3
10
Power switch is on but
LED doesn’t light
The unit has power but
no output is present at
the speakers
Loud hum coming from
speakers
No sound out of one
channel
One or both clip LED’s
flash intermittently
Power plug is loose or dis-
connected
Circuit breaker tripped or
fuse blown in circuit fuse
box
Amplifier fuse blown
No input signal
Open speaker cable
Blown speaker fuse
Ground loop
Missing ground feed
(unbalanced only)
Bridge switch not set prop-
erly
Input signal
Reconnect plug.
Disconnect all other loads
on the same circuit and
reset circuit breaker or
replace fuse.
Disconnect the power cord
and replace fuse only with
same type and value
Check that the source
equipment is properly
feeding the amplifier’s
input. The green signal
LED’s will show if signal is
present.
Replace speaker cable
with a known good one.
Check speaker cabinet for
fuses and replace as nec-
essary
Try lifting the shield
grounds from the input
cables (balanced inputs
only).
(Note: Never defeat the
ground prong of the AC
power cord. Serious
shock or electrocution
may occur.)
Replace input cables with
known good ones.
Make sure the bridge
switch is set to the appro-
priate position.
Clip LED’s light to indicate
maximum output level.
This is not a problem as
long as the LED’s don’t
stay continuously lit and
Correction
Problem
Possible Cause
IN CASE OF TROUBLE
Every F150 amplifier undergoes severe environmental “burn-in” as well as thorough com-
puter controlled and human testing. It is unlikely a malfunction will occur. However, when
something doesn’t seem to work properly, please refer to the following chart:
The following diagram illustrates the typical stereo setup. Although it shows XLR’s for
inputs and 1/4” phone plugs for outputs, a variety of alternative connectors are available
(see the following sections on “INPUT CONNECTIONS” and “OUTPUT CONNECTIONS”).
INPUT CONNECTIONS
The preferred method of connecting input signals is with balanced XLR’s (two conductors
plus a shield wire, such as Carvin’s XLR8). Balanced input signals provide the highest gain
and best noise rejection. 1/4” phone jacks are also capable of providing balanced input by
using a stereo plug (ring-, tip+ & sleeve gnd). However, not all sources provide balanced
outputs. In these cases an unbalanced 1/4” input is recommended (single conductor plus a
shield wire, such as Carvin’s SH2 or SH15).
MON 1
EFF 1
EFF 2
BAL SENDS
LEFT/3
RIGHT/4
MAIN
R
POWER
L
SENDS
C
CNTRL
STEREO RETURNS
TAPE SEND
L
R
B
A
MON 2
RM
LAMP
12V
SUB 1
PHONES
SUB 2
Left Speaker
Right Speaker
Left
Speaker
Connector
Right Speaker
Connector
Left Input
Connector
Right Input
Connector
Mixer Output
Two conductors plus shield for
balanced input or one conductor
plus shield for unbalanced input.
Two conductor non-shielded, 16AWG
or larger, cable for speaker connections.
FUSE
2
1
3
2
1
3
120VAC 60Hz 200 VA
FUSE = 2 A SLOW BLOW
WARNING – REPLACE FUSE ONLY
WITH SAME TYPE AND VALUE.
WARNING – TO PREVENT FIRE OR SHOCK, DO NOT EXPOSE TO RAIN OR MOISTURE.
WARNING – DO NOT REMOVE COVER. NO USER SERVICEABLE PARTS INSIDE.
CAUTION – TO PREVENT SHOCK DO NOT DEFEAT THE SAFETY GROUND.
WARNING – TO PREVENT A FIRE HAZARD, PROVIDE ADEQUATE VENTILATION !
75 75 WATTS
4 OHMS MIN. PER CH.
STEREO
MONO
1
2
–
INPUT 1
MONO
BRIDGE
BRIDGE
SPEAKERS
INPUT 2
BALANCED LINE
MADE
A
US
IN THE
8 OHMS
MIN.
BRIDGE INPUT
LOWER LOADS MAY RESULT
IN PREMATURE DISTORTION !
Typical Stereo Setup
CONNECTING THE SYSTEM
F150
