Page 1
PrtoroFAcr*
FolJ"t
R,T.75
'NODEL
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EI
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SPEED
ON-OFF
I
RECORD
CI{ANGE
CONTROL
BUTTON
FAST
FORWARD"'
VOLUMT CONTROL
RfdV IND-
TONT CONTROL
RUN'STOP
CONTROL
=
o
E'
FI
F
v
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Ut
I
HOWARD
AND
A Subsidiary
fhis
W. SAltS &
MODEL R.T-75
3.SPEED
TAPE
RECORDE
PLAY
Manufactured
BELL SOUND SYSTEMS, INC.
Thompson Products, lnc.
of
Marion
555
Columbus,
moleriol compiled
CO., lNC.,
.
Copyright
1956
R
BACK UNIT
by:
Road
0hio
published by
ond
INDIANAPOLIS,
Resoryod
All RighB
INDIANA
DATE
9-50
$ET 329
t0tDtR
4
Page 2
FAST
FWD.
ADJ. SCRNru
GENERAL
The
Bell Model RT-?5 is
track tape recorder.
A single
and amplifier
(1
speed
time
as eight
had
"Fast
and
speaker
stripinsidethe
put,
7/ 8,
The dual
on each
on a ?t'reel
Push
Rewind";
"Tone"
Two
or high
at 30dbm
control
"On"
3/
3
track feature
reel
hours
total or four hours
at slowest
buttons
these
controls.
output
fidelity
amplifier isavailable
level.
A removable
cabinet
adjustment,
allows
and
easy access
500 ohm output
INFORMATION
knob
"Off"
y
2 inches
turns
and
4, or ?
allows
and with light
speed.
provide
jacks
same
permit
for
buttons act
amplilier system.
plate
cover
to tubes, motor,
a three speed,
power
per
to the
second).
and selects
more
weight
on
tape, as much
each
Forward"
"Fast
use
of an external
for
the bottom
side, may
as
500 ohm out-
terminal.
dual
motor
the desired
recording
be
and
"Volume"
Aterminal
of
the
hum
fan,
Figure
I
Size:
Weight: 35 lb.
Power
td-6wffi-
Overall
?-luT.
Inputs
fier
-
Outputs
3. 2
ohms
Amplilier,
Power Output: 3
Speeds
i-?/8-Effis
Fast Forward: 1200
Fast
Rewind:
SPECIFICATIONS
16 3/
8"
x
15" x 9
approx.
Required: 110-120
Frequency
Response:
trs:-
(three):
TV.
(two):
(three):
2
microphones,
External
use any
-
high impedance.
speaker 4
watts.
Play
per
second.
ft. in
1200
ft. in 70
8" less hardware.
V
volts 60 cycle
30
I radio-phono-ampli-
Speaker,
to
or Record.
90 seconds.
seconds.
A. C. only
10,000
to
cycles at
actual impedance
16
ohmsl
7 I/2, 3
External
3/
4,
-
or
Built in
placing
prevents
This
erasure.
Page
2
interlocks
the machine in more
prevent
tape brealage, spillage,
the operator
than one
mode at a time.
from
or accidental
Wow and
Speaker:
Flutter:
6rr x
9r'
Less
heavy
tian
duty
.25%
oval,
at
?
2
I. P. S.
V
Page 3
Type
of
Erase and Bias: Iligh Frequency
Tube
Complement: 1-12AY7
1-6C4,
Controls:
l-6V6cT, 1-6X5cT.
1. Speed
2.
Run-Stop Control.
3.
Record Push.Button.
4. Tone
5. Volume
OPERATI NG
or ECC-83, l-12AX7,
Change, On-Off
push
and
button rewind.
push
and
button fast forward.
INSTRUCTIONS
(A.
Control.
C. ) 60KC.
up by
better
inputof the
minals,
the tuner
Dual Track
the microphone and lack of
recording can be made
recorderto
In
the
output.
Operation-
case
by
radio or TV voice coil ter-
the
AM-FM Tuner,
of an
good quality.
connecting the
connect
"Radio"
NOTE: Recordings are made on half the width of the
tape at one time. Since it is impossible to
splice one
and
other,
limited
be
recordings
one
to
"track"
without affecting the
which are to be
track.
edited should
edit
A
to
\=/
Preparing
remove
control is in
control is in
venient
Threading The
reelsupport
the taleup reel
oftapestraightwith
the
tape
of the radialslots in
reel
counter clockwise
and
i
take up all slack
To
Record From Microphone-
(1)
knob
mately
microphone
2
input
mixing
microphone
rubber
to absorb
recording
observing
While sound source
adjustthe
peak
on
NOTE:
run-stop
and
any sound entering
corded
control
To
Record
vision
loudspeaker,
not
satisfactory
The
Bell For Recording-
1.
Place
the
recorder
on a
the eover. Make certain that
the
the
"Off"
2.
Insert the A. C.
110-120
1.
2.
volt, 60 cycle A. C. outlet.
Tape-
Place a reel of
(6)
and an
support
Unwindabout two feet
slot.
Insert the free end of
position
"Stop"
position.
power
rtA,
empty
both hands and insert
the
wind tape on the
reel of
(8).
of
hub
of the empty reel.
three of
between reels.
1. Turn recorder
in
speed
t}te
30
seconds
plug
only
into
when
jack
with Radio, Phono.,
is
set on a hard surface,
or several
any vibrations,
by depressing
the flash of the neon record
volume control
passages.
Correct recording
If the neon level
recordingwill
the
playback.
on
playback
all,
background noise.
