Akai 1700 Service manual

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AKAI TAPE
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IASTE OF

CONTENTS

spEctFtcAnoNs..

I

HOW TO A.TEASURE DESIGNATED VALUES

I

SPEC|F|CAT|ONS..,......

tocafloN oF coNlRor.s

I

DrsAssEMrLy

IV

AND AMPL|F|ERS.........

TRANSPORI

v

ADJUSTMENT

IJ

ADJUSTMENT

II

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r,{A|NTENANCE

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n
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or
ExpLoDED vtEw
TROU3LESHOOTTNG
scHEfiATtC DTAGRAM
CoNNECTING DfAGRAl.r

oF tApE TRANSPoRT uNtTs

MECHAN|SL

TAPE TRANSPORT

OF

al4pr|FrER

oF

pRocEDURES .. ............. .............It

REPLACEI

ENT

oF coMpoNENt

..... . ..........................,

... .................... .............'10

pARTs....................................12

CHART

.,.....,............, ..'.................25

................,..............,.21

...................-..--.-.-.-......-.26

.. ...'.....'......

OF

..............'

I

2

3

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

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

................."..

UNIT

p^RTs............ ......,.1,4

,l
6
9

SPECIFICATIONS

MODEL

NUMBER

wtrGHT

(NET

IN CARTON)

DIMENSIONS

POWER RE-

qUIREMENTS

POWER CON.

SUMPTION

RECORDINC

SYSTEM:

PLAYBACK

SYSTEM:

TAPE SPEED

.I'APE

SPEED

DEVIATION

WOW AND

FLUTTER

FAST FORWARD

AND

REWIND

TIME

Akai Modcl 1700, portablc 4-track
st.rco tape rccorder.

(15

33 lbs

t3-t6'

kg) without acccssorics.

x 13-%'

lH)

(w)

x 9'

(Dl

A. C. 100, ll0, 120,200,220 or 240 volts
interchang€abl€. 50 60cycles.

80VA.

Inline 4 t.ack st€reo and 4-tfack mon-

Inlin€ 4.tiack stefeo, monaural play-

Thrce speeds

:

cml and l-%"
p€r

s€cond

capstan and pinch whe€I.)

than + 3

Less

:

Less than 0.2 % at 7-t6 ips. R.M.S.

:

(a.is

cmJ per second.

with an optional accessory

pef cent at all

Less than 0.3 % at 3-7a ips. R.M.S.
Less than 0.45 % at l-16 ips. R.M.S.

150 seconds fof 1,200 ft. tapc at 50

and 120

cles

s€conds at 60 cyclcs.

case

(15"

tape

cy-

POWJ]R

INPU'I'

LDVELS:

POWDR

OUTPUT:

INSULATION

RESISTANCE

INSULATION

YI[,LD

STRENGTH

MONITORINC

SYSTEM

MOTOR

HEADS

MICROPHONE

USED :

Microphone

-55

db

Phono

40 db

Pre-Amplifier
cps, impedanc€
Main output,34dbm.

More than

More

With headphor€

Condenser

l/l00HP.

2,900

to I,450

3,480 to 1,740
lnline +tf ack

play h€ad
Impedance..
I,000

cps.
4-track
Imp€danc€.

Round

Impedance...50,000ohms
S€Dsit;vity...
f.€quency

ir)put lcvcl

(VR.

max.jat

and radio

(VR.

max.)at l,000cps.

output, 0.7V at

50MEC ohns.

than

ore m;nute at A.C.

start;ng

Power

r.p.m. at 50
r.p.m.

stereo/monau.al

;

.3,500

erase head

. .4,000 ohms

dynamic micropho.e

R€rpoDse...70

l,000cps.

input levcl

more than

up

during reco.ding.

induction two-

factor,70

at 60 cps.

ohms + l0

;

55 db.

1,000

l00K

ohms.

(in

600ohmt.

1,000V.

pe.

cent.

cps,

record-

%

+15% at 90

ro 15,000

zt

FRDqUENCY

RDSPONStr

DISTORT'ION

SIGNAL-TO-

NOISE RATIO

CROSS TALK
CHANNEL

SEPARATION

40 to 18,000cps. at 7-%;ps;

.L 3 db.80
+ 3 db. 80

4 db. 80 at 4,000cps.

+

Within 4%at l,000cps,oVU

40 db below rccorded lev€lsignal

Within 55db

Better than

to

12,000 cps. at 7-l,

to 10,000cps.

between each trach.

80 db at l,000cps

at 3-3la;ps;
at l-7s ips.

ipsj

+3

ltotal

at all

VU.

