Magnecord PT6-A Series User manual

PT6-A INSTRUCTION MANUAL
Dj
SALES OFFICE AND FACTORY
225 WEST OHIO STREET
CHICAGO 10, ILL.
INC.
--veetepo

OPERATING PROCEDURE FOR FAST FORWARD IN PT6-AH RECORDER MECHANISM
With the recorder set up in the normal operating condition and threaded with tape, set
the control knob to STOP. Depressing the high speed knob clockwise to the right will
start the main drive motor and engage the intermediate rubber drive wheel between the
motor shaft and hub of the takeup shaft clutch. This will cause the right hand spool to
rotate clockwise, thus winding the tape forward. Total forward winding time of 7" spool
is approximately three minutes.
-
If high speed forward lever is depressed while the mechanism is driving the tape in the
normal forward manner, the high speed overdrive will be engaged and place an undue
strain on the tape between the capstan and take-up reel. It will be noted that this speeds
up the tape only slightly. This causes no harm mechanically but the program material
speeded-up will sound peculiar. _
Copyright 1949, Magnecord, Inc.

f -47. niefflormrielmir
BIAS INDICATOR:
The bias indicator lamp (II in
Fig. 0 will glow when plate supply
voltage is being supplied to the
oscillator tube. This indicates that
any previous recording on the tape
is being erased and a new recording
may be made.
TERMINAL DESIGNATIONS:
All electrical connections are made
to the Jones male and Cannon female
connectors located in the rear of the
P16-A. Signal circuits are fed through
the Cannon connector, and power is fed
through the Jones connector. See
schematic for terminal designations.
MAI NTENAN CE:
The P16-A Basic Recorder Mech-
anism is ruggedly built to withstand
the requirements of studio end field
use. Maintenance is of a minor nature
and should the unit require any re-
pairs due to accident or misuse7 - 11L,
should be returned to the distributor
from whom it was purchased. When
writing in regard to,the unit, the
type number, serial number shown on
the license notice and also the date
of purchase should be mentioned.
ELECTRICAL:
'w# 44 'e The 12Ati7 - Cisci 1 lator - tribé
be checked occasionally.
MECHANICAL:
All bearings in the P16-A are
either of the self-oiling type or the
wick-fed type. The unit is properly
lubricated before it leaves the fac-
tory and should not require any fur-
ther lubrication for at least six
months. Information on lubrication
is supplied in the PT6 Series Service
Notes.
Note: It is imperative that no
oil be allowed to accumulate on any
of the rubber covered idlers as this
. will cause slippage and impair tape
speed regulation. A soft cloth
moistened with\carbon tetrachloride
should be used to remove any oil from
the idlers.
' CLUTCH ADJUSTMENTS:
Tape tension is maintained by two
friction clutches. Their correct ad-
