Realistic sct-20 User manual

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PLEASE READ BEFORE
USING THIS EQUIPMENT
CUSTOM MANUFACTURED FOR TANDY CORPORATION
CAT. ND.
14-B10

FEATURES
Front Loading Deck
State-of-the-art mechanism permits convenient front loading into
the  compartment. This design means you can stack com-
ponents or install this deck between shelves.
Dolby* Noise Reduction System
World-famous Dolby Noise Reduction system reduces tape hiss and
tape head noise, resulting in substantially improved signal-to-noise.
This gives an added benefit of extending the dynamic range.
Tape Selection Switch
To achieve optimum results from today's technologically advanced
ultra-low noise tapes and Chromium Dioxide tapes, bias and
equalization must be matched to the tape being used. The BIAS
and EQualization Switches provide this necessary matching —
resulting in superior signal-to-noise, wider frequency response and
greater dynamic range with either tape.
Dual VU Meters
Separate Right and Left channel Level Meters are illuminated and
can be used in conjunction with individually adjustable Right and
Left Channel Record Level Controls to precisely set recording
levels.
Headphone Jack
This is located at the lower right front of the unit for quick and
easy headphone listening. Microphone Jacks are right there too —
easy to get at.
* "DOLBY" and
DO 
are trademarks of Dolby Labora-
DOL BY SYSTE M
tories Inc.
For your own protection, we urge you to record the Serial Number
of this unit in the space provided. You'll find the Serial Number on
the back panel of the unit.
Serial Number
SPECI FICATIONS
Tape System

:Standard PHILIPS Cassette
4-track stereo
C-30/60/90/120 (number indicates total
time for both sides)
Tape Speed 
: 1-7/8 ips (4.75 cm/sec)
Frequency Response : Supertape Gold, 30-12, 000 Hz (± 3 dB)
(overall)
Signal-to-Noise 
: Supertape Gold with Dolby, better than
(overall)

—58 dB
Distortion at +3 VU : 1.5% maximum
Cross-talk 
: Better than — 60 dB
Wow & Flutter 
: 0.12% maximum
(WRMS)
Erase Ratio

: Better than 60 dB
Output Level

: 0.58 volts (adjustable)
Output Impedance : Less than 10K ohms
Input Sensitivity

: Mic = — 63 dB (.053 mV)
Aux = — 18 dB (100 mV)
Input Impedance

Mic, more than 1 K ohms
Aux, 100 K ohms
Record Bias

: 85 kHz
Erase System

: 85 kHz AC erase
Fast-Forward/Rewind
Time 
: Less than 110 seconds with C-60
Power Requirements : 120 volts, 60 Hz AC (220/240 volts, 50 Hz
for European and Australian models),
35 watts
Semiconductor

Integrated Circuits, 2
complement
 Transistors, 14
Diodes, 13
Zener Diodes, 1
Dimensions 
: 4-3/16" x 14-7/16" x 9-9/16" (HWD)
(10.6 x 36.7 x 24.3 cm)
Weight

: 11 lbs. (5.0 kg)

CONTROLS
This is a quick reference guide to the many features of your SCT-
20. For operation and installation instructions, refer to later
sections of this manual.
POWER
Press in to turn power "ON"; press again to turn power
"OF F".
PHONES Jack
Plug a pair of stereo headphones into this jack to
listen to the tape being played back, or to monitor the signal
being recorded during a recording section.
MIC LEFT and RIGHT Jacks
Plug high-quality microphones into
these jacks to make "live" recordings.
Dual VU Meters
these indicate the level of the Record or Play
signal — one for each channel. They are lighted when Power is on.
RECORD LEVEL Controls
adjust for the proper level of record-
ing for each channel, as indicated on the Level Meters.
RECORD Function LED
lights up when you are in the Record
mode.
Digital Tape Counter
use to aid you in locating desired portions
of the tape. Press the button at the right to reset to "000".
DOLBY NR Button
controls the operation of the built-in Dolby
Noise Reduction System. For making Dolby Recordings and for
playing them back, press this button in; press again to release the
Dolby function.
EQ (Tape Equalization) Button