SPEAKOR

INCLUDED:

TUBES USED
SILICON

DIODE

REELS

USED:

USED :

RECORDING

LEVEL

INDICATOR

Two 5'x7'

Imp€dance...8
Allowable IDput...6
Frequency
cps,

l0db.

:!

I2AT7

:

: Horizontal,

x2, 6BM8x2.

l50Dx2

Up to 7'

r€el

A-model

dynahic

R€sponse...8o

speakers.

ohms

warts

VU m€te..

ro

12,000

1I

IIOW

NIICNSURE

TO

DESIGNATED

VALUES

SPECIFICATIONS

OF

TAI'I] SPDtrD

DEVIATION

Reco.d

:

the tap€
a standa.d
351A,
fccted
tlrroughout

tape.
tapc recorder
back, and
couDte.,
rating

the tape speed dcviatior.
Fo.
spe€d deviation
with a testing

the l,000cps.

speed

sound

for instance)

by lhe

the

th;s standard

Put

unde.

nreasure

codvert

then

power

a rough

frequeDcy

measurement,

tape for

at rating

tape sPecd

can also

recorder

which

whole

test

its

curve

sine

sp€eds

(AMPEX

is little

deviation

i€ngth

thc value

speed by

of the

on

taPe

for playing

outPut

to cvaluate

the

be measured

astop

of

with

af-

th€

bY a

into

taPe

TOTAL HARMONIC
DISTORTION

FACTOR:

Provide
,ecord.r
signals and
recording
recorder's
Then
no.mal recording
u.c the distortion
lator.

from
lcvelon
€d dhtortion
formula:
d0:d-dl d2

the input

with 1.000.ps.

.ecord
tape at
VU mete.

playback

Remove

the recorder,

the oscjllator

d0..required
d...overall
dl...noise
d2...disto.tion

to.

the siSnals

factor

distortion

l€vel

uscd

terminal

':nF ,

these signals on

the zero level

under the

condit;on

factor

the recording

then read the

to

by the following

factor of

to meas-

by an oscil

the requ;r-

8ct

factor

the oscilla-

ol the

urvF

a

on the

tapc

noisc

\{OW

AND

FLUTTER

}.RLqUI]NCY

RESPONSE:

(OVI]RALL

I'REqUENCY

RESPONSE)

Playback

:

that guarante€s

p€r cent,

h 0.07

otr wow

valuc

the sedsibility

Since
tcr frequency
5 cps. d.ops,

is put
frequency
OCT circuit
justed

to 3db/OCT

value is

Connccr

rcco.dcr,

f.equency

Audio
Adjusl toDe

the tape
aL€r out
response

to

frequency Oscillator.

by .onnectidg
put then read

thc 3,000cps

wo\d and flutter

aid read

mere.

of

2cps

bclow

the frequency

circuit,

bclow 2.ps.

for adjustment

called

thc input

.ccord a sine

at 100 cps

volume

to adjusl a

to

maximum

sianda.d

the effect;ve

wow and flut-

is put

auditory com-

tcdninal of

curve swecp

-10

flat,

VTVM

the frequency

tape

with-

and above
over 5cps.

th€

and
to 6db/
This ad-

from

db.

playback

tosp€-

devia'

the

SICNAL

TO
NOISE: Playback

OUTPUT:

CROSS

TALK:

the sine curve,
rccorded on a
th€ reco.der
Removc
noisc level under
Calculate

in d€cibel.

I'layback

curvc tape

sine

the zero VU

at

recorder.
with

€ight
Square
vide the figure
thc r.m.s.

Record 1,000 cps.
the
signal
Filter.
Compare
in decibels.

the voltag€

third tack, then playback

through a

standard recorder

to measur€

the taPe, then measure

the same condition

the ratio between

on the recorder

which

level on a standard

T€rDinatc the

ohms.

rcading, then di

by eight ohms

output.

Powcr

signal at

l,000cps. Band

the output

250 cPS.

the voltag€

thc 1,000 cps.

was

test recorder

of tracks I and

tape

on

the

the two

record€d

to get

+3VU

this

Pass

on

3

2-

LOCATION OF CONTROLS

I

f

Supply

o

Cyclc

o

Capstan storage

0

@
@

Tape

o

trras€

o

@

Right channel volumc control

o

Right channel

@

Left channcl

o

Right channel

Left channel

@

Left channel

@

Speed

Take-up reel shaft

@

Capstan

(D

Pinch

(D

Automatic stop lever
Record/Play switch

@

rccl shaft

convcrsion switch

post

guide

head

tonc control

microphone

microphone input
volumc cont.ol
tone control

change switch

shaft

wheel

@

input

jack

jack

Rewind/FasFforward switch
Record safety button
Automatic
Stereo headphonejack
VU

@

stop switch

h€ter

conv€rsion switch

@

Track s€lector switch

@

(D

Cycle conversion sw;tch

Hum adjust

(D

Speaker output
Speaker output
Voltage

Preamp output

Preamp output

o

Phono/Radio input

@

Hun

@

Phono/Radio input

o

(right)

jack (righr)
jack

sele.tor switch

jack (right)
jack

(left)

adjust

llert)