justment causes the tape to move from
one reel to the other in either direc-
tion without throwing or stalling.
The clutches are located on the rear
ends of the supply reel spindle and the
take-up reel spindle. The supply reel
spindle clutch is located at the right
,(facing the rear of the unit) and con-
sists of an oiled felt washer pressing
against a knurled disc which is free
to rotate in a clockwise direction but
prevented from turning in the opposite
direction by a spring leaded pawl.
Pressing against the opposite side of
the felt washer is a sponge rubber pad.
A split, knurled adjustment ring bears
against the sponge rubber pad and is
locked in olace by meant of e set screw.
The set screw must be backed off before
the adjustment ring can be turned. Ror
tating the adjustment ring clockwise in-
creases the clutch friction.
The supply reel spindle clutch ad-
justment should maintain a drag as the
supply reel rotates when the PT6-A is
in forward operation. This drag should
be sufficient to stop the supply reel
without permitting the tape to loop
or throw when the control switch is
turned from 'FORWARD" to "STOP". The
amount of friction should be the mini-
mum necessary to accomplish this.
Too much clutch friction will in-
crease the tape drag to a point at which
the tape speed will be below normal.
The take-up reel friction clutch is
located on the left side (facing the
rear). This is similar in appearance
to the other clutch but employs no
pawl. It is also necessary to back off
the set screw before adjusting this
clutch.
The_take-up reel spindle friction,
ei — the sPindle . to - the 1r71M,MM
synchronous motor drive when the con-
trol knéb is set to "FORWARD" and acts
as a brake on the take-up reel when the
control knob is set to "STOP". The
clutch adjustment should provide suf-
ficient friction for the take-up reel
and capstan to move the tape at normal
speed forward when the take-up reel is
almost completely full and the supply
reel nearly empty. It should also
provide sufficient braking to maintain.
tape tension and prohibit tape throw
when the control switch is turned to
"STOP" after the take-up reel has been
rotating at high speed during rewind.'
The split knurled ring should be ad-
justed to provide the minimum clutch
friction to accomplish these two- func- ,
tions. About 5 inch oz. for each clutch
is correct friction,
OILING THE CLUTCH FELTS:
The feft washers have been oil
treated at the factory to provide
the correct amount of slippage. It
may be necessary to give each felt
washer (supply spindle and take up
spindle) one drop of high quality sew-
ing machine oil after several months
of use.
CAUTION:
()0 NOT OVER-OIL THE CLUTCH FELTS
AS THIS MAY CAUSE OIL TO BE THROWN
ON NEARBY IDLERS CAUSING SLIPPAGE
IN THE DRIVE SYSTEM. ONE DROP PER
FELT IS SUFFICIENT.)
P16 -A INSTRUCTION MANUAL

