Pioneer CT-F950 User manual

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Cassette
compartment rllumination
2. FRONT PANEL FACILITIES
Opowen
swlrcH
The power
comes
on whenthe POWER
switch
is
depressed.
The
level meter and tape counter, and the cassette
compartment
illumination'will
thencome
on.
€)DUST
COVER
When
you are
not usingthe deck,alwayskeepthiscover
in place
to prevent
dust and dirt from adhering to the head section
and
rotatrnE
parts.
@REMAINING
TAPEMARKER
lf thismarkeris
visible,it meansthatthere
isenoughtaperemain-
inq
for several
minutes
of recordingor playback.
@)rNpuT
(RECORDTNG
LEVEL)
CONTROLS
Usetheseto adjust
the levelof the input signals from theMIC
jacks
or rear
panel
INPUT
iacks.
Turning
thesecontrols
to the right increases
the
level
The controls are coupled to the left and right channets,but
you can also use them to adjustthe right channel
(back)
and
the 1g11
channel
(front)
independently
@ourpur (eLAYBAcKLEVEL)coNTRoLS
Usetheseto adjust
theoutput signal
levelduring
playback.
Turn-
ing the controlsto the
rightincreases
the level.
The controlsare
coupled
when turned but it is also
possible
to adjustthe right
channel
(back)
andtheleftchannel
(front)
independently.
When playing back a referencetape (160 nwbim), a reference
playback
level
(0dB)
isobtained
with these controls
setto the
"6"
click
stop
position.
@rnpe
SELECToR
This selectorallows the biasand equalizer
characterist.ics
to be
selectedduringrecordingand theequalizer
characteristics
during
playback
In line
with the type of tape
you are
using
METAL: For
using
metaltapes
STD: For usingordinaryor LH rapes
CrOr: Forusingchrome
tapes
Fe-Cr: Forusingferrichrometapes
oMrc
,ACKS
These
arethe input
jacks
for microphone
recording
plug
the left
channel
microphone
into the L lack
and
the right
channel
micro-
phone
into the R.iack.
IOHEADPHONES
JACK
This is the output jack for your stereo headphones. You will be
able to hear sound from signàlsselectedby the MONITOR switch-
es Use this Jack
when you wànt to monitor the quality of a
recordrng or when you wanl to listen to a làpe pilvately on the
CT F950 Adjusl the output level
with the
OUTPUT controls.
NOTES:
a Use lou-tmpedance heodphones If you use o high-imped,once
model, you uill not be oble to obtoin sufficrcnt uolume
c You u'ill domage thë microphone if you plug it into the
HEADPHO.\'E:S jock by mistahe
@rrueur
sELEcroR
swtrcH
Use this switch to select the program source which you intend to
record
LINE: Set to this position for recording a program source
which isconnected ro the rear
panel INPUT jacks.
MIC: Set to this position for recording signals
from a micro-
phone,
or microphones,connectedto the
MlC,acks.
NOTE
You will be oble to record Eignals from the INPUT jachs il the
LINE suitch is depressed euen when the microphone. ore
plugged into the MIC jochs
@ooLgy*
NR
swtrcH
5et this
switch
to ON for recording
with the built-in
Dolby
noise
reduction system
and for the playback
of rapeswhich have
been
recorded
using
the
Dolby
N
Rsvstem.
@arns
coNTRoL
Use this control to adlust the bras in accordance
with the
characteristics
of the tape
being
used lr is
setso
that the center
(click
stop)
position
corresponds
to thestandard
bias.
@MONtTOR
SWTTCHES
You will be
able
to lisren
to therecorded
signals
(playback
sound)
if you depress
rhe TAPE while you are recordtng
a program.
You will be able to lisren
ro rhe signals (recording
inpur)
just
beforethey arerecorded
if you depress
the
SOURCE.Userhese
swirchesto monitor your recording Depressthe TApE during
olavback
*N4anufactured
under licensefrom Dolby,Laboratorres.
*Dolbr and [[ .]rctrddemarks
of Dolbr.,Laboratories
4

