Ampex 400 Series User manual

AMPEx
SERIES 4b0
OPERATION AND
MAINTENANCE MANUAL
SERIES
400

MODELS
402
&
403
COP4SOIE
AMPEX
ELECTRIC
CORPORATION
REOW000
CITY
CALIFORNIA

MODELS
402
&
403
TWO
CASE
pORTABLE
AMPEX
ELECTRiC
CORPORATION
REDWOO0
CITV,CALIFORNIA

INSTRUCTION MANUAL
FOR
AMPEX MAGNETIC
TAcbE
RECORDER MODELS 400A,401,
402,403,404 and
405
TABLE CF CONTENTS
SECTION I Specifications
SECTION II Installation
SECTION 111 Operating Procedure
SECTION IV Operating Theory
SECTION
V Routine Maintenance
SECTION VI
Electronics Alignment
SECTION VII Mechanical
Service Guide
SECTION VIII Mechanical
Adjustments
SECTION IX Parts List
FIGURE 0
Reel Hold Down Knob
FIGURE 1
Single
Case
Portable Electronic Assembly Schematic
FIGURE 2 Rack, Console, Two Case Portable Electronic Assembly Schematic
FIGURE
3
Single Case Portable Power Supply Schematic
FIGURE 4
Rack, Console, Two Case Portable Power Supply Schematic
FIGURE 5
Control Circuit Schematic
FIGURE 6
Input
Transformer
Connections
FIGURE 7 Remote Control and
60 Cycle
Amplifier Connections
FIGURE 8 Playback Amplifier Equalization
FiGURE
9 Record Amplifier Equalization
FIGURE 10
Single
Case Portable Electronic
P
ssembly-Front View
FIGURE 11 Single Case Portable Electronic Pssembly -Top View
FIGURE
12
Single Case Portable Electronic ssemnbly -Bottom View
FIGURE 13
Rack, Console, Two Case Portable Electronic Assembly-Front View
FIGURE 14
Rack, Console, Two Case ‘ortable Elec.Ass’y.-Top & Rear View
FIGURE 15
Rack, Console, Two Case Portable Elec. Ass’y.-Bottom View
FIGURE 16
Mechanical Assembly-Top View
FIGURE 17 Mechanical Assembly-Bottom View
FIGURE 18 Mechanical Assembly-Rear View
FIGURE
19 Mechanical Assembly-Side View
FIGURE 20
Reel Idler
and
Flywheel
FIGURE 21 Console Cabinet
FIGURE 22
Mechanical Assembly Case
SERIES
400 INDEX

SECTION 1
SPECIFICATIONS-MODELS
400A,401A, 402
&
403
The Ampex Models 400A, 401A,
402 and 403
magnetic
tape recorders are
audio recorders utilizing the standard
1/4
inch wide tape. Models 400A
and 401P
are identical in every respect cept for the head assembly. Similarly,
the Models
401 and 403 are alike except for
head assemblies. The
main
difference between
these two groups is the former incorporates an Electronic Assembly designed for
single case portable mounting. The 400A and 402 incorporate half track erase,
record and playback heads. The 401A and 403 incorporate full track
erase record
and playback heads.
Half track heads are effective over
only one half
of the tape
width. Thus, a
machine having
a half track
record
head
can record two separate audio tracks on a
standard reel of tape. Machines having half track playback heads can reproduce
either full or half track recordings. Machines having full track playback heads can
only reproduce tapes
on
which
a single
track has been recorded. Head assemblies
incorporating full track record and erase heads and half track playback heads are
available on special order. This allows recording full track tapes and playing back
either full track or half track tapes. All of the models produce
a tape
frequency
characteristic which has been accepted as standard for
the
exchange of programs
by the National Association of Radio and Television Broadcasters.
TAPE SPEELt 15 inches per second and 7-1/2 inches per second, with motor
ipiea &hThjuind equalization switches conveniently located.
FREC’UENCY RESPONSE. Pt 15 inches
/
2db
30-15, 000 cycles
At
7-1/a inches
/
2db 40-10,
000
cycles
/4db 30-15,
000 cycles
SIGNAL-TO-NOISE RATIO . Over 65 db unweighted noise to maximum recording
levelT.
Over 55 db, asmaffied by NARTB standards. By NARTB definition, the
signal-to-noise ratio is the ratio of peak recording level to the total unweighted
playback noise when
erasing a signal of
peak recording
level and in the absence
of
a new signal. Thus, bias and erase noise are included,
as
well as playback ampli
fier noise. P.11 frequencies between 50 and 15, 000 cycles are measured. The peak
recording level is defined as that level at which the overall input to output total
RMS harmonic distortion does not exceed 3% when measured on a 400 cycle tone.
STARTING TIME. Instantaneous. When starting, the tape accelerates to full speed
in less than 1710 second
because the
capstan motor operates whenever the power is
on.
STOPPING TIME. When playing at 15 inches per second, the tape moves less than
two inches after the
stop button is
operated.
MODEL 400A, 401A, 402
&
403, SECTION
1,
Page 1
11/1/52

