International Tapetronics Corporation 770 Series User manual
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•
TECHNICAL
MANUAL
(890-0024-000)
770 SERIES
REEL-TO-REEL
REPRODUCER
/
25
Hz
DETECTOR
tnTERnATIOnAL
TAPETROnlCS
CORPORATIOn
2425
SOUTH
MAIN
STREET •
BLOOMINGTON,
ILLINOIS
61701
OCopyri
ght
1981
lnternaUonal Tapetronics Corporati
on
.
Made under
one
or
more
of
the following
pa
tents:
3,
800.3233,
801
. 043 3, 801,3293,833,925 3. 865.719
other patents pending
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0381
DM
PREFACE
THE ITC
lNSTRUCT
IO
N
MA
N
UAL
Int
ernational Tapetronics Corporation Manuals
are
wr
itten
with
the intent
of
assisting the reader-user
toward a better understanding
of
I
TC
equipment
Most
instruction manuals are seldom read except
at
the time
of
crisis when equipment malfunction is suspected.
When thishappens,
the
manual is usuallymissing,
or
at
best,difficult
to
locate.PLEASE
FIND
A
CON
V
ENLE
NT
SPOT
TO
KEEP
TH
IS
MANUAL
We
at
ITC
have tried
to
produce a useable manual.
But,beinghuman, wearesubject
to
the
frailties ofbehav,
ior
.Therefore, should you discover any
errors
or
omis-
sions,
or
should you wish
to
contribute
any recommen-
dations.please sendus
your
comments.
We
will
bemost
appreciative.
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0381 DM
ITC's 770
SERIES
REEL
-TO.REEL
REPRODUCER
has
been
designed for
broadcasters
.Itis ideallysuited
for
use
in
program
automation
systems.
The
770SERIES is:
• designed
to
meet
or
exceed
the
NAB (National
Asso
ciation
of
Broadcasters)
standards
for reel-to-
reel
tape
reproducers;
• available
in
a variety
of
co
nfigurations including,
.
•.
.
one
or
tw
o track,
mono
or
stereo
capab
ilit
ies
and
. . . . ta
pe
speeds
of
3·3/4,
7-1
/2,
and
15
IPS;
•
constructed
with a heavy
1/2
inch (12.7mm) thick
aluminum tool plate
deck
for stability;
• equipped with a unique, high quality, profession
al
head
assembly;
• utilizing two induction
torque
motors
for supply
and
t
ake
up
reel handling
and
a D.
C.
servo
capstan
motor
for
tape
drive:
and
• designed for simplicity
and
serviceability of
mechan
-
ical
and
elect
ron
ic
com
ponents
.
The 770 Series
reproducer
is designed for long life,
durability,
and
ease
of
service
• low maintenance, positive action differential disc
brakes
design:
•
strong
,
cast
stainlesssteel turntable;
• long
life
control switches
and
an
il'l9enious switch
support;
• multispeed D.C.
servo
capstan
mo
tor;
• automatic
cue
lever
and
ta
pe
lift
er;
and
• unique magnetic playback head.
iii
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TAB
LE
OF CO
NT
ENTS
PREFACE
....
.........
.......
..
.....................
.
...
....
..
.
.....
.. i
TABLE
OF
CONTENTS
.. .
....
.
...................
.
....
..
....
.
.....
. .·.V
ILLUSTRATIONS
.....
.
.......
..
......
.
...
....
..
•.
................
.
..
IX
SECTION
I.
INTRODUCTION
A.
Tape
Tr
an
spo
rt . . . . . . . . . . . . . •. . . . . . . . .. . . . . . . . . . . • •. . .. . . . . . . . . . . l·l
B. H
ead
Assembly
...................
.
..
. •
....
.
...........
.
....
.•
...
1-1
C.
Ele
ct
ronics
...........
. , .. ••. . . . . . . . . . . . . . . . . . . . . . . . • . • . . . . . . . . ..
1-1
D. Specifications
.....
.
....
. .
..
.........
. •
..
,. .
....
..
.....
.
....
.
.....
1-1
1.
Power
2. Wind Time
3. Motors
4. T
ape
Speeds
5.
Tape
Width
and
Tra
c
ks
6. Reel Sizes
7. Flutter (NAB Weighted)
8. Audio
Output
9. Distortion (Amplifier)
10
. Signal-to-Noise Ratio
11.
Crosstalk
12.
Equalization
13.
Fr
equency
R
espo
nse
14.
H
eadp
hone
Output
15.
Ambi
ent
Operating T
emperature
16.
Remote Control
17.
Br
akes
18, External
Connectors
19.
Dimensions
20. Weight
E.
Warranty
......
. . .
...
...
..
.....
.
....
.
.....
.
..
. .
•.
.....
.
.....
.
...
1-2
F. Options
and
Accessories . . •. . . . .
..
........
.
..
.
...
. .
...•
.•
.
...
.
....
1-2
SECTION
II
. INSTALLATION
A.
Unpacking
and
Handling
........
.
...........................
.
.....
2-1
8.
Installation in Ra
ck
.
....
.
..........................
.
..
•.
...
.
....
.. 2-1
C.
Optional Console Housing
...
..
...
...
.
....
. ,
.....
.
...........
..
....
2-1
D.
Connecting Audio Lines
...
.
...
..
...............
.
...
...
......
•
.....
2-1
E.
Connecting R
emote
Controls
...
,
....
,
.....
.
.......
.
..........
.
....
2-2
F. Initial
Checks
Before Operation
..............
..
, .
....
,
•.
.
..........
2-2
G.
Functional
Checkout
.
••
.
....
•.
...
..
.........................
. .
..
. 2-2
SEC
TION
Ill
. OPERAT
IN
G INSTRUC
TIONS
A.
Threading
the
T
ape
...
..
...
.
....
.
..
.....
....
••
.
..
....
.
...........
.
3-1
B.
Controls and Indic
ators
.
..
..
....
..
.
......................
....
.
.•
, . 3-1
1.
Start
Switch
2.
Stop
Switch
3.
Fast
Rewind and Fast Forward
4. Reel Size Switch
5. Power
6. Speed
7.
Cue
Lever
8. LED
Ind
icator
9. Limited Range Front Panel Level Controls
V
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SECTION
IV
. SETUP,
ALIGNMENT
.
AND
CALIBRATION
A. Mechanical
Adjustment
-
Tran
sport
....................
• •
...
.........
4-1
1.
Reel
Motors
Torqu
e
Adjustment
..
...........
.
....
..
.
............
4-1
2.
Torque
Boost
Adjustment
..........
....
...
•
..........
..........
4•2
3.
Supply
Tension
Arm
D
amping
Adjustment
. .
............
•. •.
.....
.
4-2
4.
Pressure
Roller P
ressure
Adjustment
. .
•.
...
. .
.....
..
...
.
.........
4-2
5.
Solenoid
Air Damping
...............
...........
••
....
. •
...
.....
4-3
6.
Reel
Turntabl
e Height
..
...
•
........
.........
....
.
..........
.
...
4-3
a)
Measuring
Turntable
Heights
b) Adjusting
Turntable
H
eights
7.
Br
ake
Tension
Ad
jus
t
ment
....
. .
.........
...
..
. •
•.
..•.........
. . 4.4
a) Initial
Brake
A
djustment
b) Final B
ra
ke
Adjustment
8. H
ead
Height
and
Zenith
..
. .
..
•.
...
.
.........
..
