Adcom S.A.F.E. GFA-7705 User manual

G
FA-
7
70
5
GFA-7/0/
s.a.f.e:
HIGH
CURRENT,
MULTI-CHANNEL
POWER
AMPLIFIERS

GFA-7705/07
Features
•
Precision-matched
devices
used
throughout
the
signal
path.
•
Independent
power
supplies
for
each
channel.
•
Fewer
gain
stages
improve
signal
reproduction
accuracy.
•
Custom
toroidal
power
transformer
provides
better
regulation
and
greater
peak
current
capability.
•
ADCOM-Universal
pre-prepped
chassis
and
internal
power
supplies
for
easy
in-field
upgradeability
from
5
to
7
channel
configuration.
•
Independent
thermal-overload
and
distortion
LEDs
for
all
5
(to
7)
channels.
•
S.A.F
E.®
Circuit:
Self
Annealing
Fuse
Equipped—automatic
reset
protection
circuit
in
the
event
of
speaker
or
speaker
wire
dead-short.
•
High
quality,
gold-plated
5-way
binding
posts.
•
High
quality,
gold-plated
RCA
jacks.
•
Large
independent,
internal
heatsinks
for
greater
cooling
capability
of
output
devices.
•
Convenient
12
VDC
power
ON/OFF
triggering.
•
Heavy
gauge,
anodized
aluminum
front
panel.
•
Cooling
vents
for
greater
efficiency
and
cooler
operation
while
driving
low
impedance
loads.
Table
of
Contents
Introduction
Warranty
Information.
4
Description
of
Unit—
20-Amp
Device
Notification
.4
Rear
Panel..
Front
Panel..
Installation
&
Hookup
Unpacking
the
GFA-7705/07.
9
Placement
of
the
GFA-7705/07.9
Quick
Connection
Diagram.
1
0
Connecting
the
GFA-7705/07.
H
Caring
for
your
GFA-7705/07.
12
Troubleshooting
Resolving
Problems.
1
3
Service
Information...
1
4
Specifications.
1
5
3

Introduction
Congratulations
on
your
decision
to
purchase
the
GFA-7705/07
multi-channel
power
amplifier.
The
GFA-7705/
07
integrates
very
well
with
any
other
home
theater
system,
such
as
Dolby
ProLogic
™
or
Dolby
Digital
™
You
have
made
a
wise
choice
that
will
reward
you
with
exceptionally
accurate
and
musical
sound
reproduction
for
years
to
come.
To
realize
the
full
potential
of
your
new
amplifier,
please
read
these
operating
and
installation
instructions
thoroughly
before
attempting
to
make
any
connections
to
it.
ADCOM
Protection
Plan
(NORTH
AMERICA
ONLY)
ADCOM
offers
the
enclosed
valuable
Limited
Warranty.
Please
read
the
details
on
the
Warranty
Card
carefully
understand
the
extent
of
the
protection
offered
by
the
Warranty,
its
reasonable
limitations,
and
what
you
should
do
in
order
to
obtain
its
benefits.
Be
sure
to
verify
that
the
serial
number
printed
on
the
rear
panel
matches
the
serial
number
on
the
outer
carton.
If
any
number
is
altered
or
missing,
you
should
notify
us
immediately
in
order
to
ensure
that
you
have
received
a
genuine
ADCOM
product
which
has
not
been
opened
mishandled,
or
tampered
with
in
any
way.
Always
retain
your
original
sales
receipt
as
a
proof
of
purchase.
Description
of
Unit
The
GFA-7705/07
is
a
20-Amp
Device.
GFA-7705/07
is
high-power,
high-current,
wide-bandwidth
design
employing
ADCOM’s
Fast
Analog
Transform
(F.A.T.)
circuitry
with
direct-coupled
Power
Rig
output
stages.
All
channels
are
completely
monaural
from
transformer
secondaries
through
the
output
stages.
In
order
for
this
product
to
achieve
its
actual
rated
power
output
on
all
channels
and
to
avoid
repeatedly
throwing/popping
the
related
electrical
service
panel
circuit
breaker,
it
is
critical
that
the
amplifier
be
professionally
installed
on
a
20-Amp
household
AC
circuit
and
outlet,
preferably
dedicated
but
at
minimum
one
not
shared
with
other
large
current-draw
appliances
or
devices.
Common
15-Amp
household
circuits
are
easily
and
inexpensively
converted
to
20
Amp
configuration
by
any
high
voltage
licensed
electrician.
