Yamaha CT-610 User manual

secas

YAMAHA offers you 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 ts 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
ratio.
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. Signal Meter with Quality Indication
Waves that reach the antenna after being re-
flected from nearby hills or buildings (‘multipath’
CONTENTS AND FEATURES
Front Panel and Controls teaser eh kennen 4
Rear Panel and Connections — |.--------csccecececesserscneecesesecseces ais 5
| Connecting and Operating the CT-610 with Other Components +}... 6
Block Diagram and Specifications |... nen een 10
Trouble Shooting — |»-..----
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-
ment

CAUTION-READ
THIS
BEFORE
OPERATING
YOUR
CT-610
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.
a
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
settings.
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
selector.
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.
VOLTAGE SELECTOR, VOLTAGE SELECTOR, U i
a
lire
a 9 10-130" e

FRONT PANEL AND CONTROLS
FM 88 es SO sı 92 93
ı Leit a Bere braved
PLease eer re Phe Bu u De er BB BB Ba beret
1 1 I
+ I
AM 550 soo 700 soo sb
PIWER OUTPUT LEVEL FUNCTION
MUTING «FM AUTO
AAS Ces LENO aM
de y. > s r
FMMOND
3, 7 A
ON
— 2: +8 MEC CaL-
q ca
La bd a
o 10
©
@ 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.
D
@ AM Tuning Scale
This scale, marked clearly in kHz, is used when
tuning in AM stations.
8 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
location.
94 935 98 97 95 es 106 101 104
SE IS LT]
MA O A ead Enz
1
L 1 I 1 I I i ! l
1000 1f00 12004300 1400 15001600 kHz
103 104 105106 107108
O da
da Ma FM STEREO
I
POEPEPEerber bat rete Ed 11111341414
POWER
FIM TUNING
O
===]
O
@ EM 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
setting.
@ 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.
@ POWER Switch
Switch ON to connect the main electrical supply.
@ OUTPUT LEVEL Control
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.
O FUNCTION Selector Switch
This selects whether FM or AM broadcasts are to
be received, and if FM, then whether in MONO,
STEREO, with HIGH BLEND and/or MUTING,
and also offers a REC CAL position for tape
recorder calibration.
© SIGNAL Meter
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.
© FM TUNING Meter
This is used when tuning in FM stations: the
indicator points to dead center when the station is
perfectly in tune.
@ Tuning Knob |
The tuning knob is large, and the precision tuning
mechanism eliminates backlash, for smooth and
positive station selection.

| REAR PANEL AND CONNECTIONS
ein
WARNING-TO PREVENT FIRE OR SHOCK HAZARD,DO
NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE
FM ANT GND-AM ANT OUTPUT
75NUNBAL SOON EAL
- . .
2|® QQAQA je
@ YAMAHA voce creo ®
“0 A
© @ @® ©
Q FM ANT (75 Q Coaxial Cable)
This special bracket and terminal is provided for
use with 759 coaxial cable. Coaxila cable, in
@ AM Bar 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.
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 (3000 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.
@ GND (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.
Q AM ANT (External AM Antenna
Terminals)
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
terminal.
@ 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
panel.

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 OUTPUT LEVEL control so that
there
is
no
significant
change
in
volume
when
| | Amplifier Connections
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.
.
ADJUSTING
THE
AM
BAR
ANTENNA
-
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 Q
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
CTING AN FM ANTENNA _
sufficient sensitivity to operate extremely well
with a fixed antenna.
External antennas are available for use with the
30082 and 75Q terminals: the latter will use the
shielded coaxial cable which reduces losses and
interference. Antennas intended for 3002 bal-
anced feeder wire can also be used with 75Q
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.
CONNECTING COAXIAL CABLE
1 Strip insulation from outside braided sheath,
and bend back outside the insulation. Expose
the projecting central core wire as shown.
2 Slacken the two retaining screws, insert the
coaxial cable, and re-tighten the screws so that
the clip grips the exposed braided sheath.
3 Connect the central core wire to the 752
terminal.
4 If your CT-610 is provided with a coaxial jack,
use this with a coaxial plug on the 75 Q coaxial
cable, Whether you use plug or terminal, ensure
that the braiding does not come into contact
with the inner core.

||
FM
BROADCAST
RECEPTION.
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.
|_| [rm BLEND POSITION
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.
REC
CAL
POSITION
—
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 will enjoy generally better tonal
quality even if this level is a little lower than the
maximum when indication is fluctuating.