.....
.•...
. . •
••
..
4-5
a)
H
ead
Assembly
Lock
Screw
b) C
oar
se
Height
c)
Coarse
Zenith
d)
Fine
Height
and
Zenith
9.
Capstan
Motor
Speed
M
easure
m
ent
and
Ad
just
ment
s
..............
4-6
a) 3.75
ips
b)
7.5 ips
c) 15
ips
B.
Ele
ct
rical .
.....
•.
......
..
..
•
............
...
.
....
...
....
..........
4•6
1.
Reproduce
H
ead
Azimuth
and
Phasing
...
.•
........
...
...........
4-6
2.
Reproduce
Amplifier Equalization
.......
.
......
•..
....
• .
....
.•
...
4-8
3.
Reprodu
ce
Amplifier Level
....
.....
. •
...
.......
.................
4-8
4. Infrared
Tape
Sensor
...
.
...................
.....
....
.
.......
.
..
4-8
5.
Capstan
Motor
Speed
Change
...............
.
...................
4-9
SECTION V. ROUTrNE MAINTENANCE
A.
General
....
•
....
•.
.....
•
....
.
.................
. .
..
.
........
.....
5-1
B.
Main
tenance
Tools
and
Aids . .
...
....
.
...
. •
..
................
.
.....
5-1
C.
Ma
int
enance
Sc
h
edule
............
..
..........
..
...
.
.............
. 5-2
D.
Spare
Parts
....
. . . . .
..
.•
...
.•.
...
.•
........
..
..................
..
5-2
E.
Parts
/
Equipment
Return
Poli
cy
.....
••..
. .
....
••
..
.
..
.........
.
.....
5.3
SECTION VI. THEORY
OF
OPERATION
A.
Power
Supplies
. . . .
..
. .
.........
..
..............
...
..
..•......
...
6-1
1.
Solenoid
and
B
rake
2. 24 Volt DC
Supply
3. 5 Volt
DC
Supp
ly
8.
Tr
ansport
Logic
Control
.......................•.......
•
.....
••.
..
6-1
1.
Stop
Ci
rcuitry
2.
Fast
Wind
Circuitry
3.
Start
Circuitry
4.
External
Connect
io
ns
C.
Program
R
eproduce
Amplifier . .
..
.........................
...
......
6-2
D.
Optional
Motion
Sense
/
Start
M
emory
.....•...........
.
..
.
...
..
...
..
6-2
SECTION
VII
.
MECHANICAL
DRAWlNGS
AND
PARTS LIST
A
Deck,
Front
.
.....
•
...
.
......................
.
.........
.......
. . . 7-1
1.
Turn
table
and
reel
retainer
.....
, . . .
..
.
..
..
. .
.....
.
......
.
.....
..
7-2
2. H
ead
Cover
......
.
.....
...
.
....
.......
.
..
.
..
.
........
....
.•
..
.
7-2
3. H
ead
Mounting
Block .
..
. .
...
....
..
.•
....
.
......
.............
. . 7.3
4.
Tape
Guide
.............
.
..................
..
,
........
.
..
• . .
..
7-3
5.
Capstan
Motor
........
..
...
•..
....
...
. ,, ,
...........
...
.......
7-4
vi
www.SteamPoweredRadio.Com
B.
Deck,
Rear
...........
......
.
..
..
.•
..
....
..
.....
.......
.....
.
..
. . 7-5
1.
Dashpot,
Foil
Sense
Po
st
......
.....
......
..
...
.•.
..........
•.
..
7-6
2.
Pr
essur
e Roller Solenoid M
echanism
, .
...
.............
. .
....
.
•.
..
7-7
3.
To
r
que
Mot
or
/
Brake
Assembly
.....
..
,
.....
. . , . ,
................
7,8
4.
Swi
tchca
rd
. .
....
.
....
•.
....
. .
....
.
.........
. ,
.....
.
....
.•
..
..
7-9
5.
Pow
er
Transformer
.......
..
. .
....
•
...
.
....
..
•..
..
..
.
..
...
.
...
7•
10
6. Motion
Sense
...
, . . ,
..
.
................
....
•
..
.
..
•.
. ,
....
,
...
7
-1
1
SECTION
VIII
. E
LECTRICAL
ORA
WING
S
AND
PARTS
LIST
A.
Mother
Board
1.
Component
Loading
an
d Overlay
.................
•.
, . . .
•.
.....
. . 8-1
2. Schematic
..
.
..........
.....
..
....
, , . ,
...
.
.......
......
. .
...
. . 8-2
3.
Pa
rts
List .
...
.....
.
.....
•.
...
......
.
.........
.••.
...
.
........
. 8·3
8. P
ower
Cage
Wiring
Chart
...
•.
..
..
,
...
.
............•...........
..
. 8-5
C . Re
prod
uce
Amplifier
1.
Component
Loading
and
Overlay .
...................
.••
...
. . •.
..
8-6
2.
Schematic
...
........
. .
.......
...
..
.
•.
•.
..
.
..........
.......
..
8-7
3.
Parts
List .
••
. .
..
•. . . .
.••
....
..
.....
....
.
..........
.•
.....
•.
. . . 8·8
D. Switch
car
d
1.
Component
Loading
and
Over
lay
............
....
. . , •
..
.
...
•.
...
8-10
2.
Schemati
c
............
....
.
.....
. , , .
.•
........
..
....
........
. 8•
ll
3. Pa
rts
List •
........
.
.......•
. . .
...
...
......
.
.....
.
....
.••.
.
..
. 8-
12
E. Motion
Sense
1.
Component
Loading
and
Overlay
....
..
......
.•
...•
•
....
..•
.....
8-13
2. Schematic
.....
...
.......
•
..
..
•
•....
.
.......
..
.
....
.....
...
.•
8-
14
3.
Parts
List
....
....
.
.......................
••
, . , . . .
.......
.
..
. . 8•
15
SECTION
IX
. 25 Hz
DETECTOR
(OPTIONAL)
A. Introduction . . , •
....
,
....
....
.........................
..
. . , . . . . , . 9-1
1.
Gener
al D
esc
ription
..
.
...
....
.
....
..
, , ,
.•
,
...
.
..............
..
9-1
2. Specifications
..
. .
..
...
.
......
•
..
...
.
.....
. , . . .
...
,
•..
....
•
....
9-
1
a)
Input l
mpedence
b) Sensitivity
c) Bandwidth
d) D
etecto
r Enable
e)
Power
f)
Temperature
R
ange
g)
Rejection
h)
E.
O.M
. Relay
B.
In
sta
llation •
...
••
....
.•
....
..
........
....
..
...
..
...
.....
•..
. .
..
.•
9-1
l.
Unpacking
and
Handling
2.
Audio
Connectio
ns
3.
Control
Connections
4. Mounting the
Dete
c
tor
(Field
In
stallation)
C.
Principles
of
Electrical
Operation
. , .
..............
..
...
..
.......
..
..
9-2
I. Det
ecto
r Circuit
2. External Output-Relay
Dr
iver
and
Control
Circuit
3. End
of
Tone
Stop
Circuit
4. Delayed
Stop
Circuit
D.
Setup,
Alignment,
and
Calibra
ti
on
..
..
.
....
. . . ,
..•
....
•
•...
. .
.......
9-3
I.
B
oost
Adjust
2.
Detector
Sensitivity
Ad
just
3.
Stop
Delay Adju
st
4.