GT-F95Cl
1.SPECIFICATION
Systems Compact
cassette,
2-channel
stereo
Motors Capstan
drive;
DC
servo
motor
x I
Reel
drive;
DC
high
torque
motor
x 1
PlaYback
combination
tYPe
head
x 1
erasing
head
x 1
Fast
Winding
Time
.. " '
Approximately
85
seconds
(C-60
tape)
Wow
and
Flutter ... No
more
than
0'04%
(WRMS)
Frequency
Response
-20d8 Recording
Standard,
LH taPes ' ' ' 20
to 17'000H2
(25to15,000H2
t 3dB)
- - ' '2O
to 19,000H2
(25
to 17,000H2
I 3dB)
Ferriterecordingl
tape.. 20
to 11,000H2
20
to 14,000H2
Dolby
NR
OFF;More
than
59dB
Dolby
NRON;More
than
69dB
(over
5kHz)
:
: i:
liiTi:i:
.
420(w)
x 187(H)
x365.5(D)mm
Max'
16'9116
x 7'318
x'14'318
in'
Weight ' '10'1kg
(221b4oz'l
Furnished
parts.. . . Stereo
connectinS
cords
with
Pin
Plugs
x 2
Head
cleaning
swabs
x 3
OPerating
instructions
x 1
NOTE:
iir"ifi"otio"s and thedesign
subjectto possible
modifi'
càtion
without notice
dueto improuements'
Power
Requirements
Power
ConsumPtion
Dimensions
NOTES:
l. Raterence
Heads .
Ferrichrome
taPe
OdB
Recording
Chromium
dioxide
Metal
tape
3.
4.
Chromium
dioxide
tape
. . " "2O to 19'000H2
(25
to t7,000H2
t 3dB)
Metal
tape ' ' ' '20 to 19'000H2
(25
to 18,oooHz
t 3dB)
: CrO,
: DIN
45513/BLATTTlCrOt
lorequiv'
2. Reterence
Recording
Level:
Meter
OdBindicatitlg
level
(16O
nwb/mmagnetic
level
=Philips
cassette
reference
levell
Reference
Signal: 333H2
Wow & Flutter: o JIS [3kHz, with acoustic compensatron
(weightedl, rms valuel
Frequency Response: r Measured at -2OdB twet' OOLBY
NR OFF,level deviation
is
!6dB without indication'
Sign"l to Nois€ Ratio: o Measured
al the third harmonic distor'
tion 3% level,
weighted.
Sensitivity: inpur level (mV) required for reference recording
levelwith input (RECI controls s€tto maximum'
S.MaximumA|lowab|eInpul:Whi|âdecreasingsettingsofinput
(RECI level controls and increasing
level at input iacks' thisis
the maximum input level (mVl at the poinl where recording
amplif ier output waveform becomês
clipped'
Reference Output Level: Playback output level when meter
indicates
OdB.
Maximum Output Level: Playback output level
with reipêct to
reference recording level when output (PLAYI l€vel controls
areset 10maximum.
& LH: DIN 45513/BLATT6
or
42O(Wl
x 187(Hlx 365.5(D)mm Max.
* with rackmount adaptor JA'R102
* 48OlW)x 187lHlx 3801D)
mm Max.
iack
Semiconductors... Transistorsx
76
Diodes
x 84,Photo
interruPter
x 1
Subfunctions lCsxl3
. OotUy NR
system
(ONOFF)
with
LED
indicator
lamp
. Fluorescent
tube
level
meter
(-20 to+7dB)
Signal-to-Noise
Ratio
.
(Peak/Peakhold/average
selector)
Fluorescent
taPe
counter
Bias
fine
adlusting
control
knob
Memory
stoP/MemorY
PlaY
Counter
repeat/End
rePeat
I
nput
selector
Automatic
tape
slack
canceller
Cassette
compartment
illumination
Standby
mechanism
withunattended
recording
Tape
Selector
4 Position.
Click
StoP.
OutPut
VR'
5.
6.
7.
9.
10.
a
o
a
a
O
a
a
o
o
o
Unil: mm

l.l8V
l(l.12vl
3. LEVEL
DIAGRAM
PLAYBACK
P8 LEVEL
ADJ.
P8 AMP
I
(36'2
mv)
- 36GV
PB AilP Goin
.19d8
FLAT AI,IP DOLEY
AMP
I
I
-scav
7V)
- 23dBV
F
LATAMP Goin
|
3dB
OUTPIJT
VR
-6d8v
(o.5v)
AtaPGoln
HEADPHoNEs
auel
Goin
7.4rlB I
\l
- 6.a(DV
(o.a7vt
Not.;
. OdBV
' lV
. Fr.qu.Êct i 333H2
OISPLâY AHP
LINE OUl
- 7tl8V
o.44vl
- 2
4dBV
(
63.
lmv
)
RL' 8Â
LINE
ouTPul
s.]01-
|
souRcE
o
o
J
u,
u,
J
-20 VR Lc.
3dB
vR Lo.r
ild
-74dBv