5
y
1
s
For
this
reason,
the
GFA-7705/07
ships
Factory-equipped
with
a
hard-wired,
20-Amp
Plug
on
the
AC
Power
Cord.
nnfr^p^AMnliDun^I
P
LUG
°
R
HARDWIRED
AC
POWER
CORD
TO
EMPLOY
EITHER
A
15
AMP
OUTLET
OR
“AUDIOPHILE”
TYPE
DETACHABLE
POWER
CORD.
■
r^|^^7^^^^^^~^^^^~P
R
000-0
T
'
^^
ARRA
~'^^
^^^0^^^0—THE
PRODUCTAN
D
PUCE
THE
USER
AT
EXTRFMF
RISKflF
INJUR
Y
OR
DEATH.
4

Rear
Panel
Inputs
(1)
The
audio
inputs
for
the
GFA-7705
and
7707
are
through
high-quality,
gold-plated
RCA
jacks
to
minimize
hieh
RCA
-T
■
*»
~*
«*
SZ5!S££1L
L
manvc
e
b
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wh
05
h
/07
'*
P
[
eSerVed
’
you
should
use
the
quaUt^shiJ^
C0,Or
‘
C
°S
a
1
Specmca
"
y
*
*****
,
OT
«
*WfcaUoo.
YourZSca^Mp
select
the
best
cable
for
your
needs.
(See
Connecting
the
GFA-7705/07
for
more
information.)
P
Inputs
(1b)
Chassis
knock-out
for
future
expansion
channel-card
input
jack
(GFA-7705
only).
Outputs
(2)
EssjSassisHssS®*
“
■
™
S
1
vxzv
(See
CONNECTING
THE
GFA-7705/07
for
more
information.)
Outputs
(2b)
Chassis
knock-out
for
future
expansion
channel-card
output
binding
posts
(GFA-7705
only).
5

WARNING
THERE
ARE
NO
USER-SERVICEABLE
PARTS
OR
FUSES
INSIDE
THE
GFA-7705/07.
In
the
event
that
the
amplifier’s
rear-panel
circuit
breaker
fails
to
reset
(opens
again
when
power
applied
to
unit
and
unit
turned
on)
you
must
refer
the
amplifier
to
ADCOM
Factory
Service
or
ADCOM
Authorized
Service
Center.
Do
not
open
the
amplifier
nor
remove
the
topcover-Hazardous
and
Potentially
Lethal
Voltage
Present
and
Warranty
may
be
voided.
12VDC
Triggering
(3a)
ADCOM
has
provided
the
installer
the
ability
to
control
the
OFF/ON
function
of
the
GFA-7705/07
by
a
12Volt
DC
output
jack
on
the
rear
of
certain
pre-amplifiers
and
tuner
pre-amplifiers.
When
using
this
feature
the
front
panel
Power
Switch
must
be
left
in
the
in
“on”
position.
To
connect,
you
will
need
a
monaural
mini
phone
plug
to
monaural
mini
phone
plug
cable
of
appropriate
length
(not
included)
to
reach
from
the
rear
panel
of
the
amplifier
to
the
rear
panel
of
the
pre-amplifier.
Contact
your
dealer
for
information
on
using
this
feature
with
ADCOM
and
other
brand
pre-amplifiers.
Although
12VDC
is
optimal,
the
circuit
will
operate
from
approx.
5
to
30VDC.
Center
conductor
(tip)
is
positive
(+).
AC
Circuit
Breaker
(3b)
The
15-Amp
AC
Breaker
protects
the
electronic
circuits
of
the
GFA-7705/07.
Normally,
this
breaker
will
open
only
if
there
is
an
overload
or
a
component
failure
within
the
GFA-7705/07.
If
the
Power
LED
(7)
does
not
glow,
it
may
be
an
indication
that
the
AC
Breaker
has
blown.
If
you
are
using
the
12VDC
Triggering
feature
(above)
it
may
be
possible
that
there
is
no
trigger
voltage
present
or
a
problem
exists
with
that
connection.
To
determine
if
the
problem
is
caused
by
a
malfunction
in
the
12VDC
system,
remove
the
small
plug
inserted
into
the
12VDC
Triggering
jack.
Press
the
front
panel
power
switch
to
turn
off
the
amp,
and
immediately
re
press
the
power
switch.
If
the
problem
is
caused
by
the
12VDC
triggering
circuit
the
amp
will
turn
on
and
the
LED
will
glow.
DO
NOT
attempt
repair
of
the
12VDC
system.
