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D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK
SERVICE MANUAL
SPECIFICATIONS
Photo : D-EJ755
Model Name Using Similar Mechanism
D-E350
CD Mechanism Type
CDM-3125ER
Optical Pick-up Type
DAX-25E
System
Compact disc digital audio system
Laser diode properties
Material: GaAlAs
Wavelength :
= 780 nm
Emission duration : Continuous
Laser output : Less than 44.6
µW
(This output is the value measured at a distance
of 200 mm from the objective lens surface on
the optical pick-up block with 7 mm aperture.)
D-A conversion
1-bit quartz time-axis control
Frequency response
20 - 20 000 Hz
+1
­2 dB (measured by JEITA CP-307)
Output (at 4.5 V input level)
Line output (stereo minijack)
Output level 0.7 V rms at 47 k
Recommended load impedance over 10 k
Headphones (stereo minijack)
Approx.5 mW + Approx. 5 mW at 16
(Approx. 0.5 mW + Approx. 0.5 mW at 16
)*
*For the customers in France
Power requirements
For the area code of the model you
purchased, check the upper left side of the
bar code on the package.
· Two Sony NC-WMAA rechargeable
batteries: 2.4 V DC
· Sony NH-WM2AA rechargeable batteries:
2.4 V DC
· Two LR6 (size AA) batteries: 3 V DC
· AC power adaptor (DC IN 4.5 V jack):
US, CND, C&SA, MX model: 120 V, 60 Hz
AEP, FR, G, EE, E13 mode : 220 - 230 V, 50/60 Hz
UK model: 230 - 240 V, 50 Hz
AUS model: 240 V, 50 Hz
CH model: 220 V, 50 Hz
Ver 1.0 2002.02
US Model
D-EJ756CK/EJ758CK
Canadian Model
UK Model
D-EJ751/EJ755/EJ758CK
AEP Model
D-EJ750/EJ751/EJ753/EJ755/EJ758CK
Australian Model
E Model
D-EJ751/EJ758CK
Chinese Model
D-EJ751
9-873-580-01
2002B0200-1
© 2002.02
Sony Corporation
Personal Audio Company
Pubulished by Sony Engineering Corporation
Battery life* (approx. hours)
(When you use the CD player on a flat and stable sur-
face.)
Playing time varies depending on how the CD player is
used.
When using
G-PROTECTION function
on
off
Two NC-WMAA
12
10
(charged for
about 3 hours**)
NH-WM2AA
25
22
(charged for
about 5 hours**)
Two Sony alkaline
48
38
batteries LR6(SG)
(produced in Japan)
* Measured value by the standard of JEITA (Japan
Electronics and Information Technology
Industries Association).
** Charging time varies depending on how the
rechargeable battery is used.
Operating temperature
5
°C - 35°C (41°F - 95°F)
Dimensions (w/h/d) (excluding projecting
parts and controls)
Approx. 135.5
× 29.2 × 137.4 mm
(5 3/8
× 1 3/
16
× 5 1/
2
in.)
Mass (excluding accessories)
Approx. 185 g (6.6 oz.)
Design and specifications are subject to change
without notice.
Accessories
Supplied accessories
For the area code of the location in which you
purchased the CD player, check the upper left
side of the bar code on the package.
* 1 Supplied with MX models
* 2 Not supplied with MX models
D-EJ756CK/EJ758CK
AC power adaptor (1)
Headphones/earphones (1)
Rotary commander (1)
Car battery cord (1)
Car connecting pack (1)
Velcro tape for the CD player (4)
Velcro tape for the rotary commander (2)
Hand strap (1)
AC power adaptor (1)
­
aa
a
Headphones/earphones
­
a
*1
a
with remote control (1)
Headphones/
aa
*2 a
­
earphones (1)
Rechargeable
­­
aa
batteries (2)
Battery carrying case (1)
­­
aa
D-EJ755
D-EJ753
D-EJ751
D-EJ750
PORTABLE CD PLAYER


