Sony MDR-RF915R, MDR-RF945R Service manual

MDR-RF915R/RF945R

SERVICE MANUAL

Ver 1.0 2001. 05

Photo : MDR-RF945R

MDR-RF915R is the component model block one in the MDR-RF915RK. MDR-RF945R is the component model block one in the MDR-RF945RK.

COMPONENT MODEL NAME FOR MDR-RF915RK/ MDR-RF945RK

MDR-RF915RK MDR-RF945RK Wireless Stereo Headphones MDR-RF915R MDR-RF945 Transmitter TMR-RF915R TMR-RF945

US Model

Canadian Model

SPECIFICATIONS

Headphones

Power source DC 2.4 V: Built-in rechargeable battery Mass Approx. 240 g (8.5 oz.) incl.

built-in rechargeable battery

Built-in Ni-Cd rechargeable battery

Model name NC-AA Voltage 1.2 V Capacity 700 mAh

Design and specifications are subject to change without notice.

HEADPHONES

9-873-137-11

Sony Corporation

Personal Audio Company Shinagawa Tec Service Manual Production Group

MDR-RF915R/RF945R

TABLE OF CONTENTS

Specifications ............................................................................ 1

1. GENERAL ....................................................................... 2

2. DISASSEMBLY

2-1. RX-BASE Board ...................................................... 3

3-5. Free Run Frequency

Check and Adjustment (MRD-RF945R).........6

3-6. Receive Frequency

Check and Adjustment (MRD-RF945R)......... 6

3-7. Carrier Modulation Check (MRD-RF945R) ............... 6

3-8. Separation Check (MRD-RF945R) ............................. 6

3. ELECTRICAL ADJUSTMENTS..............................4

3-1. Free Run Frequency

Check and Adjustment (MRD-RF915R) ....... 5

3-2. Receive Frequency

Check and Adjustment (MRD-RF915R) ....... 5

3-3. Carrier Modulation Check (MRD-RF915R) ............. 5

3-4. Separation Check (MRD-RF915R) ........................... 5

SECTION 1

GENERAL

- Turn up the volume to a moderate

level with the VOL control. Press the TUNING button briefly for automatic tuning of the headphones. If you do not receive a clear audio signal, press it again.

MDR-RF945RK

4. DIAGRAMS

4-1. Block Diagrams ........................................................... 8

4-2. Schematic Diagram ..................................................... 9

4-3. Printed Wiring Board................................................. 10

5. EXPLODED VIEWS........................................................11

6. ELECTRICAL PARTS LIST........................................12

This section is extracted from instruction manual.

Auto power on/off function

When you remove the headphones from your head, the power turns off automatically. Do not allow the self adjusting band to be pulled up, otherwise the headphones will be switched on.

TUNING button

VOL control

- Turn up the volume to a moderate

level with the VOL control, then tune the headphones in to the frequency o the transmitter with the TUNING control until you can hear the audio signal loud and clear.

MDR-RF915RK

TUNING control

VOL control

Try the above steps 3 and 5 until the receiving performance becomes better.

The power turns on.

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-sol deredconnections. 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, particularlyt ransis tors, 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

• This set can be disassembled in the order shown below.

2-1. RX-BASE BOARD

SECTION 2

DISASSEMBLY

Five screws (P 2

× 6)

MDR-RF915R/RF945R

Cover (R), hanger

Claw

Precaution for installtion

Slide the suspender in the

direction of the arrow.

Suspender

Set the psuh

switch (1 key).

(RF945R)

Switch, push (1 key)

Remove the two solderings.

Button, tuning

RX-BASE board

Remove the

nine solderings.

Claw

Screw (P 2

× 8)

Precaution for installtion

No.205

RX-BASE board

No.204

No.201

No.201 (green)

No.202

No.203

No.203 (black)

Solder the each lead wires directly to the position as shown while being cautions of colors.

No.204

No.202 (red)

MDR-RF915R/RF945R

Set the lead wires

Set the each lead wires as illustrated below.

Cover (L), hanger

Groove

To the driver (030F032).

No.203

No.201

Groove

No.201, No.203

Groove

No.202

Groove

To the RX-BASE board

Cover (R), hanger

No.205

Groove

No.204

To the driver (030F032).