If
you
are
not
sure,
or
the
amplifier
displays
other
symptoms,
please
consult
the
RESOLVING
PROBLEMS
section
on
page
13.
AC
Power
Cord
(4)
The
AC
cord
provides
power
to
operate
all
the
GFA-7705/07’s
circuits.
The
GFA-7705/07
is
a
very
high
power
amplifier
and
as
such
must
be
directly
connected
to
the
wall
outlet
or
an
appropriate
(non-
current
limiting)
surge
protector
or
AC
line
conditioner
of
20-Amp
service
capability.
NOTE:
As
previously
described
on
Page
4,
the
attached
plug
is
a
20-Amp
fitting
which,
in
order
for
the
amplifier
to
deliver
its
rated
power
output,
should
not
be
defeated
in
order
to
accomodate
standard
15-amp
household
wall
outlets.
Please
consult
with
your
dealer
and/or
licensed
electrician
for
conversion
of
a
15
amp
outlet
and
panel
circuit
to
a
20
amp
circuit.
6

(5)
(6)
(7)
(8a,
8b)
Front
Panel
On/Off
Switch
(5)
™
e^v“S,F.
h
™
r
/n7
et
t0
frrr
t,ansfor
™
r
.«*
»*
Power
LED
(6)
seconds
to
fully
extinguish.
t
me
t0
fade
001
com
Ptetely.
It
may
take
up
to
30
“
'
he
GFA
-
7
705,
°
7
.
«*
P°«r
LED
will
no.
triggering,
source
*—«
-
7

Distortion
Alert
LEDs
(7)
The
Distortion
Alert
circuit
is
a
unique
ADCOM
distortion
detection
system
which
reads
all
forms
of
non¬
linear
distortion
such
as
THD,
IM,
slew-induced,
“clipping,”
etc.
The
Distortion
Alert
LEDs
will
light
when
distortion
reaches
approximately
1%
regardless
of
impedance,
voltage/current
phase
angle
or
the
reactance
of
the
loudspeakers
which
the
amplifier
is
driving.
Sometimes,
when
the
amplifier
is
in
use,
the
LEDs
may
occasionally
flicker
during
high
volume
listening,
particularly
if
you
are
driving
low
impedances.
This
flickering
is
no
cause
for
concern.
The
LEDs
are
simply
warning
you
that
the
amplifier
is
approaching
its
maximum
power
output
into
the
particular
loudspeakers
you
are
using.
If,
however,
the
Distortion
Alert
LEDs
glow
brightly
or
are
illuminated
most
of
the
time
during
playback,
you
are
over
driving
the
amplifier
and
should
turn
down
your
volume
control
to
reduce
the
listening
level,
otherwise
it
may
cause
the
Thermal
Protection
to
be
activated
or,
in
extreme
cases,
damage
vour
loudspeakers.
Thermal
Protection
LEDs
(8a)
The
GFA-7705/07
is
provided
with
both
a
thermal
protection
circuit
and
a
current
overload
circuit
which
will
shut
down
the
individual
amplifier's
channels
if
its
heatsink
temperature
reaches
85°
C
or
the
amplifier’s
outputs
are
shorted.
The
Thermal
Protection
LEDs
will
light
when
either
of
these
protection
circuits
are
on
its
respective
channel
has
been
triggered
and
the
amplifier
is
inoperative.
The
thermal
protection
circuitry
will
typically
be
triggered
by
very
high
power
demands
into
impedances
much
lower
than
the
amplifier
is
capable
of
driving
at
those
levels.
If
any
amplifier
channel’s
output
through
the
loudspeaker(s)
ceases
abruptly,
and
its
Thermal
Protection
LED
glows,
you
will
know
that
its
heatsink
temperature
has
become
unacceptably
high
and
the
circuitry
is
protecting
the
amplification
devices.
Please
note
that
the
Power
LED
(7)
will
remain
on
and
the
amplifier
will
still
be
energized.
Once
the
temperature
of
the
heatsink(s)
drops
to
a
safe
operating
level,
that
amplifier
will
automatically
resume
operation.
Activation
of
the
Thermal
Protection
circuitry
in
any
of
the
amplifiers
in
the
GFA-7705/07
is
an
indication
that
the
amplifier
has
been
over
driven
or
that
the
load
the
loudspeakers
are
presenting
to
the
amplifier
is
unreasonably
low.
If
you
wish
to
prevent
recurrent
activation
of
the
thermal
protection
circuitry,
you
must
reduce
the
volume-level
demands
or
correct
the
load-impedance
condition
which
may
be
causing
activation
of
this
circuitry.