{left)

jack (l€ft

jack

(rish0

3

DISASSEMBLY

I\I

OF TAPE TRANSPORT

UNITS

& AMPLIFIERS

ll l-oo!',, rh. lt l:.1.\ I\ lN(;

LI{l , ,lt-'.. ,\vl,v ," !i

ih. l'IN(ill lt()l.l.l lt

SUIlll\f

llil.

I'INCIt R()L-

irlof

L,{iJ.!

13)
r.!!^! l)1'lCK

thc S(lltli\\'S

l).\\l.ll.

nrxrl.(l 1,,,))

tl)1.

r.ri r(j

t{ll

('(1,.r

i,r

ro

l.(.,,,,tr | tlx. I)llUK

12

io,!c,,i,ig d,cif ritx;fing

I

C( )\ l R( )I- ti\( )lls

s.raL. u';i)g

r

I)liillips

o

99

r.t

ialrnd iblby

h.adcd

('11

l.oosci

(h(i

S(iltl:,\\'S,,)rrk.d

f,or)

i.t

r,)

ktr.

I

(5)

Loosen

the

SCREWS

narked

from

{a)

to

(d).

(8)

Loosen the
mark€d

RETAINING

(al

from

to

SCRDWS of dcck frame

id)

Lifl TAPE DECK and
cabinet

(B).

AMI'LIFI liR

(Dr

tr"m

,he

(9)

SEPA'AIC

TAPE DtrCK

(M)

frOM AMPLIFIER

(A).

(7)

Disconnect the PINS
PLUGS or motor marked
head

marked

{B)and {j).

of speako marked

(€)

and

(f)

and the

{a)

and

PINS of

(d),

the

Fig.

TRANSPORT MECHANISM

Y

Driving of Capstan

Fjgure l.

Motor

{Aj
(B)

Driving Belt

(C)

Capstan

(D)

FlYwheel

High-speed rotation of Mot /

(B)

Br,
to Flywheel with ample inertia and €nables rated
by absorbing

and transmitted to Capstan

mino.

rotation

Capstan Rotation 606 r.p.m.

303r.p.m. at 3-%'(9.5 cm)

l5l.5r.p.m, at l

Motor Rotation 2,900 to 1,450 r.p.m. at 50 cps.

3,480 to 1,74{r.p.m. at 60cps.

(flat

belt)

(A)

is reduced by D/trire'

(C),

which is connected

rotaiion

distortion ofDotor itself.

at 7-%'(l9cn)pe. sec.

-16'

(4.7s

per sec.

cmlper sec.

I

Driving of Pinch Roller

Put tape between rotating capstan and pinch roller
push pinch
tape

at rat€d spe€d.
roller is between I,000 to I,150
of 7-%'

(19cm)

against

rouer

per s€cond.

capstan,

this will transport

Th€ appropriate pressure of

grams at the tape sp€ed

and

thc

pinch

Fig. 2

R€coding and Play Back

(A)

TuJ[ rhe RECORD, PLA rB,4Cf

position, and pinch roller presses against capstan
tape at the rated
between

lD)
moved and wound on the take-up re€I.

The Tak€-Up Reel Spindle Base is made up of
tic
is rot^titg the
winding friction is adjust€d by
enabl€ rated

Blake
provides

ing

to,
BACK
Safet! dnice

Motor &tshitag

b rr^ns'lr.it the motol /rldtro,

(l

rollers

on the other ha d, the S*pfb

lo e/

app.opriate back tension by

to the rotation ofthe Pull€y

To prevent

(F)

mut be depressed
knob can be moved

(See

Fisures 2 and

sp€ed.

with a clutch felt in betw€€n.

and 2l

plastic

winding of the tap€.

hwg on the Plastic

lEl

accidental er^sure, the Record lnterloch

lclls

At the same time,

znd t}:'e Tahe-Ut Reel Spindle

ICI

(2)

mUel

depressed to ente.

under. Therefore, the tape-

before the RECORD,

to the

3)

ffi

knob

to

{D)

the

slipping

Reel Sbtndle

Roll€r

the .lutch fet slipp-

(3)above.

