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Trunk Mount Amplifier
(120-1971B)
Features
Faxback Doc. # 18178
Your Optimus 2 x 50-Watt Trunk Mount Amplifier is designed to give added
punch and power to your automobile's existing autosound system. The
amplifier produces up to 50 watts per channel of clean, powerful sound at
all audio frequencies with minimum distortion.
The amplifier's features include:
Full MOSFET Power Supply - produces enough power to supply the
main amplifier and has a considerable
amount of reserve power for peak "high
demand" situations.
High or Low-Level Input Signal - accepts either high-level (speaker) or
Compatible
low-level (pre-amplifier) input signals
to match your autosound system's output
for the best performance.
Input Level Control - lets you adjust the level (high or low)
of audio signals that enter the
amplifier.
Thermal Overload Protection - automatically shuts down the amplifier
when it overheats or when its load or
DC power output is shorted.
14k Gold-Plated Speaker Terminals - have high conductivity and minimum
impedance.
WARNING: If you live in a high temperature area, we recommend you install
cooling fans on the amplifier to provide a better operating
temperature environment. Contact your local Radio Shack store
for a suitable cooling fan.
If the connectors on your vehicle or automobile's autosound system are not
compatible with the amplifier's connectors, contact your local Radio Shack
store. Radio Shack stores sell adapter harnesses for many vehicles.
Place the amplifier on the desired mounting location, then follow these
steps to connect power to the amplifier, see illustration in Faxback Doc
#18004.
1. Connect one end of the supplied black (ground) wire to a nearby part
of the vehicle's metal frame (chassis ground).
NOTE: Many modern vehicle parts are made of plastic or other materials
that do not conduct electricity. You must connect the black
(ground) wire to a metal part that is not insulated from the
vehicle's frame by one of these non-conducting parts.
2. Connect the other end of the wire to the amplifier's GND terminal.
3. Connect one end of the supplied red (power) wire directly to your
vehicle's +12 volt battery power source.
4. Connect the other end of the wire to the amplifier's +12V terminal.
5. Connect one end of the supplied blue with white stripe (remote) wire's
male quick disconnect plug to your autosound system's switched power
output lead.
6. Connect the other end of the wire to the amplifier's REM terminal.
This connection turns the amplifier on/off when you turn your
autosound system on/off.
CONNECTING THE AMPLIFIER
You can connect your autosound system to the amplifier's low- or high-level
input terminals.
If your autosound system has phono-type outputs, connect them to the
amplifier's low level input terminals for a cleaner, less noisy signal. If
your autosound system has only speaker outputs, connect them to the
amplifier's high-level input terminals.
Low-Level Inputs
Your amplifier has gold-plated low-level input terminals to match radios
and equalizers with phono-type line-level outputs.
Using plug-to-plug phono cables (such as Radio Shack cat. No.
42-2356, not supplied), connect the autosound system's left and right,
low-level output phono jacks to the amplifier's corresponding left and
right LOW INPUT phono terminals, see illustration in Faxback Doc. #18004.
High-Level Inputs
If your vehicle's autosound system does not have phono-type output jacks,
connect its left and right speaker output wires to the amplifier's HIGH
INPUT corresponding L and R terminals, see illustration in Faxback Doc.
#18004.
NOTES: Be sure to connect the terminals +to+ and -to-.
If the autosound system has only three wires, connect the common
speaker wire to both of the amplifier's L and R negative (-)
terminals, see illustration in Faxback Doc #18004.
CONNECTING THE OUTPUTS
Using 18-gauge stranded speaker wire (such as Radio Shack Cat. No. 278-
1217, not supplied), connect the autosound system's left and right speakers
to the amplifier's corresponding left and right SPEAKER terminals, see
illustration in Faxback Doc. #18004.
1. Disconnect the left speaker's positive (+) wire from your autosound
system and reconnect it to the amplifier's left positive (+) SPEAKER
terminal.
Note: The positive wire's insulator might be marked with a positive
(+) symbol, a ridge, or a white stripe, or the conductor wire strands
might be gold colored.
