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6-?: MAGNETIC
5Y5TEM
SOUND PLAYBACK
A. Description
ln adAition to the standard optical sound play-
back, models NST-Z & NT+ include magnetic
soundtrack playback and models NST-3 & NT-3
include both magnetic playback and recard. The
Magl0pt selectar ssitch opsrates a lever which
positions the magnetic head against the films sound
track, at the same time the appropriate electrical
connections are rnade-
In the record models the lock-out button prevcnts
the selector from being accidently switched to
record- A special combinaticn reccrdfplay and
erase head is used for simplicity and a minimum of
adiustrnent. Both the reccrd level and playback
vofurne is accornplished with the volume control
and equalization is provided by the bass and treble
controls. The small meter provides level monitoring
during record.
Since the record and playback is accomplished
using only one head the alignment procedure
for the NST-? & NT-z and N5T-3 & NT-3 models
are thc same"
I
E}
Open the lamp house daor.
Remove the frame casting to obtain access
to the mdgnetic head.
Thread a magnetic azimuth alignrncnt tcst
film.
Set the Maelolrt" swirch rs the Mag play
position.
Connect the projector tc a durnmy load
resistor and msr set-up- {See Sec. &1-B-3-
F i s . # 1 1 3 |
Turn on the proiector and amplifirr.
Set the treble control to the Max. position
and the bass at the Minimum.
Adiust the volume conrrcI to iust before rhe
amplifier clips.
Carefully loosen thc adjustmcnt scrcw which
allows the head te be positioned on the
rnag. track-
To adjust, hold the mag. head gently $/ith
the pliers and slightly turn thc head clockwise
or counter-clockwise until the correct head
position on the mag. track is obtained_ Then,
align the head core slit right on the mag.
track by slightly bending, if necessary, the
head mounting arm to the right or left-
When the corr€ct head position and thcangle
arc obtaincd, a maximum voltage reading
will be indicated on the AC VTVM, while at
2. Set-up frocedure
Fts. #115
i-46
- ' b
45
4
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a,
b.
HU{U CO|L 131440sr11
l{T:
S/H r847F AIfp UP
NST: SfirO4EIANDUP
MAGNETIC HEAD
B. Magnetic Head AlieqrygllPrglggrll
I. Tools and Equipment Required
a. Screw driu*t s"tllio)
-
b. Magnetic Azimuth 7000H2 alignment SMPTE
te$t film loop-
c- Fliers
d. AC VTVM (Audio Range) a*d or
e. Oscilloscope
f. $ ohm 30 watt dummy load resistor
g. External speaker {fronr cover)
Fis. #114
c'
e.
f.
8.
h.
i .
d .
- 6 3 -
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