"REC"

the record mode

Slipping Rotation

to

Idlel

so that th€

of the felt

under

{4)

position.

"PLAY"

to move

(B)

moves

tape is

two plas-

The ldler

h^s a

IHI

which

But-

PLAY-

The

to

-6-

\

FAST-FORWARD MECIIANISM

TurD

lie aASZ FWD-REWIND *no,

5)

(D)

(B)

undcr lhc knob pushes

moves

into

and

lH)

FWD" position, and
the Lerer
the Plast c Rouer
the uppe. part of th. rotating motor drive bushing to
transm;t the motor rotat;on to the takc-up reel spindle. At
the same tihe,
sp;ndle to free
fast

(C).

windnrg
(Sec

ofthe tapc onto thc iakc-up rcel.

ligures 4 and

FreeRolarion Fl;gh-SpeedRotation

ll's ca-

The l.tler

above the Take-Up Reel

lF)

Brale RoUerc

lr, Srrrl! Reel Sti dlelcl,rheteby allowiDT

(A)

to

the

(I)

cone otr the reel

bctween

spacc

Spindle and

"FAST

up

f

Fig.4

Fig. 5

REWIND

"f

utn the FAST FWD-REtl/N,

position, and

up. The

lC)
per part of

MECHANISM

the cam

ldlerlDl

the

lB)

noves

rcIating Motar

Interned ate Pulle,lF) to hansmit

o

izo,

u^det $e k\ob ptshes

into thc space

dtue bushing

the high-speed
of themotor through the interm€diate
Reet

Spindte

come ofl

the

ther€by rewinding the tape

(See

F;surcs

At the

lC).

sahe time, Brale

re€l spindle b tree the

into rhe supply reel

6 and 7)

take-at leel spindte

High'Speed Rotation

'J

Fig. 7

(A)ro

"REWIND"

betwecn the

pulley to

Roll€ls

YO

o

the Leuer

and

lE)

rotation

tr? Srrrll

(H)

and

ar a fast

up-

the

(I)

lJl,

(a)

sToP

(b) FAST-FORWARD

(.)

REWIND

Id) RECORDING

NOTES :

-marks

x

O-ma.ks

o

o o

indicates
"engaged"

o o

"open"

and

o o

STOP

{A)
sp;ndles.

the .eel spindles, no triction works

7

CONTROL

Push ihc

and

As thc brake rubb€r depfesses the

Supply R*l

stop lever to

depres reel spindles to stop .otation

1B)

Spindle

R*ind

"STOP"

ldle$heel

fig. 8

positlon,

on the tape its€lf.

Take-up Reel Spindle

Bruke Ro els

of the reel

plastic rolleG under

('

RDCORD/PLAYBACK CIIANGING

turning the RLCORD/PLAYBACK

By
LEVER
to .ecording position.
If the LIVER

(bi

and

(c),

as

(c)do.s

;llushated in dotted l;nc,

not turn

propc.ly.

MECHANISM

KNOB

(N)to

then the RECORD/PLAYBACK

SWI docs not operatc

recording position, thr

the

LEVIiR

CHANGD SWITCH

prope.ly so may occu.

1a)pulls

the abnormal oscillation

the RECORDING

(SWl)turns

and

Then

must

adjust

the LI.VIR

(cl

to proper position

by loos;ng thc SCREW

.

r il.',

Itz__\,/..r',

'l-a1'1';':

.'/...

(//

,,-^:,..

,/

\l/

..)._u.

.

,4)"

JWt

lcll.

-

,z--\

,

/

_

r

ADJUSTMENT

U

1. ADJUSTMENT OF

It is imporlant that the piich

complcte alignmentwith

pressur€

wheel
unit is ope.ated

from this specificalion

tion
Check
r,ecesar

I'in.h

y.

is bctween

at the tapc spccd of7-t6

wheel pre"su,. bv r

ju"r

rhe pin, h

ad

2, ADJUSTMENT OF

take-up ;dlm wheel

The
ment ltith thc takc-up reel shaft.
fast forward condition,
upper knu.led

will

and it

play modc. Adjust idlerwhccl

or

wheel pressurc is kept between 50

idler

qh..l

;dler

The slippage occurs

wheel

contact

rapidlv

to thc lower kn urled

:ir".

..t,

PINCII

the capstan shaft.

1.000 and I,150 grahs
will result in wow and

whpFl

TAKE.UP IDLER WHEEL

must

be

thc idler

the takc-up reel shaft

of

wear.