CLOS6O
LOOPOIJAL
CAPSTAN
2
MOTOR TAPÊ
TRANSPORT
SYSTEM
a<>}a4a I Èf - -o
@opeRnrtruc
.rt (REW):
I (STOPI:
> (PLAY}:
BEC:
swlTcHEs
Depress
thisswitch
to rewindthetape.
(The
tape
will travel
at high speed
from right to left.)
Depress
this switch to send
the tape
forward at
high speed. (The tape will travel from left to
right.)
Deoress
this switch to stop the tape run and to
releasethe
operating
switches.
er-Fs|5cl
@
uEruonY/REPEAT
rNDrcAToR
This indicatorcomes
on when the MEMORY/REPEATswitches
are depressed,signifying that the deck is set to the respective
mooe.
@memonYlREPEAT
swlrcHEs
t)
Depress
this switch when playing
back a
(The
tape
will travel
from left to right.)
Depress
this switch together
with the PLAY
switch
for recording.
This switch will not wÙrk when a cassette
is not
loadedor when the erasure
prevention
tabs
of a
loaded
cassette
havebeenbroken
off.
Depress
this switch to stop the tape temporarily
during recordingor playback.
Depress
it againto
allow the tapetc continue
to travelas
before.
NOÎES;
a When ony of the operating suitches are depressed, the cor-
responding indicator (except STOP mode) uill come on
signifying that the dech i8 set to that respective mode.
. Att the opercting suitcâ€s are released, (OFF) to stop mode
uhen the POWER switch ls turned OFF'
@courureR
RESET
BUTToN
Depressthis
button to resetthe tapecounterdisplay
to "000."
@rnpe
couNTER
This indicates the position of the tape run. The counter reset to
"000" whenthe power isswitched on,
@lsvrl METER
This indicatesthe input levelduring
recording
andthe output level
duringplayback.
8y operating the METER switches,
it can be made to function
asa peak meter,a peak
hold meter
or as a levelmeter.
The input signal level is indicated when the MONITOR switch
SOURCE has been depressed,
and the playback'output level is
indicated
when theMONITOR switch TAPE has been
depressed.
@oolaY NRtNDtcAToR
This lights up when the DOLBY NR switch is setto ON and it
indicates
that a tape is being recordedor played back with the
Dolby NR system.
@ræe lNDlcAToRs
METAL: This light comes
on
METAL.
CrOr: This light comeson
CrO2.
when the TAPE selector
is set to
when the TAPE selector
is setto
MEMORY :
STOP
REPEAT
COUNTER:
END:
OFF:
Depressthis switch and the tapewill be rewoundto
that spot at which the tape counter was preset
to
"000" during reclplay, when the REW switch is
depressed
at any position
you like.
Depress
this switch and the tapewill berewoundto
that spot at which the tape counter was preset
to
"000" during reclplay,and playback
will start
from
that spot, when the REW switch isdepressed
at any
position
you like.
Depress
this switch when you want to play back a
tape during playback
or recording
from the point at
which the tape
counter was setto "000" up to the
end
of the tape.
Depress
this switch when you want to play back a
tape
from thebeginning
to the endof thât tape.
Depress
this switchduring normal tape playback
or
recording
to releasethe MEMORY and REPEAT
gWitCheS.
@mrrrn
swtrcHEs
PEAK: The meter functions as a peak lcrrel
meter when
this
switchisdePressed.
PEAK HOLD: The meter functions as a peak level meter and
the highest level of the signals
is indicated when
thisswitchis
dePressed.
AVERAGE: The meter functions as a level meter when this
switch isdepressed.
@rtmen
srART
swlTcHEs
Depressthesc switches when you are playing back or recording a
tape
with the use
of atimcr.
REC: When this switch is depressed,
the dcck will automàtical-
ly be setto the recording
mode at thc prestttimer time,
and recording wilt begin. Use this switch for recordint
FM programs when you are out of the house or other'
wise
occuPied.
PLAY: Whenthis
switchis
depressed,
the deck
will automatical-
ly be setto the ptayback
modc at the preset
timer time,
and playback will begin' Usethis switch for wake'up
playback
instead
of analarm
clock.
OFF: Always depress
this switch when you do not intend to
recotd or playback a tape using the timer' (This will
release
the REC and PLAY switches
of TIMER
sTA
RT.)

