Sony MDR-RF975RK Manual

DC IN 9V

OFF ON

FILTER

NOISE

1 2 3

CHANNEL

R

B

A

L

AUDIO IN

Connect the transmitter to audio/video
equipment. Select one of the hookups
below depending on the jack type:

A

To connect to a headphones jack

B

To connect to LINE OUT or REC OUT
jacks

DC IN 9V

OFF ON

FILTER

NOISE

1 2 3

CHANNEL

R

B

A

L

AUDIO IN

To recharge the headphone battery after
use
Since the charger shuts itself off in response to its
internal timer after 24 hours, there is no need to
worry about overcharing.

* at 1 kHz, 1 mW + 1 mW output
** The hours required to fully charge empty battery

N

First turn on the audio/video equipment
and start playing.

Remove the headphones from the
transmitter.
The transmitter’s power indicator will
light in red.

Select the radio frequency with the
CHANNEL selector.

When you put on the headphones the
headphone power turns on
automatically.

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.

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

C

To connect to TV, etc.
If noise occurs when the transmitter is
connected to the headphone jack of your
TV or VCR, set the NOISE FILTER switch
to ON.

Notes
• If you connect the transmitter to LINE OUT or REC

OUT jack, do not set the NOISE FILTER switch to
ON. Otherwise, the volume will be limited.

• The NOISE FILTER switch effects the sound only in

cases such as connection diagram C. In diagrams A
and B, the switch has no effect.

• When the transmitter is placed on or near a TV, it

may pick up a noise. In such case, place the
transmitter away from the TV.

Connect the transmitter to an AC outlet
using the supplied AC power adaptor.

Notes
• Use only the supplied AC power adaptor. Do not use

any other AC power adaptor.

• When you connect the connecting cord directly to an

earphone jack, the audio signal will not be output
through the right channel. In such a case, use the
separately sold PC-236HG plug adaptor.

• If the connected equipment has the AVLS (Automatic

Volume Limiter System) function, be sure to turn the
function off when using the transmitter. Otherwise, you
will have to turn up the volume of the headphones, and
that may cause noise.

• Do not place the transmitter near a fluorescent lamp, etc.

when using the system.

* WALKMAN is a registered trademark of Sony

Corporation.

When you use the headphones for the first time,
charge the battery in the following manner.

Connect the transmitter to a power
source.

Place the headphones on the transmitter.

Place the headphones on the transmitter such that
the charging pins on the transmitter engage the
charging contacts on the bottom of the housing.
The charge indicator on the transmitter will light in
green to indicate that the battery is being charged.
Once 24 hours have elapsed since the start of
battery charging, the charger automatically shuts
off, and the green indicator goes out.

DC IN 9V

OFF ON

FILTER

NOISE

1 2 3

CHANNEL

R

B

A

L

AUDIO IN

Operating Instructions

Manual de instrucciones

Sony Corporation © 2001   Printed in Korea

3-233-606-13(1)

Sending RF signals from the Transmitter
The transmitter starts sending the RF signals
automatically, when it detects audio signals from
the equipment connected.
If it does not detect an audio signal for more than
approximately four minutes, the transmitter will
stop sending RF signals, and the power indicator
turns off.
When the transmitter receives an audio signal
again, it starts sending the RF signals, and the
power indicator will light in red again.
If the audio signal is very weak, the transmitter
does not send RF signals. If the transmitter is
connected to a headphone jack, make sure the
volume of the equipment connected is set to 5 – 6
or higher.
You may not hear the beginning of the sound from
the headphones until the transmitter starts sending
the RF signals after detecting an audio signal.

Note
If the transmitter is connected to the headphones jack of
the source equipment, set the volume of that equipment as
high as possible without distorting the audio signal.

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.

Note
If a hissing noise is heard move closer to the transmitter.

After listening to a program
Take the headphones off and rest them away on
the transmitter, and recharge them.

Note
Do not hang the headphones by the self adjusting band,
otherwise, the self adjusting band will be pulled up and
the headphones will be switched on.