Detector
Freq
uen
cy
Tr
im
E. Mechanical Drawing and
Part
s
Li
st .
.....
.
....
....
..••
....
•.
....
. . • . 9-4
vii
www.SteamPoweredRadio.Com
Figure
2-1
Figure 2-2
Figure 2-3
Figure3-1
Figure 3-2
Figure 3.3
Figure 4-1
Figure 4-2
Figure 4-3
Figure 4-4
Figure 4-5
Figure 4-6
Figure 4-7
Figure 4-8
Figure 4-9
Figure 4-10
Figure 4-11
Figure 4-12
Figure 4-13
Figure 4-14
Figure 4-15
Figure 4-16
Figure 4-
17
Figure 4-18
Figure 4-19
Figure 4-20
Figure 4-21
Figure 4-22
Figure5-1
Figure5-2
Figure 5-3
Figure
7-1
Fig
ure
7-2
Figure 7-3
Figure 7
-4
Figure 7-5
Figure 7-6
Fi
gure
7-7
Figure 7-8
Figure 7-9
Figure
7-
10
Figure 7-11
Figure 7-12
Figure 7-13
ILLUSTRATIONS
De
ck
Dimensions
..................................
.
Connection
of
Audio Lines
.....................•.....
Sample Remote Control Schematic
..................
.
Tape
Loading
Path
...........
.....•....•.......•...
Front
View
of
the
Reproducer
..
.................•....
R
ear
View
of
Reproducer
......
•
....
•..
..
•••..
..•....
Reel Motors
Torque
Adjustment
..
..
.................
.
Motor
Torque
Adjustment
Po
ints •
...
.•
...
.•
.....
•.
...
Torque
Setting
Chart
..
..
..............
.
........
...
.
Torque
Boost Adjustment
•.
.
•....•..•
....
..
....
.
....
Pressure
Roller
Pressure
Adjustment
.................
.
Adjusting
the
Solenoid Plunger .
........
..•.....••....
Proper
Height
of
the
Reel turntable
..................
.
The
Split Collar
Gauge
.................
•
•.
.........
.
Inserting
the
Split Collar
Gauge
.....................
.
Brake
Assembly a
nd
Adjustment Points
..•..
........
••
Slip
Torque
Adjustment
..........................
..
.
Brake Slip
Torque
Chart
...........................
.
Head
Height
and
Zenith Adjustment
Po
ints
....
•...
....
Height Adjustme
nt.
...
..
..
..
....
.
.................
..
Zenith Adjustment
.........................
•.
.......
Tape
He
ight Position
............
..
....
.
.....
...
....
.
Adju
stment
Points for
Capstan
Mot
or
Speed
....
....
. . .
Phasing .
•.
...
.....
•
.....
,
....
.•.
.
......
..
.•.......
Phasing .
...
............
......•..
....
..
..
.•......
..
Phasing
......
.
...............
.
......
.
....
...
.....
.
Phasing
..
....
..........
.
...
..•..
.
.•......
•
.......
.
Reproduce
Amplifier
Controls
.......................
.
Lubricating
the
Servo
Capstan
Motor
..
. •
....
•
•.•.....
Maintenance
Schedule
.....................
.
.......
.
MaintenanceTools a
nd
Aids .
.•.
.
..•.....
•
..
....
••.
..
Deck
Mechanical Assemblies -
Fr
ont
........
.....
....
.
Reel
Turnt
able
and
Retainer •
...
.
....
.
...............
Head
Cover
..•
...
.•..
..
••.
...•.....
.•.
...
..•.
...
..
Head
Block
..............
.
....
...
.........
....
....
.
Tape
Guide
.......
...
..•
•..
...
•
.....••....
......
.
••
Capstan
Motor
..
................................
. . .
Deck
Mechanical Assemblies •
Rear
.
...
•..............
Dashpot
and
Foil
Sense
.....
...
...
.....
...........
. .
Pressure
Roller Solenoid Mechanism
.................
.
Torque
Motor
and
Brake
Assembly
..........
........
.
Switchcard Assembly
..........•......•..........
, . .
Power
Transformer
.
..
...
..
....
.
...........
..
......
.
Motion
Sense
. .
...
..
....
.
.................
..
....
••.
Page
2-1
2-2
2-2
3-1
3-1
3-2
4-1
4-1
4-1
4-2
4-2
4-3
4-3
4-3
4-4
4-4
4-5
4.5
4-5
4-5
4-6
4-6
4-6
4-7
4
.7
4-7
4.7
4-8
5-1
5-1
5-2
7-1
7-2
7-2
7.3
7.3
7.4
7-5
7-6
7-7
7-8
7-9
7-
10
7-
11
ix
www.SteamPoweredRadio.Com
)(
Figure 8 I
Figure 8-2
Figure 8
-3
Figure 8-4
f=igure 8·5
figure
8-6
figure
8·7
Figure 8-8
Figure 8-9
Figure 9-1
Figure 9-2
Figure 9-3
Figure 9-4
Figure 9-5
ILLUSTRATIONS
(continued)
Mother
Board
Component
Loading
and
Overlay
.......
.
Mother
Board
Schematic
.
....
.
...........
. . . . •
...
,
..
Power
Supply
Cage
Wiring
layout
...
....
.....
.
......
.
Reproduce
Amplifier
Component
loading
and
Overlay
..
Reprodu
ce
Amplifier
Schematic
.
..
..
.
...............
.
Switc
hcard
Component
L
oading
and
Overlay . . . . . •
..
.
Switchcard
Schematic
. . • .
..
.•
...
..
,
................
.
Motion
Sense
Component
Loading
and
Overlay .
.•.....
Moti
on
Sense
Schemat
1c . . . . . . . . .
...
. . . . .•
..
•.....
.
25 Hz
Remote
Control
Schematic
......
.•
..
....••.
....
25
Hz
Dete
ctor
R
ear
View
..
.
........
.
.......
.•..
...
,
25
Hz
Detector
Mechanical
Parts
..
...
.•.
...
. .
..
......
25 Hz
Detector
Component
Loading
and
Overlay .
.....
.
25 Hz
Detector
Schematic
. . .
......
.
..
.....
.•..
......
Page
g.J
8·2
8-5
8-6
8-7
8-
10
8-
11
8-
13
8
14
94
9A
9.5
9-6
9.7
www.SteamPoweredRadio.Com
SECTION I- INTRODUCTION
-A.
TAPETRANSPO
RT
The I
TC
770 reproduceris constructed
of
heavy 1/2
inch
(]2.7mm)
thick
aluminum tool plate. The tool plate
is stress-relieved, and is resistant
to
thermal variations.
Theprecision milled toolplatealuminum
deck
providesa
stable reference
for
each critical assembly, resulting in
improved tape handlingand phase stability.
Individual
motors
areused in thetapedrivesystem.A
DC
Servo
motor
is used
for
capstan drive. This direct
drive system. along
with
its electronic control system
providesaccuratespeed control
with
minimumwowand
flutter Heat generation is substantially
lower
than hys•
teresis syn
ch
ronousmotors.
The
two reel
driv
e
motors
are
four pole, 1800
RP
M, induction motors. These
motors
have permanently lubricated ball bearings, and
develop adequate
torque
to
provide positive control
of
the tape reels
An air damped solenoidoperates thetape lifterscind
pressure rollerassembly.
The
use
of
air
damping, and a
TEFLON
® covered plunger
in
this solenoid result
in
quiet operation and minimum maintenance.
