Tandberg TCD-420-A Service manual

TANDBERG'

n

TCD
CircuitDiagrams

42OA

with

Alignment Instructions

TANDBERG'-

The

European

Alternative

Electrical

checks and

adjustments

General

-

0

level

dB

0.775 V in
tapes.

1.2 V

in the RADIO

1.5 V in

tapes.

2.3 V in the OUTPUT

-

Before
and demagnetized.
path

is correctly

-

Carry

out

because

-

Remove

-

When

adjusting

adjustment,

Equipment

-

millivoltmeters

2

- Audio

- Frequency

- Distortion

- Wow

- Tandberg

- Measuring

Before

- MPX-FILTER (situated

and flutter

- No.

- No.

- No.

-

No.

- Maxell

- Maxell

- Fuji

adjusting,

defined

is

the RADIO

the OUTPUT

adjusting,

the adjustments

the

the base panel.

required

signal

meter

test cassettes:
(Speed check,

21

(Wow

22

(Azimuth

23

(Playback

24

cassettes:
UD XL I
UD XL II (Type

Metal

the tape

adjusted.

adjustments

the

the

top

generator

counter

meter

and flutter

or TDK Metal

set

buttons

as:

socket using Metal

It is necessary

Bias-traps

panel

adj. playb. head,
level

(Type I)

to OFF.

- Dolby

NR.*

to

Off.

socket, using Ty'pe I

sockets using Type I or II
sockets

at the back

using

path

must be

that the

in the
affect

1000 Hz)

adj., 1000 Hz)

II)

to:

order described

each other.

and the Bias-pre-

must

check, 3150 Hz)

MA

removed.

be

(Metal)

of the deck)

Metal

6300

or

tape.

tape.

cleaned

tape

Hz)

Before

II

Oscillator

The oscillator
kHz. The voltage
should
Metal

adjusting, fold

frequency

be

between 6

cassettes.

measured

page

out

is between

and 8

5.

and 100

80

on the erase head

volts

with Type

II or

Bias traps

-

Remove
Nleasure

­C207
reading

Record/Playback

- Insert
standard

-

Set
millivoltmeter
sockets.

- Press
azimuth
maximum reading

Playback

- Insert
level

-

Adjust
R317/R417

(In

- If

you
on
RADIO

the

with a millivoltmeter

and

on the millivoltmeter.

Tandberg

a

azimuth

Monitor

the

Play

the

screw

panel.

top

adjust

head

button

to each channel

button. Adjust

shown in the figure

level

Tandberg

adjustment

with the

RADIO

the

test

1000 Hz).

PLAYBACK

1.5 V

to

socket, adjust

use a Dolby

the

OUTPUT

socket).

on

L101

and L201 to minimum

- azimuth

test

cassette

cassette.

to Taoe

on each channel.

cassette

No.

and

of the OTITPUT

the

No.

LEVEL ADJ.

on the

OUTPUT sockets.

to

level

cassette,

sockets

(0.615

C107

or a

23

connect

playback

to obtain

(Playback

24

775

mV.)

adjust

to

mV in the

and

a

1.2 V

- Output

*

The

words
Dolby
Noise

Lcvel

controls

"Dolby"

Laboratories

Reduction.

to

maximum.

is registrered trade marh

Inc.,

US.

Nfi

stands

for

of

(pre-adjustment)

Bias

-

Set
Adjust

­Metal)

the

TCD
with

to

TPl and

420A

to record, Metal

R21031IJ.2203

approximately

TP2 (on

the

Osc.

(Bias

8 - 9 mV

board),

tape

loaded.

Adjustment

measured

see figure.

on

NOTE!

Adjusting the TCD

420A, using the

RADlo-socket.

Overall
Set

rator
and record
at this level.

-

-

frequency

theTCD

-

to

Rewind
Use the

on both
signals

30

a40OHz,

and

400

channels

are within

r3dB.

If

outside

|DJ.
back and

- If you
\?1991R2203,

R501/R601,

-

Make

the tolerance

M!,TAL.

check once

can not

a new recording,

more.

- Then

-

check the

18000

When

Hz.

the

the response

response

420A

to recording.

dB

(=

25

a

play

back.

Hz

signal as

that the

the

Then

make

more.

adjust to

BIAS ADJ.

TREBLE

frequency

frequency

with

the

with

Metal

tape

Adjust

mV

on the millivoltmeters)

10

kHz,

and

a 15 kHz

a reference

10 kHz

following

adjust

R2103/R2203

a

new recording,

and check

and 15 kHz

tolerance:

correct response

METAL,

ADJ. METAL.
play

back

and check

is

correct,

circuit

t

response

response

Dolby

NR.

the gene-

signal

BIAS

play

with

then

adjust

once

3 dB,

30

check

"On".