No.201

No.203

No.202

No.201, No.203

Cover (L), hanger

Groove

Cover (R), hanger

SECTION 3

–+–

IC301 pin6

IC301 pin4

OSCILLOSCPE

CH1 CH2

MRD-RF915R

Notes:

1. Use transmitter with check and adjustment alreadycompleted.

2. On adjusting the headphones section, use the transmitter as a jig.

Headphones:MDR-RF915R Transmitter:TMR-RF915R

ELECTRICAL ADJUSTMENTS

MDR-RF915R/RF945R

Setting :

Procedure:

1. Connect an oscillator with attenuator and terminator (600 Ω)

2. Connect an AC adapter to the transmitter DC IN 9V jack (J404).

3. Connect a DC 2.4V to the +B power line externally.

4. Connect lead wires to IC301 pin 4, pin 6, pin 7 and GND on

5. Connect a resistor 33k Ω between IC301 pin 4 and pin 7.

6. Connect lead wires to the speakers’ terminals (L+,L-,R+,R-)

3-1. Free Run Frequency Check and Adjustment

1. Set the transmitter AUDIO IN-A connector (J402) to no signal.

Note: In this case, operation time is about 5 or 10 minutes.

2. Check the transmitter power indicator (red) lights.

3. Set the transmitter CHANNEL switch to 1.

4. Set the RV303 (TUNE) to the center position.

5. Connect a frequency counter to IC301 pin 4 and GND on the

6. When the frequency dose not satisfy the specified value, adjust

7. Remove a 33 Ω resister between IC301 pin 4 and pin 7.

Setting :

3-2. Receive Frequency Check and Adjustment

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-

4. Keep distance between transmitter and headphones to 5 meters

5. Set the headphones volume (RV302) to minimum.

6. Set the RV303 (TUNE) to the center position.

7. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and

8. Check the waveform of the oscilloscope to CH1 is demodulated

9. If CH1 and CH2 are not satisfied in step 8, adjust the coil (L301)

10. Set the transmitter CHANNEL switch to 1.

11. Adjust the RV303 (TUNE) to receive a signal.

12. Check same step 8.

13. Set the transmitter CHANNEL switch to 3.

14. Adjust the RV303 (TUNE) to receive a signal.

15. Check same step 8.

to the transmitter AUDIO IN-A connector (J402).

the RX-BASE board.

on the RX-BASE board.

Perform confirmation for less than 5 minutes.

RX-BASE board, then confirm the frequency within 76kHz ± 50Hz

the value of the frequency counter to specification by RV301 on the RX-BASE board.

Specified values: 76kHz ± 50Hz.

Frequency counter

+ –

IC301 pin

A(L-ch) connector only.

over.

pin 4.

1kHz signal and CH2 is GND.

on the RX board to satisfied step 8.

Confirm the signal with stereo.

3-3. Carrier Modulation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (L-ch) connector only.

4. Set the headphones volume (RV302) to minimum.

5. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and pin 4.

6. Adjust the tuning control (RV303) to receive radio frequency.

7. Check the waveform of the oscilloscope that the CH1 is demodulated 1kHz signal and CH2 is GND.

8. Connect an AC voltmeter with LPF to IC301 pin 6 and GND.

9. Check the value of the AC voltmeter to 26mVrms ± 2mV

Setting :

Digital voltmeter (AC range)

–

LPF

2.2K

33000P

IC301

pin6

OSCILLOSCPE

IC301 pin6

CH1 CH2

–+–

IC301 pin4

3-4. Separation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (L-ch) connector only.

4. Connect an oscilloscope CH1 to speakers terminal (L+,L-) and CH2 to IC301 pin 4 and GND.

5. Adjust the tuning control (RV303) to receive radio frequency.

6. Check the waveform of the oscilloscope that the CH1 is demodulated 1kHz signal and CH2 is GND.

7. Connect an AC voltmeter with LPF to speakers terminal (L+,L).

8. Adjust the value of the AC voltmeter to specification by headphones volume RV302.

Specified values: 155mVrms

9. Connect an AC voltmeter with LPF to speakersterminal (R+,R-).

10. Measure the value of the AC voltmeter.

11. Check the difference of the L and R to more than 20dB.

12. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (R-ch) connector only.

