Ampex 1050 User manual

7890021-03
MAINTENANCE MANUAL FOR
TAPE RECORDER MODELS
1050, 1070, 10 80
2050, 2070, 2080
SPEAKER MODELS
1015, 1016
2010, 2011
AMPEX SERVICE COMPANY
2601 GREENLEAF AVENUE
ELK GROVE VILLAGE
ILLINOIS 60007
SEP 1973

SPECIFICATIONS
Specification Model
1070
1050 /1080 2070
2050 /2080
Pre-amp overall freq.
response
7-1/2 ips
50 to 15000 cps +- 4db 50 to 15000 cps +- 4db 50 to 15000 cps ±3db 50 to 15000 cps ±3db
3-3/4 ips
50 to 7500 cps +- 4db
50 to 7500
cps ±4db 50 to 9000
cps ±4db 50 to 9000 cps +- 4db
1-7/8 ips 50 to 4000 cps ± 4db 50 to 4000 cps ± 4db 50 to 5000 cps ± 4db 50 to 5000 cps ± 4db
Signal to Noise from peak
record level at pre-amp
7-1/2 ips 46db 47db 49db 50d db
3-3/4 ips 42db 43db 45db 46db
1-7 / 8 ips 38db 39db 40db 41db
Tone Control Range
100 cps
0 to +12db N/ A 0
to +12db N/ A
10KC
-4 to +10db N/ A
-4 to +10db N/ A
Power Output (rms) 3 watts
N/ A 6
watts
N/A
each channel
Flutter
7-1/2 ips
0.15% 0. 15% 0.12% 0.12%
3-3/4 ips
0. 2% 0. 2%
0.15%
0.15%
1-7/8 ips 0. 3% 0. 3% 0. 25% 0. 25%
Timing Accuracy
7-1/2 ips ±1.5% ±1.5% ±1%
±1%
3-3/4 ips ±3% ±3% ±2%
±2%
1-7/8 ips ±4% ±4% ±3%
±3%
Fast Wind Time
(1200 feet of tape) 130 seconds 130 seconds
130 seconds
130 seconds
Line Input Impedance 120K 120K 120K 120K
Microphone Input
Impedance
1 megohm
1 megohm 1 megohm
1 megohm
Line Input Level
. 2V min
.2V min
.2V min
. 2V min
2. OV max
2. OV max 2.0V max 2. OV max
Microphone Input Level 3mv min
3mv min 3mv min
3mv min
30mv max
30mv max
30mv max
30mv max
P.re-Amp Output Impedance 1000 ohms
1000 ohms 1000 ohms
1000 ohms
Pre-Amp Output Level
,3 v min
1 v .3 v
min
V
Power Amp Output
8 ohms N/ A 8
ohms
N/A
Impedance
OVERALL SIZE
19" X 13-1/2" X 7-1 / 2 N/ A
19" X 13-1 / 2" X 7-1 / 2"
N/ A
Mounting
Frame
N/ A
18-5 / 8" X 13" X 5-1 / 8"
N/ A
18-5 / 8" X 13" X 5-1/8"
Weight
37 lb
27 lb
39 lb
29 lb
Power
Requirements
117vac at 1 ampere
117vac at . 9 ampere
117vac at 1 ampere
117vac at 1 ampere
(Volume at minimum)

-
This manual contains information relative to 1000 and 2000 series equipments.
Anyone who is attempting repair, parts replacement, or adjustment should first
READ THIS MANUAL. This will shorten trouble shooting time and expedite parts
replacement. Please note the various paragraphs relating to specific repairs such
as head replacement, torque measurements, etc.
The information in this manual is the latest available. As additional information
becomes available, it will be presented on manual change sheets and/ or service
bulletins.
This manual supercedes all previously printed manuals
of the same part number and Service Bulletins . No. 1021 CD
1028 CD, 1044 CD, 1049 C,
i

CIRCUIT DESCRIPTION . . . . . . . . .
Playback (Left Channel 2070 only) ...
Reverse Relay (Applying 20 cps Signal)
Reverse Signal (Received from Tape)
REPEAT MODE OPERATION ....
AUTO PLAY MODE OPERATION .
MONITOR CIRCUIT . . . . . . . . .
CHANNEL 2 (RIGHT)
OPERATION .
POWER SUPPLY . . . . . . . . . .
BIAS OSCILLATOR
........ .
REMOVAL
OF RECORDER FROM CASE
CASE REMOVAL . . . . . . . . . . . .
CAPSTAN DRIVE BELT REPLACEMENT
TORQUE MEASUREMENTS . . ..... .
TABLE OF CONTENTS
..
EQUIPMENT REQUIRED FOR MECHANICAL CHECKOUT & ADJUSTMENT
MECHANICAL CHECKOUT & ADJUSTMENT .
. . . . . . . . . . . . . . . .
LUBRICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MECHANICAL
TROUBLES & PROBABLE SOLUTIONS . . • . . . . . . . . ...
PRELIMINARY REQUIREMENTS FOR ELECTRICAL CHECKS & ADJUSTMENT.
PRELIMINARY CHECKOUT INSTRUCTIONS
NOISE
FILTER ...........................
100/1 CAPACITIVE DIVIDER PROBE .............
HEAD REPLACEMENT & ALIGNMENT . . . . . . . . . . . .
1050/1080/2050/2080 ELECTRICAL CHECKS & ADJUSTMENTS
1070/2070 ELECTRICAL CHECKS & ADJUSTMENTS .
ELECTRICAL TROUBLES & PROBABLE SOLUTIONS
ORDERING
PARTS & USING THE PARTS LISTS
ASSEMBLY
PART NUMBERS ..... .
PARTS WITHIN ASSEMBLIES ......
MISCELLANEOUS ELECTRICAL PARTS
1015 SPEAKER SYSTEM PARTS LIST
1016 SPEAKER SYSTEM PARTS LIST .
2010
SPEAKER SYSTEM PARTS LIST .
PAGE
1
1
1
1
1
1
2
2
2
2
2
2
2
2
3
4
5
8
10
10
10
10
11
12
16
19
21
26
27
36
36
36
37
37
2011 SPEAKER SYSTEM PARTS LIST .
DC
TUBE & TRANSISTOR VOLT AGES .
SCHEMATICS
..........
. • . . . . . • • . . . . • . . . . . . . . . . . . . . • . . . . . . 38
• • . • • . • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 39-48
ii