2.
After level
control
on the tape.
(2)
Recordings
reeeiver
(2)
to
"Stop".
From
Radio. Phono.
by
howeverthis
beeause
on by
position
for
the
desired. Allow
the unit
to warm up. Insert the
Mic. I input
using
two microphones
or TV
thicknesses of
is striking
Set record level
the red record
microphone,
so thatthe levellamp
volume is
lamp flashes
be
overloaded and distorted
If level
lamp does not flash
will be weak and
adjustment has
to
"Run".
When recording is
can
be made from
placing
Thetape
microphone
the
the microphone near
type of recording
of background
flat
surface and
the
and
cord
"Run-Stop"
that the
plug
into a
same size on
the
"Speed"
supply
tape. Hold a section
the tape
the tape
four
placing
turns to
jack.
into
Rotate
secure
speed control
approxi-
Use
or when
programs.
place
cloth underneath it
sponge
before
button and
level indicator.
carefully
flashes
very important.
all the time,
contain high
been set,
turn the
is now moving
will be re-
finished,
Or TV-
a radio or tele-
is usually
noises
picked
con-
into
one
Mic.
turn
the
After
l.
track may
second
rewinding)
spindle,
spindle.
ing as
by removing the full
turning
Placethe emptyreel onthe right hand spindle.
2.
Rethreadthe tape andproceedwiththe
previously
3. Afterthesecondtrack has
first track
changing
To Rewind-
by
in
desired
release
When
reels
After a recording is made,
pushing
position
portion
I'Fast
rewinding
it is better to take tape
across
and is somewhat faster since it eliminates
set up by the tape running
To
If
supports and
the speed control
alsosupplies
the
the
level. If
pointer
the
pointer
pressure
tape.
at
second
ing the
from reel
Play A Recording-
l.
To
run- stop
"Volume"
speed
(l)
can beturned afterthe
recordings have
(2)
roller
2. After
track
reels
platforms.
playback.
NOTE:
When recordings
built-in speaker, remove anyphone
may
or
used,
Fast Forward-
playback,
In
portions
down and
of tape to a
hold
reel
a
is ready
as described in
"Rewindrrknob
it is
Fo
of tape
recorded on the same reel
be
it
over, t}ten
described.
to be
unnecessary to hold down. When
has
been
reel
from the right
placing
played
Step
on the
been recorded, the
without rewinding, by
#1 above.
maybe rewound
tape
downpositively.
of tape is rewound,
Forwardrr knob.
a complete or large
out
will stop
This
portion
of slot and run straight
to reel. Thissaves wearonthe head
head slot.
place
described.
the correct speed; this
amplifier. Plaee
position
the speed
play
back recordings,
tlread as
pointer (1)
power
pointer (2)
tothe
and
"Tone"
of
tape is unknown,
through the
previously
to
motor and
in
the
"Run"
controls for desired listening
unitis
played,
been
to the
"Stop"
(22)
position.
from
the capstan
the first track has
may
This
played,
be
over and
may
without rewinding,
placing
be
are
inserted
be
High-Z output
disconnect the built-in speaker.
"Fast
in either
jacks.
it is
sometimes desirable to
particular
Forward" knob until
return
This releases
been
them on opposite reel
done at any
played
the External Speaker
These
spot. To do this,
recorded, a
(without
left hand
record-
Itwill lock
push
down and
ttre tape.
of
the drag
reels
and adjust
playing.
the run-stop
stops t}e
and
played,
by turn-
time during
back
thru
plug
jacks,
arrives
tape
hand
a
reel,
on reel
Turn
control
After
the
the
the
which
when
skip
push
=o
Hr
Frl
nF
{
I
\
lrr
F
Page
3
Page 4
Figure
2
at desired
Forward"
tape should
tions of
Top-Deck
deck
from
turned
remove
straight
To
Remove
the top-deck
spot. To stop
knob.
be
a reel are
D I
SASSEMBLY
Plate-
To service
plate (5)
the
case.
Remove four
down
the two
up.
Recorder
To
remove
plate (5).
fromtherearof
grille.
case
leads
To
of the
to {irst
from
fromthe
Remove
and
liJt
before
Remove Amplifier
For some
tape
transport mechanism,
remove
Remove
each side
jackand
prevent
To
taken
to
parts
out of head
be
unnecessary
skipped.
NSTRUCTIONS
I
located
it is not necessary
Remove top-deck
tape, release
screws
flange) and
pointer
recorder
the cabinet located
four screws
recorder
lifting
recorder
mechanical
the amplifier.
sheet
three
plate.
lamp brackets,
(one
use a #10 spline
knobs.
From Cabinet-
from
Next,
removethe
straight
From
Transport
adjustments
metal
Remove four
the
slot when
directly
to remove
plate
in each
Lift
cabinet,
head
large
under
the top-
the unit
as
follows:
corner of the
wrench
top-deck
first remove
three screws
just
above
from
the
up.
Remove
completely
it
will be necessary
Remove as follows:
(hex.
the vent
bottom of the
speaker
out of case.
Mechanism-
on the bottom
head) screws
hex. head screws
2 each side.
Remove
"Fast
wear,
por-
plate
plug
head
and motor
the three Phillips head
plate
so that the
flanges as the mechanical
Tighten
hand side
surface.
cal unit, tape may
anymodelbyusinganAC
willfit the
to
15,200 use
above serial #15,200,
socket.
Rewind
(right
Tape should start
this
(1).