13. Connect an AC voltmeter with LPF to speakers terminal (R+,R-).

14. Adjust the value of the AC voltmeter to specification by headphones volume RV302.

Specified values: 155mVrms

15. Connect an AC voltmeter with LPF to speakers terminal (L+,L-).

16. Measure the value of the AC voltmeter.

17. Check the difference of the L and R to more than 20dB.

Setting :

Digital voltmeter (AC range)

–

L+ / R+ L– / R–

OSCILLOSCPE

CH1 CH2

L+

–+–

L–

IC301 pin

MDR-RF915R/RF945R

MRD-RF945R

Notes:

1. Use transmitter with check and adjustment alreadycompleted.

2. On adjusting the headphones section, use the transmitter as a jig.

Headphones:MDR-RF945R Transmitter:TMR-RF945R

Procedure:

1. Connect an oscillator with attenuator and terminator (600 Ω) to the transmitter AUDIO IN-A connector (J402).

2. Connect an AC adapter to the transmitter DC IN 9V jack (J404).

3. Short between Q303 corrector and GND on the RX board.

4. Connect a DC 2.4V to the +B power line externally.

5. Connect lead wires to IC301 pin 4, pin 6, pin 7 and GND on the RX-BASE board.

6. Connect a resistor 33k Ω between IC301 pin 4 and pin 7.

7. Connect lead wires to the speakers’ terminals (L+,L-,R+,R-) on the RX-BASE board.

3-5. Free Run Frequency Check and Adjustment

1. Set the transmitter AUDIO IN-A connector (J402) to no signal. Note: In this case, operation time is about 5 or 10 minutes.

Perform confirmation for less than 5 minutes.

2. Check the transmitter power indicator (red) lights.

3. Set the transmitter CHANNEL switch to 1.

4. Connect DC 1.2V across TP and GND.

5. Connect a frequency counter to IC301 pin 4 and GND on the RX-BASE board, then confirm the frequency within 76kHz ± 50Hz

6. When the frequency dose not satisfy the specified value, adjust the value of the frequency counter to specification by RV301 on the RX-BASE board.

Specified values: 76kHz ± 50Hz.

7. Remove a 33 Ω resister between IC301 pin 4 and pin 7.

Setting :

Regulated power supply (DC 1.2V)

–

OSCILLOSCPE

IC301 pin6

CH1 CH2

–+–

IC301 pin

3-6. Receive Frequency Check and Adjustment

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO INA(L-ch) connector only.

4. Keep distance between transmitter and headphones to 5 meters over.

5. Set the headphones volume (RV302) to minimum.

6. Set the RV303 (TUNE) to the center position.

7. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and pin 4.

8. Check the waveform of the oscilloscope to CH1 is demodulated 1kHz signal and CH2 is GND.

9. If CH1 and CH2 are not satisfied in step 8, adjust the coil (L301) on the RX board to satisfied step 8.

10. Open between Q303 corrector and GND on the RX board.

11. When the transmitter off, check the waveform of the oscilloscope as follows:

1.8V

GND

2-3sec

0.6V

12. Set the transmitter CHANNEL switch to 1.

13. Push the headphones tuning switch (S301) to receive radio frequency.

14. Check same step 8.

15. Set the transmitter CHANNEL switch to 3.

16. Push the headphones tuning switch (S301) to receive radio frequency.

17. Check same step 8.

Setting :

Regulated power supply (DC 1.2V)

–

OSCILLOSCPE

IC301 pin6

CH1 CH2

–+–

IC301 pin

3-7. Carrier Modulation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (L-ch) connector only.

4. Set the headphones volume (RV302) to minimum.

5. Connect an oscilloscope CH1 and CH2 to IC301 pin 6 and pin 4.

6. Push the headphone tuning switch (S301) to receive radio frequency.

7. Check the waveform of the oscilloscope that the CH1 is demodulated 1kHz signal and CH2 is GND.

8. Connect an AC voltmeter with LPF to IC301 pin 6 and GND.

9. Check the value of the AC voltmeter to 26mVrms ± 2mV

Setting :

Digital voltmeter (AC range)

–

LPF

2.2K

33000P

IC301

pin6

OSCILLOSCPE

IC301 pin6

CH1 CH2

–+–

IC301 pin4

3-8. Separation Check

1. Set the transmitter CHANNEL switch to 2.

2. Set the transmitter NOISE FILTER switch to OFF.

3. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (L-ch) connector only.

