Yamaha | CT-610 | Owner's Manual | Yamaha CT-610 Owner's manual

Yamaha CT-610 Owner's manual
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YAMAHA offers vou thanks and congratu-
lations on your choice of the CT-610 AM/FM
Stereo Tuner. Product of research directed
at making the best possible audio performance
available to the widest range of enthusiasts,
the CT-510 1s currently setting new standards
for its class.
1. Audio Quality-First Design
Building on YAMAHA's unique audio and ele-
ctronic engineering know-how, as developed for
the top-of-the-line CT-7000, the CT-610 features
low distortion, high sensitivity, and excellent S/N
2. High Performance Reception
Junction-type FET, three-gang tuning capaci-
tor, six special ceramic filters, and six-stage con-
stant bias current differential limiter assure superb
radio reception.
3. High Fidelity Waveform Transmission
Low distortion {and therefore high audio quali-
ty) are the result of special YAMAHA integrate
gain analysis, not only for all frequencies, but also
over a wide range of input levels, from weak,
distant stations, to powerful local stations.
4. NFB PLL MPX Stereo Demodulator Section
Negative Feedback (NFB) phase-locked loop
(PLL) multiplex {MPX) circuitry has all been built
into one high performance IC, replacing a host of
individual components, for greater reliability, im-
proved performance, and lowered cost.
5. Signai Meter with Quality Indication
Waves that reach the antenna after being re-
flected from nearby hills or buildings (*'multipath'
Front Panel and Controls —------.........e.eeenenieeennece e De e e e e eee 4
Rear Panel and Connections — ---..-........r.ereeseersevercenercorceren teca eee eee eee. 5
Connecting and Operating the CT-610 with Other Components --.... 6
Block Diagram and Specifications ecrans OP 10
Trouble Shooting ----.-..=..=.e eee eee sees 11
waves) interfere with the main broadcast signal,
and degrade performance. The CT-610 has a
special circuit which detects these waves, and uses
them to produce a ‘waver’ in the signal-strength
indication. It is simple to turn the antenna for
minimum variation, giving maximum quality.
6. Standard 333 Hz Signal for Level Setting
The REC CAL function gives a standard signal,
ideal for recording calibration and optimum level
setting. The variable level setting has a center click-
stop for known rated output.
7, Muting Circuit for Quiet Inter-Station Traverse
8. Low Distortion AM Circuitry for Added Enjoy-
The CT-610 is a high performance AM/FM
stereo tuner with excellent selectivity, sensi-
tivity, and several special features. This
manual is required reading if you are to
get the best from it.
Do not drop or otherwise jar the CT-610,
which is a precision instrument.
Do not place the CT-610 where it will be
exposed to direct sunlight, excessive heat
(for instance over a radiator or on top of an
amplifier which generates a fair amount of
heat), moisture, or dust.
Do not use chemical solvents (such as
benzene or alcohol) to remove traces of dirt.
Wipe only with a soft, slightly damp cloth.
Do not attempt to carry out internal adjust-
ments or repairs. Leave this to your local
service representative,
Do not assume your CT-610 is faulty before
checking the “Trouble Shooting’ list on page
11 for common operating errors.
Operate all switches and knobs in accord-
ance with the instructions. Avoid applying
undue force, which should never be necessa-
ry, and to not attempt to use intermediate
Keep this manual in a safe place for future
reference, and refer to it frequently until
you are perfectly familiar with all CT-610
controls and functions.
If your CT-610 has a voltage selector, check
that it is set to your local voltage before you
plug in the AC supply.
If not properly set, unscrew the two switch-
guard retaining screws, and reset the switch
to indicate your supply voltage (110—130V,
or 220—240V). Canadian models are set for
117V, 60 Hz alone, and have no voltage
Be sure to replace the switch-guard and its
two retaining screws after making the adjust-
ment, inverting it so that the new voltage
setting shows.
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6 FM Tuning Scale
This scale is frequency linear, so that stations
are spread out evenly across the dial, not clumped
together at one end. The units are MHz.
@ AM Tuning Scale
This scale, marked clearly in kHz, is used when
tuning in AM stations.
