Ampex 351 - Page 58

Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Step 9:
REWIND RELAY
Step 10:
Step 11:
Step 12:
6-10
NOTE
The erase head, under certain condi 
tions, is susceptible to magnetization
by spurious sources and can require
demagnetization.
If the capstan, tape guides or other metal
parts be come magnetized, a few passes of the
demagnetizer along their lengths and the slow
withdrawing technique should be adequate.
TAKE-UP TENSION
50 WATTS
PlAY RELAY
K502
89-0131
89-0144
Issue A
RESISTOR, HOLD-BACK
TENSION R505
150 OHMS 50 WATTS
FAST FORWARD
RELAY K503
ADJUSTMENTS
The mechanical assembly is shipped from
the factory with all adjustments set for correct
performance. It should be unnecessary to
change any adjustment before putting the
equipment into service, unless shipping dam 
age has occurred. In the course of wear in
normal service, or in the event of component
failure, and replacement of parts, some read 
justments may be necessary.
Equipment Required:
Spring Scale 0-16 oz.
Spring Scale 0-80 oz.
%-inch Nut Driver
3/16-inch Screwdriver
Nylon Lacing Twine or Strong String
7/16-inch Socket Wrench
5/64-inch Allen Wrench
RESISTOR, MOTOR TENSION., ’
BALANCE R504
750 OHMS 50 WATTS
RESISTOR, VOLTAGE DROPPING
FOR SMALL REEL OPERATION
R502 75 OHMS 50 WATTS
Control circuit box callouts
Take-up and Supply (Rewind) Tension
Take-up and supply tensions are determined
by the positioning of the sliders on resistors
R503 and R505 located in the tape transport
control circuit box. The torque of both the re 
wind and take-up motors must be adjusted to
between 5V2 and 6 ounces as read on the 16
oz. spring scale at NAB reel hub diameter.
Checking techniques are not difficult and
should be performed carefully.
Place an empty lOVa inch NAB reel
on the tape supply turntable.
Place the POWER switch in the ON
position.
Place the REEL SIZE switch in the
LARGE position.
Hold the take-up tension arm so that
the safety switch is activated (a rub 
ber band or piece of masking tape will
hold the arm as though tape were
threaded on the equipment).
Make small loops at both ends of a
thirty inch piece of nylon lacing
twine.
Attach one loop to the tape anchor on
the reel hub and the other to a 0 to 16
oz. spring scale.
Press the PLAY button and allow the
clockwise motion of the supply reel
(torque motor tension) to draw a
turn of twine onto the hub.
Make certain that the twine is now
parallel to the plane of the top of the
tape transport and that the twine is
centered and not touching either
reel flange.
Now, let the torque motor pull the
twine slowly onto the hub by follow 
ing the torque motor force with the
scale.
Using this “ following ” technique, ob 
serve the readings on the scale until
a constant reading is obtained.
If necessary, adjust the slide on resis 
tor R505 in the control circuit box
until a scale reading between 5 ] /2 and
6 ounces is achieved.
A good check consists in placing the
REEL SIZE switch in the SMALL pos 
ition, then checking the torque using
the same procedure as above. The
RESISTOR,
R503 150 OHMS