CLEANING THE HEADS:
It is necessary that the portions
of the erase head and the record-re-
produce head which come into contact
with the tare be kept free of dust,
grease and foreign matter, or the
frequency response characteristics
will suffer.-. They should be cleaned
with a soft cloth slightly moistened
with carbon tetrachloride C.P. after
every five hours of operation.
Note: Do not attempt to apply
carbon tetrachloride to any part of
the PT6-A when loaded reels are in
place as the tape is soluble in car-
bon tetrachloride and will be ruined
if it comes in contact with the solu-
tion. After using carbon tetrachloride
( RASE
SO MPIFD
0
" •C'.. 2
/2 M .17
17 .7
-
7
.002
make sure the heads are completely dry
before threading tape and be syre none
of the solution is transferred to the
tape from the fingers.
H EAi REPLACEMENT
Replacement erase or record-re-
produce heads may be obtained from the
distributor from whom the unit was
purchased provided the worn heads are
rpturned at the same time.
GUARANTEE:
The Magnecord PT6-A is guaranteed
to be free of defects in workmanship
and materials (excepting tubes) for a
period of 90 days from date of purchase.
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111Freeme""elf
P16-A
?„- - •••••• rn, r-
INSTRUCTION MANUAL
DESCRIPTION:
The Magnecorder PTS-A is a taps
recording mechanism designed for
use in combination with the ampli-
fiers and other units of the PT6 Series.
It consists of a tape transport mech-
anism, erase head, record-reproduce
head, bias oscillator and control
switch, assembled into a single unit.
Filament current and plate cur-
rent for the bias oscillator tube must
be supplied by an external ource if
the P16-A is not used in conjunc-
tion with one of the PT6 Series ampli-
fiers.
STANDARD EMPMENT:
Every P16-A unit is supplied with
one type I2AU7 tube already mounted
in its socket. This is the bias oscil-
lator. Two sets of capstan-pressure
roller combinations are furnished;with
each unit; one set for operation at
16'inches Per second, the other for
7i inches per second. One set is in
place on the front panel, the other
set is contained in a shipping bag. ,
The capstans are provided with tapered
holes to mate with the tapered capstan
shaft on the front panel. The large
capstan and small pressure roller com-
bination provides for tne higher tape
speed.
INSTALLATION:
Four knurled-head screws in the
corners of the front panel of the
PT6-A mount it in its portable case
or the Magnecorder rack amplifiers or
rack panels designed for use with the
PT6-A unit.
PREPARING THE P16-A FOR OPERATION:
The P16-A motors and oscillator
tube receive their power through the
male Jones connector on the rear of
the unit. See schematic for terminal
designation. Motor operating power,
oscillator filament power and plate
supply voltage are supplied by the
Magnecorder PT6 Series amplifiers.
The female Cannon connector on the
SALES OFFICE-360 N. MICHIGAN AVE. • PLANT-225 W. OHIO ST.
rear of the PT6-A is connected to
the record eeproduce head. See sche-
matic.
(I) Make sure the oscillator tube
locafed in the rear and at the right
side is secure in its socket.
(2) Set the control knob (I in Fig.
I) to "STOP".
(3) Make sure the correct capstan
and pressure roller (2 & 10 in Fig.
I) are in place and that the knurled
retaining screws are screwed down
firmly. The small (7¡"/sec) capstan
operates with the large rubber covered
pressure roller. Make sure that the
tapered hole in the capstan and the
tapered shaped capstan shaft are com-
pletely free of dirt or foreign part-
icles before installing the capstan.
OPERATION:
(Operator facing fro I)
Ille * Note: Warped supply and/ or eke- 4e
-UP reels may interfere w th - with
Pe tmo v e
ment of the tape thus producing wows
and flutter. The flanges of the warped
reels should be straightened by bend-
ing them outwards and applying heat
so that the plastic will soften and
retain its new shape.
(I) place the empty reel on the
take-up spindle (3 in Fig. I). Before
a reel can be installed on the spindle it
is necessary to remove the reel retainer
by pushing it toward the unit and turning
slightly counter-clockwise until thepins
are released from the slots. Place the
empty-reel on the take-up spindle (3 in
Fig. I). Put the reel retainer on the
shaft and push in until the 3 pins are
in contact with the spindle. Make sure
that the pins go down the slots in the
end of the spindle and then turn the
retainer slightly clockwise until itis
locked in place.
(2) Place a loaded reel of tape
on the supply spindle (5 in Fig. I).
The reel should be oriented so that
the tape will unwind as the reel ro-
tates clockwise. Tape should come
off to of spool with coated, or dull
side down.
CHICAGO, ILL.

