Sony CFS-B31 User manual

Frequency range
CFS-B31:
European model
FM: 87.6-107 MHz
AM: 531-1,611 kHz
Italian model
FM: 87.5-108 MHz
AM: 531-1,611 kHz
CFS-B31L:
European model:
FM: 87.6-107 MHz
LW: 153-279 kHz
CFS-B31L:
East European model:
FM: 65-74 MHz
87,5-108 MHz
LW: 153-279 kHz
TF FM: 10.7 MHz
AM/LW: 450 kHz
Aerials
FM: Telescopic aerial
European, UK, Italian model:
AM/LW: Built-in ferrite bar aerial
East European model:
LW: Built-in ferrite bar aerial
Recording system
“track, 2 channel stereo
Frequency response
50-12,500 Hz
Photo : CFS-B31
JIL
AEP Model
CFS-B31/B31L
UK Model
CFS-B31
SPECIFICATIONS
Speakers
Full range: 10 cm (4 inches) dia. x 2,
cone type
Maximum power output
2.5W+2.5W
Output
Headphones jack, 16-68 ohms
inpedance
Power requirements
For radio cassette-corder:
European, East European model:
220-230 V AC, 50 Hz
United Kingdom model
230-240 V AC, 50 Hz
9V DC, six R20 (size D) batteries
For radio memory:
3 V DC, two R6 (size AA) batteries
Power consumption
10 W AC operation
Battery life
For radio cassette-corder:
Batteries FM recording | Playback
Sony approx. approx.
SUM-1(NS) | 18 hours 8 hours
Sony AM1 approx. approx.
alkaline 30 hours 20 hours
Model Name Using Similar Mechanism | CFS-B11
Tape Transport Mechanism Type
MF-200
For radio memory: approx. one year
Dimensions
Approx. 440 x 136.5 x 150.5 mm
(w/h/d)
(17 %x 5 %x 6 % inches) including
projecting parts
Mass
Approx. 2.8 kg (6 Ib 3 02) including
batteries
Accessory supplied
Mains lead (1)
Optional accessories
Sony “MDR” headphones series
Design and specifications are subject to
change without notice.
RADIO CASSETTE-CORDER
SONTY.

TABLE OF CONTENTS
Section Title Page
SECTION. 12 GENERAL e::oscSsicasivaeriscttig aural dimen 3
SECTION 2. DISASSEMBLY
Zale sFROMECaDINGt a casGietiach omsetinsate nina a rae Ameins 4
SECTION 3. MECHANICAL ADJUSTMENTS...............5 5
SECTION 4. ELECTRICAL ADJUSTMENTS ............00. 5
SECTION 5. DIAGRAMS
5-1. IC Pin Function
* 10901 WPD1724G LCD Drive/Control ...........c:ccceseeeeeees 8
5-23. -BlOCK DIAQIAMM wiessdsccccssvevccvetavabaaaea tedasasvestenssdeadiae sa daaveete 9
5-3. Printed Wiring Board — Tuner/LCD Section —...........0. 12
5-4. Schematic Diagram —Tuner/LCD Section —........ ee 15
5-5. Printed Wiring Board — Audio/Power Section —............. 18
5-6. Schematic Diagram — Audio/Power Section —............. 21
SECTION 6. EXPLODED VIEWS
6-1. Front Cabinet Section 0.0... cc ceeesteceesneceeseteeteeeeieeenes 24
6-2. Rear Cabinet Section ........ ccc cccscssessessecenseceneecereeseeeaes 25
6-3. Mechanism Deck Section 1 (MF-200) ........ccesceeseceeenreees 26
6-4. Mechanism Deck Section 2 (MF-200) .........cccccceeeeeee 27
SECTION 7. ELECTRICAL PARTS LIST.............:ccceee 28
SAFETY-RELATED COMPONENT WARNING !!
COMPONENTS IDENTIFIED BY MARK A\ OR DOTTED
LINE WITH MARK A\ ON THE SCHEMATIC DIAGRAMS
AND IN THE PARTS LIST ARE CRITICAL TO SAFE
OPERATION. REPLACE THESE COMPONENTS WITH
SONY PARTS WHOSE PART NUMBERS APPEAR AS
SHOWN IN THIS MANUAL OR IN SUPPLEMENTS
PUBLISHED BY SONY.
HOW TO CHANGED THE CERAMIC FILTERS
This model is used two ceramic filters of CF1 and CF2.
You must used same type of color marked ceramic filters in
order to meet same specifications.
Therefore, the ceramic filter must changed two pieces together
since it's supply two pieces in one package as a spare parts.