Now
(l)
the three Phillips
plate
When the
motor
a Bell
Adjustment-
Belt
Leave
test,
Place
12 to 15
hand) and
shutoff
run-stop
start the motor
in the 7 I/2I.P.S.
starttapeunderload,
(6?)
belt
few
adjustment as
turn) which
(66).
slide
is
too tight. If
of
turns
the
tape, rewind
Remove the reels
mount
loosen
To
rewind
plug
from
their
screws in
amplifier
and
power
unit is lifted
place
and
ADJUSTMENTS
amplifier
be
plug.
part
push
in motion.
the motor
head
the mechanical
is removed
placed
turns
rewind
on the unit
power
On units
#B-20209P19
use
cord
a Bell
of tape on the
button all the
with speed
pointer (2)
placing
by
with serial #14, 000
Il the recorder
in
speed
position.
not stall.
follows, if necessary.
and
the rewind
reach
belt,
pulley
idler
If motor stalls, re',vind
machine fails
(6?)
belt
loosen
idter
under
assembly
sockets.
the right hand side
cord
Loosen
will
miss
straight
screws in
the
right
unit on a flat
from the mechani-
and
driven in
with a socket that
socket.
part
control
the
control
#B-20209P29
take-up
run
On
down.
way
meets
pointer
position.
pointer
units
reel
The motor shoutd
to rewind last
is too loose. Make
the two
pulley
bottom
(66)
screws
(l/
assembly
plate
toward the
up.
to
2
and
Page
4
Page 5
front
and
to the left.
sembly
(66)
toward
idlerassemblyaboutl/
and re-make
Fast
Forward
Leave
reeland
hold.
Next,
.
(do
not
must
be turning
against
forward
not
turn,
if
necessary:
Loosen
Figure
bottomplate
assembly
Move
very
critical.
Check adjustment
1. Do not
2.
tests.
Adjustment-
12
to l5 turns
push
fast
Tape
forward
should start
holdright
press
down).
the
button is
it is
and clutch
take-up reel
held down.
too loose.
the fast
2)
about I/ 2
and slide
(71)
away from
little
at
After adjustment
load
Place run-stop
sition.
3. Place
three speed
4.
it
toward
support
lf reel
(8)
support
speed
positions.
Graspthemajorbrake
the front
mustnotturnwhen
of the recorder.
(8)
turns,
To tighten
the rear
32,' at a
of tape
to wind in forward
hand
Observe
belt,
and to
time,
on the left hand
button all
(take
up)
the take-up
plate (9)
support
If take-up
Mal<e adjustment
forward
twn.
the fast
a time as
as follows:
tape on recorder.
adjustment
Totighten
forward
the take-up
this adjustment
is
made,
pointer (2)
control
pointer
assembly(12)
the
(?3)
belt
bra-kes are released.
move idler
left.
the
Move
theninstall reels
(supply)
the
way
down
direction.
reel from
belt
must
(8).
be slipping
when
(?B)
belt
as
screw
the fast
follows,
belt, reach
play
and
reel support
tighten screw.
in
the
"Stop"
(l)
in one of
The take-up reel
is
too tight.
and
as-
the
and
turning
(?3),
does
(see
under
pulley
(8).
is
very
po-
the
pivot
Figure
3
Adjustments
Brake
Check
adjustments:
l. Placeafull
support
(6).
Do
across from
position
depressing
by
it
immediately.
2.
support
to reel
in
ward
speed,
Tape must
(not
I'Run"
the
button down).
place
If
1.
Checkthetwo
sure from inside
pivotbracket.
for
both dimensions,
re-position
2.
between brake
should be some
thatthebrakelevercam
of the control
Test
Run. Brakes must
brake
operation
(8)
and an empty
place
not
andwhen
Place
(6)
through
reel
to reel.
tape is
the
Tape
nearly
and
thread
position
tape in head
"Fast
run-stop
not
spill
brakes
require
(Forunitswith
dimensions
bottom
This
the
brake
(This
adjustment
lever
play,
arm slide
brake release
release in all
-
(Refer
To
as follows
?" reeloftape
reel
on
the supply reel
Place recorder
up
tofastest speed,
Forward"
must not
head
(this
When
spill
a
full reel
tape straight
slot).
eliminates
tape
control
or throw
should
pivot
cam
about
loops.
adjustment,
serial
#14,000
as
shown in
plate
flange
measure 2l/4,,.
loosen
the two screws
bracket.
is for allunits).
and brake
I/
64". Also
is approximately
(45).
in Fast Forward,
Figure
slot
5)-
before making
on
the take-up reel
run
but
in
"Rewind"
stop tape
support
straight
button. Release
or throw loops.
on
the supply
across
Placerun-stopcontrol
holdingfast
has reached
ilStopt'position.
in
the
do so
as
to 15,200
Figure
to edge of
Check space
(35).
lever
check to see
in the center
Rewind,
positions.
three
reel
from reel
for-
fastest
follows:
only).
b. Mea-
brale
Toadjust
(A)
and
There
and
o
=
Hr
Fll|
VF
I
\
gt
F
Page
5
Page 6
Figure
4
To
brake lever
change
bracket, Move
t}:.e I/ 64" spacing.
cam
in control
or
left
to obtain correct spacing.
NOTE:
(Forunits
If
another, that is more
rewind
clearance betweenbrakelever
cam, loosen scretvs
bracket forward
arm slide
brakes release more in
or visa versa,
bysliding the
or left
after
Speed
Slide
Cam And
(For
l.
for
units
35,000
must
clear
approximately
gaged.
positionof
this.