CIRCUIT DESCRIPTION
I Playback (Left Channel 2070 only)
During playback, signals from the tape cause a voltage
to be induced in the playback head. Since this is a
very low voltage, .5mv or less, amplification is
required. Tube Vlab amplifies the low level voltage
and applies it to volume control R23a. Resistor R23a
controls the amount of signal applied to V2a. Output
of V2a
is applied through S6a and S5d to the tone
control circuitry and thus to V2b. Output of V2b is
used to drive NPN transistor Ql. Output of Ql is
transformer coupled to power transistors Q2 and
Q3. Both
power transistors have a small forward
bias to eliminate turn-on distortion. When Q2 is
conducting because of ac signal, Q3 is turning off
due
to lack of ac signal, and vice-versa. Capaeitor
C30 then alternately charges through speaker LSl
and Q2 to B- and discharges through LSl and through
Q3 and ground.
ll Reverse Relay (Applying 20 cps Signal)
The mechanical reverse relay appears electrically
as a very high Q parallel resonant circuit, thus
requires a very small amount of signal power for
operation and has a very narrow pass band. When
the reverse signal is applied, the following occurs:
The armature of the relay oscillates because of
mechanical coupling from REV SIG knob. Since the
coil of the vibrator has a de bias applied, there is
an ac voltage developed as a result of the mechanical
motion and changing flux path. This ac voltage
(20 cps) is applied through S5J to the grid of V6a.
Feedback from the plate of V6b applies every fre-
quency except 20 cps back to the grid. The output
at the plate, as the result of this feedback is a
very low distortion sine wave and is applied through
R142 to S5b and again S6d to S6a. Switch S5b is
applied to S6a and S5a. The 20 cps signal is then applied
to L6-Cl3, S4d, C8, and S3a to the record head Ll9
and signal is recorded on the tape. Coil L6-Cl3
and L5-C18 are traps to prevent the bias signal
from getting into the amplifier circuits. Beat fre-
quencies and overloading may result if the bias signal
gets into the amplifiers.
NOTE
For reception of 20 cps signal from tape,
see next paragraph.
Ill Reverse Signal (Received from Tape)
Assume tape is moving from left reel to right reel.
This is the condition as shown on the schematics.
When the 20 cps signal is on the tape, it induces a
voltage into
head Lla. The voltage is applied to
Vlab, output of V lb is applied to S5a, and to the grid
of V6a. Output of V6a is applied to grid of V6b.
Output of V6b
is applied through C82 and S5q to
K3 (coil). This 20 cps signal causes the armature
of K3 to oscillate (vibrate), causing closure of the
vibrator contacts. When the contacts close, Kl is
energized. This causes current flow from ground
through Ll0 and closed contacts of Klb and K2a
to 30 volt supply, causing the reverse solenoid L3
to operate. Resistor R58 provides hold-in current
when Kl contacts open. When Ll0 operates, SlOc
contacts change state and the head switch S2a switches
the heads. Relay Kl holds in for about 1/2 second
because of capacitor C83. When the capacitor dis-
charges, Kl de-energizes and relay K2 is not shorted
by Kla ·contacts and its own contact K2a. Relay K2
therefore energizes because of current flow from
ground through upper closed contacts of SlOc, through
R145, through K2 coil and to 30 volt supply. This
causes K2a contacts to change state.
When a second 20 cps signal is received, relay K3
armature vibrates causing Kl to be energized. This
causes Kla and Klb contacts to change state (for
1/2 second because of C83). Note that now contact
K2a is also closed. Solenoid L3 is shorted by closed
contacts K2a and Klb and thus de-energizes, causing
motor Bl to reverse and playback heads are switched
again by S2a. Contacts Sl0c go back to the position
shown on the schematic. Relay K2 de-energizes,
causing K2a contacts to go to position shown on
schematic. When the next 20 cps signal is received,
K2 will not energize immediately, because it will
again be shorted by contacts K2a and Kla when Kl
energizes. It will only energize after the motor
reverses.
When a plug is inserted into J8, the following occurs:
a. A 30 volt de pulse of about 1/2 second duration is
applied to a projector actuator or other device.
b. The reverse solenoid Ll0 contacts SlOa, Sl0b,
and Sl0e will not change state because when the
plug is inserted into J8, Ll0 cannot be shorted by
Klb and K2a contacts, thus recorder always moves
in the same direction unless manually reversed.
Relay K2 cannot energize because the second pair
of contacts on J8 are also open and the lower part
of K2 cannot be grounded.
REPEAT MODE OPERATION
When
the play/record knob is in Auto Play, the
recorder will reverse automatically in either direction
as described previously.
AUTO PLAY MODE OPERATION
When
the play/record knob is set to the Auto-Play
position, the recorder will play from left to right,
reverse as described previously, then will not reverse
even if another 20 cps signal is recorded in the right
to left direction. The recorder will simply disengage
itself. If the AC switch (2000 series only) has been
used as a slumber switch, the recorder will shut off
completely. The reason is as follows:
The lower contact of K2a will not be grounded by
S5s when in
the Auto- Play position. This is the
position shown on the schematics for S5. Thus when
the first 20 cps signal causes Kl to energize, the
reverse solenoid Ll0 operates reversing the motor.
Relay K2 will momentarily energize, then de-energize
1

