Harman Kardon TA10 Owners Manual - Page 8

SERVICE

NOTES

Servicing

printed

circuits

is

a

simple

matter

and

is

no

more

complicated

than

servicing

conventionally

wired

circuits.

Printed

circuit

receivers,

can

be

more

easily

re-

paired,

if

certain

precautions

are

observed.

Standard

components

are

used

throughout

and

can

be

removedand

replaced

by

any

serviceman.

No

special

tools

or

skills

are

necessary.

However,

some

parts

which

have

special

mounting

and

connection

lugs

should

be

replaced

with

exact

duplicate

parts.

AVOID

DAMAGE

TO

COPPER

FOIL

Be

careful

when

removing

components

from

the

board.

However,

if

the

copper

foil

wiring

is

damaged

a

piece

of

wire

can

be

used

to

replace

the

damagedfoil.

Small

breaks

can

be

"jumped"

with

molten

solder.

Larger

breaks

can

be

repaired

with

ordinary

hook

up

wire.

It

is

unnecessary

to

replace

the

entire

board

be-

cause

of

foil

breakage.

AVOID

DAMAGE

TO

PRINTED

CIRCUIT

BOARD

Do

not

apply

excessive

pressure

to

the

printed

cir-

cuit

board

or

components.

This

is

especially

important

to

note

when

changing

tubes.

Although

the

board

is

sturdy

in

construction

and

mounting,

it

may

crack

or

break

if

proper

care

is

not

taken

when

servicing.

In

case

the

board

is

to

be

removed

from

the

chassis,

re-

move

the

mounting

screws

around

the

edges

and

un-

solder

the

few

leads

that

connect

between

the

board

and

the

chassis.

If

this

is

done,

a

vise

with

protected

jaws

should

be

used

to

hold

the

board

while

servicing

and

care

should

be

taken

not

to

exert

excessive

pressure

against

the

board.

AVOID

EXCESSIVE

DEPOSITS

OF

SOLDER

In

some

areas

on

the

printed

circuit

board,

the

wiring

is

very

closely

spaced.

When

resoldering

a

new

component

avoid

excessive

deposits

of

solder.

Exces-

sive

solder

may

cause

a

short

or

an

intermittent

trouble

to

occur

later

which

may

be

difficult

to

locate.

AVOID

OVERHEATING

When

using

the

soldering

iron

(35

watts

or

less),

do

not

overheat

the

component

terminals

or

the

copper

foil.

Excessive

heat

(applying

soldering

iron

longer

than

necessary,

using

a

higher

wattage

soldering

iron

than

recommended,

or

using

a

solder

gun)

may

cause

the

bond

between

the

board

and

foil

to

break.

This

will

necessitate

replacement

or

repair

of

the

foil

con-

nection.

TOOLS

AND

MATERIALS

REQUIRED

(1)

Low

wattage

soldering

iron

with

a

small

point

or

wedge

(rating

should

not

exceed

35

watts).

(2)

Small

wire

brush.

8

(

3

)

(4)

(5)

60%

tin,

40%

lead,

low

temperature

rosin

core

solder.

Thin

bladed

knife.

Small

wire

pick,

or

soldering

aid.

REPLACING

COMPONENTS

SOLDERING

REPLACEMENT

COMPONENT

TO

OLD

LEADS

Cut

the

leads

where

they

enter

the

defective

compo-'

nent.

Clean

off

the

ends

of

the

leads,

leaving

as

much

of

the

leads

as

possible.

Make

a

small

loop

in

each

lead

of

the

replacement

component

and

slide

the

loops

over

the

remaining

leads

of

the

old

component.

Caution

should

be

taken

not

to

overheat

the

connection

since

the

copper

foil

may

peel

or

the

original

component

lead

may

fall

out

of

the

board.

This

is

possible

due

to

heat

trans-

fer

through

the

leads.

The

lead

length

of

the

replace-

ment

part

should

be

kept

reasonably

short

to

provide

some

mechanical

rigidity.

UNSOLDERING

AND

RESOLDERING

COMPONENTS

To

test

a

component

or

if

the

component

is

mounted

in

such

a

manner

that

the

above

method

can

not

be

used

(such

as

vertically

mounted

capacitors,

etc.

)

the

compo-

nent

can

be

replaced

by

unsoldering

it.

This

procedure

should

be

used

whenever

it

is

necessary

to

unsolder

any

connections

to

replace

defective

components.

(a)

Heat

the

connection

on

the

wiring

side

of

the

board

with

a

small

soldering

iron.

When

the

solder

melts,

brush

away

the

solder.

Do

not

overheat

the

connection.

In

the

process

of

removing

the

solder,

caution

must

be

taken

to

prevent

excessive

heating.

Therefore,

do

not

leave

the

iron

on

the

connection

while

brushing

away

the

solder.

Melt

the

solder,

remove

the

iron

and

quickly

brush

away

the

solder.

It

may

require

more

than

-

01

-

re

heating

and

brushing

process

to

com-

pletely

remove

the

solder.

(b)

Insert

a

knife

blade

between

the

wiring

foil

and

the

"bent

-over"

component

lead

and

bend

the

lead

per-

pendicular

to

the

board.

(It

may

be

necessary

to

apply

the

soldering

iron

to

the

connection

while

performing

this

step

as

it

is

sometimes

difficult

to

completely

break

the

connection

by

brushing.

)

Do

not

overheat

the

connection.

(c)

While

applying

the

soldering

iron

to

the

con-

nections,

"wiggle"

the

component

until

it

is

removed.

(d)

Remove

any

small

particles

of

solder

using

a

clean

cloth

dipped

in

solvent.

(e)

A

thin

film

of

solder

may

remain

over

the

hole

through

the

board

after

removing

the

component.

Pierce

the

film

with

the

lead

from

the

new

component

after

heat-

ing

the

solder

film

with

the

soldering

iron.

(f)

Insert

the

leads

of

the

new

component

through

the

holes

provided.

Cut

to

desired

length

and

bend

over

the

ends

against

the

copper

foil.

Resolder

the

connection

with

60/40

low

temperature

solder.

Harman Kardon TA10 Owners Manual - Page 8

Service, Notes, Replacing, Components

Page 8 highlights