Adcom GFA-7400 User manual

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A

DCOM

GFA

-7400

&

GFA-7300

High

Current

5-Channel

Power

Amplifiers

OWNER’S

MANUAL

THE

FOLLOWING

PRECAUTIONS

AND

SAFETY

INSTRUCTIONS

ARE

REQUIREMENTS

OF

UL

AND

CSA

SAFETY

REGULATIONS

Warning:

To

reduce

the

risk

of

fire

or

electric

shock,

do

not

expose

this

unit

to

rain

or

moisture.

CAUTION

RISK

OF

ELECTRIC

SHOCK

DO

NOT

OPEN

AVIS.

RISQUE

DE

CHOC

ELECTRIQUE-NE

PAS

OUVRIR

The

graphic

symbol

of

a

lightning

flash

with

an

arrow

point

within

a

triangle

signifies

that

there

is

dangerous

voltage

within

the

unit

and

it

poses

a

hazard

to

anyone

removing

the

cover

to

gain

access

to

the

interior

of

the

unit

Only

qualified

service

personnel

should

make

any

such

attempt.

The

graphic

symbol

of

an

exclamation

point

within

an

equilateral

triangle

warns

a

user

of

the

device

that

it

is

necessary

to

refer

to

the

instruction

manual

and

its

warnings

for

proper

operation

of

the

unit

Do

not

place

this

unit

on

an

unstable

cart,

stand,

tripod,

bracket,

or

table

The

unit

may

fall,

causing

serious

injury

to

a

child

or

adult,

and

serious

damage

to

the

unit

Use

only

with

a

cart,

stand,

tripod,

bracket,

or

table

recommended

by

the

manufacturer,

or

sold

with

the

unit

Any

mounting

of

the

device

should

follow

the

man-

ufacturer’s

instructions,

and

should

use

a

mounting

ac¬

cessory

recommended

by

the

manufacturer

Read

all

the

safety

and

operating

instructions

before

connecting

or

using

this

unit

Retain

this

notice

and

the

owner’s

manual

for

future

reference

All

warnings

on

the

unit

and

in

its

operating

instructions

should

be

adhered

to

All

operating

and

use

instructions

should

be

followed

Do

not

use

this

unit

near

water,

for

example,

near

a

bathtub,

washbowl,

kitchen

sink,

laundry

tub,

in

a

wet

basement,

or

near

a

swimming

pool

The

unit

should

be

installed

so

that

its

location

or

position

does

not

interfere

with

its

proper

ventilation

For

example,

it

should

not

be

situated

on

a

bed,

sofa,

rug,

or

similar

surface

that

may

block

the

ventilation

openings,

or

placed

in

a

built-in

installation,

such

as

bookcase

or

cabinet,

that

may

impede

the

flow

of

air

through

its

ventilation

openings

The

unit

should

be

situated

away

from

heat

sources

such

as

radiators,

heat

registers,

stoves,

or

other

devices

(including

amplifiers)

that

produce

heat

The

unit

should

be

connected

to

a

power-supply

outlet

only

of

the

voltage

and

frequency

marked

on

its

rear

panel

The

power-supply

cord

should

be

routed

so

that

it

is

not

likely

to

be

walked

on

or

pinched,

especially

near

the

plug,

convenience

receptacles,

or

where

the

cord

exits

from

the

unit

Clean

unit

only

as

recommended

in

its

instruction

manual

The

power-supply

cord

of

the

unit

should

be

unplugged

from

the

wall

outlet

when

it

is

to

be

unused

for

a

long

period

of

time

Care

should

be

taken

so

that

objects

do

not

fall,

and

liquids

are

not

spilled,

into

the

enclosure

through

any

openings

This

unit

should

be

serviced

by

qualified

service

personnel

when

A

The

power

cord

or

the

plug

has

been

damaged,

or

B

Objects

have

fallen,

or

liquid

has

been

spilled,

into

the

unit,

or

C

The

unit

has

been

exposed

to

rain,

or

liquids

of

any

kind,

or

D

The

unit

does

not

appear

to

operate

normally,

or

exhibits

a

marked

change

in

performance,

or

E

The

device

has

been

dropped,

or

the

enclosure

damaged

DO

NOT

ATTEMPT

SERVICING

OF

THIS

UNIT

YOURSELF.