See
The
in
the
center
when that
loosen
phenolic
units
with serial numbers
and
45,000).
the control
16" when
Positionof motor
V
motor
mounting
paragraph
control
of the speed cam notch(40),
particular
set screw
slides should
(B)
or backward.
Use this
with serial
same
(45).
adjustment
Move
#14, 000
in fast forward
this can
loosening
Damper Adjustment-
screws
lever
brake
;ure
with serial
Speed
#14,000
beginning
cams
pins (point
particular
that
on motor
plate
on motor mounting.
pins (point
on spacers
"C"
slide is engaged.
and turn
be
cam.
such
that
(35)
holding
brake lever
and
to obtain
to center
bracket to right
15, 200
to
one direction
bracket to the
(B).
equalized
be
only).
than
than in
rlght
r-)=
15,200
to
with
(40), (41),
Figure
"C"
and
25,000,
(42)
and
2)
by
slide is en-
mounting
plate
and
will effect
Figure 2) must
(41),
To adjust,
Spacing betrveen the
they
are
be
(42),
or
parallel
to
and
top
above
inch, if no
(41),
cam
The
bracket
Speed slide
motor
slots will
springs,
dampers
on the
when engaged.
bottom
cam,
(42)
and
(42)
first.
(For
2.
phenolic
(44)
pulley
permit.
(This
3,
(point
phenolic
plates.
spacebetween
rfasher,
up
units
slides
when
bracket
pressure
and
about
or
with serial #14, 000tol5,200only).
must
that
(44)
This
applies
Figure 2) must
"D"
slides
However,
down
interferewiththesmooth
its spring
with
(44).
Capstan Actuating
end
sure arm
cam
control
tension.
mounting
The
capstan actuating
play
between
(27).
(30)
and
flywheel
(2)
to
Adjust damper
screws
Cam
plate (2a)
top
Also,
there must be some
(29).
"Run".
phenolic
If
a
cam and slide
inches.
.025
adjust.
to
clear
the
particular
should be located
roller
will allow ful1
to all
units). The speed slide
hold
to
idler wheels
\ryasher
is about
Slide
Adjust
sides
of
slide
(22)
as
use of the slide
press
this damper spring
operation of the slide
on side
(30)
Adjustment-
cam
To adjust,
Loosen
springs
speed
of
(30)
and the capstan
slide
must have some
turn
set screw in
is used
.008
(40),
cam
bottom
speed
slide
is engaged.
near
as
the mounting
down
in
play
the
firmly
position
must not
against
carefully
bracket
pres-
between
run-stop
hub
cam
Page
6
Page 7
Figure
-
o
Ht
Flt
F
VF
I
\
5
Ctr
and
slide
cam
adjustment,
pressure
until
capstanshaft.
and
move
height
Record
units
35,000).
pressure
alter
still
further
of cam
Safety
(For
units with serial
with serial
Adjust record
the run-stop
point
the
front
front
of the
diagonal
of the
bottom
tacts record
proximately
With
the safety
to
the center
sliding
right
should
(2)
is
release
to right
angles
When
return
placed
control
properly
(30)
push
up or down.
wrench
roller
Now,
backup(pull
(22)
roller
provide
to
(30)
again
and
Release Cam
number
control
safety release
in
of the run-stop
to the
to
in the
(2)
cam to
slope
the
of t}le
plate.
the center.
(2)
still
(point
left
or
bottom
adjusted,
its
"up"
"Stop"
"E"
in
position
While
toward rear
pushed
is
wrench
(22)
meets
some
tighten
(31)
Adjustment-
#14,000
beginning
safety release
in
left,
the
,'Run"
adjust
pointer
Adjustheight
(point
in the
"Run"
Figure
(turning
away from
toward
capstan shaft,
clearance. Check
set screw.
15,200
to
with 25,000
cam
position.
cam so that
parallel
is
so that it con-
Figure 2)
"E"
position,
2) so
that
control shaft. Adjust
slotted
the
plate.
hole. Keep
Tighten screw.
the red record
when run-stop control
position.
making
and for
(31)
adjust
points
it
button
this
cam)
the
front)
and
with
With
the
to the
ap-
by
Motor Mounting
(For
motor mounting
mounts
spacing
of themotorpulley
shouldbe
bymoving
and
between flywheel
or by moving
At the
cheek the control
Slide
"Speed
must be
for
Volume And Tone
ineitherdirection,
linkage from
controls.
at
on top of first nut,
to .
Hum Adjustment-
recorder,
good
If the
play
012
The hum
positioned
operation.
And Spacing
units
with serial
plate (59)
if
replaced
.410 to
motor
the
the motor
same time
Cam
volume
both
another
Use
inthe
adjustment is located
looking
or removed
should
inches
.420
plate
on the
pin
adjustment
And
Damper
to
meet both
Control Alignment-
or tone controls
remedyas
controls. Loosen
3/ I
both controls. Thiswill
control
shalts andwill
at vent
Adjustment-
#14,000 to 15,200).
is mounted
(29)
andthe largest
checked.
be
and
on its spacers
plate (2
above dirnension
Adjustment".
follows:
on rubber shock
for
any reason
This dimension
can be
accomplished
(3
hex. nuts)
hex. nuts).
is checked,
as deseribed
of these dimensions
bind when rotated
The motor
Remove driver
hex. nut on
32 nut
-
and lock down
allow
prevent
opening with recorder
on right center of
The
the
diameter
under
both
tight
.010
binding"
resting
Page ?