The transport incorporatesa tape liftersystemoper•
aled
by the pressure roller solenoid which allows both
manual andautomatic operation.
The
tape is automati•
cally liftedaway from thehead(s) duringeither fast wind
mode.
To
monitor
recordedinformationwhile in thefast
windmodes, theautomaticpositioning
or
the liftersmay
be overridden by pushing the
CUE
lever toward the
heads. The lifters
will
remain in this position until the
START
/
PLAY
mode is entered,
or
the
CUE
lever is
manually returned to
its
original position.
Disc
type
brakes
with
a one-way clutch provide a
differential between the take
up
and supplyreels. Differ-
ential action is essential to provide
smooth
a
nd
even
braking action.
The
disc brakes
are
designed
for
min·
im
ummaintenance.However,
if
a touch-
up
isnecessary,
the adjustment is simple
to
makeand easily accessible.
B. HEAD ASSE
MB
LV
The
ITC
770 SERIES reproducer is equipped with a
unique, high quality professional head assembly. The
head is mounted in a machined aluminum bracket
designed toprovidesimpleand highlyaccurateazimuth,
height, and zenith adjustments.
Theazimuthpivot
point
islocated
dire
ctlybehind the
center
of
the head in both
1he
vertical and horizontal
plane.
This
fealure permitsazimuthadjustment
without
disturbing the zenith
or
height adjustments, and can be
locked into position after adjustment. The head mount-
ing arrangement permits convenient head replacement
when it is required.
As an aid to head maintenance and tape marking/
editing, the entire head assembly is housed beneath a
hinged, springloaded "
Oip
-
top"
co
ver. Thedesign
of
this
0381
DM
coverallows
it
to
beeasily opened
or
closed andremain
in either position.
C.
ELECTRONICS
The electronics
of
the 770 Series reel-
to
-reel repro•
ducer
providesimplicity andserviceability. Bulky wiring
iseliminatedbythe mother-daughterboardconstruction
with modular cables and connectors.
All assemblies, including motors, brakes, solenoids,
and P.C. boards, plug
in
for easy serviceability and
replacement in the field. All normal maintenanceadjust-
ments
are
accessible from the front panel. The equaliza.
tion and programlevel calibrations are exposed byrem·
oval
of
the switch
dre
ss
panel. Limited range level
controls, designed
to
give an 8dB boost
or
a 4dB cut in
audiolevel, are locatedon the front panel. A headphone
jack is provided
for
program monitoring
pur
poses.
All
electrornc logicis either
J.C.
, transistor,
or
simple
relay type. Active components and relays are socket-
mounted on the printed circuit boards.
O. S
PE
C
IFI
C
AT
I
ONS
I. Power:
105
to 130 volts
AC
,
60
Hz,
160
watts maximum
2. Wind Tim
e:
Less than 60 seconds for
2500
feet
of
tape.
Less than 90 seconds for 3600 feet
of
tape.
3. Motors:
Capstan •
Direct
drive
DC
servo control with
electrolyzed shaft. Reels T
wo
capacitor-start
induction torque motors.
4. Tape Speeds
7-1/2 and
15
1ps
(19
and
38
cm
/sec)
or
3-3
/4 and 7-1/2 ips (9.5 and
19
cm
/sec)
Speedaccuracy±0.2%
or
lessmeasured with
1.5
mil (0.038 mm) tape.
5.
Tape
Width and Trac
ks
:
1/4 inch (6.3 mm) tape, 1.0 mil (0.025 mm)
base
minimum.
Full
Tr
ack • mono
1/2
track -mono
or
stereo
1/ 4 track • stereo
6. Reel Siz.es:
NAB
or
EIA
with
a hub diameter
of
1.
75
inch
(44.45 mm)
or
greater. Maximum reel nange
diameter
of
10.5
inches (266.7 n'lm). Selectable
tape tension for small
or
large reels. Reels
of
dissimilar sizes, i.e. 7inches(177.8mm) and
10
.5
inches(266.7 mm), should not be used together.
7. Flutter (
NAB
We
ighted):
3-3
/4 ips0.10
'½,
or less
7-1/2 ips 0.07%
or
less
15
ips 0.05%
or
less
I,1
www.SteamPoweredRadio.Com
8.
Au
di
o
Output
:
With transformer(s) . . . +24d8 m before clipping
mt
o 600
ohm
load, balanced.
Wi
thout
tr
ansformer(s)
..
. +18d8m before clip-
ping into 600
ohm
load, unbalanced.
9. Di
sto
rtion (Amplifi
er)
:
0.5%
rms total harmonic distortion. maximum
at
t 18dBm
output
level at 1 kHz with output trans-
former(s). +16d8m
wi
thout
output
transformer(s).
10. Signal
-To-Noise
Ratio:
1
-2
52dB measured from a 700
Hz
tone,
recorded
at
185
nWb/m, with reprodu
ce
amplifier adjusted
for
+8dBm output, to tape recorded with bias but
no signal. Measurement
is
unweighted noise with
a bandwidth of 20 to 20,000 H
z.
11
.
Crosstalk
:
55dB or better with a 185nWb/ m 1 kHz tone
on
adjacent track.
12. Equa
li
za
t
io
n:
NAB with high
fr
equency adjustment for 3-3/
4,
7-1/2 end
15
ips. Automatically switched
wi
th
sp
eed
switch
be
tween low
and
high
speed
equal-
izers.
13. Freq
ue
n
cy
R
es
pon
se
:
3-3/4 ips
(+2
dB -3.5dB) 25 to 35 H
z;
±2dB 35
to
8,000 Hz.
7 1/ 2 ips (+2dB -
3d
B) 25
to
35 Hz; ±2d8
35 lo 15,000 Hz.
15 ips (+2d8 -3.SdB)
25
to 35 Hz; ±2dB
35 to 18,000 Hz
14. He
adphon
e
Outpu
t:
24 mV into 8
ohms
(wi
th AT-0001 output trans-
fo
rmer
s)
58
mV
into 8 ohms (without AT-0001 o
utp
ut
transformer
s)
IS. Ambie
nt
Op
erati
ng
Te
mp
eratu
re
:
40
° to 130°F (5° to 55°C)
16
. Re
mot
e
Cont
rol:
Start,
Sto
p, Rewind, Forwa
rd
,Speed Sel
ec
t, Foil
Sense and Mode Indi
ca
tors.
17.
Br
a
kes
:
M
ec
ha
ni
ca
l disc with one-way clutch.
10
-1
/ 2 inch (266.7 mm) rnetal r
ee
ls stop time
adjusta
bl
e from 2-1/ 2 s
ec
o
nd
s
to
10 sec
ond
s.
18.
Exte
rn
al
Con
n
ec
tors:
Latching type Beau Ser
ie
s 3300, mating
pl
ugs
furnished.
19
.
Dim
e
nsions
:
19 in
ches
(48
2.
6
mm
)
wi
de
1-1/4 inch
(31.75 mm) overhang on
ea
ch side wi
th
10
-1/2 inch (266.7 mm) reels.
14
in
ch
es
(355.6 mm) high, 2-1/4
in
c
hes
(57
.
15
mm) overhang on
top
with
10
-1/2
in
ch (266.7 mm) reels.
7-7/8" (197.6 mm)
de
ep, in
cl
uding mating
pl
ugs.
20. Weight:
Unpacked •44 pounds
(19
.96 kg)
E.