the position of this switch
determines the proper equalization to match tapes being used.
Use Cr02 (press in) for ChrOmium Dioxide tapes; use NORMal
(out position) for all other tapes. If functions in both the Record
and Play modes.
BIAS Button
the position of this button determines the proper
bias level to match tapes yo are using. Use Cr0
2
(in position) for
Chromium Dioxide tapes; use NORMal (out position) for all other
tapes. Use this
BIAS
switch simultaneously with
EQ,
(Equalization)
switch. It function only in Record mode.
RECORD
Key...press simultaneously with
PLAY key to record.
The RECORD LED
will light indicating you are in the Record
mode.
REWIND
Key...when you have a cassette loaded, press down to
rewind tape rapidly. To release this function, press
STOP/EJECT.
FAST-Forward
Key...when you have a cassette loaded, press down
to move tape rapidly in a forward direction. To release this
function, press
STOP/EJECT.
PLAY
Key...press for playback operation. For Record, press this
key simultaneously with the
RECORD
key.
STOP/EJECT Key...to
stop the tape during any function, press
once; to eject the cassette, press again.
PAUSE Key...to
temporarily stop tape travel during Record or
Play, press this key. Press again to restart tape movement.
— 3 —

TO LINE IN
TO LINE OUT
 PATCH CORDS
fi
t
To TAPE IN or
AUX IN
To TAPE OUT or
LINE OUT
FULL REEL
INSTALLATION

OPERATION
FIGURE
4
Using one of the patch cord provided, connect the Left and Right
LINE OUT jacks to the corresponding tape input jacks of you
stereo Amplifier/Receiver. Plug the line cord into any 120 volt,
60 Hz AC outlet. (220/240 volt, 50 Hz for European and
Australian models as indicated on the rear of the unit.)
Use the other patch cord to connect the LINE IN jacks to the
TAPE OUT (or RECORD OUT) jacks on your Amplifier/Receiver.
(For European models only)
If your Amplifier/Receiver has a DIN jack, use a DIN cord (not
provided) to connect the rear panel R EC/PLAY DIN jack to the
DIN jack on your Amplifier/Receiver. When using DIN jack,
disconnect LINE IN/LINE OUT jacks.
NOTE: It may be necessary to adjust the OUTPUT LEVEL con-
trols to match the input of your Amplifier/Receiver. Do this as
follows: Set up your stereo system with another signal source
(FM or records, etc.). Adjust volume, tone and balance for normal
listening conditions.

Now, switch the Amplifier/Receiver to
operate with the Tape Deck and play a cassette tape. If necessary,
adjust the OUTPUT LEVEL controls on the back of the Tape
Deck to obtain a similar output level. Switch back and forth be-
tween the two signal sources and make adjustments until you are
satisfied with the balance of the sound output. Once set, this
control requires no further attention.
PLAYING BACK TAPES
To Turn the Deck On
The SCT-20 offers the convenience of a separate ON/OFF switch.
To turn the Deck on, push POWER once; push again to turn off.
Loading a Cassette
1.
Open the Cassette Door.
2.
Press STOP/EJECT key. This brings all the keys into the "up"
position.
3.
Load the Cassette, open end
down with the full reel to your
left, into the cassette com-
partment and push it down
until it locks.
4.
Close the Cassette Door.
To remove the Cassette, the tape
movement must be stopped
(either automatically, or manual-
ly, by pressing STOP/EJECT).
Then, press STOP/EJECT again
to Eject the Cassette.
Playing the Tape
1.
Press POWER to turn the unit on. Press the Digital Tape Counter
button to reset to 000.
2.
Load a pre-recorded Cassette as noted above.
3.
Set E Q switch to the appropriate position. Press in if the tape
is Cr02 type; leave out if it is standard type tape.
4.
If you are going to play a Dolbyized tape, press DOLBY NR in.
5.
Press PLAY key and the tape will begin moving. Adjust Volume,
Tone and Balance controls on your Amplifier/Receiver for
desired sound.
6.
To temporarily stop tape playing, press PAUSE; to restart the
tape, press PAUSE again.
7.
To stop playing, press STOP/EJECT.
To move tape rapidly in a forward direction press FAST-F.
To move tape rapidly in a reverse direction, press REWIND.

