Akai 1722W User manual

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1

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STEREO

TAPE

RECORDER

mopeEL

1722W

ALSO

APPLICABLE

TO

MODEL

1722L

STEREO

TAPE

RECORDER

SECTION

1

SERVICE

MANUAL

.......

sig

eteaternateis

tentiefes,

OS

SECTION

2

PARTS

LIST

...................

0..-0.2---

20

SECTION

3

SCHEMATIC

DIAGRAM....................

40

ae

i

7

a

SECTION

1

SERVICE

MANUAL

TABLE

OF

CONTENTS

L

SPECIFICATIONS:

«

2s.

caiccenigie

bebe

a

bes

det

ehh

Mobi

as

tases

Gees

tee

4

Il.

MEASURING

METHOD

.............-.0-

2202

e

eee

eee

ete

teens

6

1.

TAPE

SPEED

DEVIATION

...........

2...

eee

eee

ne

ete

6

2.

WOW

AND

FLUTTER

......

2...

eee

ee

teen

eee

6

3.

FREQUENCY

RESPONSE

.......-.

0

eee

eee

eee

eee

6

4.

SIGNAL

TO

NOISE:

RATIO

122.

dd

hie

Sioltal

tdacee

eb

eran

eR

eheee

eS

sk:

cng

BS

eee

Bas

6

5.

TOTAL

HARMONIC

DISTORTION

FACTOR

.......-....

0200

e

ee

eee

7

6.

CROSS

TALK

(Cross

talk

between

the

tracks)

...........0

02

e

ee

eee

eee

eee

7

7.

ERASE

RATIO

..

1...

ene

ene

ee

eee

tt

eee

7

8.

POWER

OUTPUT...

ee

eee

een

ees

7

Hl.

DISMANTLING

OF

UNIT

.............

02020

e

cee

eet

eae

8

IV.

MECHANISM

ADJUSTMENT

------

2-20-2000

c

eset

cere

c

treet

entrees

testes

9

I

PINCH

WHEEL

ADJUSTMENT

ig

aa

asa

ier

Pan

eee

Spb

ca

ate

Vain

he)

Griese

Ob

TS

eAD

eel

S

ec

R-Rh

One)

o.

wh

aleco Seine

aa

9

2.

SUPPLY

REEL

TABLE

TENSION

ADJUSTMENT

........-..---.5e

ee

eee

ee

eres

11

3.

TAKE

UP

REEL

TABLE

TENSION

ADJUSTMENT

...........-------+

eee

eeee

11

4.

FWD/REC

MODE

MECHANISM

CHANGE

AND

ADJUSTMENT

..........-.----

12

5.

DRIVE

BELT

POSITION

ADJUSTMENT

.........---.

eee

eee

eee

eee

eens

12

6.

FLYWHEEL

LOOSE

PLAY

ADJUSTMENT

..........-----5

ee

eee

renee

eee

12

7.

ADJUSTMENT

OF

IDLER

#2

POSITION

AT

FAST

FORWARD

MODE

bBo

Ral

aap

et

Batata

ea

Za

14

8.

AUTOMATIC

SHUT-OFF

OPERATING

POINT

ADJUSTMENT

............-..-.

14

V.

HEAD

HEIGHT

ADJUSTMENT

........-.....06.

0000

c

eee

te

tenes

15

1.

HEAD

HEIGHT

ADJUSTMENT

...........0-

2

ee

eee

eee

ee

eee

15

2.

HEAD

SLANT

ADJUSTMENT

.........-.-

2-22

cece

eee

eee

eee

15

3.

RECORDING/PLAYBACK

HEAD

AZIMUTH

ALIGNMENT

ADJUSTMENT

.......

16

Vi.

-AMPLIFIER.

(se

ieee

26

dag

hh

he

PIS

Oe

en

tee

gigas

See

eet

17

1.

RECORDING

BIAS

FREQUENCY

CHECK

...........-.-2

eee

eee

eee

eee

17

2.

FREQUENCY

RESPONSE

CHECK

......-..

00-2

cece

ee

eet

tent

eee

17

3.

RECORDING

BIAS

VOLTAGE

CHECK

..

«1...

eee

eee

17

4."BRASE°

VOETAGE:.

