Optimus 120-1971 User manual

2 X 50 Watt Truck Amp (120-1971) Features Faxback Doc. # 8286
The Optimus 2 x 50 Watt Trunk Mount Amplifier is designed to give added
punch and power to your automobile's existing stereo system. The
amplifier produces up to 50 watts per channel of clean, powerful sound at
all audio frequencies with minimum distortion.
Other 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.
Automatic Power Switching - Powers the amplifier when you
turn on/off your automobile's
stereo system.
High or Low-Level Input Signal Compatible - Accepts either high-level
(speaker) or low-level (pre-
amplifier) input signals to
match your stereo system's
output for 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 Color Speaker Terminals - 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 stereo system are not
compatible with the amplifier's connectors, contact your local Radio
Shack store. Radio Shack stores sell adapter harnesses for many vehicles.

Do not modify the amplifier's wiring as this voids its warranty.
For your permanent records, we suggest you record the amplifier's serial
number. The number is on the bottom of the amplifier.

2 X 50 Watt Truck Amp (120-1971) Preparation Faxback Doc. # 6713
Before you install the amplifier, carefully read all instructions. If you
are unsure about any part of the installation process, we recommend that
you have a professional install your amplifier.
Note the following before you begin installing the amplifier:
Be sure your vehicle has a 12-volt DC, negative-ground electrical
system. If it does not, you cannot use this amplifier.
Before you mount the amplifier, temporarily connect the amplifier
and test it to be sure it works. Do not permanently mount the
amplifier until you are sure the connections are correct.
CHOOSING A MOUNTING LOCATION
Choose a mounting location that meets the following requirements:
Does not interfere with the vehicle's operation
Lets you drill mounting holes without damaging other vehicle
components
Allows enough space around the cooling fins to permit reasonable
airflow and cooling
INCLUDED WITH THE AMPLIFIER
The amplifier comes with the following items that are necessary for
mounting. Be sure to unpack these items before you dispose of the packing
materials.
4 Sheet-Metal Screws
4 Spring Washers
4 Flat Washers
OVERLOAD LIGHT
The overload light comes on when:

1. The Amp is overheated.
2. The speaker wires are shorted.
3. The speaker's impedance is below the rated output impedance.
4. The output power terminals are shorted/loaded down.
5. The unit is broken.

2 X 50 Watt Truck Amp (120-1971) Connecting Power Faxback Doc. # 6714
Follow these steps to connect power to the amplifier.
1. Disconnect the positive (+) wire from your vehicle's battery. This
reduces the possibility of damage to your system during
installation.
NOTE: You must reset the clock, the radio's digital tuner
memories, and other time/memory devices when you
reconnect the battery wire after wiring is complete.
2. Connect the amplifier's black (ground) wire to a nearby part of the
vehicle's metal frame.
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.
3. Connect the red (power) wire directly to the car battery's + 12-volt
power source.
CONNECTING THE SWITCHED POWER LEAD
Follow these steps to connect the switched power lead.
1. Connect the supplied orange wire's male quick disconnect plug to
your car stereo system's switched power output lead.
2. Connect the orange wire's other end to the amplifier's REM (Remote)
terminal. With this connection, the amplifier turns on/off when
you turn on/off your car stereo system.

2 X 50 Watt Truck Amp (120-1971) Connecting Faxback Doc. # 6715
You can connect your stereo system to low-or high-level input. If your
stereo system has RCA outputs, connect it to the amp's low-level input for
a cleaner, less noisy signal. If your stereo system only has speaker
outputs, connect it to the amp's high-level input.
To connect the amplifier to your stereo system, place the amplifier as
close as possible to the selected mounting location and follow the
appropriate instructions.
LOW-LEVEL INPUT
Your amplifier has gold plated color RCA terminals for low-level input to
match radios and equalizers with RCA type, line-level outputs.
NOTE: You need a set of 12-foot RCA cables for dash to trunk
mounting. We recommend Radio Shack Cat. No. 43-2356.
Follow these steps to connect the stereo system's RCA jacks to the
amplifier's LOW INPUT terminals:
1. Plug the RCA cable into the car stereo system's left and right RCA
output jacks and connect the other end to the amplifier's left and
right LOW INPUT terminals.
2. Connect the left speaker's positive (+) wire to the amplifier's
positive (+) left terminal.
3. Connect the left speaker's negative (-) wire to the amplifier's
negative (-) left terminal.
4. Repeat Steps 3 and 4 to connect the right speaker to the amplifier's
right speaker terminal.
NOTE: We recommend 16 or 18 gauge speaker wire.
HIGH-LEVEL INPUT
If your car radio does not have RCA output jacks, connect the speaker
output from the stereo system to the amplifier following these steps:
1. Connect the stereo system's speaker wires to the amplifier's