WARRANTY
International
Tape
tronics Corporation (ITC) war A
ra
n
ts
to Purchaser thal the equipment sold
1s
free oi W
defectsofworkmanship
or
mate
r
ial
nnd
con
for
ms
tothe
specifications referr
ed
to
or
set
out herein. This war
ranty, applying only to the original user. extends from
date
ofshipment for a periodoftwoyears. No claimshall
be maintained hereunder unless written notice is re-
ceived bySeller within thirty days
afte1
the discovery of
the facts giving rise
to
the
claim. The sole
or
exclusive
liability ofSeller for breachofwarrantyshall beto refund
the
purchase
price of the item sold,
or
al its option, 10
replace
or
repair the item
or
part
conce
rned FOB its
factory,
or
such
other
place
as
ti
may
designate ITC's
liability shall arise only
1f
Purchaser causes the defective
pa
rt
or
item
to
be
delivered to ITC for inspection upon
ITC's request
at
Purchaser's expense. This warranty
shall n
ot
be
effective
if
the alleged defect is
due
to
mal
-
treatment, exposure, excessive moisture
or
any
other
use of
the
equipment other than the use for whi
ch
the
manufacturer prescribed.
No warranties expressed
or
implied shall
be
app
l
ica
-
ble to
any
equipmentsold hereunder, and the foregoing
shall
co
nstitute t
he
Buyer'ssole right and remedy under
theagreementsin this paragraph
co
ntained. In no event
shall International Tapelronics
Co
rporation have any
liability for
co
nsequential damages.
or
f
or
loss, damage,
or
expense
directly
or
indirectly arising from the use of
the
products,
or
any
inability
to
use them either
separ
-
ately
or
in combination
with
other equipment
or
mate-
rials,
or
from any
othe
r
cause.
IT
C's
warranty is given solely
to
the original user and
only
to
the extentabovedescribed. Nodealer
or
agent
is
au
thorized to make any
other
or
addition
al
guaranty
or
warranty.
F.
OP
T
lONS
AND
A
CCE
S
SO
RIE
S
833-0
01
8
-2
00 25 Hz DE
TE
CTO
R
86
4-
0016,000 REMOTE CONTROL FOR
REPRODUC
ER
S
864-00
17-
000 REMOTE C
ONT
R
OL
FOR
RECORDER/ REPRODU
CE
RS
864-0014-
0)0
CONSOLE CABINET
864-0015-000 ADD-
ON
STACKING K
IT
(USE
WITH
CONSOL
E C
AB
INET)
281-0014-012 FILLER PANEL, 1-3/4H
(44
.45 mm)
USE WITH CONSOLE CABI
NET
830-0022
-02
l HEAD & TURNTABLE HEI
GHT
GAUGE
830-0036-
001
DI
SC
BRAKE ADJUSTMENT
GAUGE
831
-007
5-
003
REPR
ODUCER TEST EXTENDER
831-0119-003 RECORDER TEST
EX
T
EN
D
ER
These i
tems
are available for yo
ur
IT
C Model 770
unit. Plea
se
c
all
fo
r
co
mplete infonnation.
03
81
OM
-
www.SteamPoweredRadio.Com
SECTION
II
-
INSTALLATION
A. UNPACKING
AND
HANDLING
Carefully remove
the
ITC 770 Series reel-to-reel
reproducerfrom the shipping
carton
and
inspect the unit
for damage.
All
pa
cking material
mu
st
be
retained
if
a
claim for shipping damageis
to
be
filed.
If
shipping
damage
ls found,
contac
t International
Tapetronicsimmediatelyfor assistancein
filing
a claim.It
is suggested
that
packing material
be
retained for any
further shipment of
the
unit.
B. INSTALLATION
IN
RACK
770
Series
reel-to-reel machines
are
supplied
in
a 19
inch (482.6mm) mounting configuration. Adequate ven-
tilation isessential. Vertical spacingbetween reel-
to
-reel
machines
and
ot
her
equipmentshould
be
from
1-3
/4 inch
(44.45 mm)
to
3-1/2 inc
he
s
(88.9
mm).
The
spacing
depends
on
the
temperatu
re
inside
the
closed rack.
Please refer
to
Fig
ure
2-1
fo
r
deck
size
and
reel over-
hang dimensions.
The reel is in
close
prox
im
ity
to
the
deck
plate.
For
this reason it may
be
necessary, in
some
applications,
to
space
out
the
770 Series
deck
in
the
rack
installation. A
simple inexpensive 1/ 4 inch (6.35 mm)
spacer
can
be
made
byusing a
10
-32
socket
head
screw
and
a l/ 16inch
(1.58 mm)
flat
washer
.
Four
of
these
spacers
may
be
mounted
in
the
rack
panel
ne
ar
the
lo
cation of
the
four
mounting slots.
C. OPTIONAL CONSOLE
HOUSING
The
optional console housing for
the
770 Series is
shippedseparately,
and
requires minor assembly upon
receipt.
After Temoving
the
console from
the
packing mate·
rial, install
the
four c
asters
in
the
bottom
of
the
console
legs.
Set
the
co
nso
le
upright,
and
rotate
the
tr
ansport
deck
table
to
its
ve
rtical position by pressing
the
release
button
located
on
the
front
upper
right
hand
sideof
the
console cabinet. This
will
allow the table
to
rotate
and
lock in various planes. With
the
aid of a
noth
er
person,
ca
refullyslide
the
transport
mechanisminto
the
mount-
ing
area
.
NOTE: When handling
the
tra
nspo
rt
,
be
careful not
to
damage delicate items
su
ch
as
motors
and
brakes,
After the transport is properly located, carefully
rotate
the
table
back
to its horizontal position.
Se
c
ure
the
assembly with
the
enclosed
rack
mounting
screws
and
washers.
Included with the consoleis a 1-3/
4"
(44.45 mm) filler
panel. Thispanelshould
be
mounted
toward
the
top
end
of
the
transport
deck
assemblyin
order
to
fill
the
va
c
ant
space
.
0381 DM
/
10
1/
21
•
RH
LS
/
(266.7m"')R£ElS
-t-
-
--
:;:::,--
!.......
I•
I•
(~5S.60m
m)
l
l/
4 I•
(
82
. 5Smm)
g
~
@
◊
@o
()
~o
@o
oO
0
19
10
--=7
(482
.
60mm)
I
114
1ft
pl
.
7Smml
2.
"32
71•
(S9
. 10
mm
)
6 7181•
(1H
.6 2
Mm
)
L
72
5
/n,
.
(197
.
64
mm)
Fi
g
ur
e 2-1
D. C
ONNECTING
AUDIO
LINES
A six pin unwir
ed
plug is provided with
ea
ch 770
Series
reproducer
. This is
used
to c
onnect
the audio
output.
Refer
to
Figure
2-2
for
proper
connectionof
the
audio lines.
Care
should
be
taken
to
insure
proper
con-
nections of
each
chan
nel
on
stereo
machines. It is
recommended
that
two
conductor
shielded cables be
u
sed
for
outp
ut
connections.
2-1
www.SteamPoweredRadio.Com
TO
Jl02
~
- - - - - - - - - - - - - - - - -
HIGH
5 I \
3 I ' LOW
CHA
,.,Nt
l I
------------
-
---
HIGH
l'-
-'--
-
-------
~
LO
W
------------
-
----
6
PIN
PLUG
Figure 2-2
E.