«0

cock

coed

pie

ee

Wie

a

od

Be

2

aa

eS

ese

aE dg

aE

SOS

2S

Ge

17

5.

HUM

ALLEVIATION

COIL

ADJUSTMENT

.........-....

0-2

e

eee

eee

17

VIL

D.C.

RESISTANCE

OF

VARIOUS

COILS

.............0-02

5-062

eee

18

VIII.

COMPOSITE

VIEWS

OF

COMPONENTS.

.............---2-0

0

cece

e

ree

eens

.

19

nett

i

i

i

“9

I.

SPECIFICATIONS

An

asterisk

next

to

a

figure

indicates

the

minimum

guaranteed

performance.

TRACK

SYSTEM

4-track

2-channel

stereo/monaural

system.

—--

=a

REEL

CAPACITY

TAPE

SPEED

WOW

AND

FLUTTER

Up

to

7”

reel

7-1/2

and

3-3/4

ips.

+2%

(*4+3%)

Less

than

0.14%

(*0.15%)

R.M.S.

at

7-1/2

ips.

Less

than

0.18%

(*0.20%)

R.M.S.

at

3-3/4

ips.

TOTAL

WOW

AND

FLUTTER

Less

than

0.22%

R.M.S.

at

7-1/2

ips.

(Scotch

#175

TAPE

3,000

Hz

recording

and

playback)

FREQUENCY

RESPONSE

WIDE

RANGE

TAPE

LOW

NOISE

TAPE

1,000

Hz

-16VU

Recording,

measured

at

speaker

output

30

to

21,000

Hz

(*50

to

20,000

Hz)+3

dB

at

7-1/2

ips.

40

to

15,000

Hz

(*50

to

12,000

Hz)+3

dB

at

3-3/4

ips.

30

to

18,000

Hz

(*50

to

18,000

Hz)43

dB

at

7-1/2

ips.

40

to

13,000

Hz

(*50

to

10,000

Hz)+3

dB

at

3-3/4

ips.

DISTORTION

FACTOR

Less

than

2%

at

7-1/2

ips.

TOTAL

DISTORTION

FACTOR

Less

than

3%

at

1,000

Hz

“0’’VU

recording

at

4

mV

mic

Input,

Output

2W

and

Tone

Control

Max

using

Scotch

#211

SIGNAL

TO

NOISE

RATIO

Better

than

50

dB

(*47

dB)

at

10

dBm

output

and

Tone

Control

Max

(from

Speaker

Out)

TOTAL

SIGNAL

TO

NOISE

RATIO

Better

than

43

dB

at

10

dBm

output

and

Tone

Control

Max.

(from

Speaker

Out)

CROSS

TALK

Better

than

60

dB

(*55

dB)

Monaural

(Mic

input

4

mV,

1,000

Hz

+3

VU

recording,

measured

at

line

output)

Better

than

45

dB

(*43

dB)

Stereo

(mic

input

4

mV,

1,000

Hz

+3

VU

recording,

measured

at

line

output)

ERASE

RATIO

Better

than

70

dB

(*65

dB)

1,000

Hz

+3

VU

recording

INPUTS

MIC

INPUT

LINE

INPUT

DIN

INPUT

OUTPUTS

LINE

OUTPUT

DIN

OUTPUT

PHONE

OUTPUT

SPEAKER

OUTPUT

RECORDING

BIAS

FREQUENCY

Volume

at

maximum,

1,000

Hz

“0”

VU

indication

More

than

0.5

mV

More

than

70

mV

More

than

70

mV

(High)

More

than

5

mV

(Low)

OV

(volume

min)

to

2.3V

(volume

max)

using

a

250

Hz

eel

“0”

VU

pre-recorded

tape

at

7-1/2

ips.

1V

100

mV

at

82

each

CH.

3W/82

each

CH.

*More

than

(2W/2W)

continuous

power

at

82

63

kHz+8%

BIAS

LEAK

Less

than

-20

VU

measured

at

line

output

HIGH

FREQUENCY

DEVIATION

RECORDING

CAPACITY

FAST

FOWARD

AND

REWIND

TIME

MOTOR

With

2

dB

using

an

8,000

Hz

3-3/4

ips.

pre-recorded

tape

at

7-1/2

ips.