2. Disconnect the left speaker's negative (-) wire from your autosound
system and reconnect it to the amplifier's left negative (-) SPEAKER
terminal.
Note: The negative wire's insulator might be marked with a negative
symbol (-) or the conductor wire strands might be silver colored.
3. Repeat Steps 1 and 2 to connect the right speaker to the amplifier's
right SPEAKER terminals.
TESTING THE AMPLIFIER
1. Temporarily reconnect your vehicle battery's negative (-) cable.
2. Turn on your vehicle's ignition and verify that both the amplifier and
your autosound system work properly.
3. If both the amplifier and your autosound system work properly, proceed
to "Mounting the Amplifier," Faxback Doc. #
.
If either the amplifier or your autosound system does not work
properly, immediately disconnect your vehicle battery's negative (-)
cable and carefully recheck your connections.
Trunk Mount Amplifier
(120-1971B)
Mounting The Amplifier
Faxback Doc. # 18179
Follow these steps to mount the amplifier in the location you chose
earlier.
1. Disconnect your vehicle battery's negative (-) cable.
2. Label and Disconnect the amplifier's input and output wires to make
mounting more convenient.
3. Using the mounting holes on the amplifier as a guide, mark the
locations for the mounting holes.
4. Drill 9/64-inch holes in the marked locations, taking care not to
damage anything behind the mounting surface.
5. Attach the amplifier to the mounting surface using the supplied
sheet-metal screws and washers.
6. Reconnect the amplifier's wires.
7. Reconnect your vehicle battery's negative (-) cable.
Trunk Mount Amplifier
(120-1971B)
Operation
Faxback Doc. # 18180
TURNING ON THE AMPLIFIER
The amplifier automatically turns on whenever you turn on your autosound
system. The POWER indicator lights when the amplifier is on.
Thermal Overload Protection
The amplifier's overload protection circuit automatically shuts down the
amplifier and the red overload PROTECTION indicator lights under the
following conditions:
The amplifier is overheated.
The speaker wires are shorted.
The DC power output is shorted.
The ground wire is open.
The speakers' impedance is above or below the rated output impedance.
If this happens, turn off your autosound system, let the amplifier cool
down. Then before you restart, check to make sure the speaker wires are
not touching, the ground wire is properly connected to your vehicle's
chassis, and the speakers' impedance is 8 Ohms.
SETTING THE INPUT LEVEL CONTROL
LEVEL lets you adjust the level of audio signals that enter the amplifier.
For the best performance, follow these steps to adjust the input level.
1. Turn LEVEL fully clockwise to MAX.
2. Turn on your vehicle's ignition (if necessary), then turn on your
autosound system. The amplifier turns on.
3. Adjust the autosound system's volume control to a comfortable
listening level.
LISTENING SAFELY
To protect your hearing, follow these guidelines:
Do not listen at extremely high volume levels. Extended, high-volume
listening can lead to permanent hearing loss.
Always start by setting the volume to the lowest level possible before
you begin listening, then gradually increase the volume as necessary.
Once you set the volume, do not increase it. Over a period of time,
your ears adapt to the volume level, so a volume level that does not
cause discomfort might still damage your hearing.
Trunk Mount Amplifier
(120-1971B)
Care And Maintenance
Faxback Doc. # 18177
REPLACING A FUSE
If the amplifier shuts down but the red PROTECTION indicator does not
light, you might need to replace the power wire's 15-amp tube-type fuse
(Cat. No. 270-1073), the blade-type fuse (Cat. No. 270-1082), or both
fuses.
Follow these steps to check a fuse and replace it, if necessary.
1. Turn off your sound system.
2. Disconnect your vehicle battery's negative (-) terminal
3. To remove the red power wire's fuse, grasp the two ends of the fuse
holder and twist them counterclockwise, then pull the ends apart.
To remove the front panel's automotive fuse, grasp the fuse's plastic
end and pull it out.
4. Remove and replace the fuse.
Caution: Do not use a fuse other than the specified fuse. Doing so
might damage your amplifier.
5. Grasp the two fuse-holder's ends, push them in and twist them
clockwise.