CONNECTING
REMOTE
CONTROLS
R
emote
contro
l functions
are
provided
through
con
-
nector
Jl0l
for START,
STOP,
REWIND,
FORWARD.
and
associated
lamp
circuits
(24volt,40 ma.).
Ali
switch
-
ing runctions
require
a single pole, normally
open,
momentary
contact
switch.
A IS
conducto
r plug is supplied with
the
machine
for
wiring
th
e
remote
functions. Figure 2-3
shows
a sample
remote
control
schematic.
2-2
..I._
STOP
SW
ITCH
READY
LAMP
7
_I_
START
SWITCH
I I
f--------v
8
13
15
PIN
PLUG
RUN
L.AMP
REWI
ND LA.MP
FAST
_I_
FORWARD
SWIT
CH
FAST
FORWARD
LAMP
Figure
2·3
F. INI
TIAL
CH
ECKS BEFORE OPERATION
Check
all
motors
and
rotating
parts
before
operat
ing
th
e 770
Series
machine.
The
caps
t
an
motor
and
pressure
roller
shou
ld
rotate
freely.
The
two
reelturntablesshould
rotate
wi
th
some
resistance
due
to
the
action
of
the
brakes
beingengaged. Be
certa
in
that
P.C
.
cards,
relays,
and
ribbon
cable
connectors
are
properly
seated.
Insure
that
the
line
frequency
and
voltageare
correct,
117 volts
±10%,
60
Hz.
before plugging in
the
power
cord.
G.
FUNCT
IO
NAL
CH
ECKOUT
1.
Plug
the
unitin
and
turn
the
ON
/
OFF
switch
to
the
ON
position.
Th
e
capstan
motor
should
rotate
clockwise
as
viewed from
th
e front.
2.
Push
REWIND, FORWARD,
STOP
,
and
RUN.
Nothing
should
happen
.
3.
Bl
ock
the
lig
ht
path
m
the
tape
sensor
with
the
reel
size
switch in
the
large
re
el position.
All
operatio
ns
are
to
be
viewed from
the
front of
th
e deck.
a)
Push
FORWARD
(blue) -
Th
e t
ake
-
up
motor
should
run
at
full
speed
counterclockwise.
The
supply
motor
shou
ld
run
slowlyclockwise. B
oth
brake
solenoidsshould activate
and
release
the
brakes.
b) P
ush
REWI
ND
(white) -
Th
e supply
motor
should
run
at
full
speed
clockwise.
Th
e
lake-up
motor
should
run
slowlycounterclockwise. Both
brake
solenoids should activate
and
release t
he
brakes
.
c)
Push
STOP
(yellow) . Reel
motors
should
stop
.
Brake
solenoids
should
deac
tivate
and
apply
the
brakes.
d)
Push
RUN (gr
een)
Pr
essure
roller should
engage. T
ake
-
up
motor
should
turn
counter
-
clockwise. Rewind
motor
should
turn
clockwise
after
th
e
boost
interval. Br
ake
solenoids
should
activate
and
release
the
brakes
.
e)
Fr
om
the
rewind
or
forward modes,
push
STOP.
There
should
be
approximately 1-1/2
se
c
ond
delay
be
f
ore
t
he
run
mode
can
be
en
t
ered
.
NOTE
:
If
motion
sense
has
been
installed,
th
e
run
mode
can
be
entered
at
any
timefrom a
fast
mode.
0381
OM
www.SteamPoweredRadio.Com
SECTION
III
. OPERATING INSTRUCTIONS
A. T
HR
EADING THETAPE
The
ITC 770 Series reel-to-reel
reprodu
ce
r is
de
-
signed toallow
tape
threadingwithout opening
or
closing
any
doors
or
interferring
components.
Please refer
to
Figure 3-1 for a diagram of
the
tape
loading
path
. If
the
tape has
been
lo
aded
correc
tly
the
ready
indicator LED
on
the
front panel
will
illuminate.
Figure 3-1
0
l•P!
!HO
WH
t.0•0f'O ~RO•tRLI
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0 ° 0 0
I
B. C
ONTRO
LS
AND
INDICATORS
Refer
to
Figure 3-2 for a front view of
the
reproducer.
All
of
the
variousswitching functions
are
shown.
1.
The
ST
ART SWITCH ·
The
start
switch
will
not
function
if
t
he
tape
has
not
been
l
oaded
properly,
i.e.
across
the
tape
sensing LED
photo
-transistor
located to
the
left
of
the
magnetic
heads
.
Activating
the
ST
ART
SWITCH
pu
ts
the
trans
-
port
in
the
run
mode
at
the
selected speed. When
the
start
switchis pressed,
full
torque
is momentar-
ily
applied
to
the forward reel motor causing
the
tape
to
moveinstantly.
The
durationof this
"torque
boost"
may
be
adjusted
at
the
r
ea
r of
the
machine.
See
Figure 3-3.
Normally,
the
start
switch
ca
nnot
be
activated
when
the
machine is
in
the
fast forward
or
rewind
mode
of operation. An optional motion
se
n
se
cir-
cuitry isavailable
to
allowfor this typeofswitching.
A built-in
start
mode
delaycircuitpreventsentering
the
start
mode
for approximately
one
se
c
ond
after
coming
out
of
the
f
ast
forward
or
fast rewind
mode
of operation.
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2.
The
STOP
SWITCH
can
be
activated
whene
ver
tape
is
loaded
on
the
machines.
Stop
will
terminate
all
other
operating
modes
of
the
machine
.
3.
Th
e FAST REWIND
and
FAST FORWARD
modes
may
be
ente
red
from
any
other
operating
mode
except
when
a
stop
signal is
present.
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4.
The
REELSIZE
SWITCH
is
used
to
select
the
tape
tension
for
different size reel
hubs.
When
using
the
4-1/ 2 inch (114.3
mm)
NAB
hub
the
switch
must
be
in
the
largereelposition.
When
using
the
2-1/ 2inch
(63.5mm)EIA
hub
the switchshould
bein
the
small
reel position.
For
best
tape
handling. intermixing
of
different reel sizes is
not
recomm
ended.
H
two
different
size
reel
hubs
have
to
be
used
simultaneously,
the
following
procedures
should
be
used
to
minimize
tape
handling
damage
:
•
To
stop
ou1
of
either
fast wind
mode
activate
the
opposite
fast wind
mode
switch
until
the
tape
motion
has
ceas
ed,
and
then activate rhe
stop
switch
immediately
lo
set
the
me
chanical
brakes.
5.
The
POWER
switch either appli
es
or
remove
s
power
to
th
e machine. A
6.
The
SPEED
swi1
ch
con
trols the
speed
of
the
cap
• W
st
an
motor
and
provides
any
necessary
equaliza
tion switching, High
and
Low positions
are
pro
v1ded for 3-
3/4
-7-1/2 JPS,
or
7-1/2
15
JP
S
operation.
7.
The
CUE
LEVER provides a
means
for manual
control
of
the
tap
e lifters. N
or
mally,
the
tape
lifters
are
engaged
in
the
stop
mode
and
the
high
speed
mode
. Pushing
the
cue
le
ver
upward in
these
modes
disengages
the
tape
lifters
and
permits
tape
cueing.
Pushing
the
cue
lever
downward re-en-
gages
the
tape
lifters. Entering
the
start
mode
alwaysdisengages
the
tape
lifters
and
returns
them
to
the
automatic
mode
of
operation
.
8.
