Pioneer CT-F850 User manual

CASSETTE TAPE DECK
T=F-Ss50
Y PIONEER’

MODEL CT-F850 COMES IN SIX VERSIONS DISTINGUISHED AS FOLLOWS:
HE AC 220V and 240V (Switchable)
AC 120V, 220V and 240V (Switchable)
KU AC 120V only U.S.A. mode!
KC AC 120V only Canada mode! ;
Europe model
HB AC 220V and 240V (Switchable) United kingdom model
AC 120V, 220V and 240V (Switchable) General export model
U.S. military model
e This service manual is applicable to the CT-F850/KU, KC. For servicing of the other types,
please refer to the additional service manuals.
CONTENTS
1. SPECIFICATIONS ...............0200es 3
2. FRONT PANEL FACILITIES.............. 4
3. LEVELDIAGRAM.................-05- 6
4. DISASSEMBLY ............ 0.02 eee eee 8
5. PARTS LOCATION ...............00005 11
6. BLOCK DIAGRAM ............-200000- 13
7. CIRCUIT DESCRIPTIONS
7.1 Recording and playback circuit ........ 15
7.2 Tape selector and equalizer........... 15
7.3 Level meters circuit................ 16
7.4 Dolby NR circuit ................. 17
7.5 Control circuits ..............000- 18
7.6 Muting circuits ...........020000ee 20
8. MECHANICAL ADJUSTMENTS
8.1 Pinch roller pressure adjustment ....... 25
8.2 Tape speed adjustment ............. 25
8.3 Tape guide adjustment.............. 25
9. ELECTRICAL ADJUSTMENT
9.1 Head azimuth adjustment............ 26
9.2 Playback equalizer adjustment ........ 27
9.3 Playback level adjustment ........... 27
9.4 Level meter adjustment ............. 27
9.5 Bias trap adjustment ............... 27
96 Erasure current adjustment........... 27
97 Bias adjustment ...............0-- 28
9.8 Recording frequency response......... 28
9.9 Recording level adjustment........... 29
9.10 Recording Dolby NR level adjustment... . 30
9.11 Playback Dolby NR level adjustment .... 30
10. EXPLODED VIEWS
TOET . (EXtENOn sui eeee Sie biden cae els Sa 32
10.2 Mechanism assembly 1.............-.- 35
10.3. Sub-chassis ....... 0... 2.02 e ee aes 37
10.4 Mechanism assembly 2.............. 38
11. SCHEMATIC DIAGRAMS, P.C. BOARD
PATTERNS AND PARTS LIST
11.1. Miscellaneous parts list ............. 41
11.2 Connectiondiagram ............... 42
11.3. Schematic diagram ................ 43
11.4 P.C. boards connection diagram. ....... 46
11.5 Mother assembly(RWX-302).......... 49
11.6 Power supply and control assembly ..... 53
(RWR-076)
11.7. Indicator amp assembly ............. 55
11.8 Sensing assembly ...............4. 55
11.9 Indicator assembly ..............0.. 55
11.10 Function indicator assembly .......... 56
11.11 Switch assembly ............0...00- 56
11.12 Fuse assembly ................00. 56
12: PACKING a8 .5 3 okie Oe ed bei eiaieties 57

