Sony MDRRF-945-R Service manual

MDR-RF915R/RF945R

SERVICE MANUAL

Ver 1.1 2001. 06

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

9-873-137-12

2001F0200-1

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

Ver 1.1 2001.06

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 kΩ 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

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