as K2a contact does not have a ground return.
However, reverse solenoid L10 has hold-in current
supplied through R146 and remains energized. When
the second 20 cps signal causes K1 to energize,
reverse solenoid L10 will not be shorted by contacts
K1b and K2a, because K2a will not be at ground poten-
tial. Thus the 20 cps will come and pass and the
recorder will remain in motion from right reel to
left reel. When the tape is exhausted from the right
reel, the tape tension switch Sll will open and remove
power from the reverse solenoid and play solenoid.
The recorder will therefore go into neutral (no tape
motion) and the motor will return to the rotation
giving left to right tape motion. If the slumber switch
is used, when the play mechanism returns to neutral,
micro switch S9 will open removing power from
recorder completely.
MONITOR CIRCUIT
During record, it may be desirous to monitor what
is being reco rded onto the tape. In models 1070 and
2070,
switch S7ab applies a very small signal to the
inputs of the power smplifier. The speakers therefore
produce very low volume signals when the Monitor
switch is on. The models 1050, 1080, 2050, and
2080
have the same feature except that the switch is
a front pane l control (S14abc).
CHANNEL 2 (RIGHT) OPERATION
The right channel operation is almost the same as
left channel operation except that the reverse signal
is not associated with this channel.
POWER SUPPLY
The power supplies are conventional. The higher
voltage power supply uses a voltage doubler. The
lower voltage power supply is full wave.
BIAS OSCILLATOR
The bias oscillator is a tuned push-pull oscillator
operating at a frequency of approximately lOOkc.
Its output is transformer coupled to the erase heads.
Bias power for the record heads is supplied through
variable capacitors C12 and C49.
REMOVAL OF RECORDER FROM CASE
Top Plate Removal
1. To remove the top plate the plastic head cover
and the lower front trim strips must be removed.
The head cover is removed by pressing inward along
the inside surfaces and lifting off the head cover.
The lower front plastic trim strip is removed by
pushing inward slightly on the i nside edge facing the
heads and lifting off. If pl a stic reel covers and
auto-thread reels are installed , they also must be
removed.
2. Remove the four Allen screws at upper and lowe r
ends of top plate. Remove the 2 Phillips s cre ws which
were beneath the head cover and the two which were
beneath the lower front plastic trim strip.
3. The top plate will slide off towards the reels.
2
CASE REMOVAL
1. To remove the recorder from the case, remove
two Phillips screws in each side casting. These are
castings at sides which have speaker parts in them.
2. Remove the two Phillips screws at the top of case
securing the large decorative casting. These are
exposed when top plate is removed.
3. Remove the two Phillips screws at the bottom of
case securing the large decorative casting. These
are also exposed when top plate is removed.
4. Lift out recorder from the case.
5. The case is installed in reverse manner of removal.
CAPSTAN DRIVE BELT REPLACEM ENT
To replace the capstan drive belt (flywheel drive belt),
proceed as follows :
1.
Refer to the capstan drive belt illustration . Remove
the pin at the bottom of the play solenoid. This allows
the plunger and brass rod to be removed from the
solenoid.
2. Remove the four screws as shown in the illus-
tration.
3. Carefully remove the defective belt from motor
pulley and shift fork. Lift up on the capstan housing
thrust plate and belt will slide out from beneath
thrust plate. Note that the play actuator lever must
be moved to allow easy removal of belt.
4. Replace belt in reverse manner of belt removal.
Carefully install on motor pulley and in belt shift
fork.
5. Replace screws in capstan housing and plunger into
play solenoid.
6. Replace pin in play solenoid. Replacement is com-
plete and recorder is ready for use.
TORQUE MEASUREMENTS
Torque is a measured force times the distance
between the point of measurement and a pivot point.
For exa mpl e , 5 oz. in. of torque would be a force of
5
oz. at 1 inch from the pivot point. A wheel 3 inches
in diameter requiring 2-1/2 oz. of pull to move or
prevent from moving represents a torque of 3. 75 oz.
in. (1.5 x 2.5). In the
case of an arm or rod, the force
required to move or hold stationary must be at right
angles to the arms or rod. Otherwise torque measure-
ment will be erroneous. In addition, static friction and
or inertia someti m es must be overcome. Therefore,
it is adviseable when measuring torque to move the
reel very slowly in direction of reel take-up to
relie ve fr iction or i nertial effects when measuring reel
holdb a ck and tak c-up torques. Note that the torque
indications will be different when gauge is held station-
ary and when g au ge is just moving. When mea suring
holdback tension , note torque measurement after reel
has just started to rotate because of pull placed on
reel by spring gauge and pull on gauge is steady while
reel just rotates.

REMOVE SCREW
REMOVE
SCREW
REMOVE PIN BY
SPREADING
BRACKET
REMOVE
SCREW
Capstan Drive Belt Replacement
EQUIPMENT REQUIRED FOR MECHANICAL CHECKOUT AND ADJUSTMENT
The following equipment or its equivalent is required
for mechanical checkout and adjustment:
Spring gauge, 0 to 8 oz.
0 to 32 oz.
0 to 64 oz.
a. Flutter Meter, Varo Model FL3D
b. Long Nose Pliers
c. "E" Ring Pliers
d. Set of Allen Wrenches
e. Phillips Screwdrivers
f. Head Cleaner, Ampex P ' N 010823
g. Head Demagnetizer, Ampex P/N 010820
h.
Flutter Tape, Ampex P/N 31326-01 (7-1/2 1ps)
and 31336-01 (3-3/4 ips)
j. Alignment Tape, Ampex P/N 31321-04
k. Reel of blank (erased) tape of type to be used
on recorder.
l. Ammeter, AC, 0 to 3 amperes
m. Special reel - consists of two standard 3 or 4
inch hub reels which are cemented together. Enables
accurate torque measurements. Reel has string or tape
installed on top r eel, thereb y preventing tape or string
from rubbing on frame casting.
3