The optimum distance is up to approximately 150
feet (46 m) without the system picking up some
interference. However, the distance may vary
according to the surroundings and environment. If
the system picks up some noise while using it
within the above mentioned distance, reduce the
distance between the transmitter unit and the
headphones, or select the other channel.

Notes
• When you use the headphones inside the effective areas

of the transmitter, the transmitter can be placed in any
direction from the listener.

• Even within the signal reception area, there are some

spots (dead spot) where the RF signal can not be
received. This is a characteristic inherent to RF signals,
and does not indicate malfunction. By slightly moving
the transmitter, location of the dead spot can be
changed.

1

24**

60 minutes

25 hours

, Turn on the transmitter first, then put on the

headphones.

, Check the connection of the audio/video

equipment or the AC power adaptor.

, Check that the audio/video equipment is turned

on.

, Turn up the volume on the connected audio/

video equipment, if the transmitter is connected
to the headphones jack.

, Change the radio frequency with the CHANNEL

selector on the transmitter, then press the
TUNING button again.

, The mute function is activated.

Use the headphones near the transmitter.

, The headphones’ POWER indicator light is weak

or turned off.
• Charge the built-in rechargeable battery or if the

POWER indicator is still off after charging the
built-in rechargeable battery, take the
headphones to a Sony dealer for replacement of
the rechargeable battery.

, If you connect the transmitter to LINE OUT or

REC OUT jack of an audio reproducer, make sure
that the NOISE FILTER switch is set to OFF.

, Make sure that the NOISE FILTER switch is set to

either ON or OFF (If the switch gets stuck
between ON and OFF, the sound will be cut off).

, If the transmitter is connected to the headphones

jack, turn down the volume of the connected
audio/video equipment.

, Change the radio frequency with the CHANNEL

selector on the transmitter.

, The headphones’ POWER indicator light is weak

or turned off.
• Charge the built-in rechargeable battery or if the

POWER indicator is still off after charging the
built-in rechargeable battery, take the
headphone to Sony dealer for replacement of the
rechageable battery.

, If you connect the transmitter to LINE OUT or

REC OUT jack of an audio reproducer, make sure
that the NOISE FILTER switch is set to OFF.

, Move closer to the transmitter. As you move

away from the transmitter, more noise is likely to
be heard.

, If the transmitter is connected to the headphones

jack, turn up the volume of the connected audio/
video equipment.

, Change the radio frequency with the CHANNEL

selector on the transmitter, then press the
TUNING button again.

, The headphones’ POWER indicator light is weak

or turned off.
• Charge the built-in rechargeable battery or if the

POWER indicator is still off after charging the
built-in rechargeable battery, take the
headphone to Sony dealer for replacement of the
rechageable battery.

, If you connect the transmitter to LINE OUT or

REC OUT jack of an audio reproducer, make sure
that the NOISE FILTER switch is set to OFF.

General
Carrier frequency

913.5 – 914.5 MHz

Channel

Ch1, Ch2, Ch3

Modulation

FM stereo

Frequency response

18 – 22,000 Hz

Transmitter TMR-RF975R
Power source

DC 9 V: supplied AC power adaptor

Audio input

phono jacks/stereo mini jack

Dimensions

Approx. 130 

×

 135 

×

 150 mm

(5 

1

/

4

 

×

 5 

3

/

8

 

×

 6 in.) (w/h/d)

Mass

Approx. 200 g (7 oz.)

Headphones MDR-RF975R
Power source

DC 2.4 V: Built-in rechargeable

battery

Mass

Approx. 350 g (12.3 oz.) incl.
built-in rechargeable battery

Built-in Ni-MH rechargeable battery
Model name

NH-AAC

Voltage

1.2 V

Capacity

1,000 mAh

Optional accessory
Plug adaptor

PC-236HG (stereo mini jack 

y

monaural mini plug)

Design and specifications are subject to change without
notice.

Thank you for purchasing the Sony
MDR-RF975RK Wireless Stereo Headphone
System. Before operating the unit, please read this
manual thoroughly and retain it for future
reference.
Some features are:
• Wireless system that allows you to listen to a

program free from the restriction of a cord

• High fidelity sound reproduction
• A compact transmitter with an AC power

adaptor (supplied) enables simple charging of
the headphone battery. Just by placing the
headphones on the transmitter, headphone
battery can be charged.