Mr91fflerellle!teee=

r 71 '7 .7
(3) Turn the supply reel clock-
wise by hand so that approximately
18 inches of tape or leader will
unwind.
(4) Insert the end of the tape
or leader in the slot on the inside
of the take-up reel.
(5) Rotate the take-up'r -e- el
clockwise until there are at least
two full turns of tape on the reel.
(6) Slip the tape into its normal
travel path; under trie idler (6 in
Fig. 1; over the erase head (7 in
Fig. 1; over record-reproduce head
(9 in Fig. I); oetween capstan (2 in
Fig. I) and pressure roller (10 in
F ig. I).
(7) Rotate take-up reel to re-
move slack.
(8) Connect the unit to the Mag-
recorder PT6 amplifier. Note: If
the PT6-A is to be used with some
other amplifier, 117 volt 60 cycle
AC must be suppl ied to the motors;
and filament powér at 6.3 volts .3
amperes and plate supply of 300 volts
at 40 ma must be suPPl ied to the os-
cillator tube. See schematic.
(9) Turn the control knob to
"FORWARD". This puts the unit into
forward operation at a speed de-
' termined by the capstan being used.
If the tape does not move smoothly
between the capstan and pressure
roller, lift the pressure roller
slightly to permit the tape to
align itself properly.
(10) To rewind the tape, turn the
control knob to "STOP", then place tape
over lift bar so that the tape is lift-
ed clear of the heads. Turn the con-
trol knob to "REWIND". The rewind
mechanism, driven by a shaded pole
motor, wi 11 completely rewind 1200
feet of tape (full 74" reel) in ap-
proximately 40 seconds. The loaded
reel will rotate at an increasingly
higher speed as the tape is trans-
ferred back to the supply reel during
rewind. The control knob may be turned
to "STOP" at any time during rewind
without danger of tape throw. Be sure
that the tape is lowered to its normal
position on the heads before attempting
to record or reproduce.
Note: The control knob should'
never be turned quickly from "RE-
WIND" to "FORWARD". If it is de-
sired to reverse the direction of
the tape travel from rewind to for-
ward the knob must be turned to
"STOP' and the tape allowed to come
to a complete halt. Then the knob
may be turned to "FORWARD".
(II) The bias indicator light
in Fig. 1) will glow when the
oscillator tube plate supply voltage
is applied through the Jones male
connector. If the PT6-& is being
used with any of the Magnecord PT6
Series amplifiers, the light will
go on when the ampl ifier Selector
Swi tch is turned to 'RECORD". An
inter-lock in the PT6-A will turn
off the oscillator and the lamp
whenever the PT6-A control is turned
to "STOP" or "REWIND". See schematic.
SIGNAL I NPUT:
It is necessary that the audio
signal be suitably equalized both in
recording and playback. Correct pre-
emphasis and post-emphasis is supplied
in the Magnecorder PT6 Series record-
ing amplifiers by means of built-in
circuits.
EQUALIZATION:
If the PT6- A, Basic Recorder
Mechanism is to be used with some
other amplifier, the curves shown
in Figures 2 and 3 will be of value
in the design of proper equalizers.
Figure 2 shows the desired frequency
response for the signal current fed
into the recording head (pre-emphasis).
Figure 3 shows the desired frequency
response'of the amplifier that is fed
by the reproduce head (post-emphasis).
rhe combination of these characteristics
will yield a substantially flat response
at the output of the playback amplifier
from 40 to 15,000 cycles-with a tape
speed of 15" per second. To obtain es-
sentially flat response from 50 to 7500
cps using 74" per second tape speed it is
necessary to use Magnecord plug-in equal-
izer designed specifically for slower speed:
IMPEDANCE MATCHING:
When the head is used for repro-
ducing purposes it should work into a
transformer of 60 ohms input impe-
dance. When the head is used for re-
cording it should have a maximum cur-
rent of approximately one milliampere
in its coils. This current should be
developed through a resistor of ap-
proximately 600 ohms in series with
the head. This resistor makes the head
circuit effectively a resistive load.
OSCILLATOR CURRENT SUPPLY:
Filament and plate current for the
I2AU7 tube are supplied by Magnecorder
PT6 Series ampl ifiers. If another ampli-
fier is to be used a source of filament
power of 6.3 volts at 0.3 amperes and
plate power of 300 volts at 40 milli-
amperes must be supplied.
Note: The PT6-A is normally con-
nected for 6.3 volts at 0.3 amperes
for the oscillator tube heater. How-
ever, the connections to the tube may
be changed for operation from 12.6
volts at 0.15 amperes. Refer to
sch em at i c.
PT6-A INSTRUCTION MANUAL

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MAGNETIC TAPE PLAYBACK AMPLIFIER CHARACTERISTIC

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-
PT6-A INSTRUCTION MANUAL
SALES OFFICE
360 N. MICHIGAN AVE.
CHICAGO 1, ILL.
PLANT
225 W. OHIO ST.
CHICAGO 10, ILL.