Page 8
A
PHOTOFACT "€XPLODED"
O
Ho*od
V Srms
a Co., lnc. 1956
VIE\?
Page
Figure
6A. Exploded View
0f Parts Above Baseplate.
I
Page 9
o
=
H*
Fln
70F
I
\
{,|
F
Figure
68. Exploded
View
0f
parts
A PHOTOFACT
o
Below
"EXPLODED"
How.d v.
s.h. & co., tic. 1955
Baseplate.
VI€W
Page
9
Page 10
on
back
from
in
"Tone"
hum.
Ilead
to
wave length.
withan
the speaker
"Tone"
of case. To
all strongelectricalfields,
amplifiers,
motors, etc.
controls at maximum.
Try
line cord
And Pressure
prope
To
have
A.
rly check head
a reel
of
Play alignment
C. vacuum
pre-recorded
or 3.2
controls full
adjust,
plug
Pad Adjustments-
tube voltmeter
ohm load.
on. Output
position
Adjustwith
both
ways.
alignment it
alignment
tape
volts or higher.
CAUTION:
viding amplifier
Dirtyhead, improperpressure
head
alignment
pole
away from
is dirty,
carbon
cleaning.
canbehadwithmaximum pressure
Adjust record-play
pad
should
pole.
pad.
erase
a maximumreading
pad.
NOTE:
thescrew(point
to t}te left
out until
the A.
Be sure recorder
prevent
Threethings
erasure
cancause low meter
and
angle. Check
1.
Check head to
piece
or
bakelite
pole
the
clean
with head cleaning
tetrachloride.
2.
Adjustpressurepads
pad
shiJted
be
After
maximum
pressure pad
Hold
pad
spring
Adjustmentof
back
of I
which means
pad,
the other
3. Head
alignment is
Figure
"F"
of the head.
the maximum
C.
vacuum
tube voltmeter.
is in
of alignment
tubes are working
padpressure,
these
be sure there is no
portion.
piece
and lowers
Wipe dry immediately
so
first. For
slightly
output is
with a spring scale.
either
when adjustment
pad
Turn this
CLEAN I NG
to the right of center
obtained, adjust erase
bracket
ounce, Re-check
pad
must
accomplished
1) whichis
voltage
reading
such
recorder
as transformers
Adjust
"Volume"
for minimum
away
and
is neces sary
of I mil
back through recorder
Turn
voltage should be 1.3
tape
connected across
"Volume"
"Play"
position
tape.
readings)
and
pro-
properly).
orwrong
as follows:
things
on
Dirt
holds the tape
output.
solvent, alcohol,
dirt
tfie
If head
or
after
that maximum signal
poles
on
best results, this
(16)
of I
while
Adjust for
ounce.
pulling
record-play
may
affect
the other,
is made to one
also be checked.
by turning
located directly
screw slightlyin
is
obtained on
and
catedwith a very light
point
at
surfaces.
of friction
pulleys,
2.
All
be cleaned with
drop
of #10 or 20
CAUTION:
When oiling any
partismounted,
only one small
must
and
(
to
Take-Up Reql
that might
Be sure no
extending
TROUBLES AND
Play, Record,
I. Fast forward
broken.
2.
as described
allowingpulleyto turn
Tighten set screw.
of
foroilorgrease.
solvent.
Recorder Will Not Rewind
as d-lscribed under
pulley
for
solvent.
Take-up
under
3. Setscrewinforwardpulley (?2)
4. Set
5.
screw in clutch
Checktake-up
1. Rewind spring
2. Rewindbelt
3.. Setscrew inrewindpulley
to turn on its shaft.
4.
Checkrewind belt
grease.
oil or
grease.
only
rollers,
a dry
soft
motor
oil.
be kept
periphery
transfer
oil is
above
Fast
belt
(8)
Forward-
(73)
Support
Or
"Fast
on
belt
If necessary,
(64)
(67)
"Rewind
If
necessary,
This lubricant
and wiped
and rotating
cloth and lubricated
bearing on which a rubber
clean from
orpartusing
drop of
oil.
off all rubber
flywheel
of
oil or
portion
on the
baseplate.
REMEDIES
Not
Will
spring
may
Forward Adjustment".
its shaft.
Take
(65)
be too loose. Adjust
Tighten set screw.
plate (9)
(73)
and associated
cleanwith
Tape-
disconnected
should
other
shalts should
with I
a belt, apply
idlers,
and off
to
of capstan
Up
may
be
be loose.
petroleum
a
grease
belts
parts
them.
Tape In
loose,
pulleys
Oil and
grease
disconnected
may
or broken.
improperly adjusted. Adjust
Adjustment".
Belt
(68)
loose,
Tighten set screw.
(6?)
and associated
clean with a
allowing
pulleys
petroleum
be
or
The capstan
play-record-erase
and
ulationof
tape
sha-ft,
coating oxide
asitpassestheseparts.
approximately
parts
these
cleaned
tetrachloride.
pressure
the
when cleaning
CAUTION:
l. All
should
be free of dirt and foreign
Page
l0
every
except
with head
ten hours
the
cleaning solvent,
Use alcohol
rollerl never
any rubber
Topreventseratchingtheheadpole pieces,
never
use a metal
LUBRICATION
the wiping surfaces of mechanical
pressure
head
which is
Thesepartsshould
pressure
roller,
are subject
worn off the tape
of runningtime.
roller
alcohol,
or
water when cleaning
use
carbon tetrachloride
driving surface.
tool when
material
guide,
tape
to an accum-
be cleaned
A1l
(22)
may
be
or carbon
cleaning.
linkages
and be lubri-
Tape Spills Or Throws Loops
In
-'
of
Adjust
Wow And Flutter
Position-
"Stop"
1. Brake spring
2. Brake
as described
assembly
under
(Record
In analyzing the source
observe whether
period
speed
of rotation
roller.