FLUTTER AND WOW.At
15 inches well under 2/10% RMS measuring all
fluTtooeitflThm 0
to 300 cycles using a tone of 3,000 cycles. At
7-1/a inches per second
under 1/4%.
PLAYBACK TIMING ACCURACY. 2/10% or /3.6 seconds
in a 30 minute re
cording.
PLAYING T1ME. 32 minutes at 15 inch
speed with
standard NARTB
reel; 64
minutes at
7-TR
inch
speed on each track. The standard RMA reel may also
be used on the tape supply turntable. The Models 400A and 402 Magnetic Tape
Recorders are designed to record on only one half of the standard 1/4 inch
wide tape in accordance with RMA standards. By turning the
reel over and re
cording on the other half, twice the amount of program can be
stored
on a single
reel, thereby affecting a 50% saving in tape.
REW1ND TIME.
Approximately one and a half minutes for the full 2, 400 foot
NARTB reel.
CONTROLS. Four buttons
control the functions
of Start Play, Fast Forward,
ewi5d inZ Stop. A separate record
button
energizes the record relay, which
drops
out
when the machine is stopped. Since
the functions are relay
operated,
the control buttons
may
be placed at
a
remote location.
COMPLETE LUG-IN HEAD HOUSING. Erase, record and playback heads are
contained in a single plug-in head housing.
SIMULTANEOUS MONITORING. Independent record and playback systems
allow thetape
to
be monitored while recording.
INUTJ switch allows the recorder to accommodate either microphone level
Fo’
{Iiipedance input or
to
bridge
600
ohms
plus 4 VU
line balanced or
un
balanced. Minus 70 dbm on microphone input
will produce recommended record
level.
PLAYBACK AMPLIFIER. Plus 4 VU output into 600 ohms balanced or un
balanced. Will feed higlflmpedance amplifier
directly with approximately one
volt.
METERING. A 4 inch VU
meter
is mounted on the front panel and provides for:
A. Direct monitor of record input signal before or during recording.
B.
Monitor of recorded output signal
from playback head while re
cording or during playback.
C. Reading bias
current.
D. Reading erase current.
MODEL 400A, 4OlA, 402 & 403, SECTION 1, Page 2
11/1/52

PHONE MONITORING. A
phone moniwr jack is provided for direct monitor of
eod1riuT iijhaT £fore or during reco.ding,
and
monitor of
recorded outut
signal ftom playback head while recording or during playback, .tn
4-B
switch
is incorporated in order that direct compat son can oe made aetneen the original
p1ogram and the recorded program while a recording is being u-4ade. The same
switch transfers the VU meter for level comparison 2nd monit’ring.
‘AOUNTINGS. Models 400A and 401P
are
available
as a single
case portable.
c4sdels 40l’nd 403 are available in a console cabinet, for rack mountings, or
as a two case portable.
POWER
INUT
REC’UIREMENTS.
115
Volts
AC
2
Amperes.
Recorders are avail
able Io iither 60 or 50 cycle
operation.
Sec
serial dumber plate before
operating.
DIMENSIONS.
Stngle
Ca5ctortable_
Complete recorder
in single case
Height - 13-3/4 inches
Width - 20 inches
Depth - 17-1/2 inches
Weight
- 83 pounds, approximately
Rack Mounting - Standard 1" wide panel-Commercial aoLching
Mechanica’ Unit-15-3/4" high panel
Electronic Unit-7" high panel
Power Supply-3-l/2" 3’igh panel
Studtj Console
- Complete recorder in cabinet
Height - 32 nches
Width - 23 inches
Depth - zs-i/z iri’hes
Two Case Portable
- Mechanical and electronic assemblies in
separate cases
Mechanic.l
Assembly:
7/idth-21 inches
Depth-iS inches
Height-iS inches
Weight-62 pounds
Electronic assembly in large
casehas
extrs
space for four-channel
mb:er or for
stow
age of cables and microphone
Width
- 21 inches
Depth - 13 inches
Height - 19 inches
Weight - less mixer-50 pounds
VIODEL 404, 401A, 402
& 403,
SEC
TION I, ?age
3
11/1/52

Electronic assembly in small case spzce
for power supply and
electronics cnly
no extra space
Width-21 inches
Depth - 13
inches
Height - 12 inches
Weight -45 pounds, approximately
ACCESSORY ITEMS.
All
recorders
in the 400 series are available with connectors ins ta.lei
in the Mechanical Assembly for "plug in" of remote controls, the Model
:75
Precision 60 cycle Power Supply, or the
Model
80
Speed
I
ock Equipme:.t.
The Model 375 Precision 60 Cycle power Supply is designed to pr’vide a
source of constant frequency to the capstan drive motor in localities whee the
available 60 cycle power Is not stable in
frequency.
The Model 380 Speed Lock Equipment is designed to automatically :ontrol
the playback speed of Series 400 recorders to synchronize with motion
r
cture
equipment.
P
remote
control box is available with five pushbuttons and two
i.it
i
cator lights mounted on a sloping panel
in
a
small wooden
case. Catalog ii
3766.
This unit is wired
and ready
to
ope.rate. . -
Piso available are remote controls on a flat plate for flush mounting in
st4dio control consoles. Catalog #3766-1. This unit is not wired. Wiring must
be done by the purchaser ta fit his installation.
A four channel high level Miser-Preamplifier
is. available for use with
Models 402 and 403
rack m--it aiid portable recorders. Catalog #3761,
An accessory pedestal is available for Model 402 and 403
Studio Con
soles to increase
their heir’c to 41 inches Catalog
#3795.
A set of casters is also
available for
the Studio Console.
Catalog 3963,
MODEL 400ft, 4011, 401 & ‘103, SECTION I, rage
4
11/1/52