6. Let the amplifier cool down before you restart it.
Trunk Mount Amplifier
(120-1971B)
Specifications
Faxback Doc. # 18182
10% THD Output Power @ 14.4 VDC 1 kHz:..............................50W x 2
Frequency Response:...........................20-20,000 Hz (plus/minus 3dB)
Input Impedance:...................................................10k Ohms
Input Sensitivity (for 10% T.H.D. Output Power):
Low Input:........................................................250 mV
High Input:........................................................2.5 V
Power Supply Voltage:.............................DC 14.4 V Negative Ground
Matching Speaker Impedance:........................................4-8 Ohms
Maximum Current Draw:...................................................15A
Dimensions:.....................................2 1/16 x 7 7/8 x 7 7/8 inch
(52 x 200 x 200 mm) HWD
Net Weight:...............................................3.9 lbs (1.77 Kg)
Audio Connection Information
(120-Series)
Plug/Male 2 Ch. System
Faxback Doc.# 19994
+----+--------------+---------------+------------+------------------------+
|Pin |
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|No. | WIRE COLOR | WIRE SPECS. | LABEL
REMARK
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK
| AWG #20
| 2P CORD
| FRONT L- | STRIP SOLDER
|
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|
|
+----+--------------+---------------+------------+------------------------+
| 2 | GRY/BLK | FRONT R- |
+----+--------------+---------------+------------+------------------------+
| 3 |
+----+--------------+---------------+------------+------------------------+
| 4 |
+----+--------------+---------------+------------+------------------------+
| 5 | BLACK | AWG 206 | GROUND | 6.3mm r FORK TERMINAL |
+----+--------------+---------------+------------+------------------------+
| 6 | ORG/WHT * | | DIMMER | STRIP SOLDER
+----+--------------+---------------+------------+------------------------+
| 7 | PINK/WHT * | | PHONE MUTE |
+----+--------------+---------------+------------+------------------------+
|
"
"
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"
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"
"
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| 8 | WHITE
| AWG #20
| 2p CORD
| FRONT L+ |
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"
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | FRONT R+ |
+----+--------------+---------------+------------+------------------------+
| 10 | |
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"
"
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+----+--------------+---------------+------------+------------------------+
| 11 |
+----+--------------+---------------+------------+------------------------+
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| 12 |
RED
| AWG #20
|
| +12 V TO | 250/ 1A FUSE & 24M/M |
| IGNITION | TRANS STRIP SOLDER |
|
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+----+--------------+---------------+------------+------------------------+
| 13 | YELLOW
|
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"
| +12 V TO | 250/ 1A FUSE STRIP
| BATTERY | SOLDER
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+----+--------------+---------------+------------+------------------------+
| 14 | DARK BLUE/ |
"
| AMP REMOTE | WIRE BANDING &
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WHITE
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| TURN ON |
| 500mA MAX |
|+12 V OUTPUT|
TUBE HEATING
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+----+--------------+---------------+------------+------------------------+
* May or may not be present depending on features of individual radios.
(2CH/4CH SWITCHABLE UNIT)
+----+--------------+---------------+------------+------------------------+
|Pin |
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|No. | WIRE COLOR | WIRE SPECS. | LABEL
REMARK
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK
| AWG #20
| 2P CORD
| FRONT L- | STRIP SOLDER
|
|
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|
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+----+--------------+---------------+------------+------------------------+
| 2 | GRY/BLK | FRONT R- |
+----+--------------+---------------+------------+------------------------+
| 3 | GRN/BLK | REAR L- |
+----+--------------+---------------+------------+------------------------+
| 4 | VIO/BLK | REAR R- |
+----+--------------+---------------+------------+------------------------+
| 5 | BLACK | AWG 206 | GROUND | 6.3mm r FORK TERMINAL |
+----+--------------+---------------+------------+------------------------+
| 6 | ORG/WHT * | | DIMMER | STRIP SOLDER
+----+--------------+---------------+------------+------------------------+
| 7 | PINK/WHT * | | PHONE MUTE |
+----+--------------+---------------+------------+------------------------+
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"
"
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"
"
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"
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"
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"
"
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| 8 | WHITE
| AWG #20
| 2p CORD
| FRONT L+ |
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"
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | FRONT R+ |
+----+--------------+---------------+------------+------------------------+
| 10 | GREEN | REAR L+ |
+----+--------------+---------------+------------+------------------------+
| 11 | VIOLET | REAR R+ | |
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"
"
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"
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"
"
+----+--------------+---------------+------------+------------------------+
RED
| AWG #20
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| +12 V TO | 250/ 1A FUSE & 24M/M |
| IGNITION | TRANS STRIP SOLDER |
+----+--------------+---------------+------------+------------------------+
| 13 | YELLOW
|
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"
| +12 V TO | 250/ 1A FUSE STRIP
| BATTERY | SOLDER
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+----+--------------+---------------+------------+------------------------+
| 14 | DARK BLUE/ |
"
| AMP REMOTE | WIRE BANDING &
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WHITE
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| TURN ON |
| 500mA MAX |
|+12 V OUTPUT|
TUBE HEATING
+----+--------------+---------------+------------+------------------------+
* May or may not be present depending on features of individual radios.