A
red
LED indi
ca
tor
is found
on
the
l
ower
right-
hand
corner
of
the
770Series.
It
is a visual md1cator
that
the
tape
1s
loaded properly
and
that
a
stop
command
is not
present.
9. Limited
range
fr
o
nt
panel level
co
ntrols
may
be
used
to
vary
the
program
output
levelaproximately
+8
or
-
4d8
from
the
calibrated (vertical) position.
0381
DM
www.SteamPoweredRadio.Com
SECTION
IV
.
SETUP,
ALIGNMENT,
AND
CALIBRATION
A.
MECHAN
I
CAL
ADJUSTMENT-TRANSPORT
1. REEL
MOTORS
TORQUE
ADJUSTMENT
Reel
motor
torque
in
the
770 may
be
measured
by
usinga small spring
scale
ca
pableofmeasuring
up
to
one
pound
or
250
grams
.
Use
an
empty r (177.8 mm)reel
with 2
¼H
(57.15mm)
hub
,
and
tightly tiea 4 foot (121.92
cm) section of twine
around
the
cente
r
hub
of the reel.
Loop several
turns
of twine
around
the
reel
hub
and
con
ne
ct
the
free
end
of
the
twine
to
your spring
scale
.
See
Figure 4-
1.
It
should
be
noted
that
either
torque
motor
may
be
used for
se
tting
the
proper
tension.
These
motors
a
re
con
nected
in
series during
the
run
mode
of operation.
Therefore, their torques
will
be
essentially
the
same.
Power resistors
used
to adjust
torque
settings
on
the
770Series are accessible by removing the stainlesssteel
cover located directly
on
top of
the
electronics housing
on
the
back
of
the
770
Series
deck.
CAUT
ION: RE-
M
OVE
POWER
CORD
FROM
SOC
KET BEFORE
ADJUSTING RESISTORS.
While the
torques
are
being
measured
,
the
reel motor
not beingused
should
be
heldstationary
and
not
allowed
to
rotate.
If
rotationis permittedt
he
final
torque
setting
will
be
affected,
t,;<:RU5E
TORO\IE
Rf28
S
MA
LL A
ElL
T
AP
E
ADJUST
* MOTOR
REEL
SIZE
SWITCH
L
ARGE
SMALL
LARGE
RI
H ~ 1
30
LARGE REEL _ HOL O U CK
/
TAPE
ADJ/
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usr
I
Figur
e4-2
TORQUE
ADJUST
ADJUSTING
TORQUE
RESISTOR
SET
TING
Rl34
6
.0
oz
. - I
70
g
R 12 8
3.0
oz. -
85
g
R
13
0 1.
0oz
. -
28g
To
adjust the reel
motors
torque
properly, first adjust
the
largereel
torque
with
the
reel sizeswitch, S105in
the
large reel position.
Once
this adjustment has
been
made
transfer
the
reel size switch, S105,
to
the
small reel
position
and
adjust the smallreel
torque
.
See
Figure4-2.
R
ef
er to Figure 4-3 for
the
proper
torque
settings.
ff
USE
2 1/ 4 "
DIAMETER
RE
EL
HUB
.
0381
OM
HEAVY TWINE
SPRING SCALE'
REWIND TOROUE
MOT
OR
ASSEMBLY
0
7•
REELS
2 114'
OI
AMEl
ER
HUB
/
Figure
4-1
Figure 4-3
HE
AVY
TWINE
SPRING
SC
AL
E~ '
FOR
WA
RD
TOROUE
MOTOR
A
SSE
MBLY
www.SteamPoweredRadio.Com
•
2.
TORQUE
BOOST
ADJUSTMENT
The
torqul.:!
boost
time
Is
controlled
by
potentiometer
Rl
19,
and
1s
locdted on the
mother
board. This
pot
en-
tiometeris accessible from the
mar
panel
of
the
electron-
ic::;
housing
on
the
770 Series
deck.
See
Figure 4.4.
AdJUtitmenl
1s
made
with
a nat blade scre
wd
river. First
attach
two
large reels
lo
the mac.hinc
and
thread them
prop<>tly
.
M~ke
cet
ta1n
the reel size switch
1s
in
the large
reel
po:,1tI0I1
Then. fast wmd the tape
until
almost the
entire
lc>ngth
b
on
the
forward
take
up
reel. N
ext.
repeatedly :,tart
and
stop the machine Adjust
Rl
19
\1
otqul"
boos, adJu::.tment)so
thc1t
tape maintains
proper
wr,1p
on
tlw
headand
exhibits
minimum
bounce.Several
adjustments
may
be
necessary
to
obtain
opt
imum
per
form,it1l
,,
.
to'kfi~u•t
"0llt"
~Ot f:HU0
l I
Figure
4-4
3. SUPPLY TENSI
ON
ARM
DAMPING
ADJUSTMENT
4-2
a)
With
aninsulated nat bladescrewdriver,adjust the
supply tension arm airpot (See Figure4-
17)
so that
thetension
arm
exhibitsa s
mooth
,gentlereturn
to
the upward most position. Roughly speaking,
it
should takeapproximatelyone second
for
the
arm
to
return
when pulled
down
to
its
lowermostposi•
tion.
After
pulling the
arm
down.
allow a moment
for
the
airpot
to
stabilize before releasing the ten-
sion arm.
b)
With
almost the entire length
of
tape wrapped
on
the forward take-upreel. repeatedly
start
and
stop
the
machine and observe the
amount
of
tape
"bo
un
ce'' present.
c) Adjust
the
airpot
until
the tapedoes
not
lose con•
tact
with the heads. Please
note
that
the
airpot
has
an effective range
of
approximately one
quarter
of
a
turn
.Therefore,
make
this
adjustmentcautiously
as
a small adjustment change can have major
impact
in
controlling
the
tape
"bounce"
.
4. PRESSURE ROLLER PRESSURE ADJUST-
MENT
Th
isadjustment will normally be re
quir
edonly aher
pressure roller replacemen
t.
but
for
optimtrm azimuth
andphasestability,a
nd
!ap
edriveability, pressureroller
pressure should be checked periodically
a) Attach a strong piece ol twme aro
un
d
tht
rollc-r
shaft and the
other
end
to
aspring
seal<>
capable
of
measuring up
to
10
po
unds (4.536 k
g)
Se<>
Figure
4.5,
SPRING
SCALE
TWINE
PRESSURE
ROLLER
CAPSTAN
Figure 4•5
b)
Blocl~ the
opto
-sensor with a piece
of
non-trans-
parent adhesive tape such
as
masking tape and
place the machine
into
the
RUN
mode. Begin pull-
mgonthesprmgscale handle
in
theopposite direc
tion
the
solenoidispulling
until
the pressure
roller
is disengaged
from
thecapstan.
c)
Theinstant
the
pressurerollerleaves thecapstanis
the
point
at
which themeasurement must
be
taken.
The
pulling
for
ce
at
this pointshould be between 6
and 7 pounds.
d)
If
adjustment isrequired, loosen theclevis
lock
nut
and rotate the solenoid plunger
as
follows: (See
Figure
4-6).
•
To
increase pressure. rotate the plunger
to
penetratedeeperintothesolenoid.
Do
notallow
the plunger
to
"bottom
out''
to
the seat
of
the
solenoid.
•
To
decrease pressure, rotate the plunger
for
less penetration into the solenoid.