HIGH INPUT L and R terminals.
NOTE: Be sure you connect the + and - terminal correctly.
2. If the stereo system has only three wires, connect the common
speaker wires to both of the amplifier's L and R negative terminals.
3. Connect the left speaker's positive (+) wire to the amplifier's
(+) left terminal.
4. Connect the left speaker's negative (-) wire to the amplifier's
(-) left terminal.
5. Repeat Steps 3 and 4 to connect the right speaker to the amplifier's
right speaker terminal.

2 X 50 Watt Truck Amp (120-1971) Mounting Faxback Doc. # 6716
Mount the amplifier as follows in the location you chose earlier. Unplug
the wiring harnesses to make mounting more convenient.
1. Using the mounting holes on the amplifier as a guide, mark the
locations for the mounting holes.
2. Drill 9/64-inch holes in the marked locations, taking care not
damage anything behind the mounting surface.
3. Attach the amplifier to the mounting surface using the supplied
sheetmetal screws and washers.
Plug in the wiring harnesses.
TURNING ON THE AMPLIFIER
The amplifier automatically turns on whenever you turn on your
radio/cassette player. The POWER indicator lights when the amplifier is
on.
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 counterclockwise.
2. Turn on your stereo system and turn up the volume to about one-third
of its full range. Turn on the ignition, if necessary, to turn on
the amplifier.
3. Adjust LEVEL until the volume is at the maximum level you desire
the radio/tape player to produce.
4. Adjust the stereo system's volume control to a comfortable listening
level.
CAUTIONS: Never turn LEVEL up any farther than you need to get clear
sound at 2/3 volume.
The overload red indicator illuminates under the following
conditions:

The amplifier is overheated.
The speaker wires are shorted.
The ground wire is open.
The speaker's impedance is above or below the rated output
impedance.
The Amplifier's overload protection circuit automatically
shuts down when any one of the above conditions occurs. If
this happens, turn off your sound system and let the
amplifier cool down before you restart.
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.

2 X 50 Watt Trunk Amp
(120-1971) Troubleshooting Faxback Doc. # 17062
Q: Green lights fade at power-up and the unit loses power.
A: Check the 12 V power lead to make sure when you turn on the remote
switch on, the voltage level doesn’t drop. Make sure the power lead
is heavy gauge wire and that the ground is good. Always use fuse at
the battery term.

2 X 50 Watt Truck Amp (120-1971) Maintenance Faxback Doc. # 6717
The Optimus Trunk Mount Amplifier is an example of superior design and
craftsmanship. The following suggestions will help you care for your
amplifier so you can enjoy it for years.
Keep the amplifier dry. If it gets wet, wipe if dry immediately.
Liquids can contain minerals that corrode electronic circuits.
Use and store the amplifier only in normal temperature environment.
Temperature extremes can shorten the life of electronic devices and
distort or melt plastic parts.
Handle the amplifier gently and carefully. Dropping it can damage
circuit boards and cases and can cause the amplifier to work
improperly.
Keep the amplifier away from dust and dirt, which can cause premature
wear of parts.
Wipe the amplifier with a damp cloth occasionally to keep it looking
new. Do not use harsh chemicals, cleaning solvents, or strong
detergents to clean your amplifier.
Modifying or tampering with the product's internal components can cause a
malfunction and invalidate your product's warranty. If your amplifier is
not performing as it should, take it to your local Radio Shack store for
assistance.