1. SPECIFICATIONS
Systems.........-- Compact cassette, 2-channel stereo
Motors ..........-. Capstan drive; DC servo motor x 1
Reel drive; DC high torque motor x 1
Heads: ji 0 ee Sa eeene dee ears Oe ae Sendust recording/
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
—20dB Recording ;
Standard, LH tapes .............. 20 to 17,000Hz
(25 to 15,000Hz +3dB)
Ferrichrome tape .............-- 20 to 18,000Hz
(25 to 17,000Hz +3dB)
Chromium dioxide tape ...........- 20 to 18,000Hz
(25 to 17,000Hz £3dB)
Metal tape... 2... ....-2-00 0006 20 to 19,000Hz
(25 to 18,000Hz +3dB)
OdB Recording ;
Chromium dioxide tape .........-. 20 to 11,000Hz
Metal tape ............2-002-08- 20 to 14,000Hz
Signal-to-Noise Ratio. . . Dolby NR OFF; More than 59dB
Dolby NR ON ; More than 69dB
(over SkHz)
Harmonic Distortion ........ No more than 1.2% (OdB)
Inputs (Sensitivity/Maximum allowable input/Impedance)
MIC (L, R);0.3mV/100mV/10kilohms, 6mm diam. jack
(Reference MIC impedance; 250 ohms to 10 kilohms)
LINE x 2; (64mV/25V/85 kilohms) Pin jack
Outputs (Reference level/Maximum level/Load impedance)
LINE x 2; (450mV/630mV/50 kilohms) Pin jack
HEADPHONES x 1; 70mV/98mV/8 ohms, 6mm diam. jack
Semiconductors
Amplifier Section ........ Transistors x 49, ICs x 10,
Diodes x 51 (including Zener Diodes x 3, LEDs x 7)
Motor control Section ..... Transistors x 3, Diode x 1
Subfunctions
@ Dolby NR system (ON-OFF) with LED indicator lamp
© Fluorescent tube level meter (—20 to +8dB)
(Peak/Average selector) ©
Bias fine adjusting control knob
4 position tape selector (STD/METAL/CrO,/Fe-Cr)
Automatic tape slack canceller
Cassette compartment illumination
Standby mechanism with unattended recording
Output level controls with click stop for reference
playback level
CT-F8ss50
Power Requirements .............-. AC 120V 60Hz
Power Consumption ...........--02000% 50 watts
Dimensions ....... 420(W) x 150(H)} x 361(D) mm Max.
16-9/16 x 5-15/16 x 14-1/4 in.
Weight .......... 0.02. 9.2kg (20 Ib 4 oz.)
Furnished parts.......... Stereo connecting cords with
pin plugs x2
Head cleaning swabs x 3
Operating instructions x 1
NOTE:
Specifications and the design subject to possible modifi-
cation without notice due to improvements.
NOTES:
1. Reference Tapes: Standard & LH: DIN 45513/BLATTE6 or
equiv.
: CrO,: DIN 45513/BLATT7(CrO, ) or equiv.
. Reference Recording Level: Meter OdB indicating level (160
nwb/m magnetic level = Philips cassette reference level)
. Reference Signal: 333Hz
. Wow & Flutter: e JIS [3kHz, with acoustic compensation
(weighted), rms value]
5. Frequency Response: @ Measured at —20dB level, DOLBY
NR OFF, level deviation is $6dB without indication.
6. Signal to Noise Ratio: @ Measured at the third harmonic distor-
tion 3% level, weighted. e
7. Sensitivity: Input level (mV) required for reference recording
level with input (REC) controls set to maximum.
8. Maximum Allowable Input: While decreasing settings of input
(REC) tevel controls and increasing level at input jacks, this is
the maximum input level (mV) at the point where recording
amplifier output waveform becomes clipped.
9. Reference Output Level: Playback output level when meter
indicates OdB.
10. Maximum Output Level: Playback output level with respect to
reference recording level when output (PLAY) level controls
are set to maximum.
N
Ww
Unit mm

2. FRONT PANEL FACILIES
Cassette compartment illumination
Pe ens
fp neenfemnn |
SENOUST COM
CLOSED LGOP DUAL CaPSTAN
2-MOTOR Tap
(POWER SWITCH
The
power
comes
on
when
the
POWER
switch
is
depressed.
The
level
meter
and
the
cassette
compartment
illumination
will
then
come
on.
@ DUST COVER
When
you
are
not
using
the
deck,
always
keep
this
cover
in
place
to
prevent
dust
and
dirt
from
adhering
to
the
head
section
and
rotating
parts.
(@ REMAINING TAPE MARKER
If
this
marker
is
visible,
it
means
that
there
is
enough
tape
remain-
ing
for
several
minutes
of
recording
or
playback
@TAPE COUNTER
This indicates the position of the tape run.
(5) TAPE COUNTER RESET BUTTON
Depress this button to reset the tape counter display to “000.”
(MONITOR SWITCH
This switch is used to:select the output signals including those of
the
headphones.
The
level
meter
display
is
also
selected
simulta-
neously and so when adjusting the recording level, be sure to set
this switch to SOURCE (depressed position).
For recording: If you depress this switch to SOURCE, you will
be able to listen to the signals (recording input)
just before they are recorded. If you then release
to switch to TAPE, you will be able to hear
the signals immediately after they have been
recorded (playback sound).
Select this switch while you are recording
(alternately between TAPE and SOU RCE) and
monitor the recording.
Release the switch to TAPE. You will not be able
to listen to the playback sound if the switch is set
to SOURCE.
For playback:
©® © © ® @
@METER SELECTOR SWITCH
PEAK: When this switch is depressed to PEAK, the meter
functions as a peak meter.
AVERAGE: When the switch is released to AVERAGE, the
meter functions as an ordinary level meter.
(DOLBY NR SWITCH
Set this switch to ON for recording with the built-in Dolby noise
reduction system and for the playback of tapes which have been
recorded using the Dolby NR system.
@TAPE SELECTOR
This selector allows the bias and equalizer characteristics to be
selected during recording and the equalizer characteristics during
playback in line with the type of tape you are using.
METAL: For using metal tapes
STD: For using ordinary or LH tapes
CcrO : For using chrome tapes
Fe-Cr: For using ferrichrome tapes
(BIAS CONTROL
Use this control to adjust the bias in accordance with the
characteristics of the tape being used. It is set so that the center
(click stop) position corresponds to the standard bias.