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Mechanical
Assembly
When replacinga motor or a belt, be careful of
the sequence
of disassembly andreassembly of the
variouscomponents
concerned.
1. Remove the capstanmotor by undoing screws
Oto @.
2. Remove
solenoidA by undoingscrews
O to ().
Flywheel
assembly
Capstanbelt
UL cord clamperD
3. Remove
the plungerchassis
assembly
by undoing
scre\ils
Oto 9.
4. Remove the sub-c*rassisassembly by undoing
screws
I to (0.
5. Remove the take-up motor by undoing screws
@ and O, and remove solenoid B by undoing
screws
(DandO.
Solenoid
B
Take-upmotor
Supply
pulley
assembly
Capstan
motor Sub belt
chassisasembly
Solenoid
A
Subchæsis
assemblY
Fig.
4-5 Disassembly
of mechanism
asembly

Mechanical
AssemblY
After removing
the front panel,undo screws
Oto@.
Mechanism
asemblY
o-@
Fig.4-2 Removethe
mechanism
assembly
Sub-head Assembly, Pinch-roller Arm Asembly
and Pressure
Arm
1. Removethe sub-head
base
assembly
by undoing
screurs
Oand O and the socket-head hexagonal
bolt.
2. Remove the feed side pinch-roller arm assembly
by looseningthe height adjuster (unt).
3. Remove the take-up side pinch-roller arm
assembly
by taking off E-washerQ.
4. Remove the pressure
arm by taking off E-washer
O When the pinch pressure spring is replaced
with a new one. take care to ensure that the
cT-Fg|scl
new springisproperly seated.The requirements
of the sub-section
entitled "Pinch roller pressure
adjustments" (Page
30) included in the section
"Mechanical
adjustments"shall
besatisfied.
Fluorescent
Indicator Tube
1. Removethe indicator lensassembly
by undoing
screwsoto@.
2. Remove the indicator amplifier assembly by
undoingscrews
O to O.
3. The fluorescent indicator tube is mounted on
the indicator assembly. Remove it by means
of
a soldering iron. Take great carewhen handling
the indicator tube so as
to avoid damagingit.
lndicator
assembly -è*n"ring iron
o-o
Fluorescent
indicator
@
o-o
I
ndicator
amplif
ierassemblY
o-() I
ndicator
lens
assemblY
Fig.
4-3 Remove
thefluorescent
indicator
tube
Heishtadjuster
(nut)
-
,.ry) ô
Socket*read ,.'u
hexagonal
bolt
EwasherQl K\
5 E
washer
tp^pin"n-'ott* arm
assemblv
o
Sub-head
assemblY
Fig.
4-4 Remove
the
sub-head
assembly,
pinch'roller
arm
assembly
and
pressure
arm

PANEL
VIEW
5. PARTS LOCATION
FRONT
Guide
(R)
RN
K€08
Halfcover
RN
K.777
Guide
(L)
RNK.566
Esculcheon
panel
RAH.285
Function
switch
RAC-108
Push
knob
(Al
RAC{91
FRONT
VIEWWITH
FRONTPANEL
REMOVED
Taker.rp
reel
assembly
(B)
RXB-190
Supply reel
assembly
BXB-189
Reelcap(B)
RNK-815
Powerswitch
RSA-021
Sub-headbase
assembly
RXB-255
Push
switch(A)
RSG064
Volume
5k (B)(BIAS)
RCSO20
Front panel
assembly
RXX.251
REC
VR knob
(R)
assembly
RAA.225
REC
VR knob
(L)
assembly RAA-22:
PB
VR knob
(Rl
assembly
RAA-22!
PB
VR knob
(L)
assembly
RAA-22
Tapeselector knob assembly
RAA-301
BIAS
VR Knob
RAA.231
Volume20k (B)
RCV464
MIC
iack
R
KN{44
Headphone jack
RKN046
Push
switch (Bl
RSG{68

TOPVIEW
WITH
BONNET
REMOVED
Power supplY æsembly
RWR{)67
Powertransformer
RTT-I75
(KUI
RTT-I8s
(KCl
@ntrol ass€mbly
RWG-103
Motor
RXMO47
REAR
PANEL
VIEW
Bonnet
RNA€64
cT-Fs'E'Cl
assembly
RWX-359
RECEOassembly
RWX361
lC amp assembly
RWX-360
Push
srvitch
(A)
RSG064
Pushsaritch
(Bl
RSG068
Indicator
amp
assembly
RWX328
cord
ain relief
RDG{)22