•
• ,
• •:'
•
1
•
Jervedgime'-
-74ler

BIAS INDICATOR:
The bias indicator lamp (II in
Fig. 0 will glow when plate supply
voltage is being supplied to the
oscillator tube. This indicates that
any previous recording on the tape
is being erased and a new recording
may be made.
TERMINAL DESIGNATIONS:
41 ,
All electrical connections are made
to the Jones male and Cannon female
connectors located in the rear of the
PT6-A. Signal circuits are fed through
the Cannon connector, and power is fed
through the Jones connector. See
schematic for terminal designations.
MAI NTENANCE:
The P16-A Basic Recorder Mech-
anism is ruggedly built to withstand
the requirements of studio and field
use. Maintenance is of a minor nature
and should the unit require any re-
pairs due to accident or misuse, it
should be returned to the distributor
from whom it was purchased. When writing
in regard to the unit, the type number,
serial number, the date and from whom
'purchased should be mentioned.
ELECTRICAL:
The I2AU7 oscillator tube should
be checked occasionally.
' MECHANICAL:
All bearings in the PT6-A, are
either of the self-oiling type or the
wick-fed type. The unit is properly
lubricated before it leaves the fac-
tory and should not require any fur-
ther lubrication for at least six
months. Information on lubrication
is suliplied in the PIG Series Service
Notes.
Note: It is imperative that no
oil be allowed to accumulate on any
of the rubber covered idlers as this
will cause slippage and impair tape
speed regulation. A soft cloth
moistened with carbon tetrachloride
should be used to remove any oil from
the idlers.
CLUTCH ADJUSTMENTS:
Tape tension is maintained by two
friction clutches. Their correct ad-
justment causes the taPe to move from
one reel to the other in either direc-
tion without throwing or stalling.
The clutches are located on the rear
ends of the supply reel spindle and the
take-up reel spindle. The supply reel
spindle clutch is located at the right
(facing the rear of the unit) and con-
sists of an oiled felt washer pressing
against a knurled disc which is free
to rotate in a clockwise direction but
prevented from turning in the opposite
direction by a spring loaded pawl.
Pressing against the opposite side of
the felt washer is a sponge rubber pad.
A split, knurled adjustment ring bears
against the sponge rubber pad and is
locked in place by means of a set screw.
The set screw must be backed off before
the adjustment ring can be turned. Ro-
tating the adjustment ring clockwise in-
creases the clutch friction.
The supply reel spindle clutch ad-
justment should maintain a drag as the
supply reel rotates when the PT6-A is
in forward operation. This drag should
be sufficient to stop the supply reel
without permitting the tape to loop
or throw when the control switch is
turned from "FORWARD" to "STOP'. The
amount of friction should be the mini-
mum necessary to accomplish this.
•
Too much clutch friction will in-
crease the tape drag to a point at which
the tape sPeed will be below normal.
The take-up reel friction clutch is
located on the left side (facing the
rear). This is similar in appearance
to the other clutch but employs no
pawIr It is also necessary to back off
the set screw before adjusting this
clutch.
The take-up reel spindle friction
clutch couples the spindle to the
syncWronous - motor drive when the con-
trollknob is set to "FORWARD" and acts
as a brake on the take-up reel when the
control knob is set to 'STOP". The
clutch adjustment should provide suf-
ficient friction for the take-up reel
and capstan to move the tape at normal
speed forward when the take-up reel is
almost completely full and the supply
reeIgnearly empty. It should also
provide sufficient braking to maintain
tapeltension and prohibit tape throw
whenthe control switch is turned to
'STOP" after the take-up reel has been
rotating at high speed during rewind.
The split knurled ring should be ad-
justed to provide the minimum clutch
friction to accomplish these two func-
tions.
OILI,NG THE CLUTCH FELTS:
--- The felt washers have been oil
treated at the factory to provide
the correct amount of slippage. It
may be necessary to give each felt
washer (supply spindle and take up
spindle) one drop of high quality sew-
ing machine'oil after several months
of use. .
-e .
CAUTION:
()0 NOT OVER-OIL THE CLUTCH FELTS
AS THIS MAY CAUSE OIL TO BE THROWN
ON NEARBY IDLERS CAUSING SLIPPAGE
IN THE DRIVE SYSTEM, ONE DROP PER
FELT IS SUFFICIENT.)
PT6-A INSTRUCTION MANUAL