MECHANICAL CHECKOUT AND ADJUSTMENT
Preliminary Requirements
The following are required for all tests and adjust-
ments unless otherwise specified:
a. Line voltage at 117 V AC.
b. Pre-amp output terminated with 100,000 ohm
resistor.
c. A filter, down 3 db at 30 and 18,000 cps must be
used for all noise measurements. (See filter construc-
tion details).
d. Demagnetize the heads, capstan, and tape guides.
Check
for cleanliness also. If necessary, clean with
head cleaner.
Mechanical Checks
a. Apply power to the recorder. Measure the AC
line current with the recorder in neutral (no motion).
Line
current should be approximately one ampere.
b. Supply Reel Holdback Torque. The supply reel
holdback torque should be between 1.9 and 2. 7 ounce-
inches in both forward and reverse PLAY modes.
The supply
reel holdback torque should be between
. 7 and 1.4
ounce-inches in both forward and reverse
WIND modes.
If torque is not within the above limits, adjust-
ment can be made by moving the triangular shaped
bracket beneath the casting. (Refer to illustration.)
The screw is loosened and the bracket is moved in
the
direction necessary to give proper holdback torque.
Then the screw is tightened. The adjustment is the
same for both reels.
4
NOTE
The supply reel will become the take-up reel
and vice-versa, depending upon tape motion.
c. Take- Up Torque. The take-up reel should have a
torque of between 1. 9 and 2. 7 ounce-inches when in
forward and reverse PLAY modes
If torque is not within this limit, adjustment can
be made by
turning the screw which changes spring
tension on the white hold-back pulley. This is the
white pulley having the
small black tire which engages
with the large white turntable pulley.
d. Capstan
Idler Pressure. In the PLAY mode, a
force of 2.3 to 2. 65 pounds applied at right angles to
the capstan idler arm at the capstan idler shaft should
just lift the idler clear of the capstan.
If the force required to just disengage the capstan
idler is not within the above limit, adjustment can
be made by turning the screw at the lower right of
the left hand
idler or at the lower left of the right
hand idler, (Refer to illustration.)
e. Speed. The average speed with a tape pack radius
of 2 to 2-1/2 inches on each reel should be as follows:
7-1/2 ips - plus or minus 1%
3-3/4 ips - plus or minus 2%
1-7/8 ips -plus or minus 3%
f. Fast Wind Time. The time required to transfer
1200 feet of 1-1/2 miltapefromsupplyreel to take-up
reel should be 120 seconds or less.
g. Flutter. Flutter should be measured using Ampex
Flutter Tape, part number 31326-01. Flutter at 7-1/2
ips should be 0.12% or less, 3-3/4 ips, 0.15% or
less, and at 1-7/8 ips, 0.25% or less. These specifi-
cations are for tape movement in either direction.

LUBRICATION
MOTOR LUBRICATION
The
motor bearings should have several drops of
Ampex Oil
P/N 01-0825 after each 1000 hours oper-
ation. A small oil port is located on each bearing
casting. Do not allow oil to run out between bearing
and motor shaft as this is an indication of excessive
oil. This oil is similar to OC-11 lubricant.
TRANSPORT MECHANISM LUBRICATION
Lubrication of the tape mechanism can be performed
by using the following recommendations:
1. Use Ampex P/N 087-060 (grease · similar to Shell
BRP#1) on
all moving but not rotating parts such as
yoke bearings, etc.
2. Use Ampex P/N 087-516 (fluid, d.c. 266,000
centistokes), on the tape tension switch (beneath cast-
ing) ONLY.
3. Use Ampex
P/N 087-527 grease to deaden ringing
sounds where necessary. It should never be used on
fast moving or rotating parts.
4. Use Ampex P/N 01-0825 on all rotating or fast
moving parts. This is the same type oil as is used to
lubricate the motor.
5

PROBL EM
Tape s ticks in tap e guide
Poor sp eed chan ge action
Poor s lack tak e- up
6
LOOSEN TO
AOJ BRAKES
TAKE-UP
AOJ
TAKE-UP
AOJ
Kl SIOabc
REV. SOLENOID
SWITCH
ADJ
Adjustments (beneath deck)
LOOSEN TO
AOJ BRA KES
MECHANICAL TROUBLES AND PROBABLE SO LUTIONS
POSSIBLE SOLUTION
5
Check brass tape guides. The clearance between tap e gui de over
capstan idler arms shall be approximately .005. It is a MUST th at
the tape guide shall not, at any place, touch either the i dler arm or
the capstan roller. If necessary, adjust tape guide as required , by
cautiously bending tape guide over idler arm. Check ta pe for proper
width.
Position speed selector knob at 3-3 / 4 ips (center positi on) and pull
compensating rod into selector knob nest; rod shall e nter freely.
Reposition selector knob at 1-7/8 and 7-1 / 2 ips (the two extreme
positions) and repeat check as above (3-3/ 4 ips). The c ompens a ting
rod shall enter the knob nest as freely as possible in b oth extreme
positions. Equalize any interference by bending ro d as r e quired.
Place assembly horizontally and check the slack take-up l eve r : The
lever shall have from .010 to .032 clearance between the de lrin tu be
and the
left-hand capstan idler cam. To adjust, insert the tip of
screwdriver in slot at the lower right tab and open it as req u ired.
NOTE:
Use a thick enough screwdriver blade to op en tab so that
it will not nick and/or damage lever; make su re that lever
stays flat.
Actuate play knob back and forth; it should operate free ly.

