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SERVICE MANUAL
NOISE CANCELING HEADPHONES
US Model
Canadian Model
AEP Model
E Model
Tourist Model
SPECIFICATIONS
MDR-NC11
Ver 1.1 2004.02
9-873-539-02
Sony Corporation
2004B05-1
Personal Audio Company
C
2004.02
Published by Sony Engineering Corporation
Notes on chip component replacement
· Never reuse a disconnected chip component.
· Notice that the minus side of a tantalum capacitor may be dam-
aged by heat.
General
Type
dynamic, closed
Driver units
9 mm dia
Power handling capacity
50 mW
Impedance
20 ohms at 1 kHz
(when the power is on)
8 ohms at 1 kHz
(when the power is off)
Sensitivity
102 dB/mW (when the power is on)
98 dB/mW (when the power is off)
Frequency response
10 ­ 22,000 Hz
Frequency range of active noise attenuation
50 ­ 1,500 Hz more than 10 dB at
300 Hz
Power source
DC 1.5 V, 1
× R03 (size AAA) battery
Mass
Approx. 47 g (1.7 oz) including battery
box, cord, and battery
Supplied accessories
Earbuds (S
× 2, M × 2, L × 2)
Holder (1)
Carrying case (1)
Plug adaptor for in-flight use (single/dual) (1)
Operating Instructions (1)
Design and specifications are subject to change without
notice.


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2
MDR-NC11
SECTION 1
GENERAL
Installing a battery
1 Open the lid on the rear side of the battery box.
2 Insert one R03 (size AAA) battery by matching
the + and ­ on the battery to the + and ­ in the
battery box.
3 Close the lid.
Battery life
When to replace the battery
Replace the battery with a new one when the POWER
indicator dims.
Battery
Sony alkaline battery LR03/AM-
4 (N)
Sony battery R03/UM-4 (NU)
Approx. hours
40 hours
20 hours
Selecting the
earbuds
The M size earbuds are attached to the headphones before
shipment. If you feel the M size earbuds do not suit your
ears, replace them with the supplied S or L size earbuds.
Plug adaptor (supplied)
When connecting to dual or
stereo mini jacks of in-flight
musicservices.
PC-MP1HG
(not supplied)
When connecting to the
remote control of a
WALKMAN*, etc.
To headphone jack
on airplane seats
When connecting to the
headphone jack (stereo mini
jack) of a WALKMAN*, etc.
2 Wear the headphones marked R in your right
ear and the one marked L in your left ear. Push
the earbud into your ear carefully so that the
earbud fits the hole of your ear snugly.
Note
Unless the headphones correctly fit your ears, noise
canceling will not function.
Adjust the earbuds position to sit on your ear comfortably,
and push them into the inside of your ears so that they fit
your ears snugly.
3 Turn on the power of the headphones.
The power indicator lights in red. The power
switch is located on the battery box. When
power is turned on, ambient noise is reduced,
and you can listen to music more clearly at a
lower volume.
4 Turn on the power of the AV equipment.
5 Adjust the volume.
Turn the VOL control.
(If you turn down the volume, the sound does
not mute completely.)
Notes on using on the airplane
· The supplied plug adaptor can be connected to dual and
stereo mini jacks.
· Do not use the headphones when use of electronic
equipment is prohibited or when use of personal
headphones for inflight music services is prohibited.
If you have any questions or problems concerning the
system that are not covered in this manual, please consult
the nearest Sony dealer.
After listening to music
Turn off the power of the headphones.
Notes
· The noise canceling function is only effective for noise in the
low frequency band. Although noise is reduced, it is not
canceled completely.
· Do not cover the microphone of the headphones with your
hands. The noise canceling function may not work properly.
· The noise canceling function may not work properly unless
the headphones are put on firmly.
· You can use the headphones even without turning on the
power. In this case, the noise canceling function is not active,
and the headphones operate as passive headphones.
· After you turn on the power of the headphones, you may hear
a slight hiss. This is the operating sound of the noise canceling
function, not a malfunction.
· In a quiet place, or depending on certain noises, you may feel
that the noise canceling function is not effective, or that noise
is accentuated. In this case, turn off the power of the
headphone.
· Interference noise can occur from nearby cellular phones.
Should this occur, locate the headphones further away from
the cellular phone(s).
Using the clip
You can fasten the battery box by its clip on a shirt pocket.
When carrying the headphones
You can attach the headphones to the supplied holder to
keep them together. The headphones and the battery box
can also be separately stored in the partitioned carrying case
(supplied).
While using the headphones, you can attach the holder to
the headphone cord.
Clip
Precautions
· Clean the headphones with a soft dry cloth.
· Do not leave the jackplug dirty otherwise the sound may
be distorted.
· Be sure to bring the headphones to the Sony dealer when
requiring a change of earbuds or repair work.
· The CE mark on the unit is valid only for products
marketed in the European Union.
· Do not leave the headphones in a location subject to direct
sunlight, heat or moisture.
· Do not subject the headphones to excessive shock.
· Handle the driver units carefully.
· To clean the earbuds, first remove them from the
headphones, and then clean them with water and mild
detergent. After cleaning, dry each earbud carefully
before use.
· The earbuds will need to be replaced from time to time. If
they are worn out by daily use or longtime storage,
replace them with new ones.
· If you fell drowsy or sick while using these headphones,
stop use immediately.
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.
Do not use headphones while driving and
cycling, etc.
As headphones reduce outside sounds, they may cause a
traffic accident. Also, avoid listening with your headphones
in situations where hearing must not be impaired, for
example, a railroad crossing, a construction site, etc.
Holder
Holder
Insert the # end first.
POWER
ON
OFF
Microphone
L
R
L
VOL
VO
L
dual jacks
stereo mini jacks
* WALKMAN is a registered trademark of Sony
Corporation.
Listening to music
1 Connect the headphones to the AV equipment.
Features
· Noise canceling headphones reduce ambient noise, and
provide a quieter environment to enhance audio
entertainment. Ambient sound is synthesized with an
anti-sound signal produced by the noise canceling circuit,
and reduced.
· Ultra compact earphones with 9mm driver unit fits
comfortably in the ear and closed type earphone structure
delivers deep bass sound.
· Soft silicon rubber earbuds are used for stable and
comfortable fit in the ears.
· Volume control function for easy connecting to your
portable audio player.
· New earphone holder minimizes cord tangles during
strage.
· Operates as passive headphones when noise canceling
circuit is not activated.
· Plug adaptor is supplied to connect directly to stereo or
dual jack of inflight music services.
This section is extracted from
instruction manual.


