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ROCKFORD-FOSGATE
POWER II INSTALLATION MANUAL
IMPORTANT
The Power II amplifier is designed to be professionally installed.
The length and nature of your warranty are dramatically affected if
you attempt to install it yourself (See Warranty).
This is because professional installers are experienced with making
your car sound right the first time. Professional installers make
their installations durable because the last thing they want is to have
you come back screaming at them because your system isn't working.
If you still want to install your own unit, read the following instruc-
tions
completely....and
Good Luck!
If you decide to have your dealer install your system, throw this booklet
away and relax.
DESCRIPTION
The Rockford-Fosgate Power II is a state-of-the-art
90
Watt per channel
stereo amplifier, designed to provide top-quality sound in cars, vans,
boats, or anywhere a
9
to
15
Volt battery is available.
The Power II is designed to be used with a Rockford-Fosgate equalizer/pre-
amplifier and any high-quality music source. There are several preamp
equalizers available, including the ZX, the Z, and the 250 preamp.
The Power II is protected by main battery line fuses and by internal
"Short
Stop"
circuitry which detects shorted speakers or internal problems
and shuts down the amplifier for about
1
second.
The Power II incorporates internal battery line filtering and extensive
ground loop prevention circuitry.
In order to get the most sound from its inverted power supply, the Power
II uses floating speaker grounds.
This also allows extremely simple
"bridged"
or
"strapped mono"
operation in special applications.
WIRING FOR THE POWER II
See Figures for wiring diagrams
Power Connection (White
12-Gauge
Wire)
The White wire must be connected directly to the positive terminal of the
battery to provide a power source with low voltage drop and low noise. If
the power wire is connected to any other point (the fuse block, for instance)
the amplifier's power output will be reduced and oscillations and noise may
distort the sound.
If the power wire must be extended, use only
12-gauge
or
larger wire and make a good splice.
The power wire comes with an in-line fuseholder for a
20-Amp
AGC (3AG)
fast-
blow fuse.
Do not use a higher-current fuse as the amplifier will not be ad-
equately protected.
Ground Connection (Black
12-Gauge
Wire )
The ground wire must be connected directly to the car chassis, near the amp-
lifier.
Ground loops are aggravated by the length of the ground wire or any
resistance in the ground path.
For this reason we don't recommend extending
the ground wire in any installation.
The ground point in the car should be a
piece of chassis metal that is welded to the main body of the car. Painted
surfaces should be scraped or sanded clean before the ground lug is bolted down.
(Cover the bare-metal area with paint or grease to prevent rust.)
Turn-On Connection (Red Wire from 6-Pin Connector)
The Power II is turned on by applying Positive
12
Volts to the red wire. Usually,
the red wire is connected to source unit's "Accessory" or "Auto-Antenna" lead,
either of which will go positive when the source is turned on.
Although the majority of high-quality automotive source units have an
Accessory or Auto-Antenna output,
there are many variations which may re-
quire different turn-on methods.
If the source has no Auto-Antenna lead
(or if Auto-Antenna goes down during tape operation):
a)
b)
c)
d)
Find the internal switched power voltage inside the source unit and
solder a lead to it.
Run the lead out through the back of the unit
(being sure to use a grommet for insulation from the case) and
connect to the Power
II's
red turn-on wire.
Or:
Install a switch in the car with one terminal connected to
+12
Volts and the other to the Power II red lead.
Or:
Obtain a
Rockford-Fosgate
accessory current-sense converter
(Model
CS-101)
and connect in series with the unit's power lead.
The
CS-101
senses the increase in the source unit's current when it
turns on, and applies a positive voltage to the turn-on lead.
Or:
Connect the Power
II's
red lead to the Accessory point at the
car's
fuse block.
In this case the amplifier will be on whenever
the car is on.
This method will allow the amplifier to amplify any
noise and turn-on and turn-off transients, and may therefore be unsat-
isfactory.
Interconnect Cable
(5-Pin
DIN Cable)
The DIN interconnect cable connects the Power II to its equalizer/preamplifier.
The cable supplies DC power to the equalizer and carries the signal from the
equalizer to the power amplifier.
The internal wiring of the cable is shown
below:
Shield--Ground
Red
-----+18 Volts
Black--
-18
Volts
White---Right Channel
Green---Left Channel
Speaker Connections (Wires from
6-Pin
Connector)
ORANGE--Left Positive
BLACK
---Left Negative
YELLOW--Right Positive
BROWN---Right Negative
For wiring to 4-Ohm woofers,
use at least 18-gauge wire if the run is less
than 6 feet.
Use at least 16-gauge for longer runs.
Be
certain to observe speaker terminal polarity throughout the system. It
is critical for the Power II to use the correct negative leads for the right
and left channels, since the right negative lead (brown) is the
"hot"
lead
for the right speaker.
DO NOT chassis ground any of the speaker leads. Un-
stable operation may result.
Speaker Impedance
The Power IT is rated for operation into loads of 2.5 ohms or greater in stereo
operation.
The primary load on the amplifier comes from directly connected speakers (not
isolated by capacitors), and the measured resistance for each side cannot be
less than 2.5 Ohms.
Single 4 Ohm woofers or parallel 8 Ohm pairs per side will
form a high-performance system.
The maximum direct load per side is an 8-Ohm
speaker in parallel with a 4-Ohm speaker.
If two 4-Ohm woofers per side are used,
they must be wired in series (since in
parallel they would equal 2-Ohms) and the Power II will deliver only half power
into the load.
Bridging Mode
The Power II amplifier is capable of driving 8 Ohm speakers in a bridged mono
configuration to deliver full power into a single speaker.
This is done by
connecting the orange wire to the speaker's positive terminal and the brown
wire to its negative terminal.
This capability can be used to run a single
woofer in a stereo system,
to run two bridged amplifiers in a high-power stereo
system, to run one amplifier as a bridged mono woofer and another as a-
high-frequency stereo amp, and many other applications. In any bridged app-
lication, DO NOT use speakers with less than 6 Ohms impedance.
Mounting the Punch
(Refer to Figure 5 for mounting diagrams)
The
Powr
II has a large
heatsink for its power level and is therefore
reasonably tolerant of various mounting positions. However, care should
be taken to be sure of adequate cooling.
Passenger Compartment Mounting
The best mounting position for cooling will allow plenty of cool air to
circulate around the fins.
Mounting the unit vertically, with the fins
going up and down,
allows the air to flow upward in a chimney effect.
This
is the best possible mounting for maximum cooling.
Mounting the unit under dash will provide satisfactory air flow. Floor or
under-seat mounting will normally work adequately, but if the air flow is
severly restricted (for instance,
if the seat bottom is less than
½
inch
from the top of an upside down Power II), the unit may overheat with contin-
uous heavy use.
The thermal protection circuit will turn the Power II off
when the heatsink temperature exceeds about degrees Celsius
(165
degrees
Farenheit).
Trunk Mounting
We have measured trunk temperatures as high as 150 degrees Farenheit in the
summertime.
Therefore it is important that trunk-mounted amplifiers have
the best possible cooling.
Mounting the unit on a vertical surface with
the fins vertical provides the best air flow for cooling. Horizontal or
"upside down"
mounting positions are not recommended for trunk installations.
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