TANDBERG TCD 42OA Alignment Instructions

TANDBERG'

TCD

42OA

CircuitDiagrams

with

Alignment Instructions

n

TANDBERG'-

The

European

Alternative

Electrical

checks and

adjustments

General

-

0

dB

level

is

defined

as:

0.775

V

in

the RADIO

socket, using Ty'pe I

or

II

tapes.

1.2 V

in the RADIO

socket using Metal

tape.

1.5 V in

the OUTPUT

sockets using Type I or II

tapes.

2.3

V

in the OUTPUT

sockets

using

Metal

tape.

-

Before

adjusting,

the tape

path

must be

cleaned

and demagnetized.

It is necessary

that the

tape

path

is correctly

adjusted.

-

Carry

out

the adjustments

in the

order described

because

the

adjustments

affect

each other.

-

Remove

the base panel.

-

When

adjusting

the

Bias-traps

and the Bias-pre-

adjustment,

the

top

panel

must

be

removed.

Equipment

required

-

2

millivoltmeters

- Audio

signal

generator

- Frequency

counter

- Distortion

meter

- Wow

and flutter

meter

- Tandberg

test cassettes:

- No.

21

(Speed check,

1000 Hz)

- No.

22

(Wow

and flutter

check, 3150 Hz)

- No.

23

(Azimuth

adj. playb. head,

6300

Hz)

-

No.

24

(Playback

level

adj., 1000 Hz)

- Measuring

cassettes:

- Maxell

UD XL I

(Type I)

- Maxell

UD XL II (Type

II)

- Fuji

Metal

or TDK Metal

MA

(Metal)

Before

adjusting,

set

buttons

to:

- MPX-FILTER (situated

at the back

of the deck)

to OFF.

- Dolby

NR.*

to

Off.

- Output

Lcvel

controls

*

The

words

"Dolby"

is registrered trade marh

of

Dolby

Laboratories

Inc.,

US.

Nfi

stands

for

Noise

Reduction.

Before

adjusting, fold

out

page

5.

Oscillator

The oscillator

frequency

is between

80

and 100

kHz. The voltage

measured

on the erase head

should

be

between 6

and 8

volts

with Type

II or

Metal

cassettes.

Bias traps

-

Remove

the

top

panel.

-

Nleasure

with a millivoltmeter

on

C107

and

C207

and

adjust

L101

and L201 to minimum

reading

on the millivoltmeter.

Record/Playback

head

- azimuth

- Insert

a

Tandberg

test

cassette

No.

23

or a

standard

azimuth

cassette.

-

Set

the

Monitor

button

to Taoe

and

connect

a

millivoltmeter

to each channel

of the OTITPUT

sockets.

- Press

the

Play

button. Adjust

the

playback

azimuth

screw

shown in the figure

to obtain

maximum reading

on each channel.

to

maximum.

Playback

level

- Insert

Tandberg

test

cassette

No.

24

(Playback

level

adjustment

1000 Hz).

-

Adjust

with the

PLAYBACK

LEVEL ADJ.

R317/R417

to

1.5 V

on the

OUTPUT sockets.

(In

the

RADIO

socket, adjust

to

775

mV.)

- If

you

use a Dolby

level

cassette,

adjust

to

1.2 V

on

the

OUTPUT

sockets

(0.615

mV in the

RADIO

socket).

Bias

(pre-adjustment)

-

Set

the

TCD

420A

to record, Metal

tape

loaded.

-

Adjust

with

R21031IJ.2203

(Bias

Adjustment

Metal)

to

approximately

8 -

9

mV

measured

on

TPl and

TP2 (on

the

Osc.

board),

see figure.

NOTE!

Adjusting the TCD

420A, using the

RADlo-socket.

Overall

frequency

response

with

Metal

tape

Set

theTCD

420A

to recording.

Adjust

the gene-

rator

to

-

30

dB

(=

25

mV

on the millivoltmeters)

and record

a40OHz,

a

10

kHz,

and

a 15 kHz

signal

at this level.

-

Rewind

and

play

back.

-

Use the

400

Hz

signal as

a reference

and check

on both

channels

that the

10 kHz

and 15 kHz

signals

are within

the

following

tolerance:

r3dB.

If

outside

the tolerance

adjust

R2103/R2203

BIAS

|DJ.

M!,TAL.

Then

make

a

new recording,

play

back and

check once

more.

- If you

can not

adjust to

correct response

with

\?1991R2203,

BIAS ADJ.

METAL,

then

adjust

R501/R601,

TREBLE

ADJ. METAL.

-

Make

a new recording,

play

back

and check

once

more.

- Then

check the

frequency

response

t

3 dB,

30

-

18000

Hz.

-

When

the

frequency

response

is

correct,

check

the response

with

the

Dolby

NR.

circuit

"On".

