Sony MDXC-7890-R Service manual
MDX-C7890R
SERVICE MANUAL
SPECIFICATIONS
AEP Model
Model Name Using Similar Mechanism MDX-C7900R
Base Mechanism Type MG-164KT-138
Optical Pick-Up Name KMS-241A/J2N
MICROFILM
FM/MW/LW MINIDISC PLAYER
TABLE OF CONTENTS
1. SERVICING NOTES ................................................ 2
2. GENERAL ................................................................... 3
3. DISASSEMBLY ......................................................... 9
4. ELECTRICAL ADJUSTMENTS
Test Mode........................................................................ 14
MD Section ..................................................................... 14
Tuner Section .................................................................. 14
SECTION 1
SERVICING NOTES
• Model Identification
– Model Number Label –
5. DIAGRAMS
5-1. Printed Wiring Boards
– MECHANISM DECK Section – ................................. 17
5-2. Schematic Diagram
– MECHANISM DECK Section – ................................. 19
5-3. Schematic Diagram – MAIN Section – .......................... 23
5-4. Pr inted Wiring Board – MAIN Section – ...................... 27
5-5. Pr inted Wiring Board – PANEL Section –.................... 31
5-6. Schematic Diagram – PANEL Section –....................... 33
5-5. IC Pin Function Description ........................................... 35
7. EXPLODED VIEWS ................................................ 52
8. ELECTRICAL PARTS LIST ............................... 56
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.
S®
FM/MW/LW MINIDISC PLAYER
MDX-C7890R
MODEL NO.
POWER SELECT SWITCH
3-023-589-01 (AEP: TYPE 2)
3-023-590-01 (AEP: TYPE 1)
• TYPE A/B Discrimination
[MAIN BOARD] (Component Side)
IC700
C E
Notes on chip component replacement
• Never reuse a disconnected chip component.
A
• Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
CAUTION
Use of controls or adjustments or performance of procedures
other than those specified herein may result in hazardous radiation exposure.
Laser Diode Properites
• Material: GaAlAs
• Wavelength: 780 nm
• Emission Duration: continuous
• Laser Output Power: 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.
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.
MB90574PFV-G-113-BND ( TYPE A )
MB90F574PFV-G-113 ( TYPE B )
– 2 –
SECTION 2
GENERAL
This section is extracted from
instruction manual.
– 3 –
– 4 –
– 5 –
– 6 –
– 7 –
– 8 –
SECTION 3
DISASSEMBLY
Note: Follow the disassembly procedure in the numerical order given.
FRONT PANEL
2
Push the button (release).
1
COVER ASS’Y, PANEL (SUB) ASS’Y
1
Remove the front panel of the arrow.
3
4
panel (sub) ass’y
3
four screws
(PTT2.6
2
cover ass’y
1
×
6)
3
screw
(PTT2.6
×
6)
– 9 –
MECHANISM DECK (MG-164KT-138)
2
mechanism deck
(MG-164KT-138)
1
two screws
(PTT2.6
×
4)
MAIN BOARD
3
three screws
(PTT2.6
4
main board
5
insulating sheet
×
6) (ground point)
1
eight screws
(PTT2.6
2
heat sink
×
10)
1
two screws
(PTT2.6
×
10)
– 10 –
SERVO BOARD
)
3
two screws
(BVTT2
1
sensor flexible board
(CN102)
×
4)
3
two screws
(BVTT2
×
4)
4
servo board
2
flexible board
(CN103)
FLOAT BLOCK
float block
Release of the lock.
5
Pushing an arrw A part, raise
the float block up ward at the
front to release a lock.
A
lever (lock R)
lever (lock L)
3
spring (FL2)
2
MD cover ass’y
1
four screws
(BVTT2
×
4)
4
two springs (FL)
– 11 –
3
spring (FL2
HOLDER ASS’Y
)
y
1
spring (CHKG)
2
stop ring E (1.5)
3
lever (lock R)
5
holder ass’y
3
lever (lock L)
2
stop ring E (1.5)
4
washer (M)
1
spring (CHKG
OPTICAL PICK-UP (KMS-241A/J2N)
7
optical pick-up
(KMS-241A/J2N)
1
two screws
(K2 × 3)
2
shaft (SL2)
4
screw
(B2 × 3)
6
bearing (SL)
5
feed screw ass’
3
screw
(K2 × 3)
– 12 –
MOTOR ASS’Y (M901, M902, M903), SENSOR BOARD
1
Remove the solders
of motor (M901, M902, M903).
3
sensor board
2
two screws
(2
×
8)
8
base (SL)
7
screw
(B2
×
3)
6
motor ass’y
(M902)
5
bracket (SL)
4
screw
(P1.7
×
1.8)
!¡
screw
(P2
×
2.2)
!™
motor ass’y
(M903)
0
motor ass’y
(M901)
9
two screws
(P1.7
×
1.8)
– 13 –
SECTION 4
r
ELECTRICAL ADJUSTMENTS
TEST MODE
This set have the test mode function. In the test mode, FM Auto
Scan/Stop Level and MW Auto Scan/Stop Level adjustments can
be performed easier than it in ordinary procedure.
