Telefunken M 204 E - Rubber Roller Pressure Measurement; Drive Mechanism Adjustments; Clearance Checks (FF;Rewind); Friction Wheel, Slipping Clutch, Tape Tension, and Brakes

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Measuring

and

Adjusting

the

Rubber

Roller

Pressure

Measurement:

The

pressure

of

the

rubber

roller

should

be

measured

with

a

tape

inserted

and

the

tape

drive

button

de-

pressed.

Apply

a

contactor

or

a

spring

balance

(1000p)

to

the

right

end

of

the

roller

holder.

Therewith

lift

off

the

rubber

roller

from

the

tape

and

drive

capstan,

and

slowly

return

it

to

the

tape,

parallel

to

the

drive

capstan,

until

the

tape

just

commences

to

run.

The

reading

should

then

be

660

to

730

p,

corresponding

to

a

roller

pressure

of

900

to

1000

p.

Adjustment:

The

force

of

the

pressure

spring

can

be

adjusted

by

turning

the

nut

(H).

Fast

Forward

Drive

In

the

“Stop“

setting,

the

clearance

between

the

right

inter-

mediate

wheel

and

the

right

engagement

plate

should

be

greater

than

0.5

mm.

The

tension

spring

for

the

fast

forward

drive

should

be

hooked

in

such

that

a

force

of

1100

+

100

p

results

when

the

right

intermediate

wheel

engages

the

brake

plate.

This

force

must

be

measured

with

a

contactor

at

the

measuring

point

opposite

to

the

hook-in

toothing

on

the

lever.

The

fast

forward

drive

button

must

not

be

pressed

for

this

measurement.

Fast

Rewind

In

the

setting

“Stop",

the

clearance

between

the

left

intermediate

wheel

and

the

left

engagement

plate

should

be

greater

than

0.5

mm.

Measuring

the

Friction

Wheel

Pressure

The

friction

wheel

is

situated

between

the

right

take-up

wheel

and

the

flywheel

disc.

During

playback,

the

force

with

which

the

intermediate

wheel

is

pulled

against

the

flywheel

disc

and

the

take-up

plate

should

lie

between

160

and

200

p,

as

measured

in

the

direction

of

the

pull-in

force

at

the

measuring

point

A.

When

the

unit

is

lying

horizontal,

these

values

increase

by

about

50

p

(self

weight

of

slider).

The

intermediate

wheel

slider

must

move

lightly.

Slipping

Clutch

(50

mm

diameter

measuring

spool)

The

upper

slipping

clutch

in

the

feed

plate

and

take-up

plate

assemblies

is

adjusted

with

the

star

spring

such

that

a

slip

torque

of

1100

to

1500

pem

is

obtained,

corresponding

to

a

force

of

440

to

600

p.

The

slip

torque

of

the

lower

slipping

clutch

of

the

left

feed

plate

assembly

should

lie

between

100

and

140

pcm,

corresponding

to

a

force

of

40

to

60

p.

The

lower

slipping

clutch

in

the

right

take-up

plate

assembly

is

adjusted

with

the

three

star

springs

such

that

a

slip

torque

of

330

to

470

pem

is

obtained,

corresponding

to

a

force

of

130

to

190

p.

The

auxiliary

brake

on

the

right

bottom

feed

plate

is

adjusted

with

the

tension

spring

such

that

the

braking

torque

in

the

rewind

setting

is

100

to

180

pcm,

corresponding

to

a

force

of

40

to

70

p.

Measuring

the

Tape

Tension

The

felt

pad

pressure

on

the

record/playback

head

should

be

40

to

60

p.

The

following

tape

tension

values

are

permissible

for

recording

and

playback

operation:

‘

at

start

of

tape:

greater

than

30p

at

end

of

tape:

less

than

140p

The

measurement

should

be

made

during

playback

operation.

The

rubber

pressure

roller

must

thereby

be

lifted

off

the

drive

capstan.

After

inserting

a

full

or

nearly

empty

18

cm

diam.

tape

reel,

respectively,

pull

the

tape

with

hooked-in

spring

balance

(250

p)

past

the

heads

and

the

drive

capstan

to

the

right,

with

about

the

nominal

speed

of

9.5

cm/s.

The

tape

tension

fluctuations

over

any

one

full

revolution

of

the

left

engagement

plate

should

not

exceed

+

5

p

about

the

mean

value.

Brakes

It

is

important

to

ensure

that

the

brake

linings

and

the

brake

surfaces

of

the

feed

and

take-up

plates

are

clean.

When

neces-

sary,

they

must

be

cleaned

with

isopropyl

alcohol.

In

the

resting

state,

the

stop

brakes

must

wedge-in

securely.

In

order

to

ensure

this,

a

clearance

of

1

mm

must

exist

between

the

ends

of

the

brake

slider

plate

and

the

brake

levers

at

the

points

E.

Adjust

the

sheet

metal

ends

accordingly.

With

the

tape

drive

button

actuated,

the

clearance

between

the

brake

rubber

and

the

feed

or

take-up

plate

must

be

greater

than

1

mm.

the

auxiliary

brake

on

the

supporting

plate

of

the

left

feed

plate

assembly

must

lift

off

when

‘the

rewind

button

is

pressed.

In

all

other

operating

states,

the

auxiliary

brake

must

restrain

the

supporting

plate.

Fig.5

Depiction

of

the

head

carrier

plate

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