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7. CIRCUIT
DESCRIPTIONS
For details of the circuit of the CT-F950, refer
to the block diagram on Page 13 and also the
overall schematic diagram on Page
54.
7.1 RECORDING AND
PLAYBACK
CIRCUIT
Playback
EqualizerAmplifier
The playback
equalizeramplifierisanNFB type
amplifier which uses
a low-noisehigh-gainmono-
lithicIC
(AN370).
PlaybackFlat
Amplif
ier
(Oro:,
Oro+
)
The playback
flat amplifieris a singletransistor
amplifier possessing
flat frequency
characteristics.
It is used to amplify the output of the playback
equalizer
amplifier. A trap circuit is usedat the
input sideto prevent
entry of the recordingbias.
BufferAmplif
ier(Oros,
Oroo
)'
The buffer amplifieris an emitter followertype
circuit which is used to take the output of the
Dolby NR amplifier to the LINE OUTPUT
terminals.
rc (PA4001)
The PA4001 was developed by PIONEER as a
system IC for use in tape decks. It contains a
microphone amplifier, headphone amplifier, flat
amplifier and recording amplifier. Its block dia-
gram is shown in Fig. 7-1.
OUT tN OUT
14 13 12 11 .to 9
%cr-Fs|5cl
Microphone Amplifier
The microphone amplifier consists
of the micro-
phone amplifier section of the PA4001. It has
a
gain
of about 28d8.
7.2 TAPE SELECTOR
CIRCUIT
The CT-F950 has been designed
to use metal,
CrOz
, Fe-Cr and normal tapes. The tape selector
circuit (see
Fig. 7-2) is switched to suitable
equal-
izer and bias levelsaccording to the type of tape
employed. This switching,plus the tape indicator
(CrOz
/NIETAL) switching is performed by the
TAPE switch
Sr:or
.
PlaybackEqualizer
SwitchingCircuit
The playback equalizer may be switched to
either of 2 positions: 70ssec for METAL/
CrOz, Fe-Cr and 120ssec for STD. lVhen the
TAPE switch Srror is in the IVIETAL position
(or CrOz, or Fe-Crpositions),a bias
current flows
from Droe (or Drrr or Drro) to Qror via Rrrz,
resulting in the transistor being turned on. The
Crr
q and Rr
rs seriescircuit is thus connected to
the playback amplifier to set up the 70gsecequal-
izer amplifier. When Sr
:o
r isswitched to the STD
position, Qror is turned off, thereby reverting to
the 1201.rsec
equalizer
amplifier.
Recording BiasGenerator and BiasSelector Circuit
Metal tapes require a bias current of about
twice the level of the bias required for conven-
tional STD tapes. For this reasonthe push-pull
generator output is amplified by a bias amplifier
(composed of step-up transformers Lro r and
Ltoz plus coupling amplifiers Qroo and Qro
z)
prior to being applied to the head. The bias
amplifier input may be adjusted by the front
panel BIAS control. Whereas more conventional
bias controls vary the B voltage of the oscillator,
the system employed in the CT-F950 also varies
the erasurecurrent at the same
time. Since erasure
efficiency is a particular problem with metal
tapes, the CT-F950 has been designed to also
vary the secondary side of the oscillator trans-
former.
Bias switching for each type of tape is achieved
through the TAPE switch Sr
ror . Bias level is
changed by first maintaining a constant oscillation
level by fuzo, and then changing the voltage by
inserting resistorsin parallel. The parallel connect-
ed resistorsinvolved are R:zo and Vfuor for metal
tapes,
Rrzz and VRroz for CrOz, and Rrza and
VR:or for Fe-Cr andSTD.
OUT IN
16 15
7-1 Blockdiagramof
8 GND
our (top
vtew)
PA4001
Headphone Amplifier
The headphone amplifier consists of the head-
phone amplifier section of the PA4001. This is a
complimentary amplifier having a gain of approxi'
mately 7.4d8. The headphone output is taken
off a resistive
voltage divider.
67
IN