S.A.F.E.®
Protection
Circuit
(8b)
Self-Annealing
Fuse
Equipped:
Instead
of
blowing
internal
protection
rail
fuses
in
the
event
of
a
dead-
short
to
either
a
loudspeaker
or
speaker
cable
leads,
the
GFA-7705/07
will
enter
into
a
self-protect
SAFE
mode.
If
the
output
of
any
channel
of
the
amplifier
becomes
shorted
the
protection
circuit
will
trip
and
the
individual
Thermal
Protection
LED
for
that
channel
will
light.
The
Protection
LED
will
blink
approximately
every
5
seconds
as
the
circuit
will
attempt
to
reset;
if
the
short
has
been
corrected
the
amplifier
will
resume
proper
operation.
If
the
short
is
still
present
the
channel
will
cycle
off
again.
The
cycling
of
the
protection
circuit
will
continue
until
the
short
is
corrected
or
the
amplifier
power
is
switched
off.
8

WARNING
Whenever
connections
to
or
from
the
GFA-7705/07
are
being
made,
be
certain
that
the
AC
On/Off
Switch
(5)
of
the
amplifier
is
in
the
OFF
position,
the
AC
Power
Cord
(4)
of
the
amplifier
is
disconnected
from
the
AC
wall
outlet
and
that
all
associated
components
are
turned
off.
Installation
&
Hookup
Unpacking
the
GFA-7705/07
Before
your
new
GFA-7705/07
left
our
factory,
it
was
carefully
inspected
for
physical
imperfections
and
tested
for
all
electrical
parameters
as
a
routine
part
of
ADCOM’s
systematic
quality
control.
This,
along
with
full
operational
and
mechanical
testing,
should
ensure
a
product
flawless
in
both
appearance
and
performance.
After
you
have
unpacked
the
GFA-7705/07
inspect
it
for
physical
damage.
Save
the
shipping
carton
and
all
packing
material
as
they
are
intended
to
reduce
the
possibility
of
transportation
damage,
should
the
amplifier
ever
need
to
be
shipped
again.
In
the
unlikely
event
damage
has
occurred,
notify
your
dealer
immediately
and
request
the
name
of
the
carrier
so
a
written
claim
to
cover
shipping
damages
can
be
initiated.
THE
RIGHT
TO
A
CLAIM
AGAINST
A
PUBLIC
CARRIER
CAN
BE
FORFEITED
IF
THE
CARRIER
IS
NOT
NOTIFIED
PROMPTLY
IN
WRITING
AND
IF
THE
SHIPPING
CARTON
AND
PACKING
MATERIALS
ARE
NOT
AVAILABLE
FOR
INSPECTION
BY
THE
CARRIER.
SAVE
ALL
PACKING
MATERIALS
UNTIL
THE
CLAIM
HAS
BEEN
SETTLED.
Placement
of
the
GFA-7705/07
During
normal
home
operation
the
internal
heatsinks
of
the
GFA-7705/07
may
become
warm.
However,
there
are
instances
during
high-level
playback
into
low
impedances
when
the
heatsinks
will
become
much
warmer
than
usual.
To
ensure
the
amplifier's
long-term,
trouble-free
operation,
it
is
necessary
to
provide
adequate
ventilation
for
the
heatsinks.
Therefore,
the
GFA-7705/07
should
be
kept
away
from
external
sources
of
heat
such
as
radiators
and
hot-air
ducts.
The
GFA-7705/07
should
never
be
placed
with
other
heat-producing
components
in
a
cabinet
or
enclosure
lacking
free
air
flow.
The
top
and
bottom
panels
of
the
amplifier’s
chassis
have
been
provided
with
vents
to
allow
the
necessary
cooling
of
the
internal
components.
It
is
imperative
that
these
vents
are
not
obstructed
in
any
way.
We
recommend
that
you
do
not
stack
other
components
on
top
of
the
GFA-7705/07.
Not
only
will
heat
generated
by
the
amplifier
affect
the
performance
of
equipment
stacked
on
top
of
the
GFA-7705/07,
but
the
free
flow
of
air
through
the
ventilating
slots
in
the
amplifier
may
be
partially
obstructed.
This
is
particularly
important
if
your
system
includes
low-impedance
loudspeakers
which
are
difficult
to
drive,
or
you
will
consistently
demand
high
volume
levels
from
the
amplifier
and
speaker
system.
If
you
observe
these
recommendations,
the
GFA-7705/07
will
perform
reliably
in
any
reasonable
environment.