:f Ihf pre*u,.

if thc prcssu.e

=..".".,..

;

ll

Fig.

12

Fig.

WIIEEL

wheel shaft i5

A properpinch

ips. Any devia'

.1-.ring

load 5t.inB.

kcpt in complete align-

Whcn the unit

whe€l will contact to the

whccl du.ing record

load spr;ngsoihatlhc

and 80 grams.

is smallef thaD the

R(/.Ly Hli

kept nr

whcn the

'cale

assembly.

Px,.ssi\c.

b

flutter.

at.d.

is set in

The

OF TAPE

3. ADJUSTMENT

The .c\rind
mcnt with thc rewi.d
to the k,,urlcd
50 gfams during rewidd ope.ation. Adjust both thc idler
load spriog aDd

if

4. ADJUSTMENT

Thc

whccl

idler
part

of
sct in rewind mode, it will
taneously deliverins torque of
su.cis50grams. Adjust thc load sp.;ngofthc inrermed;ate
wheel if the

5. ADJUSTMENT OF TAKE-UP REEL SIIAI'T
ASSEMBLY

A felt clutch mat.rial is attachcd to the bottom sid€

the

reel

stretched during lhst forwafding operation due
tension. To check the
a S'inch reel

diameter, and gently pull the cnd of tapc upwarcl
spring scale.
of tension at this part will bc kept between
grams. Anoth€r felt
takc-up drive wheel. It is to pfovide proper slipping
ration
checkins friction of
between 120 and 200 grams of frictioD
best result.
takc-up dr;ve
mode,
reduced and \viil become I0
rvhether this is satisfactory ;f iot,
spring

fisure

lscc

6. ADJUSTMENT

ASSDMBLY

A felt clutch
thc reel table base plate and
protect reco.ding
winding operation.
pa.t, place onto thc supply reel
rcco.ding

pulL thc cnd of tape upward by a spring
thc

conical sp.ing so
bctwecn 400and500grams.
to thc re\v;nd
ope.atioD cluring
for checkn)g
and betwe€n 80 and

result. Whcn

best
the

amount
become l0 to 20

Check

spring and spring r€tainer

7. ADJUSTMENT

A

vertical azimuth
adjustment
align tape head, play 8,000 cycles
standard alignment
sc.ew

hole which
head assembly.

TRANSPORT

OF

whccl

idler
motor bushing should be maintained

rewind roller.

OF

intcrnediatc

and thc rubbe. ring vhich is uscd on the uppe.

the supply

pressure is not sufrc;ent.

table

du.ing

Adjust the

the

amou.t

fo. Bfakc, and spring rctainef

ll

wheel

reel shaft assembly. When

basc plat€ so

with

fecordins

Adjust the

record or play modc. The procedu.e

this part

whcel.

of f.iction of this part

(al

lefo

at

UNIT

REWIND IDLER

must be kcpt in complete

shaft. The amount

reel

INTERMEDIATE WHEDL

is located between the

contact

that reco.ding tapc w;ll not bc

amoudt

conical

clutch

star-shapcd

lvhen

to thcsc parts sihul-

motor. An

of friction of this part, plac€
tape wound by 60m/m in

sp.ing so that thc amount

matoial ;s

; same as

spring

the unit is
to 20 grams.

readjust the star-shaped

washed

WSEEL

adequate

attached

the foregoing, and

will provide the

jnst
set

will greatly

Check

accordingly.

OF SUPPLY REEL SIIAFT

matoial is uscd between

the .ewind rubbcr ring

tape from an excesive

To

tape wound by 60m/m in diameter and

that thc amount of

drive

reco.d or play mod.. The procedure

friction of this part is same as

120

the

of f.;ction will greatly be reduced and

grans.

to

whether this is proper, if not,

sce

thc

check

wheel to provide

unit

amount

table

Anothc. fclt clutch is attached

of friction will give

s.ams

js

set

washc..

the love.

tension \th;le re-

offriction of

a 5-inch

scale. Adjust

tens;on ;s kept

proper

the

;n fasi forward modc,

rcadjust coil

figure I I

{See

OF TAPE HEAD

alignment of

that

until a maximum

is positioned on the shield cover

be made at

can

tape. Rotate

playback level through the small

tape head is the only

the field

recordcd on an AmP€x

th€

of service.

azimuth al;gnment

align-

pressurc

of

about

rewind

the unit is

pres-

to

excesivc

using a

400 to

in rewind

of the tape

500
the

to

opc-

for

the

under

be

to scc

side

this

rcel with

gently

sl;pping

foregoing,

(b)

the

will

at left)

To

ol

of
to

-9-