In either case, to return tape travel to normal speed, press
STOP/
EJECT,
then press
PLAY.
Use the
Tape Counter
to aid you in locating approximate positions
on the tape.
To listen to tapes privately (or if you don't have an Amplifier/
Receiver), plug a pair of stereo headphones into the
PHONES
jack.
STEREO RECORDING
You can make recordings either from microphones (through
MICrophone
jacks) or through the
LINE IN
jacks. Make the
appropriate connections before starting the Recording session.
NOTE: We strongly urge you to use only the finest tape with
your SCT-20. Only with the finest tape will you realize the fullest
capabilities of this Tape Deck. Use either Realistic's
Supertape ®
Gold
or our
Supertape Chrome
tape.
1.
Load a Cassette into the Cassette Compartment.
2.
Make connections to record either from Mics or an Auxiliary
source (LINE IN jacks).
NOTE: When both MICrophone
and LINE IN connections are
made, only the MICrophone
input will function.
3. Set
BIAS and
EQ
switches to the appropriate positions. Press in
if you are using Cr0
2
tape. Leave in the NORMal position for
all other tapes. Mark the switch setting on the Cassette so
you'll remember to play the tape back with the same setting.
(See NOTES later on.)
4.
Press
DOLBY NR
in if you are going to make a Dolbyized re-
cording (be sure to mark the Cassette if you record with Dolby).
5.
Reset the
Digital Tape Counter
to
000.
6.
Press
PAUSE, RECORD
and
PLAY
keys and adjust the
RE-
CORD LEVEL
controls to achieve proper channel balance and
recording level. Adjust for meter readings that only
occasionally
peak up into the red area on the meters. Normal recording levels
will give meter readings between black numbers 5 and 3. This
procedure allows you to preset recording levels prior to starting
tape motion.
7. Press
PAUSE
again to release it. The tape will begin to move and
you are recording.
8.
To temporarily stop the tape while recording, press
PAUSE.
To
restart the tape, press PAUSE
again.
9.
To stop recording, press
STOP/EJECT.
To advance tape rapidly to any desired point, use
FAST-F key.
Use REWIND
to move tape rapidly in a reverse direction.
Use
Tape Counter
to aid in returning to original tape position and
to locate desired portions of the tape.
NOTE: Before changing tape motion, always press STOP/EJECT
first. It is not a good practice to go from
FAST-F or REWIND
to
PLAY
or vice versa without pressing
STOP/EJECT in between.
Abrupt changes in tape speed can result in tape spill or wrap-up.
Microphone Recording
To obtain optimum results with "live" recordings we recommend
that you use high-quality microphones. We suggest Radio Shack's
Electret Microphones, Catalog Number 33-1044 or 33-1045.
NOTE: For best voice recordings, position the microphones just
below the mouth at about 6-10" (15-25 cm).
Microphone placement
and positioning is a vital part of obtaining
good stereo recordings. We suggest you experiment a little with
distances and positioning before making any final recordings.
Making a good recording is an art
 it takes experience.
Recording from Radio or Phono
With connections made as previously noted, you can record "off-
the-air" or put your records on tape — or record any other source
being played through your Amplifier/Receiver.
TO ERASE A TAPE
It is not necessary to erase a tape before using it again.
As you record, any previous recordings are automatically erased.
However, if you want to erase a previous recording, without making
a new one, disconnect microphones and set the
RECORD LEVEL
controls to minimum. Now, load the cassette and run it through
with both
RECORD
and PLAY
keys pressed (just as though you
5

Stereo

Monophonic
head

head
1
L
•• •
3
A
4
B
were making a recording). This will erase the tape clean. Or, easier,
and for best erasure, use a Bulk Tape Eraser such as Radio Shack
sells.
MONAURAL RECORDING AND PLAYBACK
You can use your SCT-20 for monaural Record or Playback;
follow the same procedures as outlined previously for both
functions. For mic recordings, just plug the mic into the LEFT/
MONO MICrophone jack.
When you make monaural recordings through LINE IN jacks, it is
best if you use both right and left channels for the monaural signal
— this assures best sound reproduction, maximum output and
lowest noise.
4-TRACK RECORDING AND PLAYBACK
A cassette has two sides.
This Cassette Deck uses the standard four track, two channel
(stereo) system for making recordings and playing them back.
After you have recorded both right and left channels on one side,
remove the cassette, turn it over and reload — recording both chan-
nels on the other side. Also, the Cassettes can be recorded with
either mono or stereo signals.
Front side A (1)
Back side B (2)

