Document text
OWNER’S MANUAL
AM/FM STEREO
STA-20
RECEIVER
Please read before using this equipment
INTRODUCTION
Your new Optimus STA-20 AM/FM
Stereo Receiver gives you excellent
audio in a small package. It is design¬
ed so that you can use it with smaller
speaker systems such as our Minimus
7. The STA-20’s 5-watt amplifier sec¬
tion and built-in circuit equalization give
you outstanding sound quality for such
a compact system. Your receiver also
has a special EQ switch to help you get
the best possible sound, especially
when you use smaller speakers.
2
FEATURES
• 5 Watts of Power — drives almost any
high-efficiency speaker system.
• Front Panel CD/TAPE Input Jack —
lets you quickly hook up a portable CD
player or cassette deck.
• TUNED Indicator — shows you when
you are receiving the strongest signal
from an FM or AM radio station.
• TAPE OUT Jacks — enable you to
record any one of the amplifier’s pro¬
gram sources.
• EQ Switch — provides you with
uniform output at low frequencies for
a rich, full sound.
For your personal records, we urge you
to record the serial number of your
receiver in the space provided. You can
find the serial number on the receiver’s
back panel.
Serial Number:_
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION: TO REDUCE THE RISK
OF ELECTRIC SHOCK, DO NOT
REMOVE COVER (OR BACK). NO
USER SERVICEABLE PARTS IN¬
SIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONNEL
The lightning flash with arrowhead
symbol, within an equilateral triangle,
is intended to alert the user to the
presence of uninsulated “dangerous
voltage” within the product’s
enclosure that may be of sufficient
magnitude to constitute a risk of elec¬
tric shock to persons.
The exclamation point within an
equilateral triangle is intended to alert
the user to the presence of important
operating and maintenance (servic¬
ing) instructions in the literature ac¬
companying the appliance.
WARNING:
TO PREVENT FIRE OR SHOCK
HAZARD, DO NOT EXPOSE THIS
APPLIANCE TO RAIN OR MOIS¬
TURE.
© 1991 Tandy Corporation.
All Rights Reserved.
Radio Shack and Optimus are registered trademarks used by Tandy Corporation.
3
TABLE OF CONTENTS
Control Locations.5
Preparation For Use.6
Connecting Speakers.6
Positioning Speakers.7
Connecting Antennas.7
Improving FM Reception.8
Connecting a Turntable.9
Connecting a Cassette Deck.9
Connecting to AC Power.10
Typical System Connections.10
Operation.11
Using the Receiver’s Controls ••••11
Using the CD/TAPE input Jack-12
Overload Protection.12
Thermal Protection. 12
Care And Maintenance.I 3
Specifications.14
4
CONTROL LOCATIONS
Front Panel:
FM STEREO Indicator
Dial-Pointer Indicator
Tuning Control
OPT/MUJ SM N AM/FW SHMO UCEiVif)
I phones tone loudness
POWER Jack Control Button
Button
CD/TAPE Input jack VOLUME Control
BALANCE Control
Source Selector
TUNED Indicator
Back Panel:
PHONO INPUT Jacks SPEAKERS Push Terminals
TAPE OUT Jacks I pnONO GND (ground) Screw j
ydm s]
31 -q>*BHBH» I
FM AN I PHONO GND SERIAL NO I
TAPE INPUT Jacks (an ™^ T _ I EQ ° FF/ ° N Swi,ch
300-ohm Screw Terminals gjf rew Termina" 3
FM ANT (antenna) - 75-ohm Screw Terminals
AC Line Cord
PREPARATION FOR USE
Before making any connections:
• Be sure the receiver’s power cord is
unplugged.
• Be sure the [POWER] button is off.
Note: To eliminate or reduce inter¬
ference, use shielded audio cables for
all connections other than speaker
connections.
CONNECTING SPEAKERS
Your receiver is designed for use with
speakers that have an impedance of 8
ohms or higher. To fully enjoy the
receiver’s capabilities, we recommend
that you use our Minimus series speaker
systems. However, you can also use
any high-efficiency standard speakers
or other types of compact speakers.
2. Split both speaker wires approx¬
imately four inches on each end.