CLOSED LON DUAL CaPsTans
@-MOTOR TAPE TRANSPORT SYSTEM
()METALTAPE INDICATOR
This light comes on when the TAPE selector is set to METAL.
(DOLBY NR INDICATOR
This
lights
up
when
the
DOLBY
NR
switch
is
set
to
ON
and
it
indicates
that
a
tape
is
being
recorded
or
played back
with
the
Dolby
NR
system.
(3LEVEL METERS
These
indicate
the
input
level
during
recording
and
the
output
level during playback.
By
operating
the
METER
selector
switch,
it
can
be
made
to
func-
tion as a peak meter, or as a level meter.
The
input
signal
level
is
indicated
when
the
MONITOR
switch
has
been
depressed,
and
the
playback
output
level
is
indicated
when
the
MONITOR
switch
has
been
released.
(INPUT (RECORDING LEVEL) CONTROLS
Use these to adjust the level of the input signals from the MIC
jacks or rear panel INPUT.
Turning
these
controls
to
the
right
increases
the
level.
The controls are coupled to the left and right channels, but you
can
also
use
them
to
adjust
the
right
channel
(back)
and
the
left
channel (front) independently.
(5 OUTPUT (PLAYBACK LEVEL) CONTROLS
Use these to adjust the output signal level during playback.
Turning the controls to the right increases the level. The controls
are coupled when turned but it is also possible to adjust the right
channel (back) and the left channel (front) independently.
When playing back a reference tape (160 nwb/m), a reference
playback level (0dB) is obtained with these controls set to the “6”
click stop position.
(MIC JACKS
These are the input jacks for microphone recording. Plug the left
channel microphone into the L jack and the right channel micro-
phone.into the R jack.
CT-F8S8s50
. SDOROOSsEeRsIe mee
08 -20 -"0-7-5-2 0 43-88
Se tt) ly
()HEADPHONES JACK
This
is
the
output
jack
for
your
stereo
headphones.
You
will
be
able
to
hear
sound
from
signals
selected
by
the
MONITOR
switch.
Use
this
jack
when
you
want
to
monitor
the
quality
of
a
recording
or
when
you
want
to
listen
to
a
tape
privately
on
the
CT-F850.
NOTES:
@
Use
low-impedance
headphones.
If
you
use
a
high-impedance
model,
you
will
not
be able
to
obtain
sufficient
volume.
@
You
will
damage
the
microphone
if
you
plug
-it
into
the
PHONES
jack
by
mistake.
@SOPERATING SWITCHES
#4 (REW): Depress this switch to rewind the tape at high
speed. (The tape will travel from right to left.)
be (FF): Depress this switch to send the tape forward at
high speed. (The tape will travel from left to right.)
m@ (STOP): Depress this switch to stop the tape run and to
release the operating switches.
> (PLAY): Depress this switch when playing back a tape. (The
tape will travel from left to right.)
REC: Depress this switch together with the » (PLAY)
switch for recording.
This switch will not work when a cassette is not
loaded or when the erasure prevention tabs of a
loaded cassette have been broken off.
PAUSE: Depress this switch to stop the tape temporarily
during recording or playback. Depress it again to
allow the tape to continue to travel as before.
NOTES:
@ When any of the operating switches are depressed, the cor-
responding indicator (except STOP mode) will come on
signifying that the deck is set to that respective mode.
e@ The operating switches will not return to their original posi-
tions even when the power is switched OFF.
* Manufactured under license from Dolby Laboratories.
* Dolby and [XQ] are trademarks of Dolby Laboratories.