<Set the Test Mode>
1. Set the “power select” switch (S700) is “A (ON) ” position.
2. Turn ON the regulated power supply. (All LEDs on the set
lights up, and the clock is displayed.)
Note:
Press the [OFF] button, if the clock is not displayed.
3. Push the preset [4] button.
4. Push the preset
5. Press the preset
[5] button.
[1] button for more than two seconds.
6. Then the display indicates all lights, the test mode is set.
<Release the Test mode>
1. Push the
[OFF] button.
2. Return the “power select” switch (S700) to initially set position.
See the adjustment location from on page 16 for the adjustment.
MD SECTION
MD section adjustments are done automatically in this set.
TUNER SECTION
Cautions during repair
When the tuner unit is defective, replace it by a new one because its internal block is difficult to repair.
Note:
Adjust the tuner section in the sequence shown below.
1. FM Auto Scan/Stop Level Adjustment.
2. FM Stereo Separation Adjustment.
3. MW Auto Scan/stop Level Adjustment.
4. RDS S-Meter Adjustment.
FM Auto Scan/Stop Level Adjustment
Setting:
[SOURCE] button: FM
FM RF signal
generator
Carrier frequency : 98.0 MHz
Output level : 22 dB (12.6 µV)
Mode : mono
Modulation : 1 kHz, 22.5 kHz deviation (30%)
0 dB=1 µV
antenna jack (J1)
0.01
µ
F
set
Procedure:
1. Set to the test mode.
2. Push the [SOURCE] button and set to FM.
Display
SHUF
REG
3. Adjust with the volume RV2 on TU1 so that the “FM” indication turns to “FM0” indication on the display window.
But, in case of already indicated “FM0”, turn the RV2 so that
put out light “0” indication and adjustment.
Display
SHUF
REG
Adjustment Location: See page 16.
FM Stereo Separation Adjustment
Setting:
[SOURCE] button: FM
FM RF signal
generator
Carrier frequency : 98.0 MHz
Output level : 70 dB (3.2 mV)
Mode : stereo
Modulation : main: 1 kHz, 33.75 kHz deviation (45%)
antenna jack (J1)
0.01 µF
set
sub: 1 kHz, 33.75 kHz deviation (45%)
19 kHz pilot: 7.5 kHz deviation (10%)
4
speaker out terminal
level mete
Ω
+
–
Procedure:
FM Stereo Level meter Level meter
signal generator connection reading (dB)
output channel
L-CH L-CH A
B
R-CH L-CH Adjust RV4 on TU1
for minimum reading.
R-CH R-CH C
D
L-CH R-CH Adjust RV4 on TU1
for minimum reading.
L-CH Stereo separation: A-B
R-CH Stereo separation: C-D
The separations of both channels should be equal.
Specification: Separation more than 30 dB
Adjustment Location: See page 16.
– 14 –
MW Auto Scan/Stop Level Adjustment
µ
Setting:
[SOURCE] button: MW
AM RF signal
generator
AM dummy antenna
(50 Ω)
30
Ω
65 pF
set
15 pF
RDS S-Meter Adjustment
Setting:
[SOURCE] button: FM
FM RF signal
generator
0.01
Carrier frequency : 98.0 MHz
Output level : 35 dB (56.2 µV)
Mode : mono
Modulation : no modulation
antenna jack (J1)
µ
F
Adjustment Location:
– SET UPPER VIEW –
set
RV1 RDS S-METER Adjustment
Carrier frequency : 999 kHz
30% amplitude
modulation by
1 kHz signal
Output level : 33 dB (44.7
antenna jack (J1)
V)
Procedure:
1. Set to the test mode. (See page 14.)
2. Push the [SOURCE] button and set to FM.
3. Push the [MODE] button and set to MW .
Display
SHUF
TP
REG
4. Adjust with the volume RV1 on TU1 so that the “MW” indication turns to “MW0” indication on the display window.
But, in case of already indicated “MW0”, turn the R V1 so that
put out light “0” indication and adjustment.
Display
SHUF
TP
REG
Procedure:
1. Set to the test mode. (See page 14.)
2. Push the [SOURCE] button and set to FM.
Display
SHUF
REG
3. Push the preset [10] button.
4. Adjust RV1 on MAIN board so that the display indication is
“15.8”.
Display
SHUF
REG
Specification: Display indication : 15.6 to 16.4
Adjustment Location: See page 16.
TU1
RV1 MW AUTO SCAN/STOP LEVEL Adjustment
RV2 FM AUTO SCAN/STOP LEVEL Adjustment
RV4 FM STEREO SEPARATION Adjustment
Adjustment Location: See page 16.
– 15 – – 16 –
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