CLEANING THE HEADS:
It is necessary that the portions
of the er'ase head and the record-re-
produce head wh ich come into contact
with the tare be kept free of dust,
grease and foreign matter, or the
f requency response character i sti cs
will suffer. They should be cleaned
with ,a •soft cloth si ightly moistened
with carbon tetrachloride C. P. after
every five hours of operation.
Note: Do not attempt to apply
carbon tetrachloride to any part of
the PT6 -A when loaded reels are in
place as the tape is sol uble in car-
bon tetrachloride and , wi 11 be ru ined
if it comes in contact' with the sol u-
tion. After using carbon tetrachloride
E121156
2
em4s.ris e/vo.
fr O5C/L1,77 - 0,e UAW"
make sure the heads are completely dry
before threading tape and be svre none
of the solution is transferred to the
tape from the fingers.
H. EAC REPLACEMENT:
‘11b,
'Replacement erase'or record-re-
Produce heads may be obtained from the
distributor 'from whom the unit was
purchased provided the worn heads are
returned at the same time.
GUARANTEE:
The Magnec ord PT6- A is guaranteed
to be free of defects in workmansh iP
and materials (excepting tubes) for a
period of 90 days from date of purchase.
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Pressure Roller -
The pressure roller (15), which is actuated by con-
trol knob (44) through the me dia of switch control
shaft (40) and pressure roller pivot bracket (32),
keeps a positive pressure against the tape and capstan
to aid in maintaining the constant rate of tape travel.
Hi-Speed Forward -
The Hi-Speed Forward is put into operation by press-
ing the Hi-Speed Forward control knob (16), which,
in turn, actuates control shaft and wire (59), pivot
arm and wire (69), and the fast forward wheel mount-
ing bracket (72). This pulls the fast forward wheel
(73) into contact with the motor drive shaft and the
take-up hub and tube (20). Simultaneously, pivot arm
.(69) moves against the fast forward actuating switch
(79), starting the main drive motor (75).
Rewind System -
When control knob (44) is placed in "Rewind", rewind
witch (80) is actuated starting the rewind motor (46).
A DC operated solenoid is also energized during
rewind, which pulls the forward idler wheel (65) away
from the take-up hub (22), allowing the ball-bearing
mounted take-up shaft (18) to turn freely. When the
rewind operation is completed, and control knob (44)
is returned to the "Stop" position, the solenoid is de-
energized. This allows the forward idler wheel (65)
to contact the take-up hub (22) applying a braking force,
sufficient to stop the reel.
The pone-way" pawl actuated clutch on the rear shaft
extension of the rewind motor (46), operates in such
a manner so that as the tape is unwound from the re-
wind spindle (2), a certain' amount of drag is imparted
to the mot or shaft which is then transmitted to the
tape as tension. When rewinding, the pawl is disen-
gaged from the ratchet disc (52) by the direction / sen-
sitive rewind pawl spring (53) which allows the motor
shaft to turn freely. A rapid rewind results.
Take-up System -
The take-up system is driven by the main drive motor
Figure 2
(75) through two rubber-tired idler wheels (61), which
are mounted on sliding suspension arm supports (60
and 63). Idler wheels (61) are held in contact with the
hub of the flywheel (33) and the forward motor shaft
(75) by action of springs (64 and 68). This, in turn,
drives the capstan (33A), which is secured to the fly-
wheel shaft and, with the use of pinch roller (15),
conveys the tape at a constant rate of speed.
The take-up shaft (18) is driven by the forward idler
wheel (65), which makes contact with the forward
motor shaft and the take-up hub (22). The take-up hub
(22) is concentrically mounted on the take-up shaft
(18) and is coupled to the shaft thr ough a slipping
assembly (20 thru 27) similar to that employed in the
rewind system. With tape properly threaded on the
recorder and the mechanism in "Forward", the take-
' up shaft (18) slips a certain amount due to the pressure
applied on the tape by the slower running capstan and
pressure roller. Consequently, the tension imparted
to the tape causes the tape to move from one reel to
the other without throwing or stalling.
ADJUSTMENTS
Head Alignment -
The primary purpose in head alignment is to provide
the maximum frequency response. For this purpose
it is not necessary to adjust the erase head.
NOTE: Before attempting to align the' record/repro-
duce head make certain that the difficulty is
not due to an accumulation of tape coating
residue on the pole surfaces.
Alignment of PT63 Series Heads -
The head cover is provided with two holes through
which a screw driver may be passed in order to
adjust the alignment screws. Furthermore, screws
provided with lock washer s will be found on the
bracket assembly which are used to lock the heads in
place once they have been aligned. Under no condition
should the plastic head cover be removed. The posi-
• Page 3