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Specifications ............................................................................ 1
1. SERVICING NOTES ................................................... 3
2. GENERAL
Locating the Controls ......................................................... 3
3. DISASSEMBLY
3-1. Upper Lid Sub ASSY, Cabinet (Front) Sub ASSY ..... 4
3-2. MD ASSY, Main Board .............................................. 5
3-3. "Motor ASSY, Turn Table (Spindle) (M901)" ............ 5
3-4. "Motor ASSY (Sled) (M902)",
Optical Pick-up (DAX-25E) ...................................... 6
4. ELECTRICAL ADJUSTMENS ............................... 7
5. DIAGRAMS
5-1. Explanation of IC Terminals ....................................... 8
5-2. Block Diagram .......................................................... 13
5-3. Printed Wiring Boards .............................................. 14
5-4. Schematic Diagram ­MAIN SECTION (1/3)­ ....... 15
5-5. Schematic Diagram ­MAIN SECTION (2/3)­ ....... 16
5-6. Schematic Diagram ­MAIN SECTION (3/3)­ ....... 17
6. EXPLODED VIEWS
6-1. Upper Lid Section ..................................................... 19
6-2. Cabinet Section ......................................................... 20
6-3. Optical pick-up Section (CDM-3125ER) ................. 21
7. ELECTRICAL PARTS LIST ................................... 22
ATTENTION AU COMPOSANT AYANT RAPPORT
À LA SÉCURITÉ!
LES COMPOSANTS IDENTIFIÉS PAR UNE MARQUE 0 SUR LES
DIAGRAMMES SCHÉMATIQUES ET LA LISTE 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.
SAFETY-RELATED COMPONENT WARNING!!
COMPONENTS IDENTIFIED BY MARK 0 OR DOTTED LINE
WITH MARK 0 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.
Flexible Circuit Board Repairing
· Keep the temperature of the soldering iron around 270
°C during
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.
TABLE OF CONTENTS
This Compact Disc player is
classified as a CLASS 1 LASER
product.
The CLASS 1 LASER
PRODUCT label is located on
the rear exterior.
CAUTION
Use of controls or adjustments or performance of procedures other
than those specified herein may result in hazardous radiation
exposure.
Laser component in this product is capable of emitting
radiation exceeding the limit for Class 1.
DANGER
Invisible laser radiation when open and interlock failed or defeated.
Avoid direct exposure to beam.
· Abbreviation
AUS
: Australian
CND
: Canadian
FR
: French
CH
: Chinese
EE
: East European
MX
: Mexico
C&SA : Central and South America
E13
: AC220-230V area model
D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK


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D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK
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 30cm away from the objective lens.
Before Replacing the Optical pick-up Block
Please be sure to check thoroughly the parameters as per the "Optical
pick-up Block Checking Procedure" (Part No. : 9-960-027-11) issued
separately before replacing the optical Pick-up block.
Note and specifications required to check are given below.
· FOK output : IC601 yg pin
When checking FOK, remove the lead wire to disc motor.
· RF signal P-to-P value : 0.45 to 0.65Vp-p
SECTION 1
SERVICING NOTES
Laser Diode Checking Methods
During normal operation of the equipment, emission of the laser diode
is prohibited unless the upper panel is closed while turning ON the S801
(push switch type).
The following two checking methods for the laser diode are operable.
Method :
Emission of the laser diode is visually checked.
1. Open the upper lid.
2. Push the S801 as shown in Fig. 1 .
3. Check the object lens for confirming normal emission of the laser
diode. If not emitting, there is a trouble in the automatic power
control circuit or the optical pick-up. During normal operation, the
laser diode is turned ON about 2.5 seconds for focus searching.
NOTES ON HANDLING THE OPTICAL PICK-UP BLOCK OR
BASE UNIT
Fig.1 Method to push S801
SECTION 2
GENERAL
LOCATING THE CONTROLS
This section is extracted from
instruction manual.
S801
CD player (front)
CD player (inside)
qh i (headphones)
qk Battery compartment
qa Display
qd HOLD switch
qf OPEN switch
qs REPEAT/ENTER
button
9 DC IN 4.5 V (external
power input) jack
7
x (stop)/CHG (charge)
button
G-PROTECTION
switch
qg LINE OUT
0 Strap holes
3 VOL (volume) +*
1 PLAY MODE
button
2 SOUND button
8
qj
N* (play)/ >
(AMS/search) button
4
'm (AMS/
search) button
6
X (pause) button
*The button has a tactile dot.
5 VOL (volume) ­
button


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D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK
SECTION 3
DISASSEMBLY
Note : Follow the disassembly procedure in the numerical order given.
3-1. UPPER LID SUB ASSY, CABINET (FRONT) SUB ASSY
z
The equipment can be removed using the following procedure.
Upper lid sub ASSY,
Cabinet (front) sub ASSY
MD ASSY
"Motor ASSY, turn table (spindle) (M901)", Optical pick-up (DAX-25E),
"Motor ASSY (Sled) (M902)"
Main board
Set
1
2
1
2
Push in
Insert the point
· "SPRING FULL OPEN" REMOVAL
· "SPRING FULL OPEN" INSTALL
6
Switch unit
flexible board
5
Connector cover
3
Spring (full open), right
2
Spring (full
open), right
3
Spring (full
open), left
6
Spring
(full open),
left
5
2
1
4
1
Switch unit
flexible board
CN801
2
3
8
Claw
7
Six screws (B2)
8
Claw
8
Claw
1
Open
Cabinet (rear) sub ASSY
Cabinet (front)
sub ASSY
Upper lid sub ASSY
4
9
· CAUTION DURING ASSSEMBLY


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D-EJ750/EJ751/EJ753/EJ755/EJ756CK/EJ758CK
3-3. "MOTOR ASSY, TURN TABLE
(SPINDLE) (M901)"
1
CN501
MD ASSY
Main board
Cabinet (rear) sub ASSY
2
CN502 (black)
3
CN503 (white)
3-2. MD ASSY, MAIN BOARD
2
Motor ASSY, Turn table
(Spindle) (M901)
1
Screws
(B1.7x5)
Chassis