Distortion

-

Set

- Generator

- Metal

the TCD

to 1000 Hz

tape

420A

to recording.

(=

775 mV on the

milli-

voltmeters).

-

Rewind

-

Check

- If

outside the

BIAS

- Make

ADJ.
a new recording,

play

and

back.

that the distortion

tolerance,

METAL.

play

(

is

3%.

adjust R2103/R2203,

back

and check

once

more.

-

Then

check

within

Signal/noise -

-

The signal/noise

least

at
Dolby

IEC

as good

NR.

A-curve

IEC Linear

the

tolerance.

circuit

RMS

that

frequency

the

Metal tape

ratios at
as specified. Measure

"On".

68
56

3To

dB
dB

distortion

response

should

with

the

is

be

Recording

Connect
to the RADIO-socket.
Record,

400 Hz

-

Start

-

Rewind
maximum).

- The

mately

If

outside
while adjusting R105/R205,
as required.

Level

audio-generator

an

Metal

use

(= 450 mV
recording.

and

millivoltmeters

450 mV (-

the

Then

Metal

-

play

tolerance,

play back and check

tape

and two millivoltmeters

Set

the

Adjust

tape.

on the millivoltmeters).

(Output

back

should now read

to 0 dB).

2

make a new

REC. LEVEL METAL

TCD

420A

to

the generator

Level

controls

approxi-

recording

once more.

to

to

Program

-

Set the TCD

-

Record
(=11.2 V
program

ry3l9 _11th
RECORD.

meters

a

on
meters

Metal

-

420A

to Record.

400

Hz

signal from the generator

the millivoltmeters)

to 0 dB deflection

Rl35/R235,

tape

METER

and adjust

on

the Metal

LEVEL

ADJ.

the

^

Adiustments

for

type

I taPe

Adjustment

for

type

ll tape

.*\

/

Recording

Use

­the millivoltmeter).

Record,

-

lf outside rhe
R529/R629,
R205'

- Make a new
more.

Overall

Use

-

on the millivoltmeters).

If outside

adjust

- Then check
Dolby NR. circuit

Distortion

- Record
millivoltmeters).

- Rewind

- Check that

If outside

LEVEL I and

- Then
distortion once

Level

level

same

the

rewind and

tolerance

REC. LEVEL

LEVEL

REC'

recording,

frequency

level

same

the

the tolerance,

R2101/R2201,

the

Hz at 0 dB

1000

play back.

and

the distortion

the tolerance,

R21021F.2202,

check

the

for Metal

as

play

(- 2 to 0

METAL'

play

response

as for

t

3 dB,

BIAS

frequency

"On".

adjust

frequency

more.

tape

back.

dB),

not

I. Do

back

and

Metal tape

- 18000

30

I.

ADJ.

response

(=

is

BIAS

mV

775

42%.

R529/R629,

ADJ.

response and

(= 450 V

adjust

touctr

check

(=

25

with the

on

I.

Recording

on

Rl05/

once

mY

Hz,

the

REC. LEVEL

the

- Use
on

- Record,

gutside

{
R104/R204,

Make a new recording,

­more.

Overall

Use the same

the millivoltmeters).

outside the tolerance.

If

adjust

- Then
Dolby NR. circuit

Distortion

- Record
millivoltmeters)'

- Rewind and

-

Check

If outside

- Then
distortion

Level

level

same

the

millivoltmeters).

the

rewind

the tolerance,

freqeuncy

and

REC. LEVEL

response

level as

R21021R2202,

frequency

check

the

Hz

1000

that the distortion

the tolerance,

II and
check

once more.

at 0 dB

play back.

R2102/R2202

frequency

the

for Metal tape

as

play

back.

-

to 0

2

II.

back and

play

for Metal tape

t

BIAS ADJ.

"On".

adjust

30

3 dB.

response

(=

77b mV

(

is

2%.

R104/R204,

BIAS ADJ'

response

II.

(= 450 mV

adjust

dB,

check

(=

25

-

18000

with the

on

and the

once

mV on

Hz,

the

REC.
II.

Speed

Play
check
counter.on
counter).

If necessary, adjust
SPEED

check

Tandberg

back

Hz)

1000

the

ADJ. on the

and

output:

test cassette

(990

1%

control

with a

speed with

measure

t

to correct

Motor

No.

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frequency

-

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Tandberg

A/S, Post

Office Box 55, Bogerud, N-Oslo

6, Norway

1727

- G - 80

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in Norway

GrTandbers

A/S,

Part

No. 714136

by

1980

Reclamo

A/S