Figure 3
tion of this cover seriously affects the alignment.
Using alignment tape, the following procedure should
be followed:
1. Loosen the locking screws on the bottom of
both record and playback head assemblies.
2. Running the alignment tape over the assem-
bly on "Playback" determines meter reading of the
maximum output. It is not necessary, or desirable
at this step, that the head be adjusted for maximum
output, as will be seen later.
3. Back off on the alignment screws until the
playback head is definitely out of alignment. Be sure
that backing off on the alignment screws actually
allows the head assembly to turn.
4. Lock the playback he ad assembly in place
as in Step 3 by means of the locking screw.
5. With the alignment screw bring the playback
head into alignment as noted by the maximum output
determined in Step 2.
NOTE: If the alignment screw is turned too far, it will
be necessary to repeat Steps 1 through 5.
6. Remove the alignment tape and insert a
blank tape which may be used for recording.
7. Repeat Steps 1 through 5 with the unit on
"Record" using a frequency similar to that on the
alignment tape. Align the record head accordingly.
Alignment of PT6 Series Head -
I.. The right mounting screw of the record- re-
produce head is drawn up securely. This side of the
head holder is provided with a rocker action. The
left adjustment screw (12) is associated with a com-
pression spring. Rotating this screw changes the gap
alignment with respect to the tape. Proper alignment
is achieved when the maximum signal, at a given
setting of the gain control is reproduced from the
alignment tape, as the alignment screw (12) is turned
in or out.
Rewind Drag Adjustment -
Adjustments to this friction drag system are mea-
sured by means of a 0 to 1 pound spring scale on one
end of a string wound several times around the hub
of a 7" reel mounted in the normal manner on the re-
wind hub._ Since the drag is being measured, the
string should be wound on the reel to lead off in a
clockwise direction and the spring scale should be
pulled slowly upward against the friction drag. When
properly adjusted, it should take about 4 to 5 ounces
to rotate the reel.
Readjust by loosening the socket head set screw (58)
in the knurled split nut (57). Then rotate this nut,
lock the nut with the set screw after each adjustment
and before measuring the result.
Take-up Torque Adjustment -
The torque transmitted to the take-up shaft should be
measured in a similar manner to that described above
under "Rewind Drag Adjustment". With the spring
scale pulling the string vertically upward, with power
on and recorder running forward, a reading of 4 to 5
ounces should be obtained.
The amount of torque is determined by the amount of
pressure exerted on the take-up friction whe el (22)
by friction felts (21 and 23). Tightening knurled-split
nut (26) increases the torque. Always loosen éet
screw (27) in the split nut before adjusting and re-
tighten before running or measuring.
Solenoid Adjustment -
Solenoid (36) which is energized during rewind, should
Page 4

fClo
SEE HEAD
ASSEMBLY
A PHOTOFACT "EXPLODED" VIEW
© Howard W. Sams & Co., Inc. 1953
65
66
67
68
69)
HEAD ASSEMBLY
FOR PT 63
PT6 ERASE L RECORD HEADS
Page 5