bh
BLOCK DIAGRAM
SPECIFICATIONS
FM Section
Tuning range
Sensitivity (IHF, 38 MHz)
Quieting Characteristic
5 uv
10 uV
Image rejection (88 MHz)
IF rejection (88 MHz)
Spurious rejection
AM suppression
Capture ratio
Selectivity (IHF)
Signal/noise ratio
Mono
Stereo
Total harmonic distortion
Mono 400 Hz
50 Hz to 10 kHz
Stereo 400 Hz
50 Hz to 10 kHz
10
BLOCK DIAGRAM AND SPECIFICATIONS
88 to 108 MHz
1.8 uV (300 2)
0.9 uV (750)
55 dB
60 dB
55 dB
75 dB
75 dB
56 dB
1.0 dB
75 dB
77 dB
71dB
0.15%
0.3%
0.25%
0.8%
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 ratio (80 dB/m)
Image rejection (1000 kHz)
IF rejection (1000 kHz)
Spurious rejection (1000 kHz)
40 dB
40 dB
30 dB
50 Hz to 10 kHz +0.5 dB
20 Hz to 15 kHz +35 dB
5uV
Signal meter fluctuation (re-
duction in indicated level).
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 level/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)
General
Semiconductors used
Power supply
Power consumption
Dimensions (W x H x D)
Weight
0.1V to 1.0 V/2.5 kQ
500 mV/2.5 kQ
25 mV to 250 mV/2.5 kQ
125 mV/2.5 kQ
50 mV to 500 mV/2.5 kQ
250 mV/2.5 kQ
22 Transistors, 3 ICs, 1 FET,
10 Diodes, 4 Zener Diodes,
2 LEDs, and 6 FM ceramic
filters.
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)

E
NJ
f
|
TROUBLE
SHOOTING
Before
assuming
that
your
CT-610
is
malfunctioning,
check
the
following
trouble-shooting
list,
which
details
corrective
action
you
can
take
yourself,
without havirig to call a service representative.
Fault
AM Broadcast
Reception
A persistent ‘hum’ occurs when the
station is tuned in.
Intermittent crackling or continuous
background ‘roaring.’
Cause
Cure
Known as modulation hum, this can affect whole
areas where reception conditions are unfavorable.
Atmospheric electricity or electrical storms, possibly
fluorescent
lighting
or
other
electrical
equipment.
High pitched whistles, etc., particularly
at night.
Signals from adjacent stations are interfering with
reception.
|
In
certain
areas
this
cannot
be
eliminated,
but
sometimes
changing
the
CT-610's
position
will
give
an
improvement.
Difficult
to
eliminate,
an
external
antenna
and
good
ground
connection
will
give
considerable
improvement.
Nothing
can
be
done
to
cut
out
this
interference,
but
try
turning
down
the
TREBLE
control.
FM Broadcast
Reception
Occasional crackling interference
(particularly with remote, weak
signal stations)
Noisy interference becomes particular-
ly marked for stereo broadcasts, and
spoils enjoyment.
np nn
The FM STEREO indicator flickers ..
when listening to stereo broadcasts.
Reception suffers from unclear,
distorted sound, although an external
FM antenna is being used. |
The
CT-610
is
being
operated
alongside
a
TV
set.
Electrical noise from automobile or motor cycle
ignition systems.
Interference from other electrical equipment,
particularly thermostats.
FM stereo broadcasts are inherently more liable to
this at remote, low signal strength locations.
Signal input from the antenna is too weak.
You are not perfectly tuned in to the station.
Signal input from the antenna is too srong.
During stereo test transmissions, sound
which should come from only one
channel can be heard faintly from
the other.
PA ——_—_—_ nn
This
is
known
as
crosstalk,
and
normally
occurs
to
some
extent.
E
Increase the distance between the TV and CT-610.
-
_
—_
_
_
_—
_
nn
i
raaanaaaaaaoaoaoa
o
raaa
a
aaa
n
Set
up
an
external
FM
antenna,
located
as
high
and
as
far
from
the
road
as
convenient,
and
use
coaxial
cable
feeder.
Fit
an
interference
suppressor
to
the
offending
item
of
electrical
equipment.
Set up an externa! 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.
Use an external FM antenna suitable to your local
signal strength.
J i rn.
Tune in correctly (see the section on FM Broadcast
Reception).
En m Er oS a ie
'
Connect
an
attenuator
between
the
antenna
and
the
CT-610.
Try reverting back to the T-typ
e FM internal antenna provided.
Provided
the
‘leakage’
of
one
channel
into
the
other
is
very
small
compared
with
the
normal
level
for
that
channel,
this
does
not
constitute
a
fault.
11

~~
@
YAMAHA
NIPPON GAKKI CO., LTD. HAMAMATSU , JAPAN
Printed in Japan 3