Sony CDX-4250 - Fm/am Compact Disc Changer System User manual

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Model Name Using Similar Mechanism CDX-4180
CD Drive MechanismType MG-363X-121
Optical Pick-up Name KSS-521A
SERVICE MANUAL
US Model
Canadian Model
CDX-4250
E Model
CDX-4500
CDX-4250/4500
FM/AM COMPACT DISC PLAYER
MICROFILM
SPECIFICATIONS
Photo: CDX-4250

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SERVICE NOTE
CAUTION
Use of controls or adjustments or performance of proce-
dures other than those specified herein may result in haz-
ardous radiation exposure.
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.
NOTES ON HANDLINGTHEOPTICAL PICK-UP BLOCK OR
BASE UNIT
The laser diode in the optical pick-up block may suffer electrostatic
breakdown because of the potential difference generated by the
charged electrostatic load, etc. on clothing and the human body.
During repair, pay attention to electrostatic breakdown and also use
the procedure in the printed matter which is included in the repair
parts.
The flexible board is easily damaged and should be handled with
care.
NOTES ON LASER DIODE EMISSION CHECK
The laser beam on this model is concentrated so as to be focused on
the disc reflective surface by the objective lens in the optical pick-up
block. Therefore, when checking the laser diode emission, observe
from more than 30 cm away from the objective lens.
NOTES ON PICK-UP FLEXIBLE BOARD
The pick-up flexible board in this set is secured to the optical pick-up
with an adhesive tape. Once the tape is removed, an adhering force
becomes weak, and it cannot be reused.
Therefore, if the optical pick-up is replaced, replace also the pick-up
flexible board with a new one.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK !OR DOTTED LINE
WITH MARK !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.
ATTENTION AU COMPOSANT AYANT RAPPORT
À LA SÉCURITÉ!!
LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE !SUR LES
DIAGRAMMES SCHÉMATIQUES ETLALISTE DES PIÈCES SONT
CRITIQUES POUR LA SÉCURITÉ DE FONCTIONNEMENT. NE
REMPLACER CES COMPOSANTS QUE PAR DES PIÈCES SONY
DONT LES NUMÉROS SONT DONNÉS DANS CE MANUEL OU
DANS LES SUPPLÉMENTS PUBLIÉS PAR SONY.

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TABLE OF CONTENTS
1. GENERAL
Location of Controls.................................................................. 4
Getting Started........................................................................... 4
CD Player .................................................................................. 5
Radio ......................................................................................... 5
Other Functions ......................................................................... 6
Additional Information .............................................................. 7
Connections ............................................................................... 8
2. DISASSEMBLY
2-1. Cover ASSY ........................................................................ 10
2-2. Front Panel ASSY ............................................................... 10
2-3. Display Board ..................................................................... 11
2-4. CD Mechanism Block ......................................................... 11
2-5. Main Board ......................................................................... 12
2-6. Heat Sink ............................................................................. 12
2-7. Chassis (T) Sub ASSY ........................................................ 13
2-8. Lever ASSY......................................................................... 13
2-9. Servo Board......................................................................... 14
2-10. Roller ASSY ........................................................................ 14
2-11. Chassis (OP) (O/S) ASSY ................................................... 15
2-12. Optical Pick-up Block ......................................................... 15
3. ELECTRICAL ADJUSTMENTS
Tuner Section........................................................................... 16
CD Section .............................................................................. 18
4. DIAGRAMS
4-1. IC Pin Description............................................................... 19
4-2. Circuit Boards Location ...................................................... 21
4-3. Printed Wiring Boards –CD Mechanism Section–.............. 23
4-4. Schematic Diagram –CD Mechanism Section– .................. 25
4-5. Printed Wiring Board –Display Section– ............................ 27
4-6. Schematic Diagram –Display Section–............................... 29
4-7. Printed Wiring Board –Main Section– ................................ 31
4-8. Schematic Diagram –Main Section (1/2)– .......................... 33
4-9. Schematic Diagram –Main Section (2/2)– .......................... 35
5. EXPLODEDVIEWS
5-1. Chassis Section ................................................................... 40
5-2. Front Panel Section ............................................................. 41
5-3. CD Mechanism Section (1) ................................................. 42
5-4. CD Mechanism Section (2) ................................................. 43
5-5. CD Mechanism Section (3) ................................................. 44
6. ELECTRICAL PARTS LIST........................................... 45

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SECTION 1
GENERAL This section extracted from US,
Canadian model’s instruction manual.