You
should
also
pay
attention
to
such
normal
considerations
as
protection
from
excessive
dust
and
moisture.
Occasional
vacuuming
of
accumulated
dust
on
the
chassis,
panels
and
around
the
ventilating
slots
should
be
all
that
is
required.
The
optimal
performance
of
your
new
GFA-7705/07
will
ultimately
depend
on
the
care
with
which
you
make
the
connections
between
the
amplifier,
preamplifier,
surround
sound
decoder
and
the
loudspeakers.
All
input
and
output
signal
connections
should
be
made
only
with
high
quality,
low
capacitance,
shielded
cables
following
the
recommendations
in
the
Inputs
and
Outputs
section
of
CONNECTING
THE
GFA-7705/07.
Quick
Connections
For
those
of
you
who
are
in
a
hurry
to
hook
up
your
amplifier
into
your
system,
we
have
included
this
quick-connection
section.
The
wiring
is
straight
forward
and
expeditious
if
you
use
the
proper
cables
and
follow
this
diagram
exactly.
If
you
have
any
difficulties
or
questions,
please
refer
to
the
appropriate
section
of
this
manual
for
complete
descriptions
and
instructions.
9

Connecting
the
GFA-7705/07
Remember,
that
the
Left
and
Right
designations
are
as
you
are
sitting
down
in
your
listening/viewing
area
Theyareas
fdSs
”***
and
°
UtpUtS
are
gr
°
Uped
in
5
or
7
bracketed
sets,
one
set
for
each
channel.'
LB
-
Left
Back
(GFA-7707
only)
LS
—
Left
Surround
LF
—
Left
Front
C
—
Center
RF
—
Right
Front
RS
—
Right
Surround
RB
-
Right
Back
(GFA-7707
only)

Inputs
(1)
To
preserve
the
correct
effects,
be
certain
to
connect
the
RCA
cables
to
the
proper
RCA-input
connector.
If
the
cables
are
color
coded,
then
use
this
sequence
for
the
connections:
^
ue
..Left
Front
fted...Right
Front
G
feen
...Center
White
with
Blue
Stripe....Left
Surround
White
with
Red
Stripe.Right
Surround
The
recommended
maximum
RCA
cable
capacitance
should
be
less
than
or
equal
to
30pF
per
foot
when
measured
between
the
two
conductors,
and
less
than
or
equal
to
50pF
per
foot
when
measured
between
one
conductor
and
the
shield.
Outputs
(2)
NOTE.
The
GFA-7705/07
is
“polarity
correct”.
That
is,
it
does
not
invert
phase
from
input
to
output.
Any
positive
signals
at
its
inputs
will
appear
as
a
positive
signal
at
its
outputs.
In
connecting
the
amplifier
to
the
loudspeaker,
it
is
vital
to
maintain
proper
polarity
(positive
to
positive,
negative
to
negative).
On
the
GFA-7705/07,
the
positive
terminal
is
color
coded
RED
and
labeled
“+,”
and
the
negative
is
color
coded
BLACK
and
labeled
The
positive
terminal
on
the
corresponding
loudspeaker
will
be
color
coded
RED,
or
will
be
labeled
“+,”
“pos,”
"positive,”
“8
ohms,”
or
“A
ohms.”
The
negative
terminal
on
the
speaker
will
be
color
coded
BLACK,
or
will
be
labeled
“neg,”
negative,”
“C,”
“Common,”
“G,”
or
“ground.”
It
is
necessary
that
your
speaker
cables
be
terminated
with
“U”-
the
most
contact
area
insuring
long-term
reliability.
The
spade
connector
should
have
a
maximum
width
of
0.57
inches
and
an
opening
width
of
no
less
than
0.25”
(see
diagram
on
right).
type
spade
connectors.
These
will
give
To
properly
connect
the
speaker
cable
to
the
binding
posts
turn
the
insulated
head
of
the
binding
post
clockwise
until
the
wire
or
connector
is
firmly
secured.
Finger
pressure
is
sufficient
and
you
should
not
use
pliers
or
other
tools
which
could
damage
or
over
tighten
the
binding-post
assembly.
The
binding
posts
have
been
designed
in
such
a
way
that
finger
pressure
is
all
that
is
required
to
cause
a
“pinching”
action
among
the
different
metal
surfaces
to
ensure
proper
connection.
It
is
very
important
to
use
the
correct
size
of
wire
in
order
to
avoid
unnecessary
loss
of
amplifier
power
in
the
cable,
reduction
of
amplifier
damping
factor
and
other
undesirable
conditions.