( .........,_
PROBLEM
Poor record slide o pera tio n
Poor take- up in play / record operation
Auto reverse does not function
Check top and bottom r everse
solenoid brass rods .
Tape rides out between capstan and
idler wheel.
Poor tape pack and excess iv e flu tte r
POSSIBLE SOLUTION
Check record slide operation. Position recorder vertically on
bench,
turntables on top and front toward operator. Put play knob in
PLAY mode and check. Approximately 1/ 64 clearance shall be
required between record slide lock-pin and top surface of record
locking lever. With record slide pushed down, again put play knob
in
play mode and check. Approximately the same clearance (1/64)
should be
available between record slide lock-pin and lower surface
of record locking lever.
Finally, with record locking lever open, push record slide down and
watch clearance between record slide lock-pin and lip of record
locking l ever; there shall be a minimum of .010 between the two.
If required, bend record locking lever as required.
Check play wind pulleys. Position recorder vertically on bench,
tur nt ables up, and check. Hold play knob in PLAY mode, push each
pulley over spring, and watch; pulleys shall seat with recess onto
play dr ive pulley springs. Further, pulleys shall veryfreely return
fully against play actuator when gently released.
Hold play knob in play position and check; a minimum of .005 to a
maximum of .037 clearance shall be available between actuator and
en d of play wind pulleys.
To ad ju st play, bend tonque in center of actuator as required, with
a
scr e wdriver.
Check reverse solenoid reverse rod. Reverse rod shall operate
fr e el y; it shall be straight and shall not in any way interfere with
ot h er part s , such as wires, etc., within the full length of its travel.
If required, gently straighten rod by hand. Also check that the
head shift switch is not binding and moves freely.
"E " rings should have between 1/ 32 and 1/ 16 end play over thrust
plate actuating lever. If required, reposition "E" rings with grip
ri ng p li ers.
CAUTION: To prevent "E".rings from excessive opening andfall-
ing out, at all times keep the grip ring plier properly
adjusted. Plier stop shall be so adjusted, that "E" shall
fit over rods snugly.
Check and adjust (2) capstan idler arm tension. Use any small rod
or A llen screw bit and gently pull auto-tape switch delrin sleeve up
with
finger and insert rod through magnetic casting hole to hold
tape switch up.
CAUTION: Do not bend
parts. With Allen screwdriver, loosen the
two idler rollers retaining screws part way, and turn
recorder in PLAY mode.
P/ U Chatillion scale and string loop, insert loop over one of two
idler rollers. Set marker to zero on s cale, and pull scale tangent
w ith center line of idler roller and capstan. Watch rotation of idler
roller carefully, and stop pulling scale at the instant that roller
ceases to rotate. Scale shall read between 2 lb. 3 oz. and 2 lb. 13
oz.
If te nsion is too high or too low, adjust cam screw as required.
Repe at operation to check the other idler. Be sure that cam screw
n uts are retigh t ened after readjustment.
Set speed selector at 7-1/2 ips. Actuate play knob and run trans-
port in play mode and forward (directional knob to the right). Check
tak e- up torque at right turntable; torque shall measure 1. 7 to 2.9
oz
.-in., on gage. Adjust nylon screw over banana spring at right
clutch under tr an sport as required to bring torque within specifi-
cati ons.
7

PROBLEM
Tape spools from supply r eel.
Fast wind poor or slow .
8
POSSIBLE SOLUTION
Keep
transport running in same direction; check holdback brake
torque at left turntable. Torque shall again measure 1. 7 to 2.9 oz.-
in., as above. Adjust brake lever as required with adjusting fork to
bring torque within specifications. Secure lever by locking screw
under turntable at left.
CAUTION: Never loosen brake lever locking screw more than 1/4
turn to prevent index extrusion on lever from coming
off index hole of base plate.
Reverse motion by pulling directional knob all the way to the left.
Check take-up torque at the left turntable; as above.
Check holdback brake -wind mode. With transport positioned on
fixture, head assembly in front, run transport in forward, wind
mode. Check holdback torque.
Check fast wind. Use a full (1100ft.) reel of tape and load on recor-
der turntable horizontally positioned on bench; load an empty, small
hub (1100 ft.) reel on remaining turntable; thread a maximum of 25
ft. of tape from the full reel and stop recorder.
Locate directional knob to pull tape from the full reel, and start
recorder with fast wind knob in wind mode. Watch the reel with the
25 ft. of tape; it should start immediately as fast wind knob is
actuated and with normal speed.
If the near empty reel is too slow to start, or it stops completely,
clean wind belt, wind pulleys, tires and brake drums with a clean
rag dampened in toluol. If it fails again, the drive brake drum under
the full reel of tape may have too smooth an O.D. surface. It then
cannot adequately be driven by the wind pulley tire because it slips
and the only solution left is to replace the brake drum. P /N 425 5007.
When a
brake drum has been changed on a recorder, the unit should
be rechecked, and if required, readjusted for holdback brakes,
clutches, and the .005 to .037 clearance between actuator and end
of play wind pulley.
Check auto-tape switch. Use a full (1100 ft.) reel of tape on turn-
table at the side of auto-tape switch. Thread tape through head, and
wind a small amount of tape on opposite reel (approx. 25ft.)
Position recorder vertically on bench and run it in play mode and
at 7-1/2 ips; reverse directional knob and see that the auto-tape
switch does not fully open while the slack in the tape is being taken
up, and in so doing, stop the mechanism. Repeat the reversal
several times; the mechanism should not come to a stop.
If defective: Disassemble end frame and power supply, and disas-
semble dampener by removing grip ring with a grip-ring pliers
properly adjusted so that ring is not over-expanded. Completely
and neatly clean I.D. of dampener and O.D. of switch with cloth
dampened in toluol. With Dow Corning tube squeeze an ample amount
of fluid over flat side of nylon rod for approx. 1/2 inch from end,
and apply fluid over entire surface of tape switch bearing O.D.
Again,
squeeze an ample amount of fluid on round side of nylon rod
for approx. 1/2 inch from end and apply over entire surface insi de
dampener bearing. Reassemble dampener over tape switch.
If above operation has been carefully done clean, and if a thick layer
of fluid has been applied over entire surface of both parts, reas-
semble parts, clean surplus fluid over the outside of parts, and the
tape switch will now open at a slower rate, allowing time for the
tape to take up. Reassemble thrust washer and grip ring. Approxi-
mately .004 clearance is required between grip ring and thrust
washer; reassemble power supply and end frame.

PROBLEM
Fast wind knob does not remain
engaged.
High flutter.
POSSIBLE SOLUTION
Check fast wind knob engagement. With tape on, position recorder
vertically on bench and run in reverse play mode. Gently move
directional knob to the right to pick up knob blacklash (being careful
not to distrub solenoid bottoming) and hold directional knob in this
position. Carefully push play mode knob down to stop mechanism,
and open fast wind knob. Fast wind knob shall open without inter-
ference from interlock lever under control plate assembly.
If there is interference , the reverse solenoid may not be properly
adjusted (see electrical problem and solution). If reverse solenoid
adjustment is proper, then the control plate assembly may be
defective and should be replaced.
Turn recorder on and check wow and flutter in forward and reverse,
at 7-1/2 and 3-3/4 speed.
If flutter contents read higher than specified, proceed as follows:
(1) check tape guides on top of idler arms; guides may rest too
tight on arms and prevent pinch rollers from applying adequate
tension on tape. Further, tape guides maybe up too far and touching
idler pulley when rotating. If so, readjust tape guides to the .005
clearance specification. Use soldering aid to bend guides gently up
or down. (2) With a Q. tip saturated with Ampex head cleaner,
gently clean faces of magnetic heads, capstan, tape guide washers
and spacers.
Check to see if capstans are touching. tape guides, tape guide
washers, or if idler pulleys may be touching tape guide washers.
If so, disassemble head assembly, reposition parts, and reassem-
ble.
If flutter reading remain higher than specifications at 3-3 / 4 speed,
replace flywheel belt. Recheck for flutter.
If flutter is still high, replace flywheel at take-up reel side of
transport (depends upon tape movement).
9