Recording
Equalizer
Selector
Circu
it
The recording equalizer is switched to 4 separate
positions (METAL, CrOz, Fe-Cr,
and STD). Tran-
Tapo solector
sr30r
E
TAL
sistors
Qror,Q+or, Qeos
and Qeoz
are tumed on
and off according to the position of the TAPE
switch Srlor, thereby switching the LC resonance
circuit in the recording equalizer, amplifier.
REC
HEAD
^rrt t'X""'o"
Ril5
clt9
I
olo!
Fig.7-2 Tape
selector
circuit
7.3 LEVEL METER
The level meter circuit is shown in Fig. 7-3. It
consistsbasically
of 3 ICs
(ICaor,
ICaoz
andICsor)
and 1 microcomputer. Levels are displayed in
digitâl form using a fluorescent indicator tube.
1. The signalobtained from the output terminals of
the headphone amplifier is converted into a IC
voltage by means of a logarithmic compression
amplifier. This DC voltage becomes the refer-
enceinput for the comparator.
2. The comparative input to the comparator is a
DC voltage obtained by passingthe indication
condition of the level meter through a digitaU
analogconverter.
3. Accordingly, the comparator continually com-
pares the reference voltage with the indication
condition of the level meter, and sends signals
to the microcomputer so as to maintain the
comparative input (level meter indication condi-
tion) equal to the referenceinput.
The level meter is primarily a peak reading
meter, however it is possible to useit either asa
VU or PEAK HOLD meter by pressing switch
Ssor-r
(VU) or Saor-z (PEAK
HOLD).
7.4 ELECTRONIC
COUNTER
The electronic counter consists of a micro-
computer (ICaoa)and a counter type fluorescent
indicator tube (Fig. ?-7). Sensing
pulsesemitted
from the mechanical assembly undergo rvave
shaping
at Qaor to Qsosand then enter the micro-
computer (ICaoe
). The input pulses
areadded
and
subtracted in the memory of the computer, and
the resultant numerical value is displayed at the
counter indicator tube.
XEAOPHONE
AMP
LEVEL
I|€lER
LOGARITHMIC
coMPRESSTOt{
AMP
saor-2: MElÉR
S€LECTOR
P.B.
EO AMP
Fig.
7-3 Level
metercircuit

7.5 DOLBY NR PROCESSOR
CIRCUIT
Recording Mode Operation
1. Input signals are first applied to the MPX filter
where the FM broadcasting station's pilot signal
is employed, and where an 85kHz bias trap is
employed to prevent mis-operation of the Dolby
NR noisereduction system.
2. From the MPX filter, the signalsare passed
on
to the buffer amplifier whose output is divided
into 2 routes. The main signalispassed
directly
to the adding amplifier, while the sub-signal is
passed via the side chain amplifier and clipper
before being recombined with the main signal
in the adding amplifier.
3. Besides being applied to the clipper, the side
chain amplifier output is also passed via the
voltage controlled amplifier and integrating
amplifier back to the side chain amplifier input,
forming a variable filter circuit.
4. In addition to the above,the side chain amplifier
output is further applied to a high-passfilter and
rectifier where it is converted into a DC voltage
for control of the voltage controlled amplifier.
5. When the level of the signal passed
through the
high-pass filter is low, the rectifier output DC
voltage will be almost "0", resulting in a
minimum tumover frequency for the variable
filter. The Ievel of the adding amplifier output
will thus be 10dB (above SkHz) higher than the
level of the main signal,thereby contraction the
dynamic range.
cT-Fs|5c,
6. The clipper produces a time lag in the signal
applied to the voltage-controlled amplifier, and
since it is not capable of responding to sudden
Ievel changes, no uncontrolled signals will be
applied
to the adding
amplifier.
7. When the level of the signal passed
through the
high-passfilter is high, the rectifier output DC
voltage will also be high, and the variable filter
turnover frequency will be increased. The sub-
signal level will therefore become almost "0", so
there will be no contraction of the dynamic
range.
Playback Mode Operation
Although each section of the Dolby NR Proces-
sor operates in the same way as during recording
mode, the sub-signal
is derived from the output of
the adding amplifier. And since the adding
amplifier is an inversion amplifier (where output
phase is opposite to input phase), the sub-signal
will be of opposite phase,
thereby forming an NFB
loop.
In Dolby NR B noise reduction systems, con-
traction and expansion occur within a fixed
frequency range determined by the variable filter
circuit. And, in order to achieve perfectly
symmetrical operation, it is necessary to fix a
reference level for the operational point. This is
the so-called "Dolby level", below which no
contraction and expansion is performed.
Adding Amplifier
MPX Filter Bufter
Amolifier
Sidechain Amplifier
Voltage.control led
Amplifier
Rectifier HighpassFilter
Fig.7-4 Dolby
NR
processor
circuit