Recording

Level

-

Metal

tape

Connect

an

audio-generator

and two millivoltmeters

to the RADIO-socket.

Set

the

TCD

420A

to

Record,

use

Metal

tape.

Adjust

the generator

to

400 Hz

(= 450 mV

on the millivoltmeters).

-

Start

recording.

-

Rewind

and

play

back

(Output

Level

controls

to

maximum).

- The

millivoltmeters

should now read

approxi-

mately

450 mV (-

2

to 0 dB).

If

outside

the

tolerance,

make

a

new

recording

while adjusting R105/R205,

REC. LEVEL METAL

as required.

Then

play back and check

once more.

Distortion

- Metal

tape

-

Set

the TCD

420A

to recording.

- Generator

to 1000 Hz

(=

775 mV on the

milli-

voltmeters).

-

Rewind

and

play

back.

-

Check

that the distortion

is

(

3%.

- If

outside the

tolerance,

adjust R2103/R2203,

BIAS

ADJ.

METAL.

- Make

a new recording,

play

back

and check

once

more.

-

Then

check

that

the

frequency

response

is

within

the

tolerance.

Signal/noise -

Metal tape

The signal/noise

ratios at

3To

distortion

should

be

at

least

as good

as specified. Measure

with

the

Dolby

NR.

circuit

"On".

IEC

A-curve

68

dB

IEC Linear

RMS

56

dB

Program

meters

-

Metal

tape

-

Set the TCD

420A

to Record.

-

Record

a

400

Hz

signal from the generator

(=11.2 V

on

the millivoltmeters)

and adjust

the

program

meters

to 0 dB deflection

on

the Metal

ry3l9 _11th

Rl35/R235,

METER

LEVEL

ADJ.

RECORD.

^

.*\

/

Adiustments

for

type

I taPe

Recording

Level

Adjustment

for

type

ll tape

Recording

Level

lf outside rhe

tolerance

(-

2

to 0

dB),

adjust

{

gutside

the tolerance,

-

2

to 0

dB,

adjust

R529/R629,

REC. LEVEL

I. Do

not

touctr

Rl05/

R104/R204,

REC. LEVEL

II.

R205'

REC'

LEVEL

METAL'

-

Make

a

new recording,

play

back and

check

once

- Make

a

new

recording,

play

back

and

check

once

more.

-

Use

the

same

level

as

for Metal

tape

(= 450 V

on

- Use

the

same

level

as

for Metal tape

(= 450 mV

the millivoltmeter).

on

the

millivoltmeters).

-

Record,

rewind and

play

back.

- Record,

rewind

and

play

back.

Overall

frequency

response

Overall

freqeuncy

response

Use the same

level as

for Metal tape

(=

25

mV on

-

Use

the

same

level

as for

Metal tape

(=

25

mY

the millivoltmeters).

on the millivoltmeters).

If

outside the tolerance.

t

3 dB.

30

-

18000

Hz,

If outside

the tolerance,

t

3 dB,

30

- 18000

Hz,

adjust

R21021R2202,

BIAS ADJ.

II.

adjust

R2101/R2201,

BIAS

ADJ.

I.

- Then

check

the

frequency

response

with the

- Then check

the

frequency

response

with the

Dolby NR. circuit

"On".

Dolby NR. circuit

"On".

Distortion

- Record

1000

Hz

at

0

dB

(=

77b mV

on

the

- Record

1000

Hz at 0 dB

(=

775

mV

on

the

millivoltmeters)'

millivoltmeters).

- Rewind and

play back.

- Rewind

and

play back.

-

Check

that the distortion

is

(

2%.

- Check that

the distortion

is

42%.

If outside

the tolerance,

adjust

R104/R204,

REC.

If outside

the tolerance,

adjust

R529/R629,

REC. LEVEL

II and

R2102/R2202

BIAS ADJ'

II.

LEVEL

I

and

R21021F.2202,

BIAS

ADJ.

I.

- Then

check

the

frequency

response

and the

- Then

check

the

frequency

response and

the

distortion

once more.

distortion once

more.

Speed

check

Play

back

Tandberg

test cassette

No.

21

(Speed

check

1000

Hz)

and

measure

with a

frequency

counter.on

the

output:

t

1%

(990

-

1010

on the

counter).

If necessary, adjust

to correct

speed with

R208'

SPEED

ADJ. on the

Motor

control

board.

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80

Part

No. 714136

Printed

in Norway

by

Reclamo

A/S

GrTandbers

A/S,

1980

l:I

Tandberg

A/S, Post

Office Box 55, Bogerud, N-Oslo

6, Norway

TANDBERG TCD 42OA Alignment Instructions

TANDBERG TCD 42OA Alignment Instructions

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