1. Check
are a free-running
they
nylon
and
Dirt
bearing surfaces must
grit
or
the
of the capstan,
the capstan
will
cause motion-modulation
When Recorder
(U)
disconnected
(12)
improperly
"Brake
Or
rate
of wow coincides with
Adjustments".
Play
Back)-
of wow, it is helpful
pressure
(29)
bearings to
fit, but not loose.
perfectly
be
Is Placed
or broken.
adjusted.
roller, or
see that
Both
smooth.
of the tape
to
the
shaft
Page 11
and
result
in a rough-type
be
taken
the
top
ing
with
of
light
poor
faces_
(39),
or
roller
lightly
Severe
stan
speed roller.
must
flywheel
climbs
motor
(if
up
capstan
absorbent
oil
on
2.
Oil
drive,
thrown
resulting
are motor
flywheel
(22).
Cleanwithasoft
dipped
wow at
shaft.
3.
If
flutter is
spin
smoothly,
rotation,
on shaft,
mounts)
not
support
re-assembly.
pulley,
in
capstan
Observe roller
motor
or speed
Vibratingspeedslide
(check
(point
enough
excessive
action.
excessively
speed
shaft fit
Figure 2)
"D"
to hold
friction
See
"Speed
4.
U
the motor is
it
(29
C. P.
and
position,
in
will cause
S.
shaftorfanordueto
pulley.
vibration,
wow
surfaces,
smooth.
capstan
smoothness
if
reflect
this is
If
ticularlyif
check
support
ing
observe
by hand,
reel
hold
(9)
reel support
vibration
idler
piece
to
A
bad or vibrating
5.
The
at its
capstan
rotational speed,
clean roller
Pressure
surface
of end-thrust
necessary.
6.
A
vibrating
flutter
the
case,
A
vibrating
A. A
bent clutch
bent, replace.
B. A
rough
the
clutch
a
broad-bladed
(8)
and
felt
run machine
vertical
It is
difficult
therefore,
bearing
When
the
and
(34),
the machine
take-up reel
run
unit in
lightly
should
METHODS
l. Noisy
bracket
of varnished
prevent
metal-to-metal
squarely
into
replace
reel
take-up
motion.
be
drive
rattles
flutter,
excessive)
(23).
tissue,
naptha-type
a
and
and
Slide
).
the machine
or
surface,
replace
if necessary.
play position.
against
felt.
cambric
smooth
onto
driving
inwow
and flutter.
speed
and
capstan
speed
high
at a
plane
in
a
without
may
be tilted
slide may
may
be due
concentricity).
press
must
but not
interfere
Cam And
out
flutter
This
may
a slightly
belt
pressure
D.
O.
(22)
roller
and
washers.
take-up
the
tal<e-up
support
plate
uneven
reelbearing
remove
in
tool
close
to face
OF
appears
support
NOISE
idler
against
off the felt
the clutch
the
bracket
cloth
Play
byloosening
Cleanup
can sometimes
sha-ft
up
and use
and shifting
surfaces
Driving
slide rollers
(29),
absorbent
thinner.
may
particular
as unit
vibration.
to a
lighily
with freedom
Damper
of
balance
at approximately
be due
bent or
can
rolter
Check for
and
must
and
tissue or
be do to a
parallel
Do
speed,
operates,
to
If speed
excessively
be warped
bad speed roller
Damper
onltiOei,
so hard
be sure
as to
Adjustment".
and vibrates
to a
bent motor
eccentric
also cause
(22)
clean
operation
engage
uniformty.
Replace roller,
reel
support
thru tape
mayalso
shalt
clutch
fit is
play
position
to
the felt surface
to
(8)
above
Lower
clutch,
REDUCTION
the
on
contact.
(8)
or be1ts.
reel
support.
be caused
(Item
9, Fig.
surface
too free.
the
take-up
while
ctutch
and
the
function
clutch
the tak;-up
onlyveryslight
(bb).
If the
baseplate,
top of
the bracket
Light
and
bear-
one drop
will
cause
sur-
(B?);
(39),
pressure
cloth
not
soak.
bent
cap-
check
roller
plane
roller
(check
(reptace).
springs
cause
of sliding
motor
motor
motor
can
cause
bearing
against
-Ctrect<
can also
68).
(9),
par-
reel
hold-
surface
take-up
properly,
plai6
drive
glue
grease
iu-st
tor
by:
To
to
applied
noise.
in run
reel support
slight
replace
upbeltisrubbingthebottom
bend
is riding
belt
shafts and
of
extra nylon
clearance,
in
bearings
both
scarredtry
if
badly scarred,
bearing
assembly.
(i.
e. coming
vibration
This
tion by
a new l2AY?
is
record slide
These
U
tance readings.
A. C. vacuum
winding at the
frequency,
"Record"
58 volts.
generator
winding at
continuityifsuspected
ing should
winding about
CAUTION:
a
to the
2.
position
vibration
bracket
Take-upreelsupport(8)
without
lightly
against
should
plate
clutch
pivot
and
using tape.
clutch
be felt.
assembly
If
(9).