3. Using a wire stripper, carefully strip
about 1/4 inch of insulation from the
end of each individual wire.
4. Connect one of the individual wires
to the right positive ( + ) SPEAKERS
push terminal located on the
receiver’s back panel. Then, connect
the other individual wire to the right
negative (-) SPEAKERS push
terminal.
For speaker connections, use speaker
cable or 18-16 gauge speaker cable
or two-conductor wire. We recom¬
mend that you use the shortest length
of wire possible.
Speaker wire consists of two individual
wires encased in insulation. Speaker
wire is usually color-coded or marked
with a ridge along one side to help you
make the proper connections between
your receiver and speakers.
1 .Cut your speaker wires to the length
needed to connect your speakers to
your receiver.
5. Using the speaker wire’s coding as
a guide, connect the positive wire to
the positive (+) terminal on your right
speaker.
Then connect the negative wire to
your right speaker’s negative (-)
terminal.
6. Repeat Steps 4-5 to connect the left
speaker to the receiver’s left
SPEAKERS push terminals.
Caution:
• Do not use speakers that have an im¬
pedance of less than 8 ohms.
• To avoid a short circuit, do not allow
stray wires to touch another terminal.
• Use only the length of wire necessary
to connect the speakers to the
receiver.
POSITIONING
YOUR SPEAKERS
Placement of your speakers depends
largely on the arrangement of your
listening room and the way you listen to
music. Experiment with different
speaker locations to achieve the best
sound.
Stereo speakers should be several feet
apart. Putting them too close together
reduces the stereo effect, while placing
them too far apart reduces the bass
effect and creates a “hole” in the
middle. Speakers usually disperse the
sound at about a 60-degree angle, so
ideally, your listening position should be
in the overlap area. You might want to
angle the speakers toward you for a bet¬
ter stereo effect.
CONNECTING ANTENNAS
Under most conditions, your receiver’s
built-in antennas are adequate for FM
and AM reception. Connect the FM
line-cord antenna to the FM ANT
300-ohm screw terminal on the back
panel of your receiver. The built-in AM
antenna requires no attention.
7
IMPROVING FM RECEPTION
If you have trouble with the FM recep¬
tion in your area, try one of the ar¬
rangements listed below.
• Build the low-cost folded dipole
antenna illustrated (available at your
local Radio Shack store). Attach the
flat cable to the 300-ohm terminals
on the receiver’s back panel. You
can tack the antenna to the back of
a record cabinet or onto a wall.
Reception is usually best when you
attach the antenna at the highest
possible position.
• A set of VHF-TVrabb/f ears or anten¬
nas made specially for FM reception
work well in suburban areas. Connect
these types of antennas to the
300-ohm screw terminals on the
receiver’s back panel.
• An outside VHF-TV antenna provides
excellent FM reception. A “splitter”
(available at all Radio Shack stores)
permits you to connect a TV set and
your receiver to the same antenna.
Your local Radio Shack store also
sells a full line of outside antennas to
help you achieve adequate recep¬
tion in fringe areas.
If you use a 300-ohm flat cable, con¬
nect it to the antenna’s 300-ohm ter¬
minals. If you use a 75-ohm coaxial
cable, connect it to the antenna’s
75-ohm terminals. When you use the
75-ohm coaxial cable, attach the
center wire of the cable to the com¬
mon terminal between the 75-ohm
and 300-ohm antenna terminals.
Then, connect the braided ground
wire under the clamp as shown
below.
8
Note: To protect your receiver, use a
lightning arrestor on any outdoor
antenna.
CONNECTING A TURNTABLE
If your turntable has a magnetic car¬
tridge, connect the turntable’s output
jacks to the receiver’s PHONO INPUT
jacks.
j INPUT—jT
TAPE OUT TAPE PHONO
If your turntable has a ceramic or crystal
cartridge, connect the turntable’s output
jacks to the receiver’s TAPE INPUT
jacks.
TAPE out
i
INPUT
TAPE
~i
PHONO
If the turntable has a ground wire (usual¬
ly black or green), connect it to the
receiver’s PHONO GND screw to
reduce or eliminate speaker hum.