® Tuning Indicator
This pointer indicates accurately the frequency of
the station to be tuned in. The slide-ruler type
pointer ensures high precision for rapid station
(9 (D
a FR STEREO Indicator Lamp
This lamp illuminates when FM stereo broadcasts
are being received. It goes out, however, if the
FUNCTION selector is turned to the FM MONO
OQ POWER indicator Lamp
This lamp illuminates when the POWER switch is
in the ON position, indicating that electrical power
has been connected. If it goes out, with the
POWER switch still ON, this can mean that the
power fuse has blown,
Switch ON to connect the main electrical supply.
This sets the output level to suit the input
requirements of your amplifier unit. Adjust it so
that the volume setting of your amplifier does not
need to be changed when switching from TUNER
to other sources, such as PHONO or TAPE. The
center click stop gives a calibrated output which is
detailed in the Specifications.
FUNCTION Selector Switch
This selects whether FM or AM broadcasts are to
be received, and if FM, then whether in MONO,
and also offers a REC CAL position for tape
recorder calibration.
This indicates the strength of the signal for both
AM and FM station, and indicates FM multipath
interference by fluttering, with the amplitude of
the variation showing the extent of the interference.
This is used when tuning in FM stations: the
indicator points to dead center when the station is
perfectly in tune.
® Tuning Knol |
The tuning knob is large, and the precision tuning
mechanism eliminates backlash, for smooth and
positive station selection.
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@ AM Elar Antenna
This rod is a special indoor antenna for AM
reception. It should be folded out, away from the
chassis of the CT-610, to get the best results. In
most situations this bar antenna will give satisfac-
tory reception, but in locations remote from the
broadcasting station, or where the terrain (hills or
mountains) or the environment (steel-frame build-
ings, etc.) are unfavorable, an external antenna
may give noticeably better results.
@ FM ANT (75 0 Coaxial Cable)
This special bracket and terminal is provided for
use with 75% coaxial cable. Coaxila cable, in
which the central core is shielded by an outer
braided sheath, reduces losses in signal strength
between the antenna and the CT-610, and also
reduces the amount of interference picked up.
Some models of the CT-610 are provided with a
coaxial-piug Jack in addition to the coaxial bracket
and terminal, as shown.
® FM ANT (300 0 Balanced Feeder)
This is the pair of terminals used with ordinary
twin type feeder wire, like that used in the indoor
FM antenna provided with the CT-610. Although
the high sensitivity of the CT-610 means that an
indoor antenna can often give satisfactory results
with local stations, a proper FM antenna will
always give better results,
O END (Ground) Connection
Connection of a ground or “earth” connection can
make a worthwhile difference to AM reception,
effectively increasing sensitivity and reducing in-
terference, particularly hum.
© AM ANT (External AM Antenna
In areas where the bar antenna proves inadequate
for satisfactory AM reception, or wherever recep-
tion of remote or low strength stations is required,
an external antenna should be connected to this
ay OUTPUT Terminals
The output terminals of the CT-610 provide a
fully variable signal, suitable for all types of
pre-main amplifier or tape recorder. The level is set
by the OUTPUT LEVEL control on the front
Use the pin-plug cables provided with the
CT-610 to connect the OUTPUT terminals on the
rear panel to the TUNER or AUX input terminals
of your preamplifier or pre-main amplifier. Make
sure that you connect the LEFT (upper) output
terminal of the CT-610 to. the left-channel input
terminal, and the RIGHT to the right-channel.
Adjust the QUTPUT LEVEL control so that
there is no significant change in volume when
switching from TUNER to other sources (PHONO
or TAPE) with your amplifier. |
You can record directly from the CT-610 with
a tape recorder: use pin-plug cables to connect the
OUTPUT terminals to the tape recorder LINE IN
terminals. Check that the LEFT (upper) output
terminal is connected to the left-channel input
terminal, and the RIGHT to the right-channel. See
also the instructions for using the REC CAL
setting of the FUNCTION switch, which can be
particularly useful when recording direct from the
CT-610. |
The high efficiency ferrite bar antenna provided
with the CT-610 is all that is required for
satisfactory reception except in low signal strength
areas, so that usually no external AM antenna will
be needed. The bar antenna is hinged so that it can
swing out: try swinging it while watching the
SIGNAL strength meter. Set it at the angle which
gives the maximum reading for the weakest station
you will normally be listening to.
In a metal-frame building, or in locations
remote from the station or where reception
conditions are unfavorable, an external AM an-
tenna should be connected to the AM ANT
terminal. Even better results will be obtained if at
the same time a good ground (earth) connection is
made. A good ground connection can sometimes
be made to a water pipe. However, under NO
circumstances should you attempt to make a
ground connection to a gas pipe. Your dealer will
advise you.