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SECTION 2
DISASSEMBLY
Note : Follow the disassembly procedure in the numerical order given.
2-1. COVER ASSY
2-2. FRONT PANEL ASSY
4 cover assy
1 claw
2 claw
3 claws
2 front panel assy
1 button (release)

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2-3. DISPLAY BOARD
2-4. CD MECHANISM BLOCK
1 PTT 2.6x6
2 PTT 2.6x6
4 claw
3 claw
5 sub panel (1) assy
7 PTT 2.6x6
3 PTT 2.6x6
6 PTT 2.6x6
2 PTT 2.6x6
1 PTT 2.6x6
4 CNP701
8 bracket (M/D)
5 CD mechanism block

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2-5. MAIN BOARD
2-6. HEAT SINK
2 PTT 2.6x
8
4 screws (+BTT)
3 screw (+BTT)
1 PTT 2.6x8
5 MAIN board
1 PTT 2.6x
8
2 PTT 2.6x10
3 PTT 2.6x8
4 heat sink

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2-7. CHASSIS (T) SUB ASSY
2-8. LEVER ASSY
5 chassis (T) sub ass
y
2 P 2x3
4 P 2x3
3 P 2x3
1 Unsolder the
lead wires.
red
white
black
4 claws
2 DISCIN board
7 lever (L) assy
3 tension spring (LR)
6 lever (R) assy
5 guide (disc)
1 PS 2x4

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2-9. SERVO BOARD
2-10. ROLLER ASSY
• When installing, take note of the positions
arm (roller) and washers.(Fig. 1)
5 PS 2x4
1 CN3
3 P 2x3
4 loading motor assy
7 SERVO board
2 CN2
6 PS 2x4
Fig. 1
4 PS 2x3
5 LOAD board
1 tension spring (RA)
2 arm (roller)
3 roller assy
washer arm arm
washer washers

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2-11. CHASSIS (OP) (O/S) ASSY
2-12. OPTICAL PICK-UP BLOCK
1 tension spring (angle)
8 compression spring (FL)
7 chassis (OP) (O/S) assy
9 compression spring (FL)
2 tension spring (KR1)
5 Fit lever (D) in the
direction of the arrow.
3 damper (T)
4 damper (T)
6 Turn loading ring in the
direction of the arrow.
1 P 2x3
2 sled motor assy
3 optical pick-up block

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FM SENS/IF Adjustment
Setting:
SOURCE button : FMI
D-BASS switch : OFF
Frequency Select switch (E model): FM 200K
Procedure:
Adjust for a maximum reading on level meter.
FEB1
87.5 MHz
Adjustment Location: See page 17.
AM SENS Adjustment
Setting:
SOURCE nMODE button : AM
D-BASS switch : OFF
Frequency Select switch (E model): AM 10K
SECTION 3
ELECTRICAL ADJUSTMENTS
TUNER SECTION 0 dB = 1 µV
Cautions during repair
When the tuner unit is defective, replace it by a new one because
its internal block is difficult to repair.
FM Center Adjustment
Setting:
SOURCE button : FMI
D-BASS switch : OFF
Frequency Select switch (E model): FM 200K
FM RF signal
generator dummy
antenna antenna
terminal
set
50
Ω
50 Ω
Carrier frequency : 97.9 MHz
Output lever : 60 dB (1 mV)
Mode : mono
Modulation : 1 kHz, 75 kHz deviation (100%)
+
–
FM CENTER
OUT
(Both side
of R24.)
IC1 pin
#¶
IC1 pin #¢
digital
voltmeter
0 dBs
–3 dBs
(fc–10) fc (fc+10) (kHz)
FM RF signal
generator dummy
antenna
50
Ω
50 Ω
4 Ω
antenna
terminal
set
SPEAKER OUT
+
–
level
meter
AM RF signal
generator dummy
antenna antenna
terminal
set
SPEAKER OUT
level
meter
+
–
30 Ω
4 Ω
15 pF
30 pF
Procedure:
Adjust for a maximum reading on level meter.
IFT1, 3
1,400 kHz
Adjustment Location: See page 17.
Procedure:
1. Adjust IFT4 on TU01 so that the readingonthe digital voltmeter
becomes in 0 ± 30 mV.
2. Output an Fcenter 10 dB signal output from FM RF signal
generator so that the LINE OUT REAR jack is –20 dBs.
3. Change the FM RF signal generator frequency and check the
deviation of the frequency on + side and – side when the LINE
OUT REAR jack drops 3 dB. (Both + side and – side is approx.
50 kHz.)
4. Re-adjust IFT4 on TU01 when the difference deviation of the
frequency does more than 10 kHz.
Adjustment Location: See page 17.