SECTION Il
INSTALLATiON
IMPORT A NT:
Before operating the recorder, read the following sections on INSTLLA
TION and OPERATION.
CAUTION:
Do not attempt to lengthen the head cables. Additional cable capacity will
affect the frequency characteristics.
Console Models: Shipped in ready to operate condition. Connect the input, output,
inJ ACpr is follows: Remove the lower screen cover at rear of cabinet.
Pull
the
cables through bottom of cabinet and plug them into rear of Electronics
Assembly.
For
connection
instructions, see following paragraphs. Replace pro
tective screen covering to rear of cabinet.
IMPORTANT. The
console cabinet
must be spaced at least 4" from the wall in the rear
and at
least 3" between
a
wall or cabinet on either side, otherwise ventilation holes will be obstructed.
Two
Case
Portable
Models: The portable machine is shipped in a ready to operate
condition, except for the connection
of interconnecting cables.
To operate the recorder place the Mechanical Assembly Case to the left
of the Electronic Assembly Case.
Unlatch and remove the top cover and cable
access door on the right side of the Mechanical Assembly Case. Unlatch and re
move the front and rear doors on the Electronic Assembly Case.
Uncoil the interconnecting
cables from behind the cable access door and
plug them into mating
receptacle at
the
rear of the Electronic Assembly.
Connect the input, output, and
AC power to rear of Electronic Assembly.
Single Case Portable Models: These machines are shipped in a ready to operate
condition.
Remove
the
front panel cover and the top cover. All connections are
readily accessible from the front panel.
NOTE: Nhen storing the portable machines avoid setting the Mechanical Assembly
case on either of the handle ends. This will cause the Turntable Motor Tire to
rest on the Brake Drumand will
produce a flat in the tire if left in this position
any appreciable time.
Rack Mounted Models: The rack mounted machine should be mounted on a standard
T91nhrliiakw1th the Mechanical
unit above the main Electronic Panel. The
Electronic Power Supply Panel should be mounted directly above the Mechanical
/ ssembly
to
prevent
the possibility of 60 cycle field from entering the Electronic
Assembly.
SERIES 400 SECTiON 11, Page 1
ii/i/sz -

If
two
Series 400 Recorders are to be irounted on a standard rack,
the following placement is recommended starting at the top of the rack;
1. Install a spacer panel at the top of the rack if desired.
2.
Install below this panel the Mechanical Assembly for machine #1.
3. Install the Electronic Assembly for machine
#1.
4. Install a spacer panel.
5.
Install the
Mechanical
P ssembly for machine #2.
6. Install the Electronic Assembly for machine #2.
7. Install a spacer panel.
8. Install both Power Supply Panels at the bottom.
The cable on the power supply for the upper recorder will have
to be extended in length. Extension cable
#3814
is available for
this purpose,
The numbers
set off in parentheses in the following text are reference
numbers that refer to the Parts List Section IX and the figures in the rear of
this book.
I.
Connect the Power Cable,
catalog #2413, fom the AC Power Input Con
nector
J4092
on the Electronics Assembly
to a source of 115 Volt PC
power.
IMPORTPNT:Thts machine is available for either 50 or 60 cycle operation.
The power line frequency is indicated on the serial
number plate which
is lo
cated on the Power Supply Panel for rack mounted machines and
on
the exterior
of each case in the portable machine.
Ii. OlTT: Refer to Figure 1 or 2.
A.
For Studio
Line:
Plus 4 VU, 600 ohm line output,
balanced or unbalanced,
is available
across
Terminals 2 and 3 of the Line Out Connector,
.7404°,
Pin
1
is the
chassis ground,
if unbalanced output is desired; tie either side of the line to
ground.
It is necessary to supply 600 ohm termination to this output at all
times in order to
maintain
correct meter
calibration while recording or play
ing back. Therefore, if the output is not feeding a
terminated line or if the out
put is not connected, such as on remote pickups, the Line Output
Termination
Switch, 5404, must he switched to ON.
B. For Connection to
High
impedance
Amplifier Input:
Connect pin 3 of the Line Out Connector J404, to the high side of the
amplifier input. Strap pins 1 and 2 of the connector and connect to the ground
side of the amplifier input. The
Line Output Termination Switch S404, must
be left in the position designated ON at all times, as explained in A above.
SERIES 400, SECTION ii, Page 2
11/1/52