1 Set the FUNCTION switch on the front panel
to AM.
2 Turn the tuning knob until the tuning indicator
is at the station's frequency.
3 Adjust the tuning knob to give the maximum
reading on the SIGNAL meter.
4 Note that the TUNING meter does not work
for AM.
First, connect the T-type internal (indoor)
antenna provided with the CT-610 to the 300 ©
BAL Terminals on the rear panel. The two arms of
the “T’ should be tacked at full stretch to the
ceiling or walls of your room. Try them in
different positions, and choose that which gives
the best reception for the weakest station to which
you will normally be listening. If you cannot
obtain satisfactory reception even varying the
angle of the horizontal T through a full 180”, this
is an indication that you need an external FM
antenna. |
The T-type antenna is adequate only in high
signal strength areas under favorable conditions. In
all other cases, an external multi-element FM
antenna is needed. To ensure the very best results,
a motor driven antenna assembly with remote
control of orientation is best, but the CT-610 has
sufficient sensitivity to operate extremely well
with a fixed antenna.
External antennas are available for use with the
300% and 75% terminals: the latter will use the
shielded coaxial cable which reduces losses and
interference. Antennas intended for 30082 bal-
anced feeder wire can also be used with 75)
coaxial cable, but a matching transformer is neces-
sary at the antenna. Coaxial cable shuld be used
where the antenna must be located some way from
the CT-610, or where interference. from automo-
bile ignition, etc., is troublesome.
The external antenna should be located as close
as convenient to the CT-610, and as high as
possible. It should be oriented to give the highest
SIGNAL meter reading possible for the weakest
station you will normally be listening to. If this
direction is not too critical, you can orient the
antenna for minimum interference from auto-
mobile ignition, etc. |
Strip insulation from outside braided sheath,
and bend back outside the insulation. Expose
the projecting central core wire as shown.
Slacken the two retaining screws, insert the
coaxial cable, and re-tighten the screws so that
the clip grips the exposed braided sheath.
Connect the central core wire to the 752
If your CT-610 is provided with a coaxial jack,
use this with a coaxial plug on the 75 £2 coaxial
cable, Whether you use plug or terminal, ensure
that the braiding does not come into contact
with the inner core. |
1 Set the FUNCTION switch on the front panel
to FM AUTO, |
2 Turn the tuning knob until the tuning indicator
is at the station's frequency.
3 Adjust the tuning knob to give the maximum
reading on the SIGNAL meter, and to bring the
FM TUNING meter pointer to the exact center
position. This will ensure optimum tuning.
4 When the broadcast is in stereo, the STEREO
indicator lamp will light, and will automatically
go out when MONO broadcasts are being made.
When you are listening to a weak FM station in
stereo, there can be unpleasant high frequency
noise (a kind of ‘hiss’). If this hiss noise is
bothering you, switch to the FM BLEND position,
which cuts out the noise very effectively. By
switching to the MONO position this kind of noise
can be reduced still further, but of course you will
no longer be able to enjoy stereo reproduction.
in this position, instead of broadcast reception,
the CT-610 output will consist of a 333 Hz signal
corresponding to 50% modulation. When using a
tape deck to record from the CT-610, the OUT-
PUT LEVEL control and tape recorder input level
controls should be adjusted to give a level of —6
VU on the tape deck level meters. This can be
increased to —2 VU depending on the tape deck
and the kind of tape being used. Once you have
determined the ideal setting for your tape deck,
the REC CAL position enables you to find it again
quickly and conveniently.
So-called ‘multipath’ waves, reflected from
nearby hills or tall buildings, can seriously degrade
tonal quality in FM reception. In addition to the
obvious deterioration in tonal quality, the
SIGNAL meter can also give you an indication of
the existence of multipath waves: it will show
slight fluctuations. If you notice this, alter the
orientation of your antenna to give a steady meter
reading. You wili enjoy generally better tonal
quality even if this level is a little lower than the
maximum when indication is fluctuating.
