Ampex 350 Operation Maintenance

Page 1

OPERATION AND
MAINTENANCE MANUAL

Page 2

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Page 17

before the tape is in motion. This direct monitor feature allow: the pro-
gram to be set up through the machine without actually recording during
the set up period. NOTE: For Correct meter calibration it is important
that the Line Out be properly terminated either external to the machine or
by the use of the Line Out Termination Switch (3404).

When the program level is properly set. start the tape in motion
as indicated under PLAY. Then push the Record Button ($08). (It is des-
irable that a delay of at least 1/2 second occur before the Record Button is
depressedI to allow switching transients to die out beiore recording is
started and prevent permanent magnetization of the Record Head. The Pie--
cord Indicator (1401) next to the Record Button will now glow and the ma-
chine is recording.

It is desirable to check the record bias and erase currents occasion-
ally. In order to do this, turn the Meter and Cutout Switch (S405), to the
positions designated BIAS and ERASE, respectively. The erase is not crit-
ical and should read approximately zero on the meter scale. The bias
should read between -1/2 and + 1/2 on the VU scale. The bias is some-
what critical and must be kept within the indicated range in order to record
the higher irequencies at 3-3/4 and 7-1/2 inch tape speeds.

The bias is adjusted by means of the Bias Control (R460), located

on the electronic chassis. The meter calibration for bias measurement
can be checked as indicated in SECTION 5. 6.4.

3-4 350 - 4/11/55

Page 20

The torque of the motors in the Play and Record modes is adjusted
to equality by resistors 3503 and 23505, the tension adjusting resistors in
series with each motor. In Fast Forward. the torque of the Rewind Motor
is greatly reduced by insertion of additional resistance (R504) in series
with it. In Rewind, R504- is inserted in series with the Takeup Motor.

The basic operation of the tape tension system is illustrated in Figures
A. B, and C an the following page.

In the Fast Forward mode (Figure A), the Takeup Motor operates
at full torque, the Rewind Motor at reduced torque, and the tape is simply
pulled from the Tape Supply Reel. Since the torque of the Tape Supply ._
Turntable motor (Le. . the Rewind Motor) is applied in the opposite direc-
tion to the table's rotation. the tape is held under continuous tension as it
is pulled from the reel.

In the Rewind mode, the operation just described is exactly reversed,
as shown in Figure 3.

In the Play or Record modes, both motors operate at reduced .
torque and are effectively isolated from each other by the Tape Drive Sap-
stan and the Capstan Idler between which the tape is clamped. (Figure 3).
From the point of View of the Tape Supply Turntable. the capstan and idler
action exerts sufficient pull on the tape to overcome the opposing torque of
the Rewind Motor. which constitutes the hold back tension. From the point
of View of the Tape Takeup Turntable, the capstan and idler action is feeding
the tape to it. The tape is held under tension here. simply by virtue of the
fact that the takeup rate exceeds the feed rate. (A tape loop will be thrown
0n the right side of the Sapstan whenever any malfunction causes the feed
rate to exceed the takeu'p rate.)

In the event that such a tape loan is thrown, or the tape breaks, the
Taken-p Ilension Arm will actuate the Safety Switch (3501) and stop the machine.
The Takeup Itnsion Arm is not, strictly speaking. a part of the tape tension
system. Its primary function is to operate the Jalety Switch.

The Reel Idler Assembly functions to smooth out any transients in the
tension system. For example, in starting the tape in the Play mode, the
momentary strain transmitted through the tape to the Tape Supply Turntable
when the Sapstan Idler forces the tape against the :apstan is extremely high.
This impulse could. under some circumstances. stretch or break the tape, 0r
cause the Tape Supply Turntable to overshoot in starting. If the turntable did
overshoot in this way. the momentary decrease in hold back tension would be
sufficient to start a transient oscillation in the tape tension system. This

35:) - 6/1/53

53>
I
U3

Page 45

5.] MODEL 350 (Complete Equipment)

Rack
Rack

Mount,
Mount,
Rack Mount.
Rack Mount,
Rack Mount,
Rack J-bount.
Rack Mount,
Rack Zviount,

Jul/Z"
7.1/2"
7.1/2"
7-1/2"
3-3/4"
3-3/4"
3-3/4"
3-3/4"

Sons ole,
Sons ole.
Sons ole,
Console,
Console,
Console.
Console,
Sonsole,

Portable .
Portable,
Portable,
Portable.
Portable.
Po rtable.
Po rtable,
Portable,

Case
Case
Case
Case
Case
Case
Case
Case

NNNNNNNN

350 - 12/15/53

7-1/2 - 15", Full Track, (:0 Cycle Power
7-1/2" - 15", Half Track, 60
7-1/2" -15". Fun Track, 50
7-1/2" - 15", HalfTrack. 50
3-3/4" - 7-1/2", Full Track.
3-3/4H - 7-1/2". Half Track,
3-3/4 - 7-1/2", Full Track, 50 Cycle Power
3-3/4" - 7-1/2", Half Track. 50 Cycle Power

Cycle Power
Cycle Power
Cycle Power
60 Cycle Power
60 Cycle Power

- 15". Full Track, 60 Cycle Power
- 15", Half Track, 60 Cycle Power
- 15". Full Track, 50 Cycle Power

- 15", Half Track, 50

- 7-1/2".
- 7-1/2.
- 7-1/2".
- 7-1/2".