NOTE
:
If
the above procedures
do
not
appear
to
work.
back the plunger 7 turns
out
of
the
solenoid andrepeat Step d .
0381
DM
www.SteamPoweredRadio.Com
•
e)
Once
adjustment
is
co
rr
ect,
retighten
the
clevis
locknut.
5.
SOLENO
ID
A
IR
DAM
PING
It is
desirable
to
have
the
pressure
roller
descend
as
quickly
as
possible
to
help
control
tape
bounce,
and
fa
c
ilit
ate
rapid
starts.
At
the
same
ti
me
,
some
damping
action
must
be
maintained
to
minimize
the
mechanical
noise
level
of
the
pressure
roller
assembly.
Th
e
pressure
roller
damping
is
adjusted
by
means
of
an
air
release
valve
on
the
r
ear
of
the
pressure
roller/
tape
lifter solenoid, F
igure
4-
6.
To
make
this
adjustme
nt
,
repeatedly
start
and
stop
the
ma
chine
while
rotating
the
air
r
elease
valve
counterclockwise
until
the
pressure
ro
ller
asse
mbly
begins
to
make
a
"s
l
apping"
noise
.
At
that
point, slowly
rotate
the
valve
clockwise
until
the
"slapping"
noise
disappears
.
Leave
the
solenoid
air
release
valve
at
this
setting
.
Fig
u
..-e
4-6
SMOfH
lf•D
Figure
4-7
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ocew
At
this
point
verify
the
Torque
Boost
Adjustment
,
"Item
IV
-2"
and
,
if
necessary,
fine-tune
the
Supply
Ten-
sion
Arm
Damping
Adjustment
"
Item
JV
-3.
''
Proper
operation
can
be
verified
by
repeatedly
stopping
and
starting
the
ma
c
hine
with varying
amounts
of
tape
loaded
on
the
forward
take
-
up
reel.
6. REEL T
URNTABLE
HEI
GHT
Reel
turntable
heights
should
rarely
require
adjust
-
ment.
H
owever,
adjustments
will
be
required
when
torque
motor
maintenance
is
performed
,
and
other
parts
have
been
replaced
or
adjus
t
ed.
Turntable
height
ad
-
justment
may
also
be
required
to
adjust
the
ma
c
hines'
ability
to
wind
tape
in
the
center
of
the
reel
during
normal
run
modes.
a)
MEASURING TURNTABLE HEIGHTS
Use
the
sho
rt
end
of
lTCgaug
e
830-0022
-
021
to
measure
the
proper
height
of
the
r
eel
turnta
b
le
.
R
efer
to
figure
4-7.
NOTE
:
ITC
gauge
830
-
0022
-0
21
is a
dual
-
purpo
se
fixture,
used
to
measure
head
height
on
one
end
,
and
used
to
measure
the
770
reel
turntable
height
on
the
othe
r
end.
Be
sure
to
use
the
"
short
"
end
of
the
gauge
when
measuring
770 reel
turntabl
e
height.
Figure
4-7illustrates
the
co
rrect
positioning
of this
gauge
.
b) ADJUSTING TURNTABLE HEI
GHT
Turnt
able
height
may
be
adjusted
with
the
motor
unit
either
on
oroff
the
deck
assembly,
but
requires
the
turntable
to
be
removed
from
the
motor
shaft.
Remov
e
the
turntable
from
the
motor
shalt
by
removing
the
two
cap
screws
near
the
motor
shaft,
and
gentlysliding
the
turntable
off
the
motor
shaf
t.
In
sert
the
split
collar
gauge
830
-
0036
-
001
shown
in
F
igure
4-8
between
the
split
co
llar
and
the
motor
housing,
as
ill
ustrated
in Figure 4-9. R
eposi
tion
the
split collar
as
necessary,
by
loosening
these!
sc
r
ew
and
sliding
the
split collar
along
the
motor
shaft
until
proper
location
1s
indicated
by
th
e gauge.
Firmly
tighten
the
split
collar
se
t sc
rew
once
the
proper
position
is
found
.
The
turntable
may
now
be
replaced.
Repeat
steps
l
and
2
as
necessary
.
~
BRAKE
SCREW GA P
SPLI
T COLL
AR
GAP7_
32
nd 1
TURNTABLE
HEIGtH
ANO
BRAKE
GAUGE
(830-0036
-
001)
F
igure
4-8
4
.3
www.SteamPoweredRadio.Com
7. BRAKE TENSI
ON
ADJUSTMENT
The
770util
izes
disc
brakes
attached
to
unidirectional
bearings
and
fi
ber
br
ake
pads
whicha
ll
ow
brake
tension
adjustments
to
be
made
111
a highly
accurate
and
repeat
-
able
manner.
Figure 4-10
shows
the
brake
assembly
and
the
adjustment
points
. Fa
mihanz
e
yourself
with
thes
e
points
and
the
ad
j
ustment
pro
cedu
r
es
before
attempting
..1d1ustments.
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Figur-e
4-
10
(4)
Adjust
the
knurled
nuts
on
the solenoid arma-
ture
to
lighten
the
springs.
Set
the
gap
between
th
e
knurled
n
ut
s
and
th
e
base
of
the
threed
studs
so
that
1/4" (6.4mm)
o(
t
hreads
remains
.
This
is a
"rough
in"
adjustment.
a
11
d final
adjustment
will
occur
in a later
step.
(5)
Repe
at
steps
(1)
through
(4) for
the
other
brake
.
b) FINAL BRAKE
ADJUSTMENT
4-4
Figure
4-9
a)
INITIAL BRAKE
ADJUSTMENT
(1)
Tum
the
three
spring
nut
adjusters
on
the
brake
solenoid
housing
all
the
way
toward
the
torQue
motor
(least
spring
tension).
(2) Inserta 1/64" (0.4mm)
thick
piece
of
cardboard
(about
the
thi
ck
ness
of
a
matchbook
cover)
or
ITC
brake
gauge
830
-
0036
-001
between
the
brake
coil
and
the
inner
disc,
or
solenoid
ar
ma
-
ture,
Figure 4-9.
(3) With
the
gauge
in
place
,
loosen
the
hex
screw
in
th
e collar
at
the
rear
of
the
motor
shaft
and
ge
ntly
move
t
he
collar
toward
the
motor
until
the
thickness
gauge
is
snug
between
the
coil
and
inner
disc.
Tighten
the
hex
screw
and
remove
the
gauge.
(1)
Use
an
empty
r (17.
78
cm) reel with a 2-1/4~
(5.
72
cm)
diam
et
er
hub,
and
thr
ead
a length of
twine
around
the
hub
as
in
Section
IV
-
A-
1.
"
Torqu
e
Motor
Adjustment".
(2) M
ount
the
reel
onto
either
turntable
spindleas
shown
in
Figure
4-
11.
Ve
ry
gently pull the
spring
scale
away
from
the
spindle
and
observe
the
point
at
which slippage
occurs.
Figure 4-12
indicates
the
prop
er slip
torque.
(3)
Should
adjustment
be
requir
e
d,
Figure 4-10
shows
the
adjustment
points.
To
"tighten"
the
brakes
(increase
the
slip
torque),
turn
all t
hree
knurled
nuts
away
from
the
motor
an
equal
amount.
To
loosen
the
brakes,
turn
all
three
knurled
nu
ts
toward
the
motor
an
equal
amount.
(4)
Steps
number
2
and
3
should
be
repeated
for
A
the
other
torque
motor
. W
0381
OM
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