FUNCTION NAME
LOCATION CONTROL
O©®@
@) PHONES jack
(2) VOLUME knob
@ TONE knob
® MIC
© OPR/BATT indicator lights.
© FUNCTION switch
@ FM MODE/ISS button
(rear side)
11 PAUSE button
() m/& STOP/EJECT button
<< REW button
() »p» FF button
(2) < PLAY button
(3 @ REC button
ENTER button
(5) TUNING — button
TUNING + button
2 PRESET — button
PRESET + button
SECTION 1
GENERAL
OO O®@

SECTION 2
DISASSEMBLY
Note : Follow the disassembly procedure in the numerical order given.
2-1. FRONT CABINET
@ Three screws
(PTP3x30)
@ Push the EJECT
button
@ Connector
(CNP4)
@ Three screws
OF
(PTP3x30)
@ Connector
(CN2)
© Connector
(CN1)
@ Front cabinet

SECTION 3
MECHANICAL ADJUSTMENTS
PRECAUTION
1. Clean the following parts with a denatured-alcohol-
moistened swab :
record/playback head pinch roller
erase head rubber belts
capstan idlers
2. Demagnetize the record/playback head with a head
demagnetizer. (Do not bring the head demagnetizer close to
the erase head.)
3. Do not use a magnetized screwdriver for the adjustments.
4. After the adjustments, apply suitable locking compound to
the parts adjusted. ;
5. The adjustments should be performed with the rated power
supply voltage unless otherwise noted.
1. Torque Measurement
| Mode Torque Meter Meter Reading
30 — 70 g*cm
Playback COA (0.42 — 0.97 oz « inch)
Pee ; C0-102C 1.5—5.5 g*cm
aceSIOu 2 (0.021 — 0.076 oz « inch)
60 — 130 g + cm
-201B '
2. Tape Tension Measurement
| Mode | Tension Meter Meter Reading
CQ-403A more than 100g (3.53 oz)
SECTION 4
ELECTRICAL ADJUSTMENTS
TAPE SECTION
1. The adjustments should be performed in the order given in
the service manual. (As a general rule. playback circuit
adjustment should be completed before performing
recording circuit adjustment.)
2. The adjustments should be performed for both L-CH and R-
CH unless otherwise indicated.
« Switch location
FUNCTION sjiscaiveissciteneare TAPE
VOLUME iccsusseressvsainitoatonne MAX
TON Be vesiteeiccretaneseatssatetnentvans HIGH
Standard Output Level
SP OUT
Output level 0.775V (0 dB)
Test Tape
| Type | Sonat | Useditor
WS-48B 3 kHz, 0 dB Tape Speed Adjustment
P-4-A063 6.3 kHz, -10 dB Head azimuth adjustment
0 dB =0.775 V
Tape speed adjustment
Procedure :
Mode : playback speed checker
LFM-30 or
test tape digital frequency
WS-48B
counter
(3 kHz, 0 dB) 32Q
phones jack
Adjustment Values :
Speed checker Digital frequency counter
Frequency difference between the beginning and the end of the
tape should be within 1.5% (45Hz).
Adjustment Location :
tape speed adjustment
countrol inside motor