•
••
.•f
MAKING AN ORDINARY RECORDING
1 . Music. Music is made of sounds of dif-
ferent, loudness separated by intervals of
silence. Loud and soft sounds are shown
here as long and short lines. The music re-
presented by this diagram starts loud and
gradually becomes very quiet.
MAKING A DOLBY SYSTEM RECORDING
 1 .
What the Dolby System does first.Be-
fore the recording is made, the Dolby Sys-
tem "listens" to the music to find the places
where a listener might later be able to hear
the noise of the tape. This happens mainly
duhng the quietest parts of the music.
When it finds such a place, the Dolby Sys-
tem automatically increases the volume so

that the music is recorded louder than it
would be normally.
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2. Noise. Any recording tape, even the best
kind, makes a constant hissing noise when
played. At the very slow speeds and nar-
row track- widths used in tape cassettes,
tape noise is much more noticeable than
it is in professional tape recordings, al-
though even there it is a problem.
2. The Recording. In a Dolby System re-
cording, the parts of the music which have
been made louder stand out clearly from
the noise. As a result, Dolby System record-
ings sound brilliant and unusually clear even
when played back without the special Dolby
System circuit.
3 . Music and Noise. When a tape record-
ing is played, the noise of the tape con-
ceals the quietest musical sounds and fills
the silence when no sound should be heard
at all. Only when the music is loud will the
noise be masked and usually not heard.
However, tape noise is so different from
musical sounds that it sometimes can be
heard even then.
3. What the Dolby System does during
playback. When the tapes are played on a
high fidelity tape recorder equipped with the
Dolby System circuit, the loudness is auto-
matically reduced in all of the places at
which it was increased before recording.
This restores the music to its original loud-
ness again. At the same time, the noise
which has been mixed with the music is
reduced in loudness by the same amount—
usually enough to make it inaudible.
•
•
• .•

TYPICAL

RECORDING
LEVEL
Average Peak
between 5 and 0
of the black numbers.
EXCESS LEVEL
SIDE A
'-04
4,4
1kti
TABS
• 
NOTES AND APPLICATIONS
CHOOSING THE RIGHT TAPE
Choice of tape is vital to good recordings. For most voice record-
ings (dictation, notes, lectures, etc.) either the CONCERTAPE or
REALISTIC Cassettes are appropriate. For average-to-good music
and other recordings, we recommend REALISTIC cassettes. For
low noise, wide-range recordings, we recommend SUPERTAPE
GOLD. For the very finest fidelity and lowest noise recordings,
use REALISTIC Cr02 Cassettes (in conjunction with Cr02 switch
positions).
Recording Level is a very important consideration if you are inter-
ested in obtaining top-quality recordings. Since we have incor-
porated individual channel controls, you have added control and
flexibility.
Meter readings should not be too high or too low. Proper recording
levels will be achieved when peak meter readings only very oc-
casionally touch into the red area. Normal peak levels will produce
peak meter swings up to between 6 and 0 of the black numbers.
Recording levels which consistently peak into the red area will
result in distortion and/or poor high frequency response. Re-
cording levels which peak only occasionally to 3 (or lower) of the
black numbers will have excessive noise — especially noticeable in
the soft passages. Therefore, you must learn to adjust recording
levels for a happy medium — to assure lowest noise and widest pos-
sible dynamic range.
Cassettes have a built-in erase protection device. On the back are
two small tabs. To prevent accidental erasure, carefully break off
the appropriate tab as shown below. With side A (or 1) up,
breaking "tab A" will prevent accidental erasure of the material on
side A (or 1), Tab B is for side B (or 2).
When the tab has been broken off, you can not press the RECORD
key down (don't try to force it down). If you decide to erase or re-
cord a cassette which has the tabs broken off, just cover the appro-
priate opening with tape.
To re-record a cassette, it is not necessary to erase previous re-
cordings. Previous recordings are automatically erased when a new
recording is made.
To erase a tape, follow the same procedure as for Recording, but
disconnect inputs and reduce RECORD LEVEL controls to mini-
mum. Then run the tape through (press RECORD and PLAY
keys); this automatically erases previous recordings from the tape.
Note that Erase Protect Tabs must be in place for this erase func-
tion to work. Or, you can use a bulk eraser such a Radio Shack's
Catalog Number 44-210.
To achieve optimum Record and Play results, be sure to use the
correct DOLBY, BIAS and EQ switch positions.
When playing back a Dolbyized tape, always press DOLBY NR
in
(or the tape will sound overly "bright"; that is, excessive high-fre-
quency content). When playing back a non-Dolbyized tape, leave
DOLBY NR out (or the sound will lack high-frequency emphasis).
— 8 —

BIAS and EQualization switches have been incorporated so you
can match the Deck to the tape you use. We use both to give you
extra versatility — so you can use any of the new tapes now availa-
ble (and to make sure your Deck will be compatible with any future
tape developements). Typically you'll want to use Cr02 positions
for Chromium Dioxide tapes.