CONNECTING A
CASSETTE DECK
For playback:
Connect your cassette deck’s output
jacks to the receiver’s TAPE INPUT
jacks. If you want to connect a portable
CD or cassette deck, see “Using the
CD/TAPE Input Jack.”
Note: If you use the front panel
CD/TAPE input jack, you deactivate the
back panel TAPE INPUT jacks, and only
the CD/TAPE input jack works. To use
the TAPE INPUT jacks, simply unplug
your portable CD or cassette player
from the CD/TAPE input jack.
For recording:
Connect your cassette deck’s line-in or
aux-in input jacks to your receiver’s
TAPE OUT jacks.
Note: The receiver’s TONE, BALANCE,
and VOLUME controls and [LOUD¬
NESS] button do not affect your
recording.
CONNECTING TO AC POWER
1. Check all connections, especially the
speaker connections, to ensure that
they are firm and that there are no
stray wires.
2. Be sure the [POWER] button is in the
out position.
3. Set the VOLUME control to MIN.
4. Plug the receiver’s AC power cord in¬
to a standard AC outlet.
TYPICAL SYSTEM
CONNECTIONS
1 1 IS8S !
OPERATION
USING THE RECEIVER’S
CONTROLS
1. Press [POWER] to turn on the
receiver. When the power is on, the
red dial-pointer indicator lights.
Press [POWER] again to turn off the
power.
2. Select and prepare the desired pro¬
gram source as described in the
following instructions.
Program Sources
AM — Set the source selector to AM.
Use the turning control to select the
preferred station. When you ac¬
curately tune to a station, the green
TUNED indicator lights.
FM AUTO — Set the source selector
the FM AUTO. Use the tuning control
to select the preferred station. When
you accurately tune in a station, the
green TUNED indicator lights.
If the station is broadcasting in
stereo, the red STEREO indicator
also lights.
PHONO — Set the source selector to
PHONO. Put a record on your turn¬
table and adjust the front panel con¬
trols for the desired sound. See
“Connecting a Turntable.”
CD/TAPE — Set the source selector
to CD/TAPE. This activates the
receiver’s CD/TAPE input jack or the
TAPE INPUT jacks so that you can
listen to your favorite CDs and
cassettes. This is also the source you
select if you have a ceramic or
crystal-cartridge turntable.
3. Adjust the VOLUME control to the
desired sound level. The VOLUME
control adjusts the sound level for
both channels, from MIN (minimum)
to MAX (maximum).
4. To increase high frequencies, turn
the TONE control toward HI. To
decrease high frequencies, turn the
TONE control toward LO.
5. When you use Radio Shack’s
MINIMUS series or other small
speakers, set the EQ switch (on the
receiver’s back panel) to the ON posi¬
tion to boost low frequencies. Here,
the EQ switch activates the special
equalization circuitry in your receiver
to give you the same rich, full sound
as in larger speaker systems.
If you use another speaker system,
experiment by setting the EQ switch
to both the OFF and ON positions.
Use the position that produces the
best sound.
11
6. When listening at low volume levels,
press [LOUDNESS]. This compen¬
sates for the ear’s reduced sensitivi¬
ty at low volume levels by boosting
the low and high frequencies.
7. If necessary, adjust the BALANCE
control for the best channel balance.
At the center position, the receiver
delivers equal sound to both
speakers.
Note: To listen privately using head¬
phones with a -£~inch plug, insert the
plug into the front panel PHONES
jack. When you connect the head¬
phones, the external speakers are
automatically muted.
Hearing Comfort and Your Health
Do not listen at extremely high volume
levels, especially when using head¬
phones. Extended, high-volume lis¬
tening can lead to permanent hearing
loss.
USING THE CD/TAPE
INPUT JACK
The CD/TAPE input jack lets you
quickly hook up a portable CD (compact
disc) player or cassette deck to your
receiver. You need a shielded audio
cable with a Vs-inch stereo plug
on both ends to complete the
connections.
1. Plug one end of the audio cable into
the headphone output jack of your
portable CD player or stereo cassette
deck.
2. Plug the other end of the audio cable
into your receiver’s front panel
CD/TAPE input jack.
3. Set the source selector to the
CD/TAPE position.
OVERLOAD PROTECTION
Your receiver has an overload protec¬
tion system. If your speaker terminals
receive an unusually high power surge,
this system automatically decreases
the output power to a very low level to
protect your receiver and speakers.