4 Chnl Unit
+----+--------------+---------------+------------+------------------------+
|Pin |
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|No. | WIRE COLOR | WIRE SPECS. | LABEL
REMARK
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK
| AWG #20
| 2P CORD
| FRONT L- | STRIP SOLDER
|
|
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|
|
|
+----+--------------+---------------+------------+------------------------+
| 2 | GRY/BLK | FRONT R- |
+----+--------------+---------------+------------+------------------------+
| 3 | GRN/BLK | REAR L- |
+----+--------------+---------------+------------+------------------------+
| 4 | VIO/BLK | REAR R- |
+----+--------------+---------------+------------+------------------------+
| 5 | BLACK | AWG 206 | GROUND | 6.3mm r FORK TERMINAL |
+----+--------------+---------------+------------+------------------------+
| 6 | ORG/WHT * | | DIMMER | STRIP SOLDER
+----+--------------+---------------+------------+------------------------+
| 7 | PINK/WHT * | | PHONE MUTE |
+----+--------------+---------------+------------+------------------------+
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"
"
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"
"
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"
"
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"
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"
"
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| 8 | WHITE
| AWG #20
| 2p CORD
| FRONT L+ |
|
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"
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | FRONT R+ |
+----+--------------+---------------+------------+------------------------+
| 10 | GREEN | REAR L+ |
+----+--------------+---------------+------------+------------------------+
| 11 | VIOLET | REAR R+ |
+----+--------------+---------------+------------+------------------------+
|
"
"
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"
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"
"
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RED
| AWG #20
|
| +12 V TO | 250/ 1A FUSE & 24M/M |
| IGNITION | TRANS STRIP SOLDER |
+----+--------------+---------------+------------+------------------------+
| 13 | YELLOW
|
|
"
| +12 V TO | 250/ 1A FUSE STRIP
| BATTERY | SOLDER
|
|
|
|
+----+--------------+---------------+------------+------------------------+
| 14 | DARK BLUE/ |
"
| AMP REMOTE | WIRE BANDING &
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WHITE
|
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| TURN ON |
| 500mA MAX |
|+12 V OUTPUT|
TUBE HEATING
+----+--------------+---------------+------------+------------------------+
* May or may not be present depending on features of individual radios.
5-Pin DIN
FRONT
+---------+--------------+
| Green | Right (+) |
+---------+--------------+
| White | Right (-) |
+---------+--------------+
| Brown | Left (+)
+---------+--------------+
| Gray | Left (-)
+---------+--------------+
| Red | +12 V Power |
|
|
+---------+--------------+
REAR
+---------+--------------+
| GRN/BLK | Right (+)
+---------+--------------+
| WH/BLK | Right (-)
+---------+--------------+
| BR/BLK | Left (+)
+---------+--------------+
|GRAY/BLK | Left (-)
|
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+---------+--------------+
+---------+--------------+
| Orange | S.P.L.
+---------+--------------+
| Black | Ground
+---------+--------------+
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| Red w/ | Memory
| White | Backup
|
|
+---------+--------------+
(CS 10/10/95)
LN-03/04
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