And use NORMal for all other
tapes. However, you may firid you'll get better results with some of
the special tapes if you use Cr02 Bias and NORMal Equalization
settings for recordings.
We suggest that if you are using one of the special formulation tapes,
try different combinations till you obtain the one which results in
the best overall level, frequency response and lowest noise.
NOTE: BIAS functions only during Record mode (has no effect
during play). EQ functions in both Record and Play.
The Dolby System incorporated in your Tape Deck will enable you
to make tape recordings with substantially improved signal-to-noise
ratio, which gives the effect of extending dynamic range. It will
provide approximately 10 dB improvement in signal-to-noise in the
frequency range of tape hiss-noise.
You can duplicate tapes by recording from another tape deck/
player or put 8-track tape programs on cassettes. Or, you can put
your favorite records onto cassettes. Make appropriate connections
from another tape player or phonograph to the LINE IN jacks as
noted previously.
Storage of tape is no major problem, provided you do not expose it
to extreme temperatures or high humidity. Also, do not expose
your tapes to magnetic fields (magnets, large transformers, etc.).
Avoid dust and dirt. You may find storage containers to be extreme-
ly useful accessories; see your local Radio Shack store.
Demagnetize the tape heads and clean the tape handling parts pe-
riodically

this will insure maximum frequency response and
lowest noise. After a few hours of recording or playing, dust, lint
and tape oxide will begin to build up on the tape heads and guides;
this affects record and play quality. To achieve the professional
quality this system is capable of, such dust, line and oxide must be
cleaned off. Also, the heads tend to retain residual magnetism after
some hours of use

this introduces noise on both record and
playback. To clean, we recommend using Radio Shack Catalog
Number 44-1160 Cassette Head Cleaner or use cleaning sticks (44-
1093) and Recorder Cleaner ( 44-217).

To remove residual
magnetism, use a Tape Head Demagnetizer such as 44-211 or 44-
215. Or, the easiest way to do this is to use a 44-631 Cartridge
Cleaner/Demagnetizer.
REALISTIC GUIDE TO TAPE RECORDERS is a very helpful pub-
lication available at your Radio Shack store. It has a number of
interesting chapters covering practical aspects of tapes, recorders
and accessories, plus a number of hints to enhance enjoyment of
your Realistic Cassette Tape Deck.
9

SERVICE AND MAINTENANCE
Only the highest quailty parts are used in your unit and it should re-
quire little or no service as long as you observe a few general rules.
Although the SCT-20 is a ruggedly-built unit, reasonable care
should be used to avoid rough handling. Avoid exposure to dirt
and dust and areas of high heat and humidity.
Always keep your unit clean—especially the tape heads and tape
handling parts—this will insure long life and maximum fidelity.
Over a period of time it is normal for a certain amount of dust,
lint and powder from the tape to accumulate on these parts. This
prevents proper contact of the tape and results in improper tape
handling (producing noise, partial "drop-outs" and poor frequency
response). Periodically clean the tape heads and tape handling parts
with tape head cleaner, cue-tips or a cassette cleaner tape. Your
local Radio Shack store carries a complete line of tape care acces-
sories.
Over long periods of constant use, the tape heads will tend to retain
some magnetism. A magnetized head will produce noise. Thus, it is
important that the heads be demagnetized periodically. We recom-
mend using either Radio Shack Catalog Number 44-215 or 44-211.
Or, just use our 44-631 to clean and demagnetize by simply playing
this Cleaner Demagnetizer Cassette.
Periodic lubrication will insure proper operation of all moving parts.
At least once a year you should bring your unit into your local
Radio Shack store for standard lubrication and simple preventative
maintenance by our service technicians.
CAUTIONS
The erase protection tabs on a cassette are a precaution against
accidental erasure or re-recording. Do not attempt to force down
the RECORD key if the cassette in the unit has these tabs re-
moved.
Before Recording or Playing back, be sure the cassette is properly
seated in the cassette compartment.
Do not touch the face of the Tape Heads with any magnetic or
metallic object.