Record/Playback Head Azimuth Adjustment
Procedure :
1. Mode : Playback
test tape
P-4-A063
(6.3 kHz, -10 dB) VTVM
ee jack
2. Turn the adjustment screw for the maximum output level. If
these levels do not match, turn the adjustment screw until
both of output levels match together within 2 dB.
L-CH
peak output
level
. ast
Screw
position
3. Phase Check
Mode : playback
test tape
P-4-A063
oscilloscope
(6.3 kHz, ~10 dB) L-CH
L-CH 320 |
phones jack RCH
inphase 45°
good
Adjustment Location :
adjustment screw
REC/PB head
TUNER SECTION
¢ Switch location
TONE sevcosscctetevorlreskecaeeens mechanical center
AM (LW) SECTION
BAND : AM (LW)
AM FF signal
generator
Put the lead-wire
Va antenna close to
the set.
C——
30% amplitued modulation
by 400 Hz signal.
Output level : as low as possible
FM SECTION
BAND : FM
FM RF signal
generator
0.01pF
| » telescopic
(oummeema
antenna
terminal
22.5 kHz frequency deviation by
400 Hz signal.
Output level : as low as possible VTVM
phones jack
* Repeat the procedures in each adjustment several times, and
the frequency coverage and tracking adjustments should be
finally done by the trimmer capacitors.

AM IF ADJUSTMENT
Adjust for a maximum reading on VT VM.
Adjust for a maximum reading on VTVM.
u
( ) : CFS-31L LW
Adjustment Location :
[TUNER BOARD] ( Component Side)
AM (LW) FREQUENCY
COVERAGE ADJUSTMENT
71
FM IF ADJUSTMENT
T3
POG
ee
ad
VCO Adjustment
Procedure :
FM
RF
signal
telescopic
generator
antenna
terminal
Carrier frequency : 98 MHz
Modulation : no modulation
Output level : 0.1V (100 dB)
1. Connect the frequency counter to @ and @ pins of IC1 as
shown the figure below.
2. Turn the set to 98 MHz.
3. Adjust RV1 for 76 kHz + 500 Hz reading on frequency
counter.
[TUNER BOARD] ( Component Side)
frequency
counter
25
FM FREQUENCY COVERAGE
ADJUSTMENT
ANT2
cTt }
FM FREQUENCY COVERAGE
ADJUSTMENT
L2
FM TRACKING ADJUSTMENT
L1
cre J
AM IF ADJUSTMENT
T2

SECTION 5
DIAGRAMS
5-1. IC PINFUNCTIONS
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Pinnon | PinName [vo [SSCS
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[7 fei OY Charen oupe—SSCSCSC~C~“‘“S*Ss*“‘“SCSCSCSCSCSCS~*SY
a
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ie aE aN A
X’tal clock (75 kHz)
ee eres
| 32. | VREG Te Connect to capacitor (for X’tal voltage drive)
PAS hel
er Oe | ee
ac i
Connect to capacitor (for LCD voltage drive)
35 PAI rae
ne
PAO ade
37 — 39
40
4l
42 — 44
: i Manag =
PC3 | O | FM/AM (LW) band switch “H”=AM (LW) “L”=FM
pee
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[si=ss
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|
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e Abbreviation
IT: Italian model
EE : East European model

CFS-B31/B31L
5-2. BLOCK DIAGRAM
13
FM DISCRI
ar
ae
’
FM/AM
FRONT-END
FM/AM
IF,
MPX
PRE
AMP
POWER
AMP
a
Ic1
U/2
e
69
IC1
(2/2)
1301
RV301
RV302
10302
TONE VOLUME
TELESCOPIC
IF
he
MIC3O1
ae
ANTENNA
A
:
19
SacNES
=
[
FM
FRONT-END
]
(6)
Ets
FILTER
-E=D+(13)
FM
IF
iS
|
ae
|
(6)
t
i
i
(9)
AM
FROMT-END
MUT
ING
SP201,
202
FERRITE
ES
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a
FROMT-EN0
|
FILTER
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AM
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TUNING
INDICATOR
MUT
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AM
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SELECT
302-1
FUNCTION
6) 69
TAPE/
*R-CH
is
omitted.
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path,
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CFS-B31/B31L
5-3. PRINTED WIRING BOARD — TUNER/LCD SECTION —
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5
6
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Location
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Location
ANT
|
FM
D-1
TELESCOPIC
D-4
A
|
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C-4
Pe
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[TUNER
BOARD]
z
F-3
D-5
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F-8
,
F-8
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F-13
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AUDIO/POWER
SECTION
F 1- 656-661 - (I 1)
- 09
* o—— : parts extracted from the component side.
. A: internal component.
1 Pattern from the side which enable seeing.
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