Figure 4
pull against spring (67) and lift idler wheel (65) away
from the forward motor shaft by 1/16", but maintain
contact between idler wheel (65) and the take-up shaft.
When the mechanism is switched from "Rewind" to
"Stop" and the solenoid relaxes, spring (67) returns
idler wheel (65) to contact with the forward motor
shaft. This shaft is not turning and in turn, idler
wheel (65) is prevented from turning and thus stops
the free rotation of drive wheel (22) which acts as a
brake on the take- , up shaft.
Solenoid (36) should be positioned so as to accomplish
the above results. The solenoid is mounted by means
of two screws in slotted holes in the back panel above
the forward drive motor. Care should be taken that,
when readjusting the solenoid, the plunger does not
bind within the tube. To check this, place the re-
corder with its panel horizontal (reel shafts vertical)
and operate the control knob (with power applied to
mechanism) between "Rewind" and "Stop". Return
spring (67) has adequate tension to return idler
wheel (65) to its normal position when there is no
binding of the solenoid plunger.
CLEANING
The head assemblies, capstan and pressure roller
are subject to an accumulation of tape coating residue,
which is worn off the tape as it passes these parts.
Use a soft cloth dipped in carbon tetrachloride to clean
the head surfaces, capstan, and pressure roller.
NOTE; The binder in the tape is soluble in carbon
tetrachloride. Therefore, have the tape off
of the machine when cleaning the heads; and
be sure that all surfaces are dry of this
cleaner before rethreading the tape.
CAUTION:Do not use a brush when cleaning the heads
as this could possibly mar the pole
surfaces.
LUBRICATION
1. Most moving parts in this recorder are
""reenfew.r — "-z1fflit
. located in "Oilite" bearings, which retain oil over
long periods of time. The "Oilite" bearings are kept
oil damp by felt pad wicks. The wicks should be
oiled, not the shafts or bearings themselves.
CAUTION:Do Not over-oil. Any excess oil seeps to
the outer edges of the moving parts causing
slippage in the drive mechanism. Should
this ever occur, wipe off all parts thus
affected with a clean soft cloth which has
been dipped in carbon tetrachloride. The
drive surfaces must be dry of oil to func-
tion properly.
(a) Forward Drive Motor
Two dr op s SAE #20 oil, front and back bearings
every six months.
(b) Capstan Shaft Bearings
Two drops SAE #20 oil, front and back bearings every
« six months.
(c) Pressure Roller and
Tape Guide Roller Shafts
Two drops of Finoil on each shaft, once a month.
CAUTION:It is important that there be no excess on
these bearings, or it will be deposited on
the tape.
(d) Idler Wheels
Equipped with felt washer at hub. One drop of SAE
#20 oil on felt washer every six months.
(e) Rewind and Take-up Clutch
Do not oil unless clutches begin to squeak; then one
or two drops of oil on each of two felt pads.
Page 6

Figure 5
--14 3
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—18 IF— ,
.—o-1-110 91
112 6 111
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28.5v 1
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34
214
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®
4 a,
'I -
2 85V
8
A-75V
2214
250
50
e 2
o'
e"
es
e 6
e7
FORWARD
V
Lep
REWIND
THE COOPERATION OF THE MANUFACTURER OF THIS
EQUIPMENT MAKES IT POSSIBLE TO BRING YOU THIS SERVICE
TO ERASE HEAD
FORWARD MOTOR
A PHOTOFACT STANDARD NOTATION SCHEMATIC
©Howard W. Sams 8, Co., Inc. 1053
PMSTANCE KAINVOS
CT
Rege
TO RECORD READ
TO AMP. UNIT
Tuba FRI I Ma 14.3 RI 4 FM M 117 R. à RI 9
Y I ow°,
T MEASURED FROM PIN 4 OF POWER PLUG AIM WITH CONTROL SWITCH IN FORWARD POSITION
VOLTAGE MEASUREMENