Sony XR-4890 User manual

MICROFILM
SERVICE MANUAL US Model
Canadian Model
Model Name Using Similar Mechanism XR-C5100
Tape Transport Mechanism Type MG-25F-136
SPECIFICATIONS
XR-4890
Photo: XR-4890
FM/AM CASSETTE CAR STEREO
– Continued on next page –

– 2 –
TABLE OF CONTENTS
1. GENERAL
Location of Controls ....................................................... 3
Resetting the Unit ........................................................... 4
Detaching the Front Panel............................................... 4
Setting the Clock ............................................................. 4
Installation....................................................................... 5
Connections ..................................................................... 6
2. DISASSEMBLY ......................................................... 9
3. ASSEMBLY OF MECHANISM DECK ............ 11
4. MECHANICAL ADJUSTMENTS ....................... 14
5. ELECTRICAL ADJUSTMENTS
Tape Deck Section .......................................................... 14
Tuner Section .................................................................. 14
6. DIAGRAMS ................................................................. 15
6-1. Printed Wiring Board –MAIN Section– ........................ 17
6-2. Schematic Diagram –MAIN (1/2) Section–..................19
6-3. Schematic Diagram –MAIN (2/2) Section–..................21
6-4. Printed Wiring Board –PANEL Section– ...................... 23
6-5. Schematic Diagram –PANEL Section– ......................... 25
6-6. IC Pin Function Description ........................................... 27
7. EXPLODED VIEWS................................................ 29
8. ELECTRICAL PARTS LIST ............................... 32
Flexible Circuit Board Repairing
• Keep the temperature of the soldering iron around 270 ˚C dur-
ing repairing.
• Do not touch the soldering iron on the same conductor of the
circuit board (within 3 times).
• Be careful not to apply force on the conductor when soldering
or unsoldering.
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.

– 3 –
SECTION 1
GENERAL This section is extracted from
instruction manual.

– 4 –

– 5 –

– 6 –

– 7 –

– 8 –

– 9 –
FRONT PANEL ASS’Y
COVER ASS’Y
Note: Follow the disassembly procedure in the numerical order given.
SECTION 2
DISASSEMBLY
1 Push the button
(release).
2 Remove the front panel ass’y
to the direction of the arrow
A .
A
1
1
1
2
2
2
3
cover ass’y

– 10 –
SUB PANEL, MECHANISM DECK (MG-25F-136)
MAIN BOARD, HEAT SINK
3 connector
(CN351)
2 sub panel
1 three screws
(PTT2.6
× 8)
1 three screws
(PTT2.6
× 8)
5 screw
(PTT2.6
× 6)
6 mechanism deck
(MG-25F-136)
4 flexible flat cable
(CN301)
3 Two ground point
screws
5 two screws
(PTT 2.6
× 8)
5 two screws
(PTT 2.6
× 10)
1 screw
(PTT2.6
× 8)
5 two screws
(PTT 2.6
× 8)
6 heat sink
2 rubber cap (25)
1 two screws
(PTT2.6
× 8)
4 main board

– 11 –
SECTION 3
ASSEMBLY OF MECHANISM DECK
Note: Follow the assembly procedure in the numerical order given.
HOUSING
ARM (SUCTION)
1 Install the catch to the hanger.
7 Holder the hanger by bending the claw.
6 Fit projaction on D part.
4 Fit claw on B part.
5 Fit projection on C part.
2 Install the hanger onto
two claws of the housing.
3 Put the housing
under
A part.
D part
B part
A part
C part
8 Hold the hanger by
bending the claw.
hanger
housing
2 Move the arm (suction) in the arrow
direction and fit on projection.
1 Fit the arm (suction) on the shaft.
projection

– 12 –
LEVER (LDG-A) / (LDG-B)
GEAR (LDG-FT)
shaft A
shaft B
shaft C
1
Fit the lever (LDG-A) on
shafts
A – C and install it.
3 type-E stop ring 2.0
shaft
B
shaft A
2
Fit the lever (LDG-B) on
shafts
A and B and
install it.
4 Align hole in the gear (LDG-D)
with hole the lever (LDG-A)
5 gear (LDG-FT)
6 polyethylene washer
3 Move the lever (LDG-B)
in the arrow direction.
2 tensiton spring (LD-1)
2 tensiton spring (LD-2)
gear (LDG-FB)
lever (LDG-A)
hole
hole
gear (LDG-D)
1

– 13 –
GUIDE (C)
2 guide (C)
1 three claws
MOUNTING POSITION OF CAPSTAN/REEL MOTOR (M901)
3 Capstan/reel motor(M901
)
2 Two precision screws
(P 2
× 2)
1 Belt
30 °

– 14 –
SECTION 4
MECHANICAL ADJUSTMENTS SECTION 5
ELECTRICAL ADJUSTMENTS
1. Clean the following parts with a denatured-alcohol-moistene
swab:
playback head pinch roller
rubber belt capstan
idlers
2. Demagnetize the playback head with a head demagnetizer.
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 power supply
voltage unless otherwise noted.
•Torque Measurement
Mode Tension Meter Meter Reading
Forward CQ-403A more than 90 g
(more than 3.18 oz)
Reverse CQ-403R more than 90 g
(more than 3.18 oz)
•Tape Tension Measurement
0 dB=0.775 V
TAPE DECK SECTION
Tape Speed Adjustment
Setting:
Speed checker Frequency counter
–1.5 to +2.5% 2,955 to 3,075 Hz
Procedure:
1. Put the set into the PB mode.
2. Adjust adjustment resistor for inside capstan motor so that the
reading on the speed checker or frequency counter becomes in
specification.
Specification: Constant speed
Mode Torque Meter Meter Reading
Forward CQ-102C 30 – 65 g•cm
(0.42 – 0.90 oz·inch)
Forward CQ-102C 0.5 – 4.5 g•cm
Back Tension (0.01 – 0.06 oz·inch)
Reverse CQ-102RC 30 – 65 g•cm
(0.42 – 0.90 oz·inch)
Reverse CA-102RC 0.5 – 4.5 g•cm
Back Tension (0.01 – 0.06 oz·inch)
FF, REW CQ-201B 60 – 200 g•cm
(0.83 – 2.78 oz·inch)
set +
–
test tape
WS-48A
(3 kHz, 0 dB)
LINE OUT
10 k Ω
speed checker
or
frequency counter
0 dB=1 µV
TUNER SECTION
The tuner section has no adjustment.
Adjustment Location:
– SET UPPER VIEW –
Tape Speed Adjustment
TU 1

– 15 – – 16 –
IC331 TDA7462D
SE3L
SE3R
MUTE
SDA
SCL
PAUSE
OUT FL
OUT FR
OUT RL
OUT RR
SUBOUT+
SUBOUT–
VDD
GND
CREF
SE1L
SE1R
MD+
MD–
CDL+
CDL–
CDR–
CDR+
PDR
PDGND
PDL
SE2L
SE2R
INPUT
GAIN &
AUTO
ZERO
PAUSE
DETECT
INPUT MULTIPLEXER &
MIXING STAGE
REAR SIDE
SELECTOR
FRONT SIDE
SELECTOR
LOUDNESS
CONTROL
CIRCUIT
INPUT
GAIN
BEEP
LOUDNESS
CONTROL
CIRCUIT
SOFT
MUTE
VOLUME
CONTROL
CIRCUIT
COMPANDER
TREBLE/
BASS
CONTROL
CIRCUIT
SUBWOOFER
OUT
FADER
SUBWOOFER
LP
IIC
BUS
DIGITAL CONTROL CIRCUIT
POWER
SUPPLY
FRONT
FADER
FRONT
FADER
REAR
FADER
REAR
FADER
VOICE BANDPASS
HP LP
SDA
SCL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
+
–
+
–
+
–
+
–
OVER VOLTAGE
PROTECT
REGULATOR
12 3 45 6 7 8 9 10 1211
NC
MODE2 MODE1
STB
VDD
AMP
VCC
ANT
COM
AM
FM
GND
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
TAB
PW-GND
OUT2–
ST-BY
OUT2+
Vcc1
OUT1–
PW-GND1
OUT1+
SVR
IN1 IN2
S-GND
IN4 IN3
AC-GND
OUT3+
PW-GND3
OUT3–
Vcc2
OUT4+
MUTE
OUT4–
PW-GND4
DIAGNOSTICS OUT
IC661 BA3918-V2
IC751 TDA7385
• IC Block Diagrams – MAIN Board –
IC21 TB2118F (EL)
SECTION 6
DIAGRAMS
IC301 CXA2509AQ-T4
VDD
AMP
AMP
AMP
VDD2
12 3 45 6 7 8 9 10
24 23 22 21 20 19 18 17 16 15
11 12
14 13
XO
OSC
CE
DIN
CK
DOUT
SR
I/O-1
I/O-2
OUT-1 OUT-2
VDD2 IFC
VDD FM IN AM IN D-GND FM CP OUT VT AM CP OUT VCC REG
A-GND
XI
SERIAL
INTERFACE
I/O
PORT
OSCILLATOR
ON/OFF
BUFFER
REFERENCE
DIVIDER
PHASE
COMPARATOR
20BIT
IF COUNTER
PRESCALLER
12BIT
PROGRAMMABLE
COUNTER
+
–
REGULATOR
18BIT
18BIT 22BIT
40BIT SHIFT
REGISTER
REF
VCC
SEEK/RECP SEEK/RECP
+
–
SIG
4BIT SWALLOW
COUNTER
OUTPUT
PORT
+
+
+
–
+
–
+–
+
–
+–
12345 6 7 8 9 10
20
19
18
17
16
15
14
13
12
11
2122232627282930
31
32
33
34
37
38
39
40
2425
PBFB1
PBRIN1
PBREF1
PBFIN1
35
36
PBGND
VCT
PBFIN2
PBREF2
PBRIN2
PBFB2
PBEQ1
PBOUT1
VCC
TAPEIN1
AUXIN1
MSLPF
LINEOUT1
NC NC
G2FB
G1FB
MSTC
DGND
MSOUT
NC
NC
INSW
TAPESW
MSMODE
DRSW
MSSW NC NC LINEOUT2 DIREF AUXIN2 TAPEIN2 PBEQ2 PBOUT2 GND
F2
120µ/70µ
X1
X1
VCT
+
F1
120µ/70µ24dB
F3
LPF
VCC
DETECT
MS ON/
OFF
FWD/RVS
TAPE EQ
TAPE/AUX
NR BIAS
24dB
MS
MODE
T2
T1
1
2
3
4
56
7
8
9
10
VCC
IN2
S-GND
IN1
NC
NC
OUT2
NC
P-GND
OUT1
CONTROL
CIRCUIT
MOTOR
DRIVE
CIRCUIT
BUFFER
BUFFER
IC351 LB1930M-TLM

– 17 – – 18 –
XR-4890/4900
6-1. PRINTEDWIRING BOARD — MAIN SECTION —
Ref.No. Location
• Semiconductor
Location
Noteon Printed Wiring Board:
•X: parts extracted from the component side.
•¢: internal component.
D1 F-1
D51 E-11
D52 E-11
D351 I-12
D352 G-13
D501 J-5
D551 F-12
D552 F-12
D553 I-9
D554 F-12
D571 D-10
D572 D-10
D581 G-11
D588 E-9
D591 F-11
D601 J-13
D610 D-11
D611 D-11
D613 D-11
D614 C-11
D621 E-6
D622 E-7
D623 E-6
D624 E-7
D701 J-3
D702 K-3
D704 K-3
D705 K-5
D706 K-5
D707 K-5
D708 K-5
D709 K-5
D710 J-3
D711 K-5
D712 K-5
D713 K-5
D721 D-8
D722 D-8
D723 D-8
D724 D-9
D731 B-7
D732 D-7
D733 D-7
D734 B-7
D781 D-13
IC21 E-3
IC301 H-4
IC331 D-5
IC351 I-12
IC501 I-7
IC551 J-12
IC611 E-14
IC751 B-7
Q51 E-11
Q52 E-11
Q121 G-4
Q151 G-6
Q171 A-4
Q181 A-3
Q251 G-6
Q271 A-3
Q281 B-3
Q351 H-13
Q352 H-12
Q353 H-12
Q354 H-12
Q551 I-10
Q571 D-9
Q581 G-11
Q583 F-9
Q591 F-11
Q592 F-10
Q601 J-13
Q602 J-12
Q621 F-7
Q622 F-7
(Page 24)

6-2. SCHEMATIC DIAGRAM — MAIN (1/2) SECTION — • Refer to page 15 for IC Block Diagrams.
– 19 – – 20 –
XR-4890/4900
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•¢: internal component.
•C: panel designation.
•U: B+ Line.
• Powervoltageisdc14.4Vand fedwithregulateddc power
supply from ACC and BATT cords.
• Voltage and waveforms are dc with respect to ground
under no-signal conditions.
no mark : FM
< > :TAPE PLAYBACK
∗: Impossible to measure
• Voltages are takenwith aVOM(Inputimpedance10MΩ).
Voltage variations may be noted due to normal production
tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal production
tolerances.
• Circled numbers refer to waveforms.
• Signal path.
F: FM
f: AM (MW)
E:TAPE PLAYBACK
•Waveforms
1
2
IC501 !§ XO
IC501 !™ OSC2
2.8Vp-p
18.432MHz
5.0Vp-p
32.768MHz
(Page 21, 22)

– 21 – – 22 –
XR-4890/4900 6-3. SCHEMATIC DIAGRAM — MAIN (2/2) SECTION —
• Refer to page 15 for IC Block Diagrams.
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•¢: internal component.
•C: panel designation.
•U: B+ Line.
• Powervoltageisdc14.4Vand fedwithregulateddc power
supply from ACC and BATT cords.
• Voltage and waveforms are dc with respect to ground
under no-signal conditions.
no mark : FM
< > :TAPE PLAYBACK
∗: Impossible to measure
• Voltages are takenwith aVOM(Inputimpedance10MΩ).
Voltage variations may be noted due to normal production
tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal production
tolerances.
• Circled numbers refer to waveforms.
• Signal path.
F: FM
f: AM (MW)
E:TAPE PLAYBACK
• Abbreviation
CND : Canadian model.
(Page 19, 20)
(Page 25)

– 23 – – 24 –
XR-4890/4900
6-4. PRINTEDWIRING BOARD — PANEL SECTION —
Note:
•X: parts extracted from the component side.
•¢: internal component.
•b: Pattern from the side which enables seeing.
Ref. No. Location
• Semiconductor
Location
D902 B-12
D903 B-12
D904 B-11
D951 C-9
Q945 C-2
(Page 17)
Ref. No. Location
• Semiconductor
Location
IC901 A-8

– 25 – – 26 –
6-4. SCHEMATIC DIAGRAM — PANEL SECTION —
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
• All resistors are in Ωand 1/4W or less unless otherwise
specified.
•¢: internal component.
•C: panel designation.
•U: B+ Line.
• Powervoltageisdc14.4Vand fedwithregulateddc power
supply from ACC and BATT cords.
• Voltage and waveforms are dc with respect to ground
under no-signal conditions.
no mark : FM
< > :TAPE PLAYBACK
∗: Impossible to measure
(Page 22)
• Voltages are takenwith aVOM(Inputimpedance10 MΩ).
Voltage variations may be notedduetonormal production tol-
erances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be notedduetonormal production tol-
erances.
• Circled numbers refer to waveforms.
• Signal path.
F: FM
f: AM (MW)
E:TAPE PLAYBACK