PRELIMINARY REQUIREMENTS FOR ELECTRICAL CHECKS AND ADJUSTMENTS
The following equipment or its equivalent is required
for making electrical checks and adjustments. Also
refer to mechanical checkout and adjustment section
for additional equipment.
a. 2 - l00k resistors
b. 1 - Noise filter (see construction details)
c. 1 - 100/1 capacitive voltage divider (see con-
struction details)
d. 1 - Oscillator, hp 200cd
e. 1 - ACVTVM, hp 400h
f. 1 -
Oscilloscope, general
g. 4 - Interconnecting cables and jacks
h. 1 - #1820 28 volt lamp
j. 1 - Varo Flutter Meter, Model FL3D
k. 1 -
Variable Voltage Transformer (3 amp)
1. Head Cleaner Ampex P/N 7010110-01
PRELIMINARY CHECKOUT INSTRUCTIONS
For all tests, the pre-amp outputs must be ter-
minated with lOOk resistors. Cable lengths to test
equipment must be kept as short as possible.
NOISE FILTER
R2
Cl
NOISE FILTER
A schematic for the noise filter is shown below.
All components should be mounted inside a metal
box. The connectors are banana plug type, spaced
on center 3/4 inches apart.
100/1 CAPACITIVE DIVIDER PROBE
Construction details are given for the 100/ 1 capaci-
tive divider probe. All components must be well
shielded to prevent hum pick-up. This probe reduces
loading effects to about 3 pf when connected to
circuitry. The probe is accurate only when connected
to an ACVTVM having an input impedance of 10
meg ohms shunted by 25 pf.
ADJUSTMENT
OF PROBE (frequency compensation)
Probe adjustment is made by applying a 1 volt lOOkc
sine wave to the tip of the probe. The acvtvm is set to
the .01 volt
range and capacitor C2 is adjusted so the
acvtvm indication is .01 volt. The probe will be cali-
brated accurately enough to cover all Ampex tape
recorders.
Rl, 5% W
Cl, .05 UF, ± 10%,400 VDCW
Rl
INPUT
C2
R2, IOK, !5%, 1/2 W
OUTPUT C2,
750 PF, ±5%, 400VDCW
10
100/1 CAPACITIVE DIVIDER PROBE
--
LEAD
Rl, 50MEG +- 5% 1/2W
R2, 680K ± 5% 1/2 W
L ___ J
3 to 4 ft of RG 58 C/U
Cl, 2.2 PF +- 5% 500 VDC
C2, 60-350 PF, VARIABLE

HEAD REPLACEMENT ANDAUGNMENT
Head Replac em ent
Should any of th e heads require replacement the
following method should be used.
1. Remove top cover plate. Then remove the three
screws securin g the head mounting assembly. This
will allow eas y acce ss to the heads.
2. Remove the th r ee s c rews securing the defective
head to the hea d a ss embly.
3. Unsolder th e four wires from the defective head
noting from which te r minals the various wires are
removed.
4. Resolder the w ir es to the replacement head using
a 15 watt newly ti nned iron. Make the soldering con-
nections very quickly to avoid damaging the replace-
ment head.
5. Install the head to the head mounting casting. Make
sure the three spri ngs are re-installed to allow for
head adjustment.
6. Reinstall the head assembly on the recorder and
thread tape on r eco rder.
MOVE UP OR DOWN
TO ADJ. BRAKE S
7. Carefully turn the three screw s so that all planes
of the head are perpendicular to the tape. The shiny
part of the head must be exactl y p arallel to the oxide
surface of the tape. The br ass liners in the head
should be visible when looking at the head after tape
is put on transport. The upper edge of the upper pole
pieces of the head should ju st come to the upper edge
of the tape. Using alignm ent t ape P/N 31321-04,
adjust the 3 head screw s f or equal output of each
channel using 3kc tone.
8. Using alignment tape P/ N 31321-04, adjust the
azimuth screw (see illustrati on) for maximum out-
put using the 15kc tone.
9. The erase head azimuth is adjusted by visually
observing that head height is corre ct and that the head
gaps are at right angles to tape. Then record a 15k
signal (tracks 1 and 3) at opera ti ng le vel as determined
by record neon lamps. Inter ch ange the reels and erase
(record level at ZERO) tr acks 2 and 4. Then.put
recorder in reverse play ( rig ht to left tape motion)
and measure output on orig inal tracks on which 15kc
signal was recorded. The signa l should be within the
recorder frequency spec if ication at 15kc. If 15kc signal
is out of specification, it is m ost likely because the
erase head azimuth or height is i mproper and requires
adjustment. Adjust as require d.
PLAY RECORD
HEAD SWI TCH S2ob
HEAD AZIMUTH ADJ.
Head Adjustments
11