2 X 50 Watt Truck Amp
(120-1971) Specifications Faxback Doc. # 8287
10% THD Output Power @
14.4 VDC 1kHz at Stereo Mode:......................................50W x 2
Frequency Response:...............................20 - 20,000 Hz (+/- 3dB)
Input Impedance:..................................................10k Ohms
Input Sensitivity (for 10% THD Output Power):
Low Input:.............................250mV
High Input:..............................2.5V
Power Supply Voltage:................DC 14.4V Negative Ground (10.5 - 16V)
Matching Speaker Impedance:.....................................4 - 8 Ohms
Maximum Current Draw:..................................................15A
Dimensions:................................1 15/16 x 7 3/32 x 9 27/32 inch
(49 x 180 x 250mm) HWD
Net Weight:...............................................3.52 lbs (1.6Kg)

Audio Connection Information
(120-Series) Plug/Male 2 Ch. System Faxback Doc.# 19994
+----+--------------+---------------+------------+------------------------+
|Pin | | | | |
|No. | WIRE COLOR | WIRE SPECS. | LABEL | REMARK |
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK | AWG #20 | FRONT L- | STRIP SOLDER |
| | | 2P CORD | | |
+----+--------------+---------------+------------+------------------------+
| 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 | " |
+----+--------------+---------------+------------+------------------------+
| 8 | WHITE | AWG #20 | FRONT L+ | |
| | | 2p CORD | | " |
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | " | FRONT R+ | " |
+----+--------------+---------------+------------+------------------------+
| 10 | | | | |
+----+--------------+---------------+------------+------------------------+
| 11 | | | | |
+----+--------------+---------------+------------+------------------------+
| 12 | 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 & |
| | WHITE | | TURN ON | TUBE HEATING |
| | | | 500mA MAX | |
| | | |+12 V OUTPUT| |
| | | | | |
+----+--------------+---------------+------------+------------------------+
* May or may not be present depending on features of individual radios.

(2CH/4CH SWITCHABLE UNIT)
+----+--------------+---------------+------------+------------------------+
|Pin | | | | |
|No. | WIRE COLOR | WIRE SPECS. | LABEL | REMARK |
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK | AWG #20 | FRONT L- | STRIP SOLDER |
| | | 2P CORD | | |
+----+--------------+---------------+------------+------------------------+
| 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 | " |
+----+--------------+---------------+------------+------------------------+
| 8 | WHITE | AWG #20 | FRONT L+ | |
| | | 2p CORD | | " |
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | " | FRONT R+ | " |
+----+--------------+---------------+------------+------------------------+
| 10 | GREEN | " | REAR L+ | |
+----+--------------+---------------+------------+------------------------+
| 11 | VIOLET | " | REAR R+ | " |
+----+--------------+---------------+------------+------------------------+
| 12 | 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 & |
| | WHITE | | TURN ON | TUBE HEATING |
| | | | 500mA MAX | |
| | | |+12 V OUTPUT| |
+----+--------------+---------------+------------+------------------------+
* May or may not be present depending on features of individual radios.
4 Chnl Unit
+----+--------------+---------------+------------+------------------------+

|Pin | | | | |
|No. | WIRE COLOR | WIRE SPECS. | LABEL | REMARK |
+----+--------------+---------------+------------+------------------------+
| 1 | WHT/BLK | AWG #20 | FRONT L- | STRIP SOLDER |
| | | 2P CORD | | |
+----+--------------+---------------+------------+------------------------+
| 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 | " |
+----+--------------+---------------+------------+------------------------+
| 8 | WHITE | AWG #20 | FRONT L+ | |
| | | 2p CORD | | " |
+----+--------------+---------------+------------+------------------------+
| 9 | GRAY | " | FRONT R+ | " |
+----+--------------+---------------+------------+------------------------+
| 10 | GREEN | " | REAR L+ | |
+----+--------------+---------------+------------+------------------------+
| 11 | VIOLET | " | REAR R+ | " |
+----+--------------+---------------+------------+------------------------+
| 12 | 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 & |
| | WHITE | | TURN ON | TUBE HEATING |
| | | | 500mA MAX | |
| | | |+12 V OUTPUT| |
+----+--------------+---------------+------------+------------------------+
* 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 (-) |
+---------+--------------+
+---------+--------------+
| Orange | S.P.L. |
+---------+--------------+
| Black | Ground |
+---------+--------------+
| Red w/ | Memory |
| White | Backup |
+---------+--------------+
(CJD/ir-02/28/96)
LN-03/04