FM Section
Tuning range
Sensitivity (IHF, 38 MHz)
Quieting Characteristic
10 nV
Image rejection (88 MHz)
|F rejection (88 MHz)
Spurious rejection
AM suppression
Capture ratio
Selectivity (IHF)
Signal/noise ratio
Total harmonic distortion
Mono 400 Hz
50 Hz to 10 kHz
Stereo 400 Hz
50 Hz to 10 kHz
88 to 108 MHz
1.8 uV (300 22)
0.9 uV (7552)
55 dB
60 dB
55 dB
75 dB
75 dB
56 dB
1.0 dB
75 dB
77 dB
Sub-carrier suppression
Stereo separation
400 Hz
50 Hz to 10 kHz
Frequency response
Muting signal level
Multipath indication
AM Section
Tuning range
Sensitivity (IHF, bar antenna)
Selectivity (1000 kHz)
Signal/noise ratia (80 dB/m)
Image rejection {1000 kHz)
IF rejection (1000 kHz)
Spurious rejection {1000 kHz)
40 dB
40 dB
50 Hz to 10 kHz +
20 Hz to 15 kHz +.
Signal meter fluctuation (re-
duction in indicated leve!)
525 to 1605 kHz
52 dB/m
25 dB
50 dB
50 dB
40 dB
45 dB
Total harmonic distortion (80 dB/m) 0.6%
Audio Section -
Output !evei/Impedance (1 kHz)
FM {400 Hz, 100% mod.)
With level centered
AM (400 Hz, 30% m od.)
With level centered
- REC, CAL. signal 333 Hz
With level centered
(corresponding to 50% FM modulation)
Semiconductors used
Power supply
Power consumption
Dimensions (W x H x D)
0.1V to 1.0 V/2.5 ka
500 m V/2.5 kQ
25 mV to 250 mY/2.5 kQ
125 mV/2,5 kQ
50 mV to 500 mY/2.5 kQ
250 mV/2.5 kC
22 Transistors, 3 ICs, 1 FET,
10 Diodes, 4 Zener Diodes,
2 LEDs, and 6 FM ceramic
120 V, 60 Hz USA & Canada
220—240/110—130 V,
50/60 Hz Europe
7 Watts
435 x 160 x 349 mm
(17-1/8” x 6-1/4" x 13-3/4"")
6 kg (13.2 ibs)
Before assuming that your CT-610 is malfunctioning, check the following trouble
without having to call a service representative.
shooting list, which details corrective action you can take yourself,
AM Broadcast
A persistent ‘hum’ occurs when the
station is tuned in.
Known as modulation hum, this can affect whole
areas where reception conditions are unfavorable.
In certain areas this cannot be eliminated, but sometimes
changing the CT-610's position wil! give an improvement.
Intermittent crackling or continuous
background ‘roaring.’
Atmospheric electricity or electrical storms, possibly
fluorescent lighting or other electrical equipment.
Difficult to eliminate, an external antenna and good
ground connection will give considerable improvement.
High pitched whistles, etc., particularly
at night.
Signals from adjacent stations are interfering with
Nothing can be done to cut out this interference, but
try turning down the TREBLE control.
The CT-610 is being operated alongside a TV set.
Increase the distance between the TV and CT-610.
FM Broadcast
Occasional crackling interference
(particularly with remote, weak
signal stations)
Electrical noise from automobile or motor cycle
ignition systems.
Set up an external FM antenna, located as high and as
far from the road as convenient, and use coaxial cable
Interference from other electrical equipment,
particularly thermostats.
Fit an interference suppressor to the offending item of
electrical equipment.
Noisy interference becomes particular-
ly marked for stereo broadcasts, and
spoils enjoyment.
FM stereo broadcasts are inherently more liable to
this at remote, low signal strength locations.
Set up an external FM antenna
If you are already using an external FM antenna, increase
the number of elements in the antenna array.
Listen at the BLEND setting.
The FM STEREO indicator flickers -
when listening to stereo broadcasts.
Signal input from the antenna is too weak.
Use an external FM antenna suitable to your local
signal strength.
You are not perfectly tuned in to the station.
Tune in correctly (see the section on FM Broadcast
Reception suffers from unclear,
distorted sound, although an external
FM antenna is being used.
Signal input from the antenna is too srong.
Connect an attenuator between the antenna and the CT-610.
Try reverting back to the T-type FM internal antenna provided.
During stereo test transmissions, sound
which should come from only one
channel can be heard faintly from
the other.
This is known as crosstalk, and normally occurs to
some extent. |
Provided the ‘leakage’ of one channel into the other is very
small compared with the normal leve! for that channel, this
does not constitute a fault.
SINCE 1887
Printed in Japan 3-
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