Recommended
capacitance
of
the
speaker
wire
should
not
exceed
50pF
per
foot.
This
insures
high
frequencies
will
not
be
rolled-off.
11

It
is
suggested
that
the
three
front
channels
follow
this
chart
for
speaker
lengths
and
wire
gauges.
up
to
24
feet......
AWG16
up
to
36
feet.AWG14
up
to
58
feet...AWG12
Generally,
for
the
two
rear
surround
channels,
longer
runs
of
cable
are
needed,
but
since
less
program
material
is
being
transmitted
through
the
cable,
longer
runs
are
acceptable:
up
to
48
feet....
AWG16
up
to
72
feet.....AWG14
up
to
116
feet...AWG12
If
longer
runs
are
needed,
it
is
best
to
consult
with
your
Adcom
Dealer
to
maximize
the
performance
of
your
system
with
your
exact
conditions.
All
loudspeakers
having
a
nominal
impedance
down
to
4
ohms
can
be
connected
to
and
driven
by
the
GFA-7705/07.
The
amplifier
can
drive
these
low-impedance
speakers
at
more
than
adequate
power
levels
with
no
difficulty.
It
should
be
noted
here
that
many
loudspeaker
systems
which
are
nominally
rated
at
4
ohms
drop
in
impedance,
in
some
parts
of
their
frequency
range,
to
as
low
as
2
ohms
(and
sometimes
less).
You
will
not
experience
difficulties
even
with
these
very
low
impedance
loads
unless
you
demand
excessively
high
volume
levels
from
your
system.
It
is
not
recommended
that
you
run
additional
sets
of
speakers
on
any
or
all
of
the
amplifiers
in
the
GFA-7705/07
in
order
to
insure
the
integrity
of
the
system.
If
you
choose
to
add
remote
speakers
in
another
room,
it
is
strongly
suggested
that
a
switching
system
to
disconnect
the
non-home-theater
speakers
be
incorporated
when
the
surround
sound,
home-theater
mode
is
in
operation.
A
device
such
as
the
Adcom
GFS-300
or
GFS-600
Speaker
Selector
is
strongly
recommended.
A
Speaker
Selector
enables
you
to
maintain
integrity
while
giving
you
the
flexibility
to
add
speakers
throughout
your
house.
CARING
FOR
YOUR
GFA-7705/07
Great
care
has
been
taken
by
ADCOM
to
ensure
that
your
amplifier
is
as
flawless
in
appearance
as
it
is
electronically.
The
front
panel
is
a
heavy-gauge,
high-grade
aluminum
extrusion
carefully
finished
and
anodized
for
durability.
The
chassis,
top
cover
and
rear
panel
are
heavy-gauge
steel
that
has
been
powder
coated
and
baked
to
ensure
a
lasting
finish.
If
the
front
panel,
top
or
sides
become
dusty
or
fingerprinted,
they
can
be
cleaned
with
a
soft
lint-free
cloth,
slightly
dampened
with
a
very
mild
detergent
solution
or
glass
cleaner.
DO
NOT
SPRAY
OR
POUR
LIQUIDS
OF
ANY
KIND
ON
THE
GFA-7705/07.
12

Troubleshooting
Resolving
Problems
Use
the
chart
below
to
solve
common
situations
that
don’t
require
professional
attention.
If
the
steps
stated
in
POSSIBLE
SOLUTION
do
not
resolve
your
problem,
then
please
contact
your
ADCOM
Dealer
or
call
the
ADCOM
Customer
Service
Department.
Any
problems
not
covered
here
should
be
brought
to
the
attention
of
your
ADCOM
Dealer
or
ADCOM
Customer
Service
Department.
Aspgd^Jlotem^hunr:
When
there
is
a
low-volume
“hum”
audible
throughout
your
speakers,
even
with
the
main
volume
turned
all
the
way
down,
you
likely
have
a
common
phenomenon
known
as
“ground
loop.”
A
ground
loop
is
basically
a
difference
in
ground
voltages
between
two
or
more
components
which
are
connected
electrically
and
which
creates
multiple
current
paths
where
there
must
only
be
one.
This
difference
in
potential
creates
a
60
Hz
low-level
sound
(approximately
a
low
A#),
that
appears
to
“hum.”
It
can
be
caused
by
adding
new
components
to
your
system,
but
that
does
not
imply
there
is
anything
electrically
wrong
with
any
new
component.
With
the
advent
of
audio/video
and
home
theater
systems,
the
problem
has
become
commonplace.