1050/1080/2050/2080 ELECTRICAL CHECKS AND ADJUSTMENTS
TAPE RECORDER CONTROL SETTINGS
CHECK AND ADJUSTMENT
PLAYBACK NOISE (each
channel)
Connect the noise filter to the input of the
ACVTVM. Connect the input of the noise filter to
the left pre-amp output connector. The ACVTVM
indication with tape removed from operating
transport should be 27mv or less.
Set the speed selector to 3-3/4 ips . The ACVTVM
indication should be 37mv or less for operating
tape transport with tape removed. Repeat for
other channel.
SPEED
7-1/2
MONO/
STEREO
STEREO
PLAYBACK FREQUENCY RESPONSE 7-1/2 STEREO
Connect the ACVTVM to the left pre-amp output
connector. Put the standard alignment tape on the
recorder. Play the 15kc tone. Adjust the azimuth
of the right hand play/record head (left to right
tape motion) for maximum indication on ACVTVM.
Then connect ACVTVM to right pre-amp out and
furtner adjust azimuth for compromise output
between the two channels. Azimuth adjustment
is made by adjusting the rear-right-hand screw
only of the head. Reverse tape and repeat for
other head using rear left hand screw.
Put tape in reverse play direction and adjust left-
hand head azimuth for maximum compromise out-
put as was done for play /record head.
Play the 700 cps tone which is operating level.
Adjust the left channel volume control to maxi-
mum clockwise position. The ACVTVM should
indicate between 1.1 and 1.55 volts. Record this
indication as it will be used to adjust record level
neon indicators. Adjust volume control so
ACVTVM indicates . 7 volts. Play 50 cps tone on
tape. ACVTVM indication must be between . 19
and .35 volts.
Playback the 100 cps tone. ACVTVM indication
must be between . 24&. 3 5volts. Playback of 250
cps to 15,000 cps must be between .16 and. 32
volts on ACVTVM.
Repeat the playback - frequency response check
for right channel. Then repeat above for tape
movement right to left (reverse direction).
RECORD LAMP CALIBRATION
Apply 500
cps at .1 volt into the left line input.
Using a bulk erased tape of the type normally
used with the recorder, record several feet of
tape. Rewind the tape. With the ACVTVM con-
ne cted to th e left pre-amp output connec tor,
play tape and notice ACVTVM indicatio n. Suppose
the indication which was re cor ded from 700 cps
tone at operatin g level was 1 volt and the
ACVTVM indication is now 1. 5 volts.
1 
7-1 / 2 STEREO
OFF-ON-
REC/PLA Y MONITOR
REPEAT ON
(2050)
PLAY
(1050)
REPEAT
{2050)
PLAY
(1050)
RECORD
ON
ON
VOLUME
Max.
CW
Mid-Pos.
Max. CW

1050/1080/2050/2080 ELECTRICAL CHECKS AND ADJUSTMENTS (CON'T)
TAPE RECORDER CONTROL SETTINGS
MONO/
OFF-ON-
CHECK AND ADJUSTMENT SPEED STEREO
REC/PLAY
MONITOR VOLUME
RECORD
LAMP CALIBRATION (CON'T)
Reduce the line input voltage by 3.5db. Adjust R33
until the left channel record neon just lights and
then back off R33 until the neon just extinguishes.
Record level calibration is set for left channel.
Should the level of the recorded tape be lower
than 700 cps reference signal, then increase the
line input by the difference in db.
Repeat the above for the right channel.
Record 700 cps signals at operating level (neon
just extinguished). Upon playback with volume set
at maximum, ACVTVM connected to pre-amp,
connector should indicate between 1.1 and 1.55
volts.
Repeat the above for the right channel. Adjust
record level using R106.
RECORD BIAS ADJUSTMENTS
7-1/2
STEREO
RECORD
ON
As req.
Apply 500 cps at 1 volt to both line inputs. Con-
nect a 100/1 capacitive voltage divider to the
record head side of C12. Adjust C12 for 35 volts
(ACVTVM indicates .35 volts because of 100/1
attenuation). Connect the 100/1 capacitive voltage
divider probe to the head side of C49. Adjust C49
for 35 volts (.35 volt indication on ACVTVM
because of 100/1 divider). Adjust the left volume
control so the left record indicator lights, then
back off so the indicator lamp just extinguishes.
Do likewise for the right channel.
Reduce line input to .1 volts and make several
minutes of recording at frequencies of 50, 500,
10,000
and 15,000 cps. Rewind the tape and play
the recording with the ACVTVM connected to pre-
amp output. Output should be within ±4db of output
at 500 cps. If output at 15kc is high, increase bias
voltage by 3 volts for each db high. For instance,
if 15kc is 3db high, increase bias voltage by 9
volts, then recheck frequency. If 15kc is low,
decrease bias voltage by 3 volts for each db low.
Then recheck record/playback response.
Repeat overall response check at 3-3/4ips speed.
Do not adjust bias voltage. It is adjusted only at
7-1/2ips speed. Equalization should give proper
frequency response. Set record level so indicators
light, then back off so they just extinguish. Re-
sponse at 3-3/4ips should be within ±4db from 50
cps to 9kc using output at 500cps or reference.
Repeat record/play response check at 1-7/Sips.
Do not adjust bias. Response upon playback should
be +2, -6db using output at 250cps as reference.
ERASE NOISE
7-1/2
STEREO
RECORD
ON
As req.
Place a bulk erased tape on the recorder. Apply
500cps
at .5 volts into both line input connector.
Connect the ACVTVM to the left pre-amp through
the noise filter. Adjust both record levels for
13