REFER

SERVICING

TO

QUALIFIED

SERVICE

PERSONNEL.

ATTENTION

POUR

PREVENIR

LES

CHOCS

ELECTRIQUES

NE

PAS

UTILISER

CETTE

FICHE

POLARISEE

AVEC

UN

PROLONGATEUR,

UNE

PRISE

DE

COURANT

OU

UNE

AUTRE

SORTIE

DE

COURANT,

SAUF

SI

LES

LAMES

PEUVENT

ETRE

INSEREES

A

FOND

SANS

EN

LAISSER

AU-

CUNE

PARTIE

A

DECOUVERT

CAUTION

TO

PREVENT

ELECTRIC

SHOCK

DO

NOT

USE

THIS

POLARIZED

PLUG

WITH

AN

EXTENSION

CORD,

RECEPTACLE

OR

OTHER

OUTLET

UN¬

LESS

THE

BLADES

CAN

BE

FULLY

INSERTED

TO

PREVENT

BLADE

EXPOSURE

CAUTION

POWER

LINES

Any

outdoor

antenna

must

be

located

away

from

all

power

lines.

OUTDOOR

ANTENNA

GROUNDING

If

an

outside

antenna

is

connected

to

your

tuner

or

tuner-preamplifier,

be

sure

the

antenna

system

is

grounded

so

as

to

provide

some

protection

against

voltage

surges

and

built-up

static

charges.

Section

810

of

the

National

Electrical

Code,

ANSI/NFPA

No.

70-1984,

provides

information

with

respect

to

proper

grounding

of

the

mast

and

supporting

structure,

grounding

of

the

lead-m

wire

to

an

antenna

discharge

unit,

size

of

grounding

conductors,

location

of

antenna

discharge

unit,

connection

to

grounding

electrodes,

and

requirements

for

the

grounding

electrode

a

Use

No.10

AWG

(5.3

mm

2

)

copper,

No

8

AWG

{8.4

mm

2

)

aluminum,

No.17

AWG

(1

0

mm

2

)

copper-clad

steel

or

bronze

wire,

or

larger,

as

a

ground

wire.

b.

Secure

antenna

lead

in

and

ground

wires

to

house

with

stand-off

insulators

spaced

from

4-6

feet

{1

22-1

83

m)

apart.

c.

Mount

antenna

discharge

unit

as

close

as

possible

to

where

lead-in

enters

house.

d.

Use

jumper

wire

not

smaller

than

No.6

AWG

(13.3

mm

2

)

copper,

or

the

equivalent,

when

a

separate

antenna-grounding

electrode

is

used.

See

NEC

Section

810-21

(j).

EXAMPLE

OF

ANTENNA

GROUNDING

AS

PER

NATIONAL

ELECTRICAL

CODE

INSTRUCTIONS

CONTAINED

IN

ARTICLE

810

-

RADIO

AND

TELEVISION

EQUIPMENT

NOTE

TO

CATV

SYSTEM

INSTALLER

This

reminder

is

provided

to

call

the

CATV

system

installer’s

attention

to

Article

820-22

of

the

National

Electrical

Code

that

provides

guidelines

for

proper

grounding

and,

in

particular,

specifies

that

the

cable

ground

shall

be

connected

to

the

grounding

system

of

the

building,

as

close

to

the

point

of

cable

entry

as

practical

TABLE

OF

CONTENTS

SAFETY

INFORMATION.1

INTRODUCTION

WARRANTY

INFORMATION.2

DESCRIPTION

OF

UNIT

FEATURES

GFA-7400.3

FEATURES

GFA-7300.3

INSTALLATION

&

HOOKUP

UNPACKING

THE

GFA-7400/7300.4

PLACING

THE

GFA-7400/7300.4

QUICK

CONNECTION.5

CONNECTION

DIAGRAM.6

INPUTS

AND

OUTPUTS.7

CARING

FOR

YOUR

GFA-7400/7300.8

OPERATION

INPUTS

AND

OUTPUTS.9

FUSES

AND

AC

SUPPLY.10-11

LED

DISPLAYS.12-13

TROUBLESHOOTING

RESOLVING

PROBLEMS.14-15

SERVICE

INFORMATION.16

SPECIFICATIONS.17-18

INTRODUCTION

Congratulations

on

your

decision

to

purchase

the

GFA-7400

or

GFA-7300

5-channel

power

amplifier.

