WEBSTER CHICAGO 79 - Page 25

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WEBSTER

CHICAGO

A -

MACHINE

WILL

NOT

RUN

Check

the

fuse

in

the

fuse

holder (

Illustration

64,

Fig.

11).

Replace

with

1

amp.

fuse

if

open

but

be

certain

that

cause

for

open

is

removed.

B -

SPEAKER

FIELD

BURNED

OUT

Check

oscillator

coil (

Illustration

35,

Fig.

27)

for

grounded

primary.

If

defective,

replace

coil

assembly.

C-

REPLACING THE

OSCILLATOR

COIL

While

replacing

a

burned

out

oscillator

coil,

make

the

following

circuit

changes

unless

already

made.

1 —

Unsolder

the

heavy

blue

lead from

terminal

No.

3

of

the

6V6

socket.

Solder

one

side

of

a .

002

mid.

mica

condenser

to

terminal

No.

3

of

the

6V6

and

the

blue

lead

to

the

other

side.

2 —

Unsolder

the

heavy

red

lead

from

terminal

No.

4

of

the

6V6

socket,

and

solder

it

to

the

ground

terminal

on

the

coil

assembly

frame.

This

iso-

lates

the

oscillator

coil

and

prevents

burn-

out

of

the

speaker

field

if

the

oscillator

coil

should

burn

out.

D -

DOES

NOT

RECORD

Check

the

6V6

tube.

Check

connections

in-

side

microphone

plug

for

opens

or

grounds.

Make

certain

that

the

lead

to

terminal

No.

2

BULLETIN

79P038

MODEL

80

of

the

recording

head

is

not

grounded.

Check

the

oscillator

coil (

35) (

Fig.

27)

for

open

connections.

Check

condensers

C-4

and

C-7

for

opens

or

shorts.

A

simple

home

made

device

will

aid

in

test-

ing

the

oscillator

coil

and

output.

Attach

two

leads

to

a

6.3

volt

pilot

light.

Touch

one

lead

to

the

red lead

from

terminal

No.

3

of

the

recording

head

and

ground

the

other

lead.

If

the

bulb burns

brightly,

the

oscillator

cir-

cuit

is

in

good

condition.

The

control

lever

must

be

in "

Run"

position.

E -

DOES

NOT

ERASE

Switch

contacts (

Fig.

29)

may

not

be

making

contact.

Condensers

4

and

7 (

Fig.

28)

may

be

open

or

shorted.

Defective

6V6

tube.

Defective

oscillator

coil.

See

paragraph "

C"

for

circuit

changes.

Defective

recording

head.

F -

DOES

NOT

RECORD

OR

ERASE

First

check

oscillator

and

circuit

as

suggest-

ed

previously.

If

recording

head

is

suspect-

ed,

substitute

another

head

and

check

its

operation.

Do

not

attempt

to

repair

a

re-

cording

head

but

replace

with

a

new

one.

G-

LOW

RECORDING

LEVEL

Check

tubes,

especially

6X5

and

6V6.

May

be

caused

by

weak

head,

check

by

substitu-

tion.

22