• Comfortable Circum-aural headphones with

self-adjusting head band

• Automatic ON/OFF function on headphones to

preserve battery power

1 2 3

CHANNEL

When the ear pads become dirty or damaged, you
can get replacements from your Sony dealer.
Replace them as illustrated below.

Remove the old ear pad by pulling it out
of the groove on the housing.

Place the new ear pad on the driver unit
and insert the edge of the pad into the
groove as illustrated.

Make sure that the entire edge of the ear pad is
securely inserted into the groove.

N

• When the transmitter is not to be used for a long

period of time, disconnect the AC power
adaptor from the AC outlet holding the plug. Do
not pull on the cord.

• Do not leave the wireless stereo headphone

system in a location subject to direct sunlight,
heat or moisture.

Notes on headphones
Preventing hearing damage
Avoid using headphones at high volume. Hearing
experts advise against continuous, loud and
extended play. If you experience a ringing in your
ears, reduce the volume or discontinue use.

Caring for others
Keep the volume at a moderate level. This will
allow you to hear outside sounds and to be
considerate to the people around you.

If you have any questions or problems concerning
the system that are not covered in this manual,
please consult the nearest Sony dealer.

Be sure to bring the headphones and the
transmitter to the Sony dealer when requiring
repair work.

Disposing of the headphones
Be sure to remove the built-in rechargeable
batteries from the headphones before you
dispose of the headphones.
First remove the left headphone’s ear pad.
You will see four screws. Remove the four
screws and open the housing.

Information
You are cautioned that any changes or
modifications not expressly approved in this
manual could void your authority to operate this
equipment.

If you have any questions about this product, you
may call:
Sony Customer Information Services Center
1-800-222-7669 or http://www.sony.com/

Declaration of Conformity
Trade Name:

SONY

Model No.:

MDR-RF975R
(Headphones Unit)

Responsible Party: Sony Elecoronics Inc.
Address:

16450  W. Bernardo Dr,
San Diego, CA 92127  USA

Telephone No.:

858-942-2230

This device complies with Part 15 of the FCC
Rules. Operation is subject to the following two
conditions: (1) This device may not cause
harmful interference, and (2) this device must
accept any interference received, including
intereference that may cause undesired
operation.

The model number is located at the bottom of the
transmitter and on the inside of the left housing
hanger of the headphones.
The serial number is located at the bottom of the
transmitter and on the backside of the left housing
hanger of the headphones.
Record these numbers in the spaces provided
below. Refer to them whenever you call upon your
Sony dealer regarding this product.

Model No. MDR-RF975RK
 Transmitter TMR-RF975R
 Headphones MDR-RF975R
Serial No.

Transmitter 

 Headphones 

The system for this equipment utilizes very high
frequency signals in the 900 MHz band so the
receiving performance may deteriorate due to the
surroundings. The following examples illustrate
conditions that may reduce the possible receiving
range or cause interference with reception.
• Inside a building with walls containing steel

beams.

• Area with many steel file cabinets, etc.
• Area with many electrical appliances capable of

generating electromagnetic noise.

• Transmitter is placed on a metal instrument.
• Area facing roadways.
• Noise or interfering signals exist in the

surroundings due to radio transceivers in trucks,
etc.

• Noise or interfering signals exist in the

surroundings due to wireless communication
systems installed along roadways.

N

Check that you have the following items:

• The headphones
• The transmitter
• AC power adaptor
• Unimatch plug adaptor (stereo mini jack 

t

stereo phone plug)

• Connecting cord (phono plugs 

y stereo mini

plug), 1 m

Nickel Metal Hydride
batteries are recyclable.
You can help preserve our
environment by returning
your used rechargeable
batteries to the collection and
recycling location nearest
you.

For more information regarding recycling of
rechargeable batteries, call toll free
1-800-822-8837, or visit http://www.rbrc.org/.

Caution:
Do not handle damaged or leaking Nickel
Metal Hydride batteries.