The

GFA-7400

and

GFA-7300

have

been

designed

to

be

high

performance

and

musically

accurate

in

a

configuration

specifically

designed

to

integrate

with

any

home

theater

processor.

You

have

made

a

wise

choice

that

will

reward

you

for

years

to

come

with

exceptionally

accurate

and

musical

sound

reproduction.

To

realize

the

full

potential

of

your

new

amplifier,

and

before

making

any

connections

to

it,

please

read

these

operating

and

installation

instructions

thoroughly.

ADCOM

PROTECTION

PLAN

(USA

ONLY)

ADCOM

offers

the

enclosed

valuable

Limited

Warranty.

Please

read

the

details

on

the

Warranty

Card

carefully

to

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.

2

GFA-7400

FEATURES

•

Precision-matched

devices

used

throughout

the

signal

path.

•

100,000

pF

of

power

supply-filter

capacitance

for

greater

reserve

capacity.

•

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.

•

Independent

thermal-overload

and

distortion

LEDs

for

all

5

channels.

•

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.

•

Powder-coated,

baked

chassis

and

top

cover

for

greater

durability.

•

Cooling

vents

for

greater

efficiency

and

cooler

operation

while

driving

low

impedance

loads.

•

Made

in

the

USA

GFA-7300

FEATURES

•

Precision-matched

devices

used

throughout

the

signal

path.

•

47,000

pF

of

power

supply-filter

capacitance

for

greater

reserve

capacity.

•

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.

•

Independent

thermal-overload

and

distortion

LEDs

for

all

5

channels.

•

High

quality,

gold

plated

binding

posts.

•

High

quality,

gold-plated

RCA

jacks.

•

Large

independent,

internal

heatsinks

for

greater

cooling

capability

of

output

devices.

•

Heavy

gauge,

anodized

aluminum

front

panel.

•

Powder-coated,

baked

chassis

and

top

cover

for

greater

durability.

.

Cooling

vents

for

greater

efficiency

and

cooler

operation

while

driving

low

impedance

loads.

3

INSTALLATION

&

HOOKUP

UNPACKING

THE

GFA-7500

and

GFA-7300

Before

your

new

ADCOM

amplifier

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-7400/7300,

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.

PLACING

THE

GFA-7400/7300

During

normal

home

operation

the

internal

heatsinks

of

the

GFA-7400/7300

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-

7400/7300

should

be

kept

away

from

external

sources

of

heat

such

as

radiators

and

hot-air

ducts.

The

GFA-7400/7300

should

never

be

placed

with

other

heat-producing

components

in

a

cabinet

or

enclosure

lacking

free

air

flow.

The

top

and

bottom

panel

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-7400/7300.

This

is

particularly

important

if

your

system

includes

low-impedance

loudspeakers

which

are

difficult

to

drive,

or

if

you

will

consistently

demand

high

volume

levels

from

the

amplifier

and

speaker

system.

Not

only

will

heat

generated

by

the

amplifier

affect

the

performance

of

equipment

stacked

on

top

of

the

GFA-7400/7300,

but

the

free

flow

of

air

through

the

ventilating

slots

in

the

amplifier

may

be

partially

obstructed.

If

you

observe

these

recommendations,

the

GFA-7400/7300

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-7400/7300

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-loss,

low

capacitance

cables

following

the

recommendations

in

the

Inputs

and

Outputs

section

of

CONNECTING

THE

GFA-7400/7300.

4

NOTE!

Product

shown

is

for

reference

only,

The

GFA-7400

and

GFA-7300

differ

in

appearance

but

have

the

same

basic

configuration.

CONNECTING

THE

GFA-7400/7300

Remember,

that

the

Left

and

Right

designations

are

as

you

are

sitting

down

in

your

listening/viewing

area.

