Harman Kardon HK250 Owners Manual - Page 3

USING

THE

MODEL

HK250

AS

A

MONAURAL

50

WATT

POWER

AMPLIFIER

MAINTENANCE

AND

REPAIRS

Connecting

Your

Speaker:

Strap

the

two

32

ohm

speaker

terminals

together.

Connect

your

speaker

to

the

G

and

32

ohm

terminals

if

your

speaker

has

a

nominal

impedance

of

16

ohms.

If

you

are

using

an

8

ohm

speaker,

strap

the

16

ohm

terminals

together

and

con-

nect

your

speaker

leads

to

G

and

16.

NOTE:

The

PARALLEL

-SEPARATE

switch

located

on

the

rear

panel

must

remain

in

the

PARALLEL

position

for

this

method

of

operation.

1615

SPEAKER

RIGHT

SPEAKER

LEFT

SPEAKER

OOO

4

B

16

32

OOOO

4

8

16

2

Diagram

B

Connecting

The

Model

HK250

To

Your

Monaural

Preamplifier:

Connect

a

shielded

lead

between

either

the

LEFT

or

RIGHT

INPUT

on

the

HK250

and

the

Audio

Output

on

your

preamplifier.

ADJUSTMENTS

Output

Tube

Balance

Controls:

Individual

OUTPUT

BALANCE

controls

for

LEFT

and

RIGHT

channels

are

located

on

the

top

of

the

chassis

between

the

output

tubes.

These

controls

are

preset

at

the

factory

for

minimum

distortion

and

should

not

be

readjusted

unless

the

output

tubes

are

changed.

To

adjust,

set

the

LEFT

and

RIGHT

OUTPUT

BALANCE

control

for

minimum

hum

in

your

speaker

system.

If

the

hum

level

is

inaudible,

set

the

control

to

the

exact

mid

-position.

For

critical

adjustment

the

control

should

be

set

with

an

intermodulation

distortion

meter

for

minimum

IM.

System

Hum

or

Noise:

In

any

high

fi

delity

installation,

hum

may

be

caused

by

the

interconnection

of

a

record

changer,

tuner

and

amplifier,

as

a

result

of

the

cables

and

different

grounds.

A

good

way

to

eliminate

this

problem

is

to

fi

rst

disconnect

everything

but

the

speakers

from

the

amplifier,

and

listen

for

hum.

If

the

hum

persists,

make

the

balance

adjustments

described

above.

Try

reversing

the

amplifier

power

plug.

Now

plug

in

the

record

player.

If

hum

appears,

try

reversing

the

record

player power

plug,

and

try

connecting

a

wire

from

the

record

player

chassis

to

the

amplifier

chassis.

In

this

way,

connect

the

tuner,

tape

deck

and

other

de-

vices

in

turn.

Note

that

hum

may

be

picked

up

by

defective

interconnecting

cables,

and

by

interconnecting

cables

running

too

close

to

power

cables.

Fuse:

In

the

event

of

a

potentially

damaging

failure

of

tubes

or

components,

the

Model

HK250

is

protected

by

a

4

ampere,

type

3AG

fuse,

located

on

the

rear

of

the

unit.

If

this

fuse

is

blown,

it

should

be

replaced

only

with

one

of

the

same

rating.

Replacing

with

a

fuse

of

higher

rating

will

not

protect

the

amplifier,

and

may

result

in

severe

damage,

which

will

not

be

covered

by

the

factory

warranty.

Routine

Maintenance:

Due

to

the

conservative

design

and

high

quality

components

of

the

Model

HK250,

no

routine

maintenance

other

than

yearly

tube

checking

is

advised.

Oc-

casional

resetting

of

the

output

balance

adjustments,

following

the

procedure

described

above,

will

keep

the

unit

operating

at

peak

efficiency.

These

adjust-

ments

should

certainly

be

made

after

any

tube

replacement.

Repair:

Only

the

most

qualified

service

technician

should

be

employed,

as

special

equipment

and

training

is

required

to

properly

service

a

high

fi

delity

amplifier.

This

manual

contains

information

of

great

value

to

the

repairman,

and

should

be

kept

available.

Factory

Warranty

Stations

are

maintained

in

most

major

cities.

For

the

ad-

dress

of

the

nearest

one,

or

for

any

other

information

relating

to

your

Harman-

Kardon

products,

write

to

the

attention

of

the

Customer

Service

Department,

Harman-Kardon,

Inc.,

520

Main

St.,

Westbury,

N.

Y.

Be

sure

to

include

the

model

and

serial

number

of

the

set

in

question.

A

short

description

of

your

complete

in-

stallation

is

often

of

help

in

answering

your

questions.

H

-K

Part

No.

ES771372

RVCOM2569

FT2382665

FT2382666

jE2382669

JE2382720

Z2382924

LIST

OF

REPLACEABLE

PARTS

Description

SPD

Slide

Switch

Balance

Control

100

ohm

Power

Transformer

Output

Transformer

20MFD/450V,

150MFD/50V

125MFD/250

V

Electrolytic

Silicon

Diode

.5

Amp/300V

List

Price

.45

.80

21.25

18.25

Electrolytic

2.10

2.00

3.50

Harman Kardon HK250 Owners Manual - Page 3

MFD/450V

Page 3 highlights