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4-6
Torques
and
Tape Tension
Takeup
Tension
H
oldba
ck Tension
Malfunct
i
on
s
in
Pl
ay
Mod
e
The
measurement
of
rorques
on
the
Model 601 requires the following
equipmenc:
I ) A light-movement
spring
scale ( e.g. Post-A-L
et,
0
to
8 oz., Exact
Weight
Scale Co., Columbus, Ohio.
2)
A
measuring
hub.
A standard
RETMA
plastic
re
el
may
be used. If
the
hub
diameter
is
exactly 2 inches,
the
spri
ng
scale will read
directly
io
ounce-inches. Reels
with
smaller
hubs
can
be
brought
up
to
2-
inch
diameter
by
winding
on
sufficient tape. If a reel
of
greater
than
2-inch
hub
diameter
is used, multiply
the
spring
scale
reading
by
the
hub
raditts
to
obtain
the
ounce-inch reading.
3)
A piece
of
string,
approximately 30 inches long, with a small loop
tied
at
one
end.
Torques
measured
on
the
driven
turntable
in any mode, (
i.e.
the
turn-
table
on
which
the
tape
is
being
wound)
are
a measure
of
ttikrmp ten-
sion.
Torques
measured on rhe
turntable
from which the rape
is
pulled
in any mode
are
a measure
of
holdback tension ( See Fig.
4-3).
Step I:
Step
2:
Step 3:
Pla
ce
the
measuring
huh
on
the
driven turntable.
Wind
a f
ew
turns
of
string
around
the
hub
in
the
direction
of
normal
tape
wrap,
and
attach
the
spring
scale ro
the
loop
ar
the end.
Scarr th
1
e machine in the
appropriate
mode
and, as
the
string
,is wound
on
the
hub
, allow
the
SG,le
ro move in
with
it, tak-
,,
ing
the reading while the scale
is
in morion.
Normal
torques
are as follows:
Fa
st
Forward 5
ro
7 oz-in.
R
ew
ind 5
ro 7
oz-m.
Play 2
to
3½
oz-in.
Step
1:
Place rhe measuring
hub
on
the
turntable
from which rhe
tape
is
pulled
in
the
mode
in operation.
Step
2:
Wind
rhe sering on fully in rhe direction of normal rape wrap,
and
attach
the
spring
scale.
Step 3: Stare
the
machine
in the
oppropriate
mode, and pull
the
scale
slowly in rhe d irecrion in which rape
is
norm
ally pulled from
this reel, raking rhe r
eading
while
rhe scale
is
in steady mo-
tion.
Normal
torques are as fo
ll
ows:
Fasr Forward
¾ ro l ¼ oz-in.
Rewind
¾ ro I¼ oz-i
n.
Play
5¾
tO
8¾
oz-in.
These values listed above for borh
rakeup
and
holdback tensions may
be
close to the low
er
limit when rhe machine
is
new, and will usually
move
up
toward rhe
upper
limit aftt:r tht: first
10
or
12
hours
of
opera-
tion.
Nearly
all malfuncrions in rhe play
mode
will be reflected as flucrer and
wow in excess of spt:cifications. A quick check
of
rakeup
and
hold back
tensions, discussed in rhc previous section, may lead directly
to
the
source
of
trouble. Possible causes
of
Aurrer
and
wow are suggested in
the following check list.
The
word "contaminated," as used here,
may
indicate
either
rhe pres-
ence
of
oil where it is
not
wanted,
or
accumulations
of
dirt
and
other
foreign
matter
on
pulleys
and
belr. In
either
cast,
carbon tetrachloride
i:s
recommended as rhe cleaning agent.
After
cleaning-a contaminated
part,
clean any
othe
r
part
with
which ir normally comes
imo
contacr
vvherher
or
not
that
part
shows any
immediate
evidence
of
conrami
na
-
tion. Bracketed
numbers
refer
ro
parts
shown in the explodc<l view
of
the
mechanical assembly, Fig. 4-4, which should serve as a
guide
for
a.ny
necessary
dis<l,-~sembly
and
reassembly.
R
ewind
and
fast forward malfunctions will usually
be
reAecred as an
a.pparent loss of
power
in rhose modes, loose cape
wind,
e
rr
atic rape mo-
rion
or
slippage, a
nd
, possibly
no
rewind
or
fast forward ar al
l.
The first
seep is
to
make a quick check of
rewind
or
fast forward cakeup and
holdback tensions as described previously.
The
malfunctions discussed
below
apply
ro
eirher
mode,
the
turntables, associated components, and
rape direcrions
being
opposite
of
each orher.
Scarring,
sropping,
and
shuttling
malfunctions will be evidenced by
the
throwing
of
rape loops and, in
extreme
cases, by rape breakage.
Thes
e
troubles
are
usually associated wirh low
rakeup
tension of brake mal-
functions produced
primarily
by
tampering
or misassembly, or conram-
ination
due
co
careless o
iling
or
accumulati
on
of
dirt.
The
following section covers some ad
justment
s,
cr
itical clearances,
and
a.lignment which muse be
maintained
in reassembling parrs of rhe rape
transport
mechanism
that
may have been disassembled for servicing.
Two
general precautions should
be
observed in any
requir
ed disassembly:
1.)
Always
note
rhe
number,
type,
and
location
of
washers
in
an
as-
sembly
very carefully. Should washers,
retainers
or
ocher smaU
hard-
ware
be
lost
or
damaged
in
servicing, a
kir
containing
an
assortment
of
such
hardware
(Ampex
Catalog
No.
7802)
is available
through
your
dealer.
2)
To
· remove
the
sub-place -(
1),
a preliminary ro any further disas-
sembly
of
pares
under
the
cop place casting, remove only
the
three
elastic scop-nurs
that
hold
it
,
and
clevis
pin
chat links
the
slide lever
( I
3)
co
the
lower yoke
of
the
rewind
/ fast forward acruaror (
48).
le
is unnecessary
co
remove
the
adjustment
screws (
70
and
71)
for
the
capstan
thrust
and
the
mocor rhrusc.
lf
the
settings
of
these
screws
are
changed, they
must
be
carefully readjusted as described
in
the following subsections.
The
thrust
discs (
65)
beneath these
screws,
being
coated
with
grease, will usually sray in place
when
the
sub-plate is removed. It
is
advisable,
how
ever,
co
be
sure char
they
do
not
fall out.
Ir
will generally be found easiest
co
re-install
the
sub-place
after
servicing, if rhe
PLAY
conrrol
is
energized.
The
cape transport incorporates
rubber
shock
mounts
on
the
screws
re
-
taining
rhe
motor
mounting
place
co
the cop
plat
e casting.
The
se
shock
mounts
provide
automatic
centering
of
rhe
drivemotor
and
no
adjust-
ments
are
necessary.
lrhe drivemoror
thrust
is
a hardened steel ball (
60)
against a nylon
Malfunctbns
in P
lay
Mode
Malfuncti
o
ns
in
Rewind
or F
ast
Forward
M
od
e
St
ar
ting
,
Sto
pp
ing
a
nd
Sh
ut
tling
Malf
unctions
Assembly
and
Construction
Notes
Dr
i
vemotor
Thrust
4-7
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