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Carrier frequency : 1000 kHz
30% amplitude
modulation by
1 kHz signal
output level : 33 dB (44.7 µV)
Procedure:
1. Adjust IFT3 on TU01 so that the reading on the digital
voltmeter is 1.5 ± 0.2V.
Adjustment Location: tuner unit (TU01)
AM Auto Scan/Stop Level Adjustment
Setting:
SOURCE nMODE button : AM
D-BASS switch : OFF
Frequency Select switch (E model): AM 10K
AM RF signal
generator dummy
antenna antenna
terminal
set
SPEAKER OUT
level
meter
+
–
30 Ω
4 Ω
15 pF
30 pF
+
–
digital
voltmeter
S-METER OUT
Adjustment Location: tuner unit (TU01)
– tuner unit (TU01) (component side) –
AM AUTO
SCAN/STOP
LEVEL ADJ
IFT3
AM SENS
ADJ
IFT3 IFT1
FEB1
FM SENS/IF
ADJ
IFT4
FM CENTER
ADJ
– tuner unit (TU01) (conductor side) –
IC1 R24
S-METER
OUT
FM CENTER
OUT
‘
’

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CD SECTION
Note:
1. CD Block basically constructed to operate without adjustment.
Therefore, check each item in order given.
2. UseYEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 MΩimpedance.
4. Clean an objective lens by an applicator with neutral detergent
when the signal level is low than specified valuewith the following
checks.
Focus Bias Adjustment
Setting: This adjustment is performed with the set placed
horizontally.
Focus Gain Adjustment (Coarse adjustment)
Thisadjustmentis notrequired unlessthe followingparts are replaced:
• Optical pick-up
•RV4
Procedure:
1. Set RV4 to the standard position. (mechanical center)
2. Check whether operation noise (while noise type) caused by
the 2-axis device (lens section of the optical pick-up) is
abnormally loud.
If the operation noise is too loud, turn RV4 slightly counter-
clockwise.
• If the gain is too low:
Focus does not function and no music is selected.
• If the gain is too high:
Noise caused by scratches and dust is heard and the operation
becomes unstable.
Adjustment Location: servo board
Adjustment Location: servo board (component side)
Procedure:
1. Connect an oscilloscope between TP (RF) and TP (RF. GND)
on the SERVO board.
2. Connect the power supply.
3. Push the RESET button (S881) on the DISPLAY board.
4. Insert the disc (YEDS-18) and playback.
5. Adjust RV1 so thatthe oscilloscope waveform is clear andcheck
RF signal level is correct or not.
Note: Clear RF signal waveform means that the sharp “≈” can be
clearly distinguished at the center of the waveform.
• When observing the eye pattern, set the oscilloscope toAC range
and raise the vertical sensitivity so that it may be easily seen.
Adjustment Location: servo board
RF signal waveform VOLT/DIV: 200 mV
TIME/DIV: 500 nS
level: 1.0 – 1.5 Vp-p
IC3
CN1 IC1
CN2
FOCUS GAIN ADJ
RV4
TP
(RF. GND)
IC2
TP
(RF) CN3
RV1
FOCUS BIAS ADJ
SERVO board
TP (RF)
TP (RF. GND)
oscilloscope
+
–