3. Excessivetake-upbelt(?3)
pulley
bracket
high
on motorpulley,
4. Noisy pulleys.
bearings
5. Noisy
shaft
and
washer
so as
can usually
smoothingoff
carefully.
(A-23?63p3),
to reduce
bearings. Noise
bearing.
replace.
end-noise.
6. Noises
heard
from
of the first
tube may
the motor.
AMPLIFIER
l.
Check
2.
Testallfive
jacks
3.
Refer
4.
Test
microphonic
be
to
all
not
Check
effect
tubes,
(M4)
tube
switch
must
to schematic
bias
oscillator
tube
voltmeter
play-record-erase
use
unshielded
position.
Check
bias
and scope.
Check
play-record-erase
A.
B. At
C. At
5. The
be approximately
and erase
bias voltage
At 7
I/ 2 i.
3 3/
4 i.
L 7/
8 i.
play-record-erase
160
ohms.
Wheneverthe
it
willbecome
Therefore,
testing.
flange
(?l)
slightly
Remove
Oiland replace
end
be eured
If shaft
roughness
Nylonwashers
Add
I drop
when
the volume
the loudspeaker)
12AY?
tube
and
the motor
a
cure.
TESTS
AND
inspect
poor
for
jacksfor
be
openor shorted
grounded.
for
as follows:
across
wiring.
Voltage
of being
should
This
frequency
should
across
head
p.
s.
minimum
p.
s.
minimum
p.
s. minimum
10
ohms
head
magnetized
always
open.
is
demagnetize
will
also
help
placemachine
noise.
Lower
plate (g),
vibration is
noise.
of
toward
benddown
the
If
the motor
baseplate. If
pulleys
if
there is sufficient
play
to a
minimum.
caused
by dirt and
by careful
or
bearing is slightly
with
of
crocus cloti,
help
#10 or
cleaning
20
is
may
(Vl)
in the
excited into
isolation
REPAIRS
wiring and
or open
all
head
headmaybe
and the
tested for
connections.
voltage and
Connect
the erase
socket.
Place recorder
be a minimum
with a signal
be b8 to
play
socket.
63KC.
record
-
of 3b
of 14 volts.
of l0
The erase
play-record
to some extent.
head
reduce
take-up
only very
excessive,
the take-
pulley,
slighily.
and
clean
with an
grit
reduce
oil upon
turned
be due
amplifier.
vibra-
and try
play-
circui@:'-
resis-
an
head
Due
head
volts.
volts.
tested
for
wind-
continuity
alter
up
to
in
of
-!
of
to
=
o
E,
Ill
E
llt
F
F
F
v
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II
Page
ll
Page 12
TOP VIEW
OF
AMPLIFIER.
Page
BONOM VIM
12
OF AMPLIFIER"
Page 13
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Page 14
Ref.
No.
Part
No.
IMPORTANT:
Description
MECHANICAL
When ordering
serial
number
parts
that
serial number
at the
rear of
important
and
t}tat defective
placing
when
PARTS LIST
parts
and
are
being
is located on t}te
the
t}tat this
parts
order,
Ref
.
No.
always
model
give
of
the unit
ordered for.
case. It is
number
if
Part
No.
be
be returned
possible.
the
The
grille
most
given
Description
I
2
3
4
5
6
7
I
I
l0
1l
L2
13
14
r5
16
t?
l8
i9
20
2r
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
3?
3?A
A-23628
A-23628
c-2364?D
c-23648D
D-23821A
B-23804J
A-23?63PlB
B-23805L
A-23866D
A-23?63PlB
A-23561C
B-23983
A-235?8
A-23663
B-23712(Pl)B
A-23528A
A-23530A
A-23622
A-2362tC
A-23623A
A-23529A
A-23822D
A-23636
A-23659F
A-238?6E
A-238?5E
A-25331A
A-23660A
A-23562C
A-23?58
A-23822D
A-23?63P28
A-235r8P1E
A-24000
c-23655A
A-2383?D
A-23?64
A-23?588
A-2365?
A-23548C
A-23?90
A-23515C
A-23870
A:23?61
A-23681F
A-23678D
A-2369?
A-23842P3
A-23851E
A-235368
A-23801P1C
Speed
Control Pointer
Run and Stop
Head
Cover
Pressure Roller
Top Deck Plate Assembly
Pointer
Cover
Take-Up Reel Support Ass'y.
Nylon
Washer
Take-Up
Clutch Plate
Nylon
Reel SupportAss'y.
Shaft Assembly
Washer
Brake Spring
Major
Brake Assembly
Brake Pad
Ilead Assembly
Play-Record-Erase
Head
Bracket
Head Adj.
Head Adj.
Head
Head
Head Spacer
"Truarc"
Fiber
Pressure
Play-Record
Arm
Plate
Pivot
Spring
Hold Down
Retaining
Washer
Pad Brkt. Ass'y.
Pressure Pad
Assembly
Erase Pressure
Head
Ring
Pad Arm
Assembly
Felt Pad
Pressure
Pad
Brkt. Arm
Assembly
Pressure
Slide
"Truarc"
Nylon
Pressure
Top
Pad Spring
Bearing
Retaining
Washer
Roller Assembly
Capetan
Bearing Support
Ring
Assembly
Top
Plate Sub-Assembly
Record
Record
Slide
Capstan Pressure
Interlock
Button
Bearing
Shaft Ass'y.
Arm
Assembly
Pressure
Flywheel
Pressure
Record
Ball
Roller
and Capstan Ass'y.
