TDA7263M)-Stereo
model
The audio signals output from pins 17 and 18 of
.
IC1103(MC44131 PB) are inputted to pins
1
(Left) and
5( Right) of IC1102 and passes through the pre - amplifier
circuit and drive circuit, after which it is input to the audio
amplifier. The audio amplifier is the SEPP (single-ended,
push - pull) OTL type and the outputs from pins 8(Right)
and 10(Left) drive the speakers directly.
5. VERTICAL
OUTPUT
L
An LA7833 is used for the vertical output circuit in this
chassis. The vertical ramp signal from pin 43 of IC101 is
inputted to pin 4 of IC451. This ramp drives IC451, and
vertical scanning is performed, in the first half of scanning
a deflecting current is outputted from pin 2 and passes
through the following path:
VCC(B4) + D451 + pin 3 + pin 2 +
DY + C461 +
VR451 IR459.
An electric charge is then stored in C461. In the last half of
scanning the current path is:
C461 + DY + pin 2 + pin 1 +VR451/R459
+ C461
In this way, an increasing sawtooth waveform current
flows directly to the DY to perform electron beam
deflection. During the first half of the blanking period the
vertical ramp signal suddenly turns OFF. Since there is no
longer any current flowing into the DY, the magnetic field
collapses causing an induced current to flow as follows:
DY+ pin 2+ pin 1 +VR451/R459+C461
+DY
L
Once the magnetic field in DY has dissipated, the current
path becomes:
Vcc+ pin 6+ pin 7+ C452+pin
3+ pin 2+ DY+ C461
+ VR451 /R459
and when the prescribed current value is reached, the
,
vertical drive ramp signal turns ON.
This completes one cycle.
.
6. HORIZONTAL
OUTPUT
The horizontal oscillation signal is outputted from pin 37 of
ICl 01 and used to switch the drive transistor Q431. This
switching
signal
is current
amplified
by the drive
transformer T431 and drives the output transistor Q432.
When Q432 turns ON, an increasing current flows directly
to the DY through
C441/C442 + L441/R441 + DY + Q432- C + Q432- E
and the deflection occurs during the last half of the
scanning period. When Q432 turns OFF, the magnetic
L
field stored in the DY up to that point causes a resonant
current to flow into the capacitors C420 and C423 and
charges them.
The current stored in C420 and C423 then flows back to
the DY causing an opposite magnetic field to be stored in
the DY. This field then collapses increasing a current
which switches the dumper diode in Q432 ON. The
resonance state is completed, and an increasing current
then flows again directly to the DY through the dumper
diode.
By this means, the deflection in the first half of the
scanning period is performed. When Q432 turns ON at the
end of the first half of the scanning period, the deflection
during the last half is begun, thus completing one cycle.
In the PCC circuit consisting of Q461 and Q462, the
parabola signal supplied from the vertical circuit is added
at
the
horizontal
output
stage
and
pincushion
compensation
is performed by varying the DC bias.
Further, the ABL voltage is fedback to the base of Q462 to
compensate for width variations due to variations in the
beam current.
–5–
Advertisement
Table of Contents