1050/1080/2050/2080 ELECTRICAL CHECKS AND ADJUSTMENTS (CON'T)
TAPE RECORDER CONTROL SETTINGS
MONO/
OFF-ON-
CHECK AND ADJUSTMENT SPEED STEREO
REC/PLAY
MONITOR VOLUME
ERASE NOISE (CON'T)
normal record level (neon on, then just off). Then
increase line input voltage to 2.2 volts and record
several minutes of tape with input of 2.2 volts.
Remove 500cps from line input. Insert shorted
plugs into line input connectors. Rewind tape. Put
recorder into record and erase the tape recorded
with input of 2.2 volts. Then rewind tape and put
recorder into PLAY. ACVTVM indication at left
and right, pra-amp output should be 41db below
output obtained when playing 700cps signal. For
instance, if, when playing the 700cps signal on
standard alignment tape with volume at maximum,
the output voltage was 1 volt then the noise on the
erased portion of the tape should be at least 41db
below 1 volt.
The noise level tolerance is the same for the
right channe 1.
CROSSTALK
7-1/2
STEREO RECORD ON
Max. CW
Bulk erase a tape of the type used when record
bias was adjusted. Apply a 5000cps signal to the
left line input connector. Short the line input con-
nector to the right channel. Adjust the amplitude
of the 500cps input until the left record indicator
lights, then decrease until record lamp just
extinguishes. Record several feet at this level.
Then put the recorder into reverse play. With the
ACVTVM connected to the right pre-amp output,
indication should be .016 volts or less.
Apply 5000cps to right line input. Short left line
input connector. Put recorder into forward record
and record 5000cps at normal recording level.
Connect ACVTVM to left pre-amp output con-
nector. Put recorder into reverse play. ACVTVM
indications should be .016 volts or less.
NOTE: This completes electrical check and adjustment for Model1050 recorder. The following are additional
checks required for Model 2050 recorders.
REED RELAY (VIBRATOR) FREQUENCY
7-1/2
STEREO
PA ON Min.CCW
Connect a GE#1820 lamp to a single circuit phone
plug. Insert the phone plug into the projector
actuator jack. Apply a .05 volt 18 cycle signal to
the left line input connector. Vary the input fre-
quency slowly to 19.5 cps . The lamp inserted into
the projector actuator jack should glow. Increase
the input frequency to 20. 5cps. The lamp should
remain lighted. Increase the input frequency to
21cps. The lamp should extin gu ish. Maximum
vibrations of the relay arm a ture should occur at
20cps. If necessary , adjust the spring loaded
screw at the side of the vibrator for maximum
oscillation of the a rmature as the input frequency
is advanced from 18 to 20cps. If the lamp does not
glow and maximum oscillation occurs at 20cps and
armature swing is at leas t 1/ 4 inch from low to
high position, adjust contacts so they are slightly
closer together. Then when armature vibrates,
14

r
1050/1080/2050/2080 EL ECTR ICAL CHECKS AND ADJUSTMENTS (CON'T)
TAPE RECORDER CONTROL SETTINGS
MONO/ OFF-ON-
CHECK AND ADJUSTMENT SPEE D STEREO REC / PLA Y MONITOR VOLUME
REED RELAY (VIBRATOR) FREQUENCY (CON'T)
lamp should light. If armature does not vibrate
vigorously, demagnetize the armature. This can
be done by applying 300 volts 60 cycles to the
relay coil through a 30,000 ohm resistor and
slowly reducmg the voltage to zero using a Variac
or other variable voltage transformer.
The recorder should reverse satisfactorily at line
voltages of from 105 to 125 volts. Check by apply-
ing the 20 cycle signal on the tape and checking
for reverse at 105 and 125 volts. The play/record
knob must be in repeat to check automatic rever-
sal in both directions.
To check the 20cps signal being applied to the
tape, put the signal on the tape in the normal
manner. Note whether the lower half of the left
neon glows. If not, adjust R142 until the lower
half glows. The voltage as indicated on the
ACVTVM connected to the w1per of R142 and
chassis shoulJ be between 200 and 250 millevolts.
Adjust 1f requ red by varying resistance of R142.
--.
S4abcd
Slabc
Electric al Ad ju st ments
15

1070/2070 ELECTRICAL CHECKS AND ADJUSTMENTS (CON'T)
TAPE RECORDER CONTROL SETTINGS
MONO/
CHECK
AND ADJUSTMENT
SPEED STEREO REC/PLAY
TONE VOLUME
RECORD BIAS ADJUSTMENT
7-1/2
STEREO RECORD Any
Pos.
As Req.
Apply
500cps at 1 volt to BOTH line inputs. Con-
nect a 100/1 capacitive voltage divider probe to
the record head side of C12. Adjust C12 for 35v
(ACVTVM
indicates .35 volts because of 100/1
attenuation). Connect 100/1 divider to record
head side of C49. Adjust C49 for 35 volts (.35 volt
indication on ACVTVM). Adjust left volume control
so left record level indicator lights, then reduce
so lamp just extinguishes. Do likewise for right
channel. Then .reduce line input voltage to ..1 volts
and make several minutes of recording at fre-
quencies of 50, 500, 10,000 and 15,000 cps. Rewind
the
tape and play the recording with the ACVTVM
connected to the pre-amp output. Output should
be within ±4db of output at 500cps. If output at 15kc
is high, increase bias voltage by 3 volts for each
db out of spec. For instance, if 15kc is 3db high,
increase bias voltage by 9 volts. Then recheck.
If 15kc is low, decrease bias voltage by 3 volts
for each db low. Then recheck record/playback.
Repeat overall response check at 3-3/4 speed. Do
3-3/4
STEREO RECORD Any
Pos.
As Req.
not
adjust bias voltage. Equalization should give
proper frequency response. Set record level so
record lamps light, then just extinguish. Response
at 3-3/4 should be ±4db from 50cps to 9kc using
500cps as reference.
Repeat overall response check at 1-7/Sips. Do
1-7/8
STEREO RECORD Any
Pos.
As Req.
not
adjust bias voltage. Response upon playback
should be +2, -6db using output at 250cps as
reference.
ERASE NOISE
7-1/2
STEREO RECORD Any
Pos.
As Req.
Apply 500cps
at .45 volts to both line inputs. Con-
nect the ACVTVM to left pre-amp through noise
filter. Adjust record levels for normal record
level. Then increase line input voltage to 1 volt
and
record several feet. Rewind the tape. Remove
signal from line input and short both line input
connector to ground using shorted plugs. Put
recorder into record with volume at same setting
as during recording. Erase recorded portion of
tape. Then rewind and note indication of ACVTVM
connected to pre-amp outputs through
noise filter. Indication should be at least 41db
below 500cps
signal obtained by playing standard
alignment tape. For instance, if output from
standard alignment tape at 500cps was .3v, then
ACVTVM indication should be -51.5db (.0025
volts) or less. The above is the same for both
channels.
CROSSTALK
7-1/2
STEREO RECORD Any
Pos.
As Req.
Bulk
erase a tape of the type used with the
recorder. Apply 5000cps at .1 volt into the left
line input. Apply a short to the right line input
connector. Put the recorder into record and
record several feet at normal recording level.
Then put the recorder into reverse play (tape
moving
from left reel to right reel). Connect the
17