Generally,
the
cause
is
the
Cable-TV
incoming
signal
line.
This
new
incoming
line
may
add
an
additional
ground
at
a
different
potential
from
the
AC
line
ground
of
your
other
equipment.
Symptom
Pof|ble
Season
Pbss'bte
Solution
Power
LED
does
not
glow
No
sound
AC
Power
Cord
(
4
)
not
plugged
in
AC
Breaker
(3b)
opened
12V
Trigger
Connected
but
not
activated
Plug
in
AC
Power
Cord
(
4
)
Reset
AC
Breaker
(
3
b)
Turn
on
12V
Source
Unit
Power
LED
glows,
but
no
sound
Preamp
or
source
unit
is
not
on
Connections
in
rear
are
loose
Make
sure
whole
system
is
on
Verify
all
connections
on
rear
of
amp
One
channel
not
producing
sound
and/or
Thermal
LED
Blinking
Input
(
1
)
or
Output
(2)
connectors
disconnected
or
loose
Speaker
disconnected/
shorted
Internal
protection
engaged
Verify
both
sets
of
connections
on
that
channel
Verify
connections
at
speaker/
cable
in¬
tegrity.
Bring
to
Dealer
or
Service
Center
Hum
from
all
speakers
at
any
volume
Ground
loop
(difference
in
ground
voltages
between
components)
If
cable
TV
is
present
(see
Note
1)
If
cable
TV
is
not
present
(see
Note
2)
Hum
from
all
speakers
(hum
goes
up
or
down
with
volume)
Problems
with
source
unit
(CD,
tape,
etc.)
or
RCA
cables
connecting
that
source
unit
to
the
preamp
Try
different
source
(tuner,
tape,
etc.)
and/or
different
RCA
cable
Hum
from
the
amplifier
itself
Some
major
appliance,
dimmer,
halogen
or
fluorescent
light
is
creating
interference
Make
sure
all
appliances,
dimmers
and
suspect
lights
are
off
NoteJ:
Cable
TV
systems
can
sometimes
contribute
to
ground-loop
problems
which
cause
“hum.”
To
determine
if
your
cable
system
is
the
contributing
factor,
disconnect
the
Cable-TV
incoming
signal
line
(round,
750)
at
the
wall,
or
the
first
component
to
which
the
cable
is
connected
to
(i.e.
the
cable
box,
or
VCR.)
If
the
hum
is
no
longer
present,
you
must
insert
a
"750
Ground
Loop
Isolator”
before
reconnecting
the
line.
You
should
check
with
your
ADCOM
Dealer
to
obtain
one.
If
the
“750
Ground
Loop
Isolator”
works
only
partially
or
not
at
all,
then
please
read
Note
2
to
complete
the
troubleshooting
procedure.
Note!:
Make
sure
that
the
power
amplifier
is
at
least
six
inches
from
the
Preamp
and/or
Processor.
Usually
putting
another
component
between
them
is
sufficient
to
minimize
the
hum.
If
this
does
not
reduce
the
hum,
turn
the
system
off
and
disconnect
all
Inputs
from
the
amplifier.
If
the
hum
still
persists,
then
call
your
Dealer
or
Service
Center.
If
the
hum
disappears,
re-connect
one
RCA
cable
at
a
time
to
see
if
the
specific
cable
or
component
is
responsible.
If
any
or
all
cables
cause
the
hum
to
appear,
subsitute
with
replacement
cable(s).
If
hum
continues
to
persist
then
the
preamp
or
processor
should
be
evaluated
for
proper
operation
by
your
Dealer
or
Authorized
Service
Center.
13

Servicing
ADCOM
has
a
Technical
Service
Department
to
answer
questions
pertinent
to
the
installation
and
operation
of
your
unit.
In
the
event
of
difficulty,
please
contact
us
for
prompt
advice
Please
have
the
following
information
readily
at
hand:
the
unit’s
model
and
serial
numbers
and
dealer
from
whom
it
was
purchased.
If
your
problem
cannot
be
resolved
through
our
combined
efforts,
we
may
refer
you
to
an
authorized
repair
agency,
or
authorize
return
of
the
unit
to
our
factory.
To
aid
us
in
directing
you
to
a
convenient
service
center,
it
would
be
helpful
if
you
indicate
which
major
city
is
accessible
from
your
home.