Tone

Control

Max

2

hours

stereo

recording

using

a

1,200

ft.

tape

at

3-3/4

ips

80/100

sec.

using

a

1,200ft.

tape

at

60/50

Hz

2-4

pole

induction

2-speed

motor.

type:

IC-16Y

Revolutions:

1,790/1,490

r.p.m.

at

60/50

Hz

(Low

Speed)

3,580/2,980

r.p.m.

at

60/50

Hz

(High

Speed)

HEADS

RECORDING/PLAYBACK

HEAD

ERASE

HEAD

Type:

P4-150

Gap:

2

microns

Impedance:

1,25022415%

at

1,000

Hz

D.C.

Resistance:

912

Type:

E4-200

Gap:

0.6

mm

Impedance:

2002+5%

at

100

kHz

D.C.

Resistance:

22

:

eee

TRANSISTORS

2SC458LG(B)

(C)...

4

2SCLOTSTSD)

.

4

2SC711

(D)

(E)...

4

28C1312

(F)

(G)...2

2SC968

(3)

(Red)...

2

DIODES

IN34A

...

2

10DC-1

(Blk)

...1

:

10DC-1

(Red)...

2

SPEAKERS

2

built

in

(S”

x

7’)

Oval

speakers

Impedance:

82

POWER

SUPPLY

100

to

240V

A.C.

50/60

Hz

120V

A.C.

60

Hz

for

CSA/UL

Models

220V

A.C.

50

Hz

for

CEE

Models

POWER

CONSUMPTION

SOW

DIMENSIONS

1722W

358(W)

x

360(H)

x

248

(D)mm_=

(14”

x

14.1”

x

9.8")

1722L

359(W)

x

366(H)

x

248

(D)mm__—((14.1""

x_

14.4"

x

9.8")

WEIGHT

1722W

13.2

kg

(29

tbs.)

1722L

14.0

kg

(30.8

Ibs.)

NOTE:

Specifications

subject

to

change

without

notice.

ee

em

H.

MEASURING

METHOD

1.

TAPE

SPEED

DEVIATION

3.

FREQUENCY

RESPONSE

a

Line

Audio

1722w

(Output

Input

Frequency

Frequency

Counter

Oscillator

Fig.

1

As

shown

in

Figure

1,

connect

a

Frequency

Counter

to

the

Line

Output

of

the

recorder.

Take

a

frequency

counter

reading

at

the

beginning,

middle,

and end

of

tape

winding

during

playback.

The

maximum

value

of

these

respective

readings

will

represent

tape

speed

deviation.

Fig.

3

High

Sensitivity

V.T.VM.

1)

Connect

the

various

instruments

as

shown

in

2.WOW

AND

FLUTTER

Fig.

3

and

supply

a

1,000

Hz

sine

wave

signal

to

the

Line

Input

of

the

recorder

from

an

Audio

Wow

and

Frequency

Oscillator

through

an

Attenuator.

Set

Flutter

Meter

recorder

to

“REC”

mode

and

turn

recording

level

control

volume

to

obtain

“O”

VU

meter

Fig.

2

reading.

2)

Under

conditions

described

in

1)

above,

readjust

Method

A

Attenuator

so

that

the

Line

Input

is

-16

dB,

and

As

shown

in

Fig.

2,

connect

the

Line

Output

of

the

record

50

to

18,000

Hz

spot

frequencies.

recorder

to

the

Input

of

a

Wow

and

Flutter

Meter.

3)

Rewind

tape

and

playback

from

the

beginning.

Use

a

3,000

Hz

pre-recorded

test

tape

and

take

a

Take

V.T.V.M.

spot

frequency

readings

and

plot

wow

and

flutter

meter

reading

at

the

beginning,

values

on

a

graph.

fogs

middle,

and

end

of

tape

winding.

The

maximum

ope,

value

of

these

respective

readings

will

represent

the

NOTE:

When

measuring

frequency

response,

new

wow

and

flutter.

tape

should

be

used.

Method

B

Supply

a

3,000

Hz

sine

wave

signal

from

an

Audio

4.

SIGNAL

TO

NOISE

RATIO

Frequency

Oscillator

and

make

a

recording

on

a

Speaker

blank

tape

at

the

beginning,

middle,

and

end

of

tape

Output

Input

.

rae

‘ >

pu

npu

winding.

Rewind

and

playback

tape.