On

the

rear

panel,

the

inputs

and

outputs

are

grouped

in

5

bracketed

sets,

one

for

each

channel.

They

are

as

follows:

GFA-7300

GFA-7400

RR

(Right

Rear)

LR

(Left

Rear)...

FR

(Front

Right)

C

(Center).

FL

(Front

Left)...

Surround

Right

(SR)

Surround

Left

(SL)

Front

Right

(FR)

Center

(C)

Front

Left

(FL)

6

Olnputs:

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:

Blue

.FL

(Front

Left)

Red

.FR

(Front

Right)

Green

.C

(Center)

White

with

Blue

Stripe

.LR

(Left

Rear)

/

(Surround

Left)

White

with

Red

Stripe

.RR

(Right

Rear)

/

(Surround

Right)

©Outputs:

NOTE:

The

GFA-7400/7300

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

When

connecting

the

amplifier

to

the

loudspeaker,

it

is

vital

to

maintain

proper

polarity

(positive

to

positive,

negative

to

negative).

On

the

GFA-7400/7300,

the

positive

terminal

is

color

coded

RED

and

labeled

“+”,

and

the

negative

is

color

coded

BLACK

and

labeled

The

positive

terminal

on

the

speaker

will

be

color

coded

RED,

or

will

be

labeled

“+”,

“pos”,

“positive”,

“8

ohms”,

or

“4

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

recommended

that

your

speaker

cables

be

terminated

with

“U”

type

spade

connectors.

These

will

give

the

most

contact

area

insuring

long-term

reliability.

The

spade

connector

should

have

a

maximum

width

of

0.57

inches

and

7

~

(~

an

opening

width

of

no

less

than

0.25”

mm0

57

.

(see

diagram

on

right).

-J-

_c

■

)

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-tiqhten

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.

Sound

audio

engineering

practice

suggests

the

use

of

at

least

AWG16,

stranded,

copper

cable.

Recommended

capacitance

of

the

speaker

wire

should

not

exceed

50pF

per

foot.

This

insures

high

frequencies

will

not

be

rolled-off.

It

is

suggested

that

for

all

the

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

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.

7

All

loudspeakers

having

a

nominal

impedance

down

to

4

ohms

can

be

connected

to

and

driven

by

the

GFA-7400/7300.

The

amplifier

can

drive

these

low-impedance

speakers

at

more

than

adequate

power

levels

with

no

difficulty.

It

should

be

noted

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

volumes

levels

from

your

system.

It

is

not

recommended

that

you

run

additional

sets

of

speakers

to

the

GFA-7400/7300.

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-3,

GFS-4

or

GFS-6

Speaker

Selector

is

strongly

recommended.

A

Speaker

Selector

enables

you

to

maintain

good

sonic

integrity

while

giving

you

the

flexibility

to

add

speakers

throughout

your

house.

CARING

FOR

YOUR

GFA-7400/7300

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-7400/7300.

8

REAR

PANEL

DESCRIPTION

OF

UNIT

NOTE!

Product

shown

is

GFA-7400,

GFA-7300

is

similar.

O

Inputs

The

audio

inputs

for

the

GFA-7400/7300

are

through

high-quality,

gold-plated

RCA

jacks

to

minimize

high-frequency

losses,

noise,

etc.

They

will

accept

standard

RCA-type

plugs,

one

for

each

of

the

five

channels;

Front

Left,

Center,

Right

Front,

Left

Rear,

and

Right

Rear.

To

insure

that

the

performance

designed

into

the

GFA-7500

is

preserved,

you

should

use

the

highest

quality

audio

cables

possible.

There

are

many

cables

which

are

color-coded

and

specifically

designed

for

this

application.

Your

Adcom

dealer

can

help

select

the

best

cable

for

your

needs.

(See

CONNECTING

THE

GFA-7400/7400

for

more

information).

0

Outputs

The

GFA-7400’s

connections

to

the

loudspeakers

are

made

through

high-grade,

5-way,

gold-plated

binding

post

terminals.

There

are

two

terminals

for

each

speaker,

which

are

colored

RED

for

the

positive

(+)

output

and

BLACK

for

the

negative

(-)

output.