7.6CONTROLCIRCUIT
PLAY Operation
1.lVhen a cassetteshellisloaded,the cassette shell
detection switch will go into the SHELL position
and the slack elimination circuit (Described
later) will commence functioning.
2. When the PLAY switch 'Sgoa
is pressed
on, the
voltage at Pin 17 of lCsor will becomea High
level (Hereafter abbreviated to H level). Cur-
rent from +Br will flow from the capstanmotor
CM to Qszz. As a result, Qszz will become
conductive, and CM will start to rotate, At the
sametime, current from *81 will flow through
Qszr,the reelmotor RM, Rssr and
Qsrz,
ând
henceRM will alsostart or rotate.
3. The voltageat Pin 15 of lCsor will alsobecome
an H level. Current from fBr will flow through
the pinch solenoid
$[,rror, Qsrz 31d Qsrr,
hence SLrror will operate and the unit will go
into the PLAY mode.
RECOperation
1. When a cassetteshell having erasureprevention
tabs is loaded (The erasure prevention switch
Srros will go into the NO HOLE position),
the
PLAY switch Sgosand the REC switch Ssoc
will go on simultaneously. The operation of the
pinch solenoid Srror and the capstan
motor
CMisthe sameasfor "PLAY operation".
2. The voltageon Pin 16 of ICsor becomes
H level.
As basecurrent flows from Rsoe,
Rtro to Qtos,
Qo
og becomes conductive, the bias oscillator
circuit operates
and the unit goes
into the REC
mode.
Whena cassetteshellwhich doesnot haveerasure
prevention tabs is loaded (Srros goesinto the
HOLE position), Pin 5 of ICsor will become
Low level (Hereafter called L level), regardless
of the position of Ssoa,and hencethe unit will
gointo the REC mode.
FF, REW
Operation
1.When the FF switch Ssoz
is turned on,Pin22
of ICso
r will becomeH level. Cunent from *Br
will flow through Qszr, the reel
motor RM and
Qs
ro,andthus RM will start to rotate.
2. Current from *Br will flow through the brake
solenoid
SLrrou,Rsls and
Qsre,
hence
SLrroz
will operate and the brake will be removed.
,1
E|
3. The REW operation is basically the sameasthe
FF operation except that the polarity of the
voltage
supplied
to RM isreversed.
PAUSEOperation
1. As previously explained, when the unit is in
either the PLAY or REC modes, current from
*Br flows into the pinch solenoid
SLrror, the
capstanmotor CM, the reel motor RM and the
biasoscillatorcircuit.
2. If now the PAUSE switch is pushedon, Pin 15
of ICsor will become L level. As a result,
Slrror will not operateand RM will notrotate
(Refer to section entitled "PLAY operation").
Hence the PLAY or REC condition will be
temporarily removed.
TIMER START Operation
r PLAY Operation
1.Press the TIMER START PLAY switch Saor-s
on, and then put the POWER switch on using
the timer etc. WhileCarzis chargingup, Pin 4
of ICsor will become
L level.
and thus the unit
will operate in the same ïyay as if the PLAY
switch S4o3ïyere
put on.
2. Whenthe power supply voltagereaches
its final
value(after about 4 seconds),
Pin 14 of lCsor
will become H level, and the unit will go into
the PLAY mode.
. REC/PLAY Operation
1.Press the TIMER START PLAY switch Ssor-e
on, and then put the POWER switch on using
the timer etc. While Car
r andCarzarecharging
up, Pins4 and 5 of ICsor will become
L level,
and thus the unit will operate in the sameïyay
asif the PLAY switch Ssosandthe REC switch
Ssoawereput on simultaneously.
2. In the same
u/ay asfor PLAY operation, Pin 14
of ICsor becomesH level, whereupon the unit
commences
REC/PLAY operation.
MEMORY STOPOperation
Pressthe MEMORY STOP switch on, and then
press the REW switch on. When the tape counter
indication reaches "999", the REW operation
will stop.
1. Press
the MEMORY STOP
switch Saor-r on, and
pressthe REW switch Sgor on. lVhen the tape
counter indication reaches
"999", a pulse
will be
sentfrom the microcomputer (ICaoe
).
I
|'t

I
F=
Tà
EG
l-o
âE
oô
lo
z-,
Èo
ôo
o
o
o
o
o
I
o
o
o
o
o
o
o
o
o
o
o
a
ô
o
È
o
o
o
c
a
E
c
E
J
U9
a
o
o
o
o
o
o
;ù
ot
Fig.
7-5 Control
circuit

