Sony SRFM-75-PM Service manual
SRF-M75PM
SERVICE MANUAL
Ver 1.0 1999. 04
SPECIFICATIONS
US Model
Canadian Model
AEP Model
E Model
Australian Model
US, Canadian, and
E models
AEP,
Australian models
MICROFILM
FM STEREO/AM PLL SYNTHESIZED RADIO
SECTION 1
SERVICING NOTES
TABLE OF CONTENTS
1. SERVICING NOTES............................................... 2
2. GENERAL ................................................................... 3
3. DISASSEMBLY ......................................................... 4
4. ELECTRICAL ADJUSTMENTS
TUNER Section .............................................................. 6
PULSE MONITOR Section............................................ 8
5. DIAGRAMS
5-1. Block Diagram ................................................................ 9
5-2. Printed Wiring Boards..................................................... 12
5-3. Schematic Diagram ......................................................... 15
5-4. IC Pin Function Description ........................................... 20
6. EXPLODED VIEW................................................... 21
7. ELECTRICAL PARTS LIST ............................... 22
Forced Reset
The system microprocessor can be reset in the following procedure.
Use these procedure when the unit cannot be worked normally
due to the overrunning of the microprocessor, etc.
Procedure:
1. Set to radio OFF.
2. While pressing the
[SCAN] button, press two buttons of
[START/STOP] and [BAND] simultaneously for 5 seconds.
3. The unit is reset, and display blinking “
Notes on chip component replacement
• Never reuse a disconnected chip component.
• Notice that the minus side of a tantalum capacitor may be damaged by heat.
AM 12:00”.
– 2 –
SECTION 2
GENERAL
This section is extracted from
instruction manual.
US, Canadian, and
E models
AEP , Australian
models
– 3 –
· This set can be disassembled in the order shown below.
)
SECTION 3
DISASSEMBLY
Set
Note: Follow the disassembly procedure in the numerical order given.
Cabinet (Front) Assy
Cabinet (Rear) Assy
Key Board
CABINET (FRONT)/(REAR) ASSY
2
three screws
(B1.7 × 8)
Main Board Knob (A
1
Remove the battery case lid
of the arrow.
4
2
two screws
(B1.7 × 8)
cabinet (rear) assy
KEY BOARD
2
Open the key board
to direction of the arrow.
3
cabinet (front) assy
1
three claws
– 4 –
1
four claws
MAIN BOARD
Note: Check that two switch (S1,
S2) is latched with two
adaptors when carrying
out installation.
5
main board
S1
S2
3
4
two claws
knob (vol)
KNOB (A)
1
1
2
screw
(B1.7
claw
claw
×
8)
1
Remove two solders.
2
two knobs (A)
3
two adaptors
– 5 –
SECTION 4
r
d
(
)
+
–
MAIN board
TP (MPX)
+
1 µF
frequency
counter
ELECTRICAL ADJUSTMENTS
TUNER SECTION 0 dB=1 µV
[AM]
Setting:
Band switch: AM
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: as low as possible
[FM]
Setting:
Band switch: FM
FM RF signal
generator
22.5 kHz frequency
deviation by 400 Hz
signal
Output level: as low as possible
Put the lead-wire
antenna close to
the set.
set
MAIN board
TP (FM IN)
0.01 µF
set
2
jack (J1)
2
jack (J1)
32
32
Ω
Ω
level meter
+
–
level meter
+
–
AM IF ADJUSTMENT
Adjust for a maximum reading on level meter
T1 450 kHz
AM VCO VOLTA GE ADJUSTMENT
Adjustment Part Frequency Display Reading on Digital Voltmeter
L4 530 kHz (531 kHz) 3 ± 0.1V
Confirmation 1710 kHz (1602 kHz) 9 ± 1V (8.5 ± 1V)
AM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L1 580 kHz (621 kHz)
CT1 1,490 kHz (1,395 kHz)
FM VCO VOLTA GE CONFIRMA TION
Frequency Display Reading on Digital Voltmeter
87.5 MHz 3 ± 0.3V
108 MHz Less than 11 ± 1V
FM TRACKING ADJUSTMENT
Adjust for a maximum reading on level meter
L2 87.5 MHz
CT2 108 MHz
( ): Except US model
• Repeat the procedures in each adjustment several times, and the
tracking adjustments should be finally done by the trimmer capacitors.
digital voltmete
MAIN board
TP (VT)
+
–
Adjustment Location: Main Board (See page 7)
FM Free-Run Adjustment
Setting:
FM RF signal
generator
0.01 µF
Carrier frequency : 98 MHz
Modulation : no modulation
Output level : 0.1 V
100 dB
MAIN boar
TP (FM IN)
set
Procedure:
1. Connect the frequency counter to TP (MPX) as shown the figure below.
2. Tune the set to 98 MHz.
3. Adjust RT1 for 76 kHz reading on the frequency counter.
Specification: 75.8 to 76.2 kHz
Adjustment Location: MAIN board (See page 7)
– 6 –
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