3. LEVEL DIAGRAM
PLAYBACK
DOLBY
PB
AMP
AMP:
TAPE
@
$2
(MONITOR)
LINE
OUT
FLAT AMP GuzpuT
LEVEL
a ad PS LEVEL CONTROL
ADJ.
@ HEADPHONES
+5.1dBV
0
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(0708v) LO-S:4d8v} @ - 7aBv
~10
(0.48V)
—(o.447Vv)
RL:50kN.
RL: 82
ee
©
-
22.7
48v
~
>
a
(56.23
mv)
(70.79mv)
(73.3
mv)
= -30
= @ -36dav
aed (15.85 mv )
a -40
>
twa
a
i
a °
-60
O dBV : IV
FREQUENCY: 333 Hz
~70 T@ -74aBv
{0.20mvV )
-80

CT-F850
RECORDING
LINE DOLBY REC BIAS
AMP. AMP. AMP. TRAP
LINE IN
REC
LEVEL
HEAD
CONTROL
INPUT
LEVEL
a
MIC
CONTROL
AMP.
(MONITOR)
osc
,
@
-3
48v
—-—_
©
-3
d8v
©®
-10d8v
(0.708v)
|@
-s8¢av
|
(a708v)
sto
Si
(0.398V)
dicta
dee
@
-18.74BVv
ERT
-20
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=
VR
MAX.
7.58mv
i
>
bseou=-
1@
-27308v
|@
aoetov
@-26a8}v
a
©
-28.5
d8v
a
24.5dBV
yo
;
(50.12
mV)
-—
301
(59.57mv)
if
(43-15m¥)
aes
-4
1.86mV)
|
<
=
7
AV
RMANG
Mince
ees
©
-4348v
w
H
VR
MAX
(708
mv)
4
-50
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ae:
{]
-60
(osomv)
!
FREQUENCY:
333Hz
-70
3
-71.9dBV
(0.25
mv)
-80 vr max:

4. DISASSEMBLY
EXTERNAL COMPONENTS
1. Undo screws 1—4 to remove the bonnet.
2. Undo screws 5—10 to remove the front panel.
38. Undo screws 11—18 and remove washer 19 to
remove the base plate.
Fig.
4-1
Disassembly
of
externa!
part

CT-F3s50
FLUORESCENT DISPLAY TUBES
Undo the single screw to remove the display
assembly. The fluorescent display tubes are
mounted inside the display assembly, and will
require the use of a soldering iron for removal.
This step must be: performed carefully in order to
prevent damage to component parts.
MECHANICAL ASSEMBLY
Once the front panel has been removed, undo
screws 1—6.
Mechanical
Indicator amp
assembly
assembly
Fig. 4-3 Removing the fluorescent display tubes
Fig. 4-2 Removing the mechanical assembly
Sub-Head
Base
Ass’y,
Pinch
Roller
Arm
Ass’y
and
4.
Pressure
Arm.
To remove the pressure arm, simply remove E
washer 2. When a pinch roller pressure spring
1.
Undo
screws
1
and
2
and
the
hexagonal
socket
is
to
be
replaced,
take
special
note
of
the
head
bolt
to
remove
the
sub-head
base
assem-
original
spring
position.
It
will
also
be
neces-
bly.
sary
to
readjust
spring
pressure
in
accordance
2.
Undo
the
height
adjuster
nut
to
remove
the
to
the
requirements
specified
under
the
section
pinch
roller
arm
assembly
on
the
supply
reel
on
‘Pinch
roller
pressure
adjustment’?
on
side.
page
25.
3. Then remove E washer 1 to remove the pinch
roller arm assembly on the take-up reel side.
SS
5
Height adjuster
Pinch roller arm assembly
(supply reel)
Hexagonal socket head bolt
Sub-head base assembly
Pinch roller arm assembly
(take-up reel)
Fig. 4-4 Removing the sub-head base ass’y, pinch roller arm ass’y and
Pressure arm

MECHANICAL ASSEMBLY COMPONENT
PARTS 3. Undo screws 6—10 to remove the plunger chas-
When the motor belt needs to be replaced, take sis assembly.
special
note
of
the
order
in
which
component
4.
Undo
screws
11—16
to
remove
the
sub-chassis
parts are disassembled and reassembled. assembly.
1.
Remove
the
capstan
motor
by
undoing
screws
5.
Then
remove
the
take-up
reel
motor
by
un-
2.
10 ¢
1—3 and washers 1—3.
Solenoid A is removed by undoing screws 4
Screws
Take-up
reel motor
Capstan
Flywheel tieror
Fig.4-5. Removing mechanical assembly component parts
doing screws 17 and 18, and washers 5 and 6.
Solenoid B is removed by undoing screws 19
and 20.