4. Connect an oscilloscope CH1 to speakers terminal (L+,L-) and CH2 to IC301 pin 4 and GND.

5. Push the headphones tuning switch (S301) to receive radio frequency.

6. Check the waveform of the oscilloscope that the CH1 is demodulated 1kHz signal and CH2 is GND.

7. Connect an AC voltmeter with LPF to speakers terminal (L+,L-).

8. Adjust the value of the AC voltmeter to specification by headphones volume RV302.

Specified values: 155mVrms

9. Connect an AC voltmeter with LPF to speakersterminal (R+,R-).

10. Measure the value of the AC voltmeter.

11. Check the difference of the L and R to more than 20dB.

12. Input a signal of 1kHz, 316mVrms to transmitter AUDIO IN-A (R-ch) connector only.

13. Connect an AC voltmeter with LPF to speakers terminal (R+,R-).

14. Adjust the value of the AC voltmeter to specification by headphones volume RV302.

Specified values: 155mVrms

15. Connect an AC voltmeter with LPF to speakers terminal (L+,L-).

16. Measure the value of the AC voltmeter.

17. Check the difference of the L and R to more than 20 dB.

MDR-RF915R/RF945R

Digital voltmeter (AC range)

–

Asjustment Location :

TP(R312-C320)

GND

RV303(TUNE) (RF915R)

S301(TUNE) (RF945R)

L301: Receive frequency Adjustment

OSCILLOSCPE

L+ / R+ L– / R–

L+ L–

RX-BASE BOARD (Conductor side)

R340

C340

IC303

C337

C341

R347

R349

R346

R341

R345

R323

S301

CH1 CH2

–+–

CF301

R342

R344

C334

C344

JC302

R343

C316

C320

R312

JC324

IC301 pin

C309

R325

R326

C335

R308

C332

C315

D301

C336

C314

C313

L301

D304 power

JC305

R328

JC301

C367

L302

C355

R327

C312

C329

C331

C317

C319

JC335

D310

C303

C308

C306

C307

IC301

C363

R309

C333

C366

R330

Q304

R322

C302

R320

Q305

IC305

R318

JC303

R321

R314

C365

R302

C351

C301

R304

Q303

R348

R354

R331

R362

R363

R364

R361

R360

R332

C323

10 6

IC302

R333

C361

R310

C362

C350

C304

R353

R334

JC306

IC301

C305

C352

C343

R355

R367

C345

JC309

C364

IC301

R305

JC311

Q301

R352

R351

JC304

R358

IC304

R315

C357

R316

C328

C330

IC301

R366

C327

C311

C342

JC336

C326

JC332

GND

RV301

CF302

R350

R356

R357

C325

JC331

JC334

(Connect a 33 KΩ resistor)

RV301: Free Run Frequency Adjustment

C310

C347

C346

D303

C324

JC333

L–

L+

R–

R+

Short

+B power line (DC 2.4V)

RV302: Volume control

MDR-RF915R/RF845R

4-1. BLOCK DIAGRAMS

RX-BASE BOARD

SECTION 4

DIAGRAMS

ANT301

FRONT END

FE UNIT

D301

RECEIVE

L301

FREQ.

RF915R

FM FE

RV303

TUNE

L302

RF945R

IC303

COUNTER

CF301

CF302

10.7MHz

REG

1316

OSC

Q301

FM IF/

DISCRI

SWITCH

Q303

AUTO

BLEND

MUTE

IF AMP/DECODE

IC301

PD1

COUNTER

FREE RUN

1/2

VCO

RV301

FREQ.

DECODE

AMP

MONO/ST

DETUNE

MUTE

STEREO

IND

TUNING

IND

RV302

VOL

6 2 5

R-CH

DETECT

IC304

IC305

Q305

RF945R

S301 TUNE

POWER AMP

IC302

MUTE

Q304

R-CH

ON/OFF SW

B+

D304

power

• Signal path. : FM

: AUDIO

• R-ch is omitted due to same as L-ch.

RECHAGEABLE BATTERY

(NICKEL-CADMIUM)

NC-AA

2PCS, 2.4V

SPEAKER

L-CH

SPEAKER

R-CH

CHARGE

TERMINAL

(TO TMR-RF915R/RF945R)

–

4-2. SCHEMATIC DIAGRAM

C311

10 16V

C366

C303

4.7/16V

R302

2.2k

0.001

CXA1538N-T4

IC301

C302

0.47

0.9

C304

0.022

FREE RUN

FREQ.