The

GFA-7300’s

connections

to

the

loudspeakers

are

basically

similar;

there

are

two

terminals

for

each

speaker,

which

are

colored

RED

for

the

positive

(+)

output

and

BLACK

for

the

negative

(-)

output.

The

high-grade

gold-plated

binding

post

terminals

on

the

GFA-7300

are

however,

different.

These

connectors

easily

accept

stripped

bare

wires

or

pins.

To

use

spade

lugs

it

is

necessary

to

remove

the

black

molded

plastic

guide

block

that

fits

over

the

binding

posts.

To

remove,

take

out

the

two

screws

at

the

top

and

bottom

of

guide

block.

Store

the

guide

block

and

screws

for

future

use.

The

binding

posts

will

accept

a

variety

of

connector

types;

the

most

secure

and

prevalent

of

these

is

the

“U”-type

spade

connectors

(at

least

0.25"

wide

and

maximum

width

of

0.57”),.

The

terminal

will

also

accept

bare

wire

(up

to

AWG10)

and

“banana”

type

plugs

(single

or

dual).

(See

CONNECTING

THE

GFA-7400/7300

for

more

information).

9

©

12VDC

Triggering.

(GFA-7400

Only)

The

GFA-7400

and

GFA-7300

are

very

high

power

amplifiers

and

as

such

must

be

directly

connected

to

the

wall

outlet

or

an

appropriate

surge

protector

or

AC

line

conditioner.

It

must

never

be

connected

to

the

“switched”

outlets

on

the

rear

panel

of

a

pre-amplifier.

Usually

this

would

mean

that

when

you

turn

on/off

your

pre-amplifier

you

would

have

to

turn

on/off

your

power

amplifier

separately.

We

have

however

provided

the

ability

to

control

the

OFF/ON

function

of

the

GFA-7400

by

a

12Volt

DC

output

jack

on

the

rear

of

certain

ADCOM

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,

not

to

exceed

250mv.

Center

conductor

(tip)

is

positive

(+).

O

AC

Fuse

The

AC

Fuse

protects

the

electronic

circuits

of

the

GFA-7400/7300.

This

fuse,

normally,

will

fail

only

if

there

is

an

overload

within

the

GFA-7400/7300.

It

may,

however,

fail

if

the

amplifier

attempts

to

deliver

very

high

power

into

very

low-impedance

loudspeakers.

In

either

case,

BE

SURE

TO

REPLACE

THE

AC

Fuse

ONLY

WITH

AN

EXACT

REPLACEMENT

FUSE.

The

proper

fuse

values

are:

GFA-7400:

Fuse

Rating

BUSS®

Littelfuse®

For

115

volt

operation.15

Amp

250

Volt.ABC-15/250V.(3AB)

314015/250V

For

230

volt

operation.

8

Amp

250

Volt.AGC-8/250V.(3AG)

312008/250V

GFA-7300:

Fuse

Rating

BUSS®

Littelfuse®

For

115

volt

operation.T8

Amp

250

Volt.MDL-8A/250V.(3AG)

313008/250V

For

230

volt

operation.T4

Amp

250

Volt.MDL-4A/250V.(3AG)

313004/250V

WARNING

Before

attempting

to

replace

a

failed

fuse,

be

certain

to

unplug

the

AC

Power

Cord

from

the

AC

wall

outlet

to

prevent

possible

electrical

shock.

Replace

the

AC

Fuse

only

with

one

identical

in

type

and

rating

as

printed

on

the

rear

panel.

DO

NOT

USE

ANY

SUBSTITUTE

FUSES

WITH

DIFFERENT

RATINGS

OR

VALUES.

Failure

to

observe

this

precaution

may

cause

serious

damage

to

the

amplifier

circuits,

MAY

CREATE

A

FIRE

HAZARD,

AND

MAY

VOID

THE

WARRANTY._

If

the

Power

LED

(©)

does

not

glow,

it

may

be

an

indication

that

the

AC

fuse

has

blown.

If

you

are

using

the

12VDC

Triggering

feature

(GFA-7400

Only)

it

may

be

possible

that

there

is

a

problem

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.

10