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S-2
BIAS
AND
ERASE
OSCILLATOR
ELECTRONIC
ALIGNMENT
ALIGNMENT
AND
TEST
EQUIPMENT
REQUIREMENTS
Head
Demagnetization
Demagnetization
Pro
ce
dure
The
d-c
plate
supply consisrs
of
a full wave rectifier
Vl08,
and
a ca-
pacitor-input L-C filter. A 6.3 volt secondary winding
on
the
power
transformer furnishes a-c
power
to
all heaters. Potentiometer R
150
HUM
BAL
is adjusted for
minimum
hum.
Al
ignment
consists in making all necessary adjustments for
proper
electronic performance. A recorder
out
of
alignment
may
be
character-
ized by poor frequency response, high noise, low
ourput,
high
distortion,
or
a combination
of
these faults. All
Ampex
recorders are completely
aligned
at
the
factory,
and
no
adjustments should
be
necessary.
The
overa
ll
performance checks outlined in Section 3 will generally serve
to
determine
if r
ealignment
is
necessary
at
any time.
Alignment
can
be
accomplished
without
removing
the
electronic as-
sembly from
the
case. If desired
the
electronic assembly can
be
with-
drawn
by
removing
the
four
screws
on
the
front
panel. Srand
the
case
in a vertical position and pull
the
electronic assembly forward. The
interconnecting cables between
the
electronic assembly and
the
rape
transport
arc
sufficiently long for access
co
all adjustments while
the
units
are
connected.
The
following equipm
ent
is
required for
proper
ali
gnment
and
resting:
A.
Audio
Oscillat
or-
Hewlett-Packard Model
200C
or
equivalent.
B.
Vacmmt
T1tbe
Vol
tm
eter- Hewlert-Packard Model
400C
or
equivalent.
C.
Amp
ex
Ali
gnment
Tap,'-Caralog
No.
5563.
This
rape
is
re-
corded ar 7 ½ ips
IO
db
below normal
operating
level as
defined in Section 3.
The
tape contains voice
an
noun
cements
of
rhe following cone sequence: reproduce head alignm
ent
tone, reference tone for reproduce level adjustment, cone
series for reproduce response check.
D.
Ampex
Head Demagnetize·r--Catalog No. 704.
E.
High
Impedance Headphones
F.
Small Screwdriver
Demagnetize rhc record and reproduce heads before
aligning
the
ma
-
chine.
The
erase head
req11ires
no
demag
netization. Magnetized heads
will generally produce
an
increase
of
5
co
10
db
in
noise level, distortion
of
the
recorded signal,
and
wi
ll
gradua
ll
y erase
the
high
frequencies
on
any
tap
e passed
over
them.
Step I:
Step
2:
Step 3:
Step 4:
Remove
both
rhe head cover
and
the
mu metal
sh
ield
over
rhe
head assembly.
Place
th
e
ON-OFF
switch in rhe
OFF
position.
Cover
the
t
ip
s
of
the
demagnerizer
with
scotch rape or mask-
ing
tape.
This
prevenrs scratching
the
heads.
Plug
the
demag-
nerizer inco a source of
11
7-volr a-c power.
The
head sequence fr
om
lefr
co
ri
ght
when
facing
the
machine,
is
erase head, record head, reproduce head.
Bring
the rips
of
rhe demagnerizer inro contact
with
rhe record
heaJ
stack.
The
tips
should straddle rhe
gap
in
the
cenrer
of
rhe stack.
Run
rhe rips slowly
up
and clown rhe srack several rimes, and rhcn
withdraw
rhe demagnerizer very slowly. Slow withdrawal
is
required
for thorough clemagnerizarion.
Step 5: R
epeat
step
4
on
the
reproduce head.
lr
is
not
necessary
to
demagnetize rhe erase head.
Step 6: Replace rhe head shield,
but
do
nor replace
the
head cover if
alignment
will follow.
The
foll
ow
ing sreps consritute rhe complete
alignment
of rhc reproduce
channel.
A. Reproduce
Head
Azimuth
Adjustmenr
B.
Reprodu
ce Level
Setting
C.
Reproduce Response Check
D.
Reproduce
Equalization
E.
Hum
Balance
Adjustment
Step
I:
Thread
the
alignment
rape
on
the
machine.
Terminat
e the
OUTPUT
conneetor with a 600
ohm
resisror and connect
the
vrvm across
this
load.
Plug
a
sec
of hi
gh
im
pedance head
phones
inro
the
phones jack
so
thar voice announcements
on
rhe tape
can
be
heard. If
nor
already done, remove
the
head
assembly cover,
but
nor rhe mu meral shield beneath it. Place
the
MONITOR
SELECTOR switch in
TAPE
position, and
start
the
machine
in
rhe reproduce mode.
The
head
alignment
cone will
be
announced first.
Step 2: Inse
rt
a small screw
driv
er
thro
ugh
rhe access hole nearesr rhe
right hand edge
of
the
head shield, and adjust
the
azimuth
screw for
maximum
output
observed
on
the
vtvm.
If
the
head
is far out of alig
nm
ent, several
minor
peaks occurri1tg on
eithe-r side
of
a
maximum
may
be
obJcrved.
Make
cerrain char
the
maximum
is
clearly 15
co
20
db
greater
than any
of
these
minor
peaks.
The
next
tone
on
rhe tape is for reproduce level setting.
Adjust
the
REPRODUCE
LEVEL (P.B. LEVEL)
pote
nt
iometer
Rl37
for a vcvm
reading
10
db
below normal operating level, which
is
approximate
ly
0.4 voles rms.
The
ne
xt
series
of
cones is for
the
reproduce r
es
ponse check.
Ob
serve
rhe response indicated
on
the
vrvm, and check
it
against specifications.
If
reproduce response fails
co
meet specifications,
the
troub
le
may
be
a
worn
or
otherwise faulty reproduce head, a partially erased
alignment
tape,
due
to
head magnetization,
or
improper
equalizarion
of
the re-
produce amplifier. Equalizarion can
be checked and adjusred as indicated
below.
Demagnetization
Procedure
Reproduce
Channel
Alignment
Reproduce
Head
Azimuth Adjustment
Reproduce
level
Setting
Reproduce
Response Check
5-3
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