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SECTION 4
DIAGRAMS
4-1. IC PIN DESCRIPTION
• IC801 µPD17705GC-534-3B9 (SYSTEM CONTROL)
Pin No. Pin Name I/O Pin Description
1 SIRCS I SIRCS input (A/D)
2 IN-SW I CD mechanism position detection
3 D-SW I CD mechanism position detection
4 SELF-SW I CD mechanism position detection
5 L-SW I LIMIT switch
6 LM-EJ O Loading motor control (Eject direction)
7 LM-LOD O Loading motor control (Loading direction)
8 AMP/ANT-ON O Power control for amplifier.
9 MONO O Force MONO output
10 SD I SD signal input
11 BAND-SW I Initialize switch input terminal
12 AREA1-SW I Initialize switch input terminal
13 AREA2-SW I Initialize switch input terminal
14, 15 RE1, 2 I Rotary encoder input 1, 2
16 SEEK O SEEK output
17 CD-ON I/O Servo drive power
18 FM-ON I/O FM select output
19 TU-ON I/O AM select output
20 NC — Not used.
21 GND3 — Ground
22 KEYIN3 I Not used (Connect to ground)
23, 24 KEYIN2, 1 I A/D key input 2, 1
25 ROT-IN I Rotary commander input
26 S-METER I FM and AM common signal meter A/D conversion input
27 TEST-SW I TEST mode select input
28 AM-IFC I AM center frequency input
29 FM-IFC I FM center frequency input
30 VDD2 — Power supply (+5 V)
31 VCOH-FM I Local oscillation frequency input (FM)
32 VCOL-AM I Local oscillation frequency input (AM)
33 GND2 — Ground
34 NC — Not used.
35 EO1-PDOUT O Error out output
36 TESTO — Connect to ground
37 AM-ON(TU-ON) O AM power output (AM select)
38 FM-ON(FM/AM) O FM power output (FM select)
39 LCL/DX O LOCAL/DX select (“H” : LOCAL, “L” : DX)
40 BEEP O BEEP output
41 ACC-IN I Accessory input
42 SCOR I SUBQ data read request
43 MUTE O System mute output
44 AMP-MUTE O Power amplifier mute output
45 TEL-MUTE O Telephone mute output
46 NC — Fixed at “H” in this set.
47 VOL-CE O Electric volume chip select
48 VOL-CLK O Electric volume serial clock
49 VOL-DATA O Electric volume serial data
50 EMPHO O De-emphasis control output
51 PW-ON O System power control
52 MD-ON O Loading motor power
53 CD-ON O Servo drive power

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Pin No. Pin Name I/O Pin Description
54 ILL-ON O Illumination output
55 C.ALARM I Caution alarm select input (Used/Not used)
56 NC I Not used (Connect to ground)
57 NC — Fixed at “H” in this set.
58 LCD-CE O LCD drive chip select output
59 EZ-SEL I SHIFT + input
60 SENS I Information input from servo IC.
61 FOK I Focus OK input
62 LD-ON O Laser diode control
63 NC — Not used. (Connect to ground)
64 [IN] ST/MONO I/O Used for both STEREO indicator display input and force MONO output. (FM)
[OUT] MONO
65 LCD-CKO O LCD driver serial clock output
66 LCD-So O LCD driver serial data output
67 INH O INHbit output
68 SQ-CKo O Q data read serial clock output
69 CD-RST O Servo IC/DAC reset output
70 SQ-SI I Q data input
71 CD-SO O Serial data output to servo IC.
72 CD-LAT O Data latch output to servo IC.
73 CD-CKO O Serial clock output to servo IC.
74 VREF — Not used.
75 GND1 — Ground
76 X-OUT — Crystal oscillator connection (4.5 MHz)
77 X-IN I Crystal oscillator connection (4.5 MHz)
78 BU-IN I Back-up detection
79 VDD1 — Power supply (+5V)
80 RESET I RESET input