Nikko NT 950 tun sm

Page 1

NIKKD " TUNER

AM/ FM STEREO TUNER

SERVICE MANUAL

CONTENTS
SAFETY INSTRUCTIONS ...................................................................................................................... T
SPECIFICATIONS u. ........................................................................... 7
DISASSEMBLY ..... I. 2
BLOCK DIAGRAM .................................................................................................................... Cs
ALIGNMENT ....................................................................................................................................... 3~8
CIRCUITS DATA

INTEGRATED CIRCUITS ......................................................................................................................................... 9~73
P.W BOARD .................................................................................................................................. 14, 15
SCHEMATIC DIAGRAM. . 16,17

PARTS LIST ................................................................................................................................... 18, 1E:

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SAFETY INSTRUCTIONS

PRECAUTIONS DURING SERVICING

1. Parts identified by the A symbol parts are critical for
safety. Replace only with same parts number specified

2. Other parts and assemblies are specified to conform
with such regulations as those applying to spurious
radiation.

These must also be replaced only with specified ref
placements.

Examples: RF converters, tuner units, RF cables, noise
blocking capacitors, noise blocking filters, etc.

3. Use specified internal wiring
a) Primary leads
b) Wires covered with PVC tubing
c) Double insulated wire

4. Use specified insulating materials for hazardous live
parts.

3) Insulation Tape

b) Insulated Barriers (Spacers)

c) PVC tubing

d) Plastic screws for fixing microswitch (Especially in
turntable)

e) Terminal strips

SPECIFICATIONS

FM Tuner Section

Usable Sensitivity
50 dB Ouieting Sens
STEREO
MONO

. ...................................... 11.2 dBf/ZpV
tV

WIDE: 39.2 dBf NARROW: 39.2 M
WIDE: 22.2 dBf NARROW: 17.2 dBI

Signal-to-Norse Ratio
STEREO 70 dB
MONO 75 dB
Total Harmonic Distortion _
STEREO .................................... WIDE: 0.08% NARROW: 0.2%
MONO ..................................... WIDE: 0.05% NARROW: 0.1%
Stereo Separation
1 kHz .. WIDE: 50 dB NARROW: 45 dB

100 Hz to 10 kHz .. ,, WIDE: 40 dB NARROW: 35 dB
Frequency Response
(50 Hz to 15 kHz)

Capture Ratio ..............

..... +10 dB. 10 dB
WIDE 1.5 dB NARROW: 2.0 dB

Alternate Channel Selectivity . 50 dB 80 dB
Spurious Response Ratio .......... 75 dB 75 :18
IF Rejection Ratio... 90 dB 90 dB
AM Suppression Ratio .. 60 dB 60 dB
Sub-Carrier Suppression.t......... 67 dB 67 d8

5. When replacing the primary components (transformer,
power supply cord switch, by-pass capacitor. etc),
wrap ends of wires securely about the terminals before
soldering,

Where hand soldering is involved. a minimum spacing
below between terminals of uninsulated live parts of
primary or supply circuitry through air or over surface
is to be maintained.

120V appliance : 3mm spacing min.
220V and 240V appliance : 6mm spacing min.

6, Observe that wires do not contact heat producing parts
(heatsinks, oxide metal resistance, rectifiers, etc.) \

7. Check that replaced wires do not contact sharp edges
or painted parts.

8. Do not leave electric conductive parts (screws,droplets.
etc.) inside the appliance.

SAFETY RECHECK AFTER SERVICING

Confirm the specified insulation resistance between power
plug prongs and externally exposed parts of the appliance
is greater than 10Mohms, however, for equipment with
external antenna terminals (tuner, receiver, etc.) specified
insulation resistance should be more than 2.2Mohms
(ground terminals, in-output jacks etc.)

Muting Threshold Level .
Antenna Impedance t.

5.2 dBf NARROW' 35.2». .
75 ohms and 300 ohms

Output Level .............................. 600 mV
AM Tuner Section
Usable Sensitivity ............................................................. 350 uV/m

Selectivity
Signal-toAN se Ratio .
Image Rerection .
IF Rejection .
Total Harmonic Distortion .

40 dB
, 50 dB
40 dB
40 dB
.. 0.5%
, 200 rnV

Output Level ...................
General
Power Requirement
U.S.A. & Canada ............................................ AC 120 V. 60 Hz
Europe ........ AC 220 V. 50 Hz
Power Consumption ................... lZW
Dimensions .............................. 440 (W) x 435 (H) x 265 (D) rnrn
(17-1/4" x 1-3/A~ x 10-2/5")
Weight, without package .......................................... 3.2 kg (7 lbs)

Specifications are subject to change without notice.