7-1/r'-
7-1/rI-
7-1/r'-
7-1/2" -
3-3/4"-
3-3/4" -
3-3/4"-
3-3/4 -

Full Track, 60
Half Track, 60
Full Track, 50

Half Trac k, 50

15". Full Track, 60
15", Half Track, 60
15", Full Track, 50
15", Half Track. 50

7-1/2", Full Track,
7-I/Z, Half Track,
7-1/2", Full Track.
7-1/2", Half Track,

Cycle Power

Cycle Power
Cycle Power
Cycle Power
Cycle Power

Power
Power
Cycle Power
Cycle Power
60 Cycle Power
60 Sycle Power
50 Cycle Power
50 Sycle Power

Sycle
Cycle

Ampex
Catalog
Number

5717
5717-1
'5717-2
5717-3
5720
5720-1
5720-2
5720-3

5718

5718-]
5716-2
5715-3
5721

5721-1
5721-2
5721-3

5719

57l9~l
5719-2
5719-3
5122

5722-1
5722-2
5722-3

6-2

Page 52

Ampex

Reference Catalog
Number Description Number
R412 100, 000 Ohm 1/2 Watt Composition Resistor RE-300
R433 330, 000 Ohm 1/2 Watt Composition Resistor f 5% REE-80'!
R414 100. 000 Ohm 1/2 Watt Composition Resistor RIB-300
R415 33. 000 Ohm 1/2 Watt Film Resistor f 1% RIB-608
R416 2. 200 Ohm 1/2 Watt Composition Resistor RE-369
R417 47, 000 Ohm 1 Watt Composition Resistor RE-22
R415 470, 000 Ohm 1/2 Watt Composition Resistor RIB-302
R419 2.200 Ohm 1/2 Watt Composition Resistor RE-369
R420 470 Ohm i/2 Watt C'.-mp051tion Resistor RIB-333
R421 22, 000 Ohm 2 Watt Composition Resistor RAE-171
R422 47, 000 Ohm 1/2 Watt Composition Resistor IKE-299
R123 1 Meg. 1/2 Watt Composition Resistor RE-ZQO
R424 50. 000 Ohm Linear Taper Potontiometcr RE-226
R425 470, 000 Ohm 1/2 Watt Composition Resistor RE-302
R426 15. 000 Ohm 10 Watt Wircwound Resistor Eli-92
R427 100, 000 Ohm 2 Watt Composition Resistor RES-179
R428 10,000 Ohm Audio Taper Potentiometer BIS-315
R429 330. 000 Ohm 1/2 Watt Film Resistor i 1% RIB-599
R430 2. zoo Ohm 1/2 Watt Fiim Resistor g 1% 112-611
B4 31 170 Ohm 1/2 \"att Composition Resistor REE-333
R432 470 Ohm 1/2 Watt Composition Resistor REE-333
R433 330. 000 Ohm 1/2 Watt Film Resistor RE~599
R434 2, 200 Ohm 1/2 Watt Composition Resistor RE-369
R-iJS 100. 000 Ohm Audio Taper Potentiometer RIB-227
R436 1 Meg. 1/2 'i'vatt I-ltm Resistor g 1% 1212-600
M37 47,0.» Chm 1/2 Watt Composition Resistor Kit-299
R438 1 EFL). Audio Taper Pctentziometer IRE-585
R439 1 Meg. I 2 52th Composition Resistor Bil-290
R440 330, 0m; 4. 11m 1/2 att Cra'riiywsition Resistor RE-427
R441 2.700 Ohm 1/2 Watt Contuusition Rnsistor Kit-373
R442 220 Ohm 1/2 Wort Lv"mpiisitiou Resistor Eli-330
R443 150, 000 Ohm 1/2 Watt Composition Resistor RIC-236
R444 560. 000 0hr" 2 Wal Jo:n;.~osnmn Resistor RE-bns
R44?- 1,500 Ohm 12, \mit Composmm. Resistor RE-afiz
H446 10.000 Ohm 2 WM C.Mii.osi1ion Resistor RBI-168
R447 47, 000 Ohm 1 Wall. iii-position [twister RIC-22
R448 22, 000 Ohm 1/2 Watt Composition Resistor RIB-298
R449 2. 700 Ohm 1/2 za'aii COLT; .sition Resistor RE-373
R450 560 Ohm 1/2 Wall Composiiion Resistor RE-446
64) 350 - 6/30/53

Page 57

MODEL 350 CONSOLE
AMPEX ELECTRIC CORPORATEON
IKDWOOD Cl". mount