Muting During Ff, Rew And Stop; Muting During Changeover From Stop To Play - Pioneer CT-F950 Service Manual

Muting during FF, REW and STOP
This circuit is designed to eliminate noise (e.g.
motor noise), during FF, REW or STOP (Fig. ?-10).
l.During
FF, REW or STOP, Pin 20 of lCsot
will become H level, and hence base current will
flow into Qsoa.
2. When Qsra becomes conductive, Qsoe and Qsro
lvill
also become conductive.
Current from
+Br wilt flow through Qsto, Qqoz, Stot-l. Rtzs,
Rlzz, Qroz and Qros. Accordingly, Qeoz and
Qcor will become conductive, and the LINE
OUTPUT will be muted.
3. At the same time, current will flow 166
tB3
through Qs r o, Ds r z, Rzal and Qzor ' Qzor will
thus become conductive and mute the recording
amplifier.
4. When the MONITOR switch Seor-r is in the
SOURCE position, the LINE OUTPUT will not
muted.
Muting During Changeover from Stop to Play
(or REC)
This circuit is designed to prevent switching
noise when the PLAY
or REC switches are
operated (Fig. 7-10).
1. When the unit is in the STOP condition, Qroz,
Qroe and Qzor will be conductive, and hence the
LINE OUTPUT and the recording amplifier will
be muted. Also, Csoo will be charged (Refer to
previous section entitled "Muting when unit is
in STOP condition").
2. When the PLAY switch is pressed on, Pin 20 of
ICsor will become L level, and hence current
will not flow through Qsoa.
3. When Qsoa becomes non-conductive, the charge
on Cso6 will decay via Rszg. Duringthe interval
that
Csoo is discharging (approximately 1
second), Qsor, Qsro,Qtoz andQroe willbecome
conductive. After about 1 second, the unit will
go into the PLAY condition, and thus switching
noise will be muted.
4. When the unit is in the PLAY condition, current
will flow from *Br through Rsrr, Rszc and
Qsoo, and thus Qsoe and Qsoz will go on.
Consequently, current from *Bs will flow
through Qsoz, Dsoe, P'zet and Qzot , and hence
the recording amplifier will remain muted.
F i g . 7 - 1 0 M u t i n g c i r c u i t 2