Roller
Safety
Bearing
Release Cam
Flywheel
-
Spring
Cam Ass'y.
Thrust
Cam Sha{t
Reel Stand
Brake Lever
Index
Spring Damper
Speed Slide
Assembly
Speed Roller
Speed
Arm
Slide
Assembly
Spring
-
Arm Ass'y.
Roller
l1/
8
(L
1/
8)
Ass'y. - I 7/
I
3?B
38
38A
388
39
39A
39B
40
4L
42
43
44
45
46
41
48
49
50
5l
62
53
54
55
56
51
58
59
60
6l
62
63
64
65
66
6?
68
69
70
?l
12
73
74
15
A-23558C
A-238528
A-2353?B
A-23801P1C
A-23558C
A-23853E
A-23801P2C
A-23558C
A-2104t
A-27042
A-27043
A-23162
A-23803C
A-23538C
B-23970F
A-23588D
A-23568P28
A-23642C
A-23568P18
A-23772A
A-23667A
A-23668
A-23742A
A-23631A
A-2?0508
A-21049
B-23952C
B-27019
B-23?338
A-23854
B-239588
B-20029P41
A-23607A
B-27026
A-23546D
A-23842PIC
B-27029
A-23583A
A-23596C
A-2359?C
A-23860C
A-23689E
A-23883C
A-2366lP28
A-238868
A-23665F
c
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A-23634C
A-23862E
A-23691C
A-23885D
B-2388?C
A-236628
A-23843C
A-27044
Speed
Roller Spring
Speed
Slide
Roller Ass'y.
33/4
Speed
Roller
Speed
Speed
Speed Slide
7 L/2
Speed
Speed
Speed
Speed
Speed Slide
Speed
Speed
Damper
Control
Nut
Control
Control Arm
Spring
Control Arm Stop
Control Arm
Control Arm Latch
Control
Push
Button
Flange
Idler
Pulley Drive
Drive
Drive
Cam,
Off Arm
Index
Arm Assembly
Motor
Motor
Motor Mtg.
Operating
Cam
Spring
Spring
Cam Arm Ass'y.
Cam Arm Lever
Rewind
Fast
Forward
Rewind Idler
Rewind Idler
Rewind Idler
Rewind
Rewind Pulley
Rewind
Motor
Motor Fan
Fast Forward
Assembly
Bracket Assembly
Fast Forward
Fast
Forward Belt Pulley
Tal<e*Up
Idler
Return Spring
Capstan
Assembly
(3
Slide Ass'y.
Roller
3/ 4 and 7 r/ 2l
Spring
Roller Ass'y.
Slide Ass'y.
Roller Spring
Slide Cam
Slide
Cam - 3 3/ 4
Cam
Change Shaft
Slide
Brkt. Ass'y.
Spring
Arm Slide
Stop
(Push
Button)
Arm Stop
Shaft Ass'y.
Arm
Idler
Brkt.
Idler
Off Arm
Mtg. Plate
Mtg.
Grommet
Spacer
Cam Assembly
Damper
Spring
Spring
Pulley Ass'y.
Brkt. Ass'y.
Pulley
Belt
Idler
and Pulley
Play Pulley
-
Play ldler
-
Belt
Bottom Bearing
-
-
I 7/
-
I l/2
-
Ass'y.
(left
(right
Ass'y.
Ass'y.
Ass'y.
Ass'y.
Ass'y.
3/
3
7 L/ 2
8
hand)
-
4
-
hand)
Page
14
Page 15
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c7
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R5
R6
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B-20053P5
B-20048P28
B-20053P25
B-2004?P98
B-20049P7
B-2004?P56
B-20047P24
B-2004?P98
B-2004?P81
B-2004?P8l
B-2004?P81
B-20041P17
B-20047P86
B-2004?P81
B-2004?P81
B-20047P1?
B-20049P7
B-2004?P86
B-2004?P1?
B-2004?P81
B-20049P98
B-20049P66
B-20049P68
B-20049P64
B-2004?P92
B-20066P130
B-20066P130
B-20066P72
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6VOCT,
6C4,
Bias
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Elect.
Elect.
Elect.
Cap.
Elect.
Cap.
Elect.
Cap.
Elect.
Cap.
Elect.
Cap.
Elect.
Cap.
Elect.
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,
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390MMF.
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2
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Control,
Adj.
w.
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Cap.,
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Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.
Cap.
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
Cap.,
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Volume
t/
Tone
Hum
w.
Resistor,
Resistor,
Resistor,
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AF
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,
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400V.
400V.
400V.
500V.
400V.
500V.
b00V.
500V.
500V.
400V.
t/
Z
Watt
2
Watt,
Watt
Watt
Watt
L/ 2
Watt
PARTS
R8
R9
R10
Rll
R12
Rl3
Rr4
Rt5
Rr6
Rr7
R18
Rl9
R20
R21
P-22
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F"24
R25
R26
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R29
R30
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R33
R34
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Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resiator,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
Resistor,
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Power
Audio
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Bias
Pilot
Neon
Neon
(Record
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Speed
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Switch
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47KO,
lMeg.
27KA,
l00Kq
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100Kq
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220Kq
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100Kq
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ig, t/
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Speaker,
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Type
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Switch
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Watt
L/ 2
Z
Watt
Watt
Watt
Watt
Watt
l/ 2
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Watt
Watt
Watt
V2Watt
Watt
2
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Watt
Watt
2
Watt
2
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Watt
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Watt
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Watt
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Page 15
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