Sony SRFM-35 Service manual

SRF-M35

SERVICE MANUAL

Ver 1.0 2000. 06

SPECIFICATIONS

AEP Model

E Model

FM STEREO/AM PLL SYNTHESIZED RADIO

SECTION 1

GENERAL

This section is extracted from instruction manual.

SAFETY CHECK-OUT

After correcting the original service problem, perform the following safety checks before releasing the set to the customer.

1. Check the area of your repair for unsoldered or poorly-soldered connections. Check the entire board surface for solder splashes and bridges.

2. Check the interboard wiring to ensure that no wires are "pinched" or contact high-wattage resistors.

3. Look for unauthorized replacement parts, particularly transistors, that were installed during a previous repair . Point them out to the customer and recommend their replacement.

4. Look for parts which, through functioning, show obvious signs of deterioration. Point them out to the customer and recommend their replacement.

5. Check the B+ voltage to see it is at the values specified.

6. 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.

— 2 —

SECTION 2

DISASSEMBLY

Note : Follow the disassembly procedure in the numerical order given.

2-1. FRONT CABINET

Tow claws

Cabinet (front) assy

Tow claws

Lid battery cas

2-2. MAIN BOARD AND KEY BOARD

Tow claws

Two screws (P2

× 8)

Key board

Main board

— 3 —

SECTION 3

)

ELECTRICAL ADJUSTMENTS

AM Section

Setting:

BAND switch: AM

AM RF signal generator

30% amplitude modulation by 400 Hz signal. Output level: as low as possible

Put the lead-wire antenna close to the set.

FM Section

Setting:

BAND switch: AM FM SENS switch: DX

FM RF signal generator

0.01 µF

22.5 kHz frequency deviation by 400 Hz signal. Output level: as low as possible

level mete

Ω

set

headphone jack (

• Repeat the procedures in each adjustment several times, and the frequency coverage and tracking adjustments should be finally done by the trimmer capacitors.

+ –

TP (ANT)

)

AM IF ADJUSTMENT

Adjust for a maximum reading on level meter.

TI 450 kHz

AM FREQUENCY COVERAGE ADJUSTMENT

Adjust for a maximum reading on level meter.

L5 531 kHz 2.7V ± 0.1V

Confirm 1,602 kHz 8.9V ± 1V

AM TRACKING ADJUSTMENT

Adjust for a maximum reading on level meter.

L2 621 kHZ

CT1 1,395 kHz

FM TRACKING ADJUSTMENT

Adjust for a maximum reading on level meter.

L3 87.5 MHZ

CT2 108.0 MHz

FM VCO V oltage Check

Setting:

BAND switch: FM FM SENS switch: DX

Procedure:

1. Tuen the set to 108.0 MHz.

2. Confirm that the digital voltmeter reading 8.9 ± 1 V.

3. Tuen the set to 87.5 MHz.

4. Confirm that the digital voltmeter reading is 2.7 V ± 0.1 V.

Connection:

For AM frequency coverage adjustment and FM VCO voltage check.

digital voltmeter

TP (LPF

FM STEREO (76 kHz) Adjustment

Setting:

BAND switch: FM FM SENS switch: DX

Procedure:

FM RF signal generator

0.01 µF

Carrier frequency: 98 MHz Modulation: 1 kHz, 22.5 kHz deviation Output level: 562

V (55 dB)

TP (ANT)

— 4 —

1. Connect the frequency counter to TP (76 kHz).

)

2. Tuen the set to 98 MHz.

Adjust RV1 so that the frequency counter reading becomes 76,000 Hz.

Specification V alue:

Frequency counter

75,500 - 76,500 Hz

Connection:

frequency counter

TP (76 kHz

Adjustment Location [MAIN BOARD]

(Component Side)

CT1 L2

AM TRACKING Adjustment

IC1

RV1 FM STEREO (76kHz) Adjustment

L5 AM FREQUENCY COVERAGE Adjustmen

CT2

FM TRACKING Adjustment

T1 AM IF Adjustment

[MAIN BOARD]

(Conductor Side)

IC2

(76kHz)

IC1

TP (ANT)

(LPF)

— 5 —

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