Audio Circuit - Sony AV-3420CE Service Manual

@ CTL pb output
pulse amp.
output (Q702)
@ monostable MV
output (Q713)
@ integrator output
TP-706
® PG pulse, TP-707
6) V syne
O) flip-flop, output
1C601, pin 9
integrator output
TP-704
@ PG pulse, TP-707
Fig. 8-7. Playback servo waveforms
0804, Q805
record
equalizer
Q806, Q807
D801, D802
detec/
amp.
Pulse amplifier Negative-going pulses from the
Q47, Q48 CTL head are amplified by Q47
'and Q48.
Monostable This multivibrator is triggered by
Q54, Q55 back CTL signal.
De amplifier This push-pull amplifier is con-
8-3. AUDIO CIRCUIT
This section describes audio record, playback,
and sound dub circuits.
8-3-1. Record Mode Audio Circuit
Audio recording level is maintained by the
AGC circuit.
The audio recording may be monitored
at the EARPHONE jack only in the TV record mode.
Audio input from either the microphone or
the TV is amplified by Q801 and Q802 with negative-
feedback equalization. The output of Q802 is again
amplified by Q803 and fed then to the audio record/
playback head through a bias trap. The age circuit
consists of Q804 through Q807 to detect and supply
negative feedback to Q802.
0808, T807
audio
monitor
output
Fig. 8-8. | Recoed mode audio circuit
8-7