Measure

wow

1722W

ee

eed

a

ae

and

flutter

with

a

Wow

and

Flutter

Meter.

(The

aches

Fig.

4

ad

wow

and

flutter

value

of

Method

B

will

be

close

to

|

2

times

of

Method

A)

Connect

the

various

instruments

as

shown

in

Fig.

4

and

playback

a

250

Hz

“0”

VU

pre-recorded

test

tape

and

adjust

volume

control

to

obtain

+10

dbm

V.T.V.M.

reading.

Then

remove

the

tape

and

measure

the

noise

level

under

the

same

condition.

Convert

each

of

the

measured

values

into

decibels.

5.

TOTAL

HARMONIC

eh

Distortion

Meter

Fig.

5

1)

Connect

the

various

instruments

as

shown

in

Fig.

5.

Load

a

Scotch

#211

tape

and

set

Tone

control

to

“MAX”

position.

2)

Record

4

1,000

Hz

sine

wave

signal

at

“O”

VU.

Playback

the

resultant

signal

and

measure

the

overall

distortion

factor.

NOTE:

1)

At

this

time,

Distortion

factor

of

the

Audio

Frequency

Oscillator

must

be

suf-

ficiently

small.

2)

When

measuring

the

distortion

factor,

new

tape

should

be

used.

6.

CROSS

TALK

(Cross

talk

between

the

tracks)

—

TAPE

DIRECTION

Fig.

6

As

shown

in

Fig.

6,

first

record

a

1,000

Hz

sine

wave

signal

on

Track

No.3

at

+3

VU

level.

Next,

record

under

a

non-input

condition.

Then,

playback

the

tape

on

Tracks

No.3

and

4

through

the

B.P.F.

(band

pass

filter

sensitivity

...

1

:

1)

and

obtain

a

ratio

between

the

two

from

the

following

formula:

Eo

C

=

20

log

(dB)

2—7—"1

where,

=

desired

cross

talk

ratio

(dB)

E,

=

1,000

Hz

signal

output

level

(V)

E,

=

1,000

Hz

cross

talk

level

(V)

Wl

N

LA

E,

=

Non-input

signal

recorded

level

(V)

7.

ERASE

RATIO

As

shown

in

Fig:

4"8@Minect

a

High

Sensitivity

V.T.VM.

to

the

Line

Output

of

the

recorder.

Playback

a

virgin

tape

and

take

a

V.T.V.M.

reading

of

the

output

level.

Next,

record

a

1,000

Hz

sine

wave

signal

at

+3

dB,

then

playback

this

recorded

signal

and

take

a

V.T.V.M.

reading

of

the

output

level.

Next,

using

this

pre-recorded

tape,

record

under

a

non-input

condition

and

take

a

reading

of

the

noise

level

output

of

the

erased

signal

and

obtain

a

ratio

between

the

two

from

the

following

formula:

Er

=20

log

(dB)

2—

1

where,

Er

=

Desired

erase

ratio

(dB)

Eo

=

1,000

Hz

signal

output

level

(V)

E,

=

Non-input

signal

recorded

level

(V)

E,

=

Virgin

tape

noise

output

level

(V)

.

POWER

OUTPUT

Speaker

High

Sensitivity

V.T.VM.

Fig.

7a”

As

shown

in

Fig.

7,

connect

an

8Q

dummy

load

resistor

to

the

speaker

output

of

the

recorder

and

connect

this

terminal

to

a

High

Sensitivity

V.T.V.M.

Playback

a

250

Hz

“0”

VU

pre-recorded

test

tape

and

take

a

V.T.V.M.

reading

of

the

output

level.

The

resultant

output

can

be

obtained

from

the

results

of

the

above

measurement

by

using

the

following

formula:

E?

P=-—

=

(W)

where,

P

=

Desired

power

output

(watts)

E

=

Measured

voltage

(V)

(R.MS.)

R

=

8

I.

DISMANTLING

OF

UNIT

In

case

of

trouble,

etc.

necessitating

disassembly,

please

disassemble

in

the

order

in

reverse

order.

nal

al

guguguqugu

glug

gugugugugugTugTuqTug7g

a

1

:

»

PAUSE

KNOB

sECHANISM:

KNOBS

shows

in

photographs.

Reassemble

—_—

SCREWS