Current will flow from Ress to Qaor, thus
Qaoz
will be turned on, and asa result of the
integral pulse,Pin 11 of ICsor will momentarily
become
L level.
l.
WhenPin11of ICsorbecomes
L levelas
aresult
of the program within the IC, the output will
go into the STOPmode, and thus the unit will
ceaseoperation.
4EMORY
PLAY Operation
. Press the MEMORY PLAY switch on, and then
put the REWswitchon.
. \[hen the tapecounter indication reaches
"999",
a pulse will be sent from the microcomputer
gCff.). Current will flow from Rssr to Qaoz,
'ûruË turning on Qeoz, and as a result of the
integral
pulse,
Pin 11 of ICsorwill momentarily
becomeL level.
.When Pins g and 10 of lCsor areto L levelby
means of the program in the IC, the unit will
momentarily go into the STOPmode and then
commencePLAY.
ounter Repeat
Pressthe REPEAT (counter) switch on. When
re tape stops during PLAY or REC/PLAY (auto
op), the unit will automatically go into the REW
.ode, and when the tape counter indication
raches
"999", it will revertto PLAY.
,Pressthe REPEAT (COUNTER) switch Seoz-r
on,and set
Pins
8 andI of ICsorto the L level.
\ilhen the tape stops during PLAY or REC/
PLAY, Pin 12 of ICsor will momentarilygo to
the L level. WhenPins8 and 9 of ICsorâreset
to the L level by meansof the program in the
IC, and Pin 12 goes
to the L level,the unit will
automatically gointo the REW mode.
.When the counter indication becomes "999",
a pulse will be emitted from the microcomputer
(ICaoc).Current will flow from Rass
to Qaoz,
resultingin Qeoz
being
turned on, while Pin 11
of ICsor will momentarily go to the L levelasa
resultof the integralpulse.
If Pin 11 of lCsor goes
to the L levelduring the
REW operation of the unit, resulting from Pin
12 going
to the L level,the unit will gointo the
PLAY mode asa resultof the programcontained
ICso
r.
GT-FS|5O
5. Because of the program contained in lCsor,
COUNTER REPEAT is not possible during FF
or REW (Auto stop ispossible).
End Repeat
Press
the REPEAT (END) switch on. If the tape
stopsduringPLYA or REC/PLAY (autostop),the
unit will automatically go into the REW mode,
and when the tape has completely rewound, the
unit will onceagain
gointo the PLAY mode.
1.Press the REPEAT (END) switchSsoz-zon,and
set
Pins
8 and
9 of ICsorto the L level.
2. For detailsof the REW operation,referto para-
graph
2 "COUNTER REPEAT".
3. When the tape completely rewinds, Pin 12 of
ICsor will once again momentarily go to the L
level.
PinchSolenoidSwitching Circuit
This circuit is designed to protect the pinch
solenoid from overheating. It operatesafter the
PLAY switch has been pressed on, by applying a
high voltage (approximately 13V) to the pinch
solenoidfor aperiod of about 0.5 seconds,in order
to increase
its attractive force, and then reducing
the voltage to about 6V after the solenoid has
operated
(Fig.7-6).
1.When the PLAY switch Ssos is pressed
on,
Qs
rr becomes conductive, the pinch solenoid
Sl,rror operatesand the unit goes into the
PLAY mode (Refer to section entitled "PLAY
mode").
_a
e
Fig.7-6 Pinch
solenoid
switching
circuit

2.
Cunent will flow from +B through
Rsao,
Csoz
and Qs
rz. A voltageapproximately equalto the
+B voltage(approximately 13V) will be applied
to the pinchsolenoidSL
r
r
or until Qs
rz becomes
fully conductive.
3.When Csor becomes fully charged (after an
interval of about 0.5 seconds), Qs
rz will be
reduced by Rsar to the minimum value (ap-
proximately 6V) necessary
to hold the plunger
in position.
4. If Pin 12 of ICsor goes
once
again
to the L level
during the REW operation of the unit, resulting
from Pin 12 going to the L level,the unit will
go into the PLAY mode asa resultof the pro-
gram
contained
in ICsor.
5.Because
of the program
contained
in ICsor,
END
REPEAT is not possibleduring FF or REW
(Auto stopis
possible).
Auto Stop Circuit
This circuit is usedto automatically releasethe
mechanism
in the eventthat the tape stops
during
PLAY, REC, FF or REW. It employsa photo-
interrupter type switch linked to the take-up reel
by meansof a belt, in order to detect the running
of thetape
(Fig.
7-7).
+83
(5 6v)
CT.F9
1.When the tape is running, pulse signals
emitted from the photo-interrupter (TLP
and
hence
Qaot,Qaoz,
Qaor,
Qsoc
and
Qsor
switch on and off continuously. At the
time, Csor will charge and discharge
While Qsor is turning on and off, the
of point A will be relatively low, andthus
will turn off.
2. Whenthe tape stopsrunning, pulsesignals
the photo interrupter lamp will disappear,
thus Qsor will go off. When this h
Csor will chargeup. The potential of po
will start to rise, and Qsoz and Qsor wil
turned on. Consequently,
Pin 12 of lCsor
become L level, and the unit will go into
STOP
mode.
3. When either the POWER switch is
and off. or the PAUSE button is
H level will be applied to the base
of Qsor
Dsos and Dsoaand thus the potential at
will not rise. Consequently, the unit will
gointo the STOP
mode.
a
+92
MUÎING CIRCUII
c504 R5r4
050t R5t3
Fig.
7
-7 Autostop
circuit