Please
address
mail
inquires
to:
ADCOM
Service
8541
East
Anderson
Drive
Scottsdale,
Arizona
85255
United
States
of
America
www.
adcom.
com
Phone,
Fax
or
Email
inquiries
to
:
Voice:
(480)
607-2277
Fax:
(480)
348-9876
Monday-Friday
9:00
AM
to
5:00PMMST
UNDER
NO
CIRCUMSTANCES
SHOULD
YOUR
UNIT
BE
SHIPPED
TO
OUR
FACTORY
WITHOUT
PR
!9g
AUTHORIZA
TION,
OR
PACKED
IN
OTHER
THAN
ITS
ORIGINAL
CARTON
AND
FILLERS.
For
fax
inquires,
please
include
a
return
fax
or
voice
number
for
the
reply.
When
calling
or
writing
about
your
GFA-7705/07,
be
sure
to
note
and
refer
to
its
serial
number
as
well
as
the
date
of
purchase
and
the
dealer
from
whom
it
was
purchased.
In
the
event
the
unit
must
be
returned
to
our
factory
for
service,
you
will
be
instructed
on
the
proper
procedure
when
you
call
or
write
for
a
Return
Authorization.
For
warranty
coverage,
a
copy
of
the
original
proof
duplicate
copy
reqUired
^
^
^
n<>
°
n8inal
Copy
’
please
contact
y°
ur
dealer
to
obtain
a
If
the
original
shipping
carton
and
its
fillers
have
been
lost,
discarded,
or
damaged
a
duplicate
carton
may
be
obtained
from
our
Service
Department
for
a
nominal
charge.
PARCEL
SERV
'
CE
<
UPS
>
0R
OTHER
APPROVED
CARRIER.
DO
NOT
SHIP
VIA
PARCEL
POST,
since
the
packaging
was
not
designed
to
withstand
rough
Parcel
Post
handling.
FREIGHT
COLLECT
SHIPMENTS
WILL
NOT
BE
ACCEPTED
UNDER
ANY
CIRCUMSTANCES.
14

GFA-7700/7707
Specifications
Power
Rating
(To
EIA/CEA-490-A
Requirements
2
°0
Watts
con
tin
u
°
us
average
power
per
channel
into
8
ohms
with
all
channels
driven
at
less
than
1
%
THD.
at
any
frequency
between
20Hz
and
20kHz
3
°0
Watts
continuous
average
power
per
channel
into
4
ohms
at
with
all
channels
driven
at
less
than
1%
THD.
any
frequency
between
20Hz
and
20kHz
THD
+
Noise
at
200
Watts
into
8
ohms
(Typical)
20Hz.
1kHz.
.
10kHz.
.
20kHz.
.
THD
+
Noise
at
300
Watts
into
4
ohms
(Typical)
20Hz.
'
1kHz...
.
10kHz.
.
20kHz.
.
Frequency
Response
@
1
Watt
into
8
ohms
(20Hz
to
20kHz)
Power
Bandwidth
(-3dB).
Dynamic
Headroom
into
4
ohms.
Signal
to
Noise
Ratio
“A”
Weighted
(200
Watts
into
8
ohms).
Gain....
Input
Sensitivity
for
1
Watt
Output.
for
200
Watts
Output.
.0.0086%
.0.0096%
.0.0156%
.
0
.
0201
%
.0.0186%
.0.0214%
.0.0354%
.0.0311%
....+0,
-0.22dB
3
Hz
to
130kHz
.1.90
dB
.-125
dB
.29
dB
..
0.1
volts
1.40
volts
Input
Impedance.
....
Damping
Factor
(20Hz
to
20kHz).
General
>800
Power
(Available
in
230VAC
on
special
order)
Power
Consumption
(Continuous,
All
Channels
Driven)
Idle
(5
Channel).
Idle
(7
Channel)..
200
watts
x
5
Ch
into
8
ohms
200
watts
x
7
Ch
into
8
ohms
120VAC
-
50/60HZ
.120W
.170W
.2200W
.2700W
Chassis
Dimensions
(H
x
W
x
D).
Maximum
Dimensions
(H
x
W
x
D).
Unit
Weight
(GFA-7705).
Unit
Weight
(GFA-7707)....
Weight,
Packed
(GFA-7705).
Weight,
Packed
(GFA-7707).’**"*
Specifications
subject
to
change
without
notice.
•8.5”
(216mm)
x
17”
(432mm)
x
17.5”
(444.5mm)
9
3/8”
(238mm)
x
17”
(432mm)
x
18.5”
(470mm)
.69.5
lb.
(31.5
kg)
..
lb.
(35.5
kg)
.81.51b.
(37
kg)
.90.4
lb.
(41
kg)
15
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2
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