If this happens, turn off the power
and check all speaker connections.
Be sure that there are no stray pieces
of wire touching between the positive
(+) and negative (—) speaker term¬
inals. Also check that your speakers
have an impedance rating of at least
8 ohms.
THERMAL PROTECTION
Your receiver also has a thermal
protection system. If the receiver
overheats, it automatically turns off
press [POWER] to the out position,
and then check to be sure the receiver’s
ventillation holes are unobstructed.
After the receiver cools (about 15
minutes), press [POWER] in.
Caution: Using speakers with an im¬
pedance rating less than 8 ohms can
cause the receiver to overheat.
12
CARE AND MAINTENANCE
Your receiver is an example of superior
design and craftsmanship. The follow¬
ing suggestions will help you care for
your receiver so that you can enjoy it for
years.
Keep the receiver dry. If it
does get wet, wipe it dry
immediately. Liquids can
contain minerals that can
damage the electronic
circuits.
Use and store the receiver
only in normal temper¬
ature environments. Ex¬
treme temperatures can
shorten the life of electronic
devices and distort or melt
plastic parts.
Wipe the receiver with a
damp cloth occasionally to
keep it looking new. Do
not use harsh chemicals,
cleaning solvents, or strong
detergents to clean the
receiver.
Modifying or tampering
with the receiver’s internal
components can cause a
malfunction and invalidate
the receiver’s warranty. If
your receiver is not oper¬
ating as it should, take it to
your local Radio Shack
store for assistance.
Handle the receiver gently
and carefully. Dropping it
can damage circuit boards
and cases and cause the
receiver to work impro¬
perly.
Keep the receiver away
from dust and dirt, which
can cause premature wear
of parts.
13
SPECIFICATIONS
• AMPLIFIER
Audio Output Power:
5 Watts Per Channel, Minimum RMS
into 8 ohms from 40-20,000 Hz, with
no more than 0.9% Total Harmonic
Distortion.
Signal-to-Noise Ratio:
70 dB (PHONO), 72 dB (TAPE)
Frequency Response:
40-20,000 Hz (-1.5 dB)
Input Sensitivity (for 5W, 8 ohms load):
PHONO 2.5 mV
TAPE 150 mV
Tape Output Level:
400 mV/50 K ohms Load
LOUDNESS Compensation:
+ 6 dB at 100 Hz/ + 4 dB at 10 kHz
TONE Effect (at MIN position):
-14 dB at 10 kHz
FM TUNER
Tuning Range: 88-108 MHz
Sensitivity (IHF, 3°/o): 7/*V (22.1 dBP)
Signal-to-Noise Ratio: 60 dB
Stereo Separation at 1 kHz: 35 dB
AM TUNER
Tuning Range: 530-1710 kHz
Sensitivity (IHF, 10°/o): 450 /*V/m
Signal-to-Noise Ratio: 37 dB
RF overload: 4%
RF interference Rejection: Rated
Excellent
POWER REQUIREMENTS:
120V AC, 60 Hz, 30W. Max.
(220/240V AC, 50 Hz, 30W. Max.
for U.K. and Australian models
available only in U.K./Australia)
14
NOTES
15
RADIO SHACK LIMITED WARRANTY
This product is warranted against defects for 2 years from date of purchase from Radio
Shack company-owned stores and authorized Radio Shack franchisees and dealers.
Within this period, we will repair it without charge for parts and labor. Simply bring your
Radio Shack sales slip as proof of purchase date to any Radio Shack store. Warranty
does not cover transportation costs. Nor does it cover a product subjected to misuse or
accidental damage.
EXCEPT AS PROVIDED HEREIN, RADIO SHACK MAKES NO WARRANTIES,
EXPRESS OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE. Some states do not permit limitation or
exclusion of implied warranties; therefore, the aforesaid limitation(s) or exclusion(s) may
not apply to the purchaser.
This warranty gives you specific legal rights and you may also have other rights which vary from state to state.
We Service What We Sell
5A1
RADIO SHACK
A Division of Tandy Corporation
Fort Worth, Texas 76102
811030550C
Printed in Taiwan