0.9

0.8

C301

IF AMP/DET

RV301

4.7k

R310

3.3k

1.6

0.9

R304

3.3k

CF302

10.7MHz DISC

1.3

C305

0.022

MDR-RF915R/RF845R

RF915R

RV303

R308

C334

10k

TUNE

JC324

2.2k

R366

150

D303

UDZ 2.2B

C347

16V

C346

0.22

C340

R340

0.1

4.7k

R341 470k

2.0

IC303

TC74HC4024

2.0

RF945R

C337 100p

JC304

COUNTER

R342 240k

2.0

7.5k

R347

R348

47k

2.0

15k

R346

R320

FE UNIT

(FRONT END)

R343

2.0

30k

R345

120k

62k

R344

R350

R351

15k

C342

0.01

Q301

FMW1-T-148

OSC

0.5

R349

10k

C341

0.1

C333

RF915R

D301

HVU363ATRU

C312

3.3

50V

JC311

1.0

1.6

0.7

C351

R305

3.3k

C306

C320

0.1

R312

15k

68p

10p

C315

C314

0.01

C313

R309 100k

2.1

2.3

R330

C350

C308

16V

C307

0.01

RF945R

C316

16V

L301

AIR COIL

C333

1.2

16V

C310

C309

C317

C352

0.001

C336

56p

µH

C332

0.33

L302

50V

150

R326

0.01

C335

RF915R

RF945R

C319

56p

0.01

R331

2.2k

1.3

RF945R

R325 330

10.7MHz

RF945R

C331

C309

2.2 50V

1 50V

CF301

JC302

R323

4.7k

C355

0.001

1.3

C329

0.01

C331

0.01

(ANTENNA)

RF945R

R356

22k

JC303

R367

JC306

47k

R352

R353

15k

C343

0.01

IC304

0.4

0.6

2SC2712L

OSC SWITCH

2.4

BA10393F

0.9

Q303

22k

47k

ERROR AMP

R358

R355

1.2

1.0

R357

0.9

22k

R354

S301

TUNE

R332

1.0k FF

C345

0.1

IC305

2.3

2.4

2.3

C344

0.1

TC7W74FU

Q305

DTC114TK

BUFFER

JC301

JC305

2.3

R361

22k

R360

22k

R364

22k

R362

10k

0.6

2.3 R363

22k

RV302(1/2)

R327

33k

R328

33k

C367

0.001

(VOLUME)

C364

0.001

RV302(2/2)

C330

2.4

R333

2.2k

1.1

C361 100p

R334

2.2k 0

1.1

C362 100p

AUDIO AMP

IC302

LA4533MTP-1

RF945R

Q304

2SC2712L

AUDIO MUTE

16V

R318

2.3

0.1

47k

C323

0.1

R314 100k

2.3

1.1

JC309

1.1

2.4

RF915R

0.01

C345

0.01

C357

C324

6.3V

C325

JC331

220

6.3V

C326

JC332

220

6.3V

R316

R315

0.1

C327

JC334

JC333

C328

0.1

220

SLR-342VCTB7

D304

(power)

C365

0.001

RECHARGEABLE

(NICKEL-CADMIUM)

R321

1.5k

BATTERY

NC-AA

2pcs,2.4V

R322

6.8k

C363

0.01

JC336

JC335

D310

RB411D

N1-CD

SPEAKER

(L-ch)

SPEAKER (R-ch)

(POWER ON/OFF)

TMR-RF915R/RF945R

(BATTERY

CHARGE

TERMINAL)

• IC BLOCK DIAGRAMS

IC302 LA4533MTP-1

POWER

P/SW

IN1

PRE GND

IN2

REF

SWITCH

AMP1

BIAS

AMP2

MUTE

CIRCIUT

MT/SW

OUT1

POWER GND

OUT2

VCC

IC305 TC7W74FU

CLR

VCC

RSQ

QDC

3Q2

Note on schematic diagrams.

Note:

• All capacitors are in µF unless otherwise noted. pF: µµF 50 WV or less are not indicated except for electrolytics and tantalums.

• All resistors are in Ω and 1/

• A : B+ Line.

• H : adjustment for repair.

• Power voltage is dc 2.4V and fed with regulated dc power supply

from battery terminal.

• Voltages are dc with respect to ground under no-signal conditions.

• Voltages are taken with a VOM (Input impedance 10 MΩ).

• Signal path.

F : FM L : AUDIO

GND

W or less unless otherwise specified.

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