Onkyo CP 1280 F Service Manual

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(, 1 12801

SERIAL N0. 3079

ONKYO® SERVICE MANUAL
QUARTZ LOCKED nmacr omv:

FULLY AUTOMATIC TURNTABLE
Model CP-l280F

TABLE OF CONTENTS

Item Page
Specifications 2
Features 2
Circuit description 3
Service procedures and alignment 6
Exploded view 9
Printed circuit board View from bottom side 1 1
Printed circuit board-parts list 12
Schematic diagram 13
Parts list 15
Packing procedures 16

ONKYO®
Alllllll lilIMPflHENIS

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SPECIFICATIONS
Type: Direct drive fully automatic
turntable with auto lead-in and
return; reject and repeat func-
tion also included; two motor
design with cueing lever.
33 cm (13") aluminum die-cast,
2.3 kg (5 lbs.) (with mat)

Turntable Platter:

Motor: Quartz lock synthesized DD
motor

Speeds: 33-1/3, 45 rpm, adjustable 16%

Wow & Flutter: less than 0.025% (WRMS)

Signal-to-Noise Ratio: better than 75 dB (DIN B)

Tonearm: Statically balanced straight type,
carbon fiber/pipe construction.

Effective Arm Length: 237 mm (9 3/8)

Overhang: 16 mm (5/8)

Offset Angle: 21 degrees

FEATURES

Improved moment-to-moment response

thanks to low tonearm mass

Ideally, the tracking force of a statically balanced tonearm,
being determined by the respective weights in front and
behind the pivot point, has nothing to do with the effective
mass of the tonearm itself. A counterweight of sufficient
weight is simply adjusted to provide the appropriate
amount of tracking force. This tracking force remains
constant only when we are dealing with a perfectly flat and
perfectly round disc. However, all records have some
amount of warp and eccentricity which upset this ideal
condition. During one revolution, the tonearm moves
sideways (caused by eccentricity) and vertically (caused by
warp) to trace the record grooves. Because the greater the
effective mass of the tonearm, the greater its inertiais (see
diagram), the result is poor tracking performance and
consequent poor moment-to-moment response.

To minimize effective mass, this tonearm employs:

(1) straight-line design, the shortest distance between pivot
and stylus tip (2) carbon fiber, with a specific gravity less
than half that of aluminum (3) a slimmer pipe thanks to the
higher rigidity of the straight-line/carbon fiber construction
(4) smallest possible shell within performance requirements
with miniature ADD-type connector. All this means the
effective mass is approximately 15 grams (with a 6 gram
cartridge), roughly half that of Onkyos standard S-type
tonearms. At a 2 gram tracking force setting, the resulting
difference in sensitivity can be seen in the following exam-
ple as the stylus moves over a typical record:

30 gram effective mass at stylus tip
15 gram effective mass at stylus tip

2.571.8g
2.271.9g

As the effective mass decreases, the variations in tracking
force dramatically decrease as well and the trackability of
the tonearm increases by the same margin.

Maximum Tracking Error: +2.5 degrees, 70.8 degrees
Suitable Cartridge Weight: 4 7 11 grams

Tracking Force: 072.0 grams
Other Devices: Tracking force direct readout
scale
Removable headshell
Dia-type antiskating control
Power supply: AC 120V/220V 50/60Hz
(or 120V 60Hz, or 240V SOHz)
Power consumption: 7 watts
Dimensions (WxDxH): 480 x 408 x 162 mm
(18 7/8 x161/16 x 6 3/8)
Weight: 11.5 kg (25.5 lbs.)
Accessories: Headshell, counterweight, over-

hang gauge, 45 rpm adapter,
instruction manual.

Specifications are subject to change for further product
improvements.

Comparison of effective mass at stylus up

counterweight 28 g

tracking force 2 9
equivalent
effective
mass at stylus tip 30 g

previous
models

counterweight 73 g

tracking force 2 9

equivalent
effective

mass at stylus tip 15 g

High torque quartz locked direct drive motor guarantees
superior rotational stability and accuracy.

The 20-pole 30-slot high torque motor with its quartz
locking system assures that excellent rotational stability is
maintained even during abrupt changes in the load. The
quartz lock system is a frequency generator (FG) connected
to the shaft to detect and correct any variations in the turn-
table speed. A reference frequency is taken from a 5.52960
MHz quartz oscillator, divided down and compared with
the signal from the F6. Any variations in speed, no matter
how small, are immediately detected and corrected by this
servo circuit.

The reference quartz oscillator uses the same type of quartz
control as that found in chronometers. It virtually elimi»
nates drift caused by time and temperature and overcomes
variations in load while locking the turntable speed to
exactly the correct value. To improve the reliability and
precision of this complex circuitry, lCs have been used
throughout, the frequency generator is completely inte-
grated to totally cancel any speed fluctuations of the plat-
ter, and an extremely stable quartz PLL circuit is em-
played.

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