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3
MDR-NC11
SECTION 2
ELECTRICAL ADJUSTMENT
NOISE CANCEL VOLUME ADJUSTMENT
Connection:
Procedure:
1. Generate a sine wave of specific frequency (250 Hz) from a
AF oscillator, and output it from a speaker placed at the for-
ward position.
2. Mount this set on the head, and turn on the [POWER] switch.
3. With this set mounted, adjust the RV1 (L-ch) and RV51 (R-
ch) so that the volume from the speaker becomes lowest au-
rally.
Note:
When the headphones are not covered with the ear pieces completely, the
adjustment may not be performed correctly.
Make sure that the ear pieces cover the headphone completely.
Adjustment Location:
­ MAIN BOARD (Component Side) ­
+
­
amplifier
speaker
AF oscillator
NOISE CANCEL
RV51 (R-ch)
VOLUME ADJUSTMENT
RV1 (L-ch)
S101
[POWER]
OFF t ON


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4
MDR-NC11
SECTION 3
DIAGRAMS
3-1.
BLOCK DIAGRAM
P1
(LINE INPUT)
RV1
NOISE CANCEL
VOLUME (L)
BUFFER AMP
Q2
VOL
RV101
R-CH
R-CH
POWER AMP
IC101
POWER
AMP
9
2
1
S101
POWER
OFF
ON
DRY BATTERY
SIZE "AAA"
(IEC DESIGNATION R03)
1PC. 1.5V
POWER AMP
(IC101) B+
REGULATOR
IC102
B+
SWITCHING
Q101
D201
POWER ON
(L-ch)
(R-ch)
R-CH
HP1 (1/2)
(MICROPHONE)
(L-ch)
(R-ch)
HP1 (2/2)
(HEADPHONE)
: LINE INPUT (POWER ON)
: LINE INPUT (POWER OFF)
SIGNAL PATH
R-ch is omitted due to same as L-ch.
LED DRIVE, OSC
Q201,202


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MDR-NC11
5
5
Note on Printed Wiring Board:
· X : parts extracted from the component side.
· Y : parts extracted from the conductor side.
·
: Pattern from the side which enables seeing.
(The other layers' patterns are not indicated.)
3-2.
NOTE FOR PRINTED WIRING BOARD AND SCHEMATIC DIAGRAM
Note on Schematic Diagram:
· 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
and 1/4 W or less unless otherwise
specified.
· C : panel designation.
· A : B+ Line.
· H : adjustment for repair.
· Power voltage is dc 1.5 V and fed with regulated dc power
supply from battery terminal.
· Voltages and waveforms are dc with respect to ground in
no-signal conditions.
no mark : POWER ON
(
) : POWER OFF
· Voltages are taken with a VOM (Input impedance 10 M
).
Voltage variations may be noted due to normal produc-
tion tolerances.
· Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
· Circled numbers refer to waveforms.
· Signal path.
F
: LINE INPUT (POWER ON)
J
: LINE INPUT (POWER OFF)
Caution:
Pattern face side:
Parts on the pattern face side seen from
(Conductor Side)
the pattern face are indicated.
Parts face side:
Parts on the parts face side seen from
(Component Side)
the parts face are indicated.
· Waveforms
1
IC102 1 (S.D), Q101 (Collector)
2
Q201-1 (Base)
3
Q201-1 (Collector), Q202-1 (Base)
20 mVp-p
36.4
µs
1.1 Vp-p
36.4
µs
0.8 Vp-p
36.4
µs
4
Q201-2 (Base)
0.8 Vp-p
36.4
µs
5
Q201-2 (Collector), Q202-1 (Collector), Q202-2 (Base)
1.3 Vp-p
36.4
µs
6
Q202 (Emitter)
70 mVp-p
36.4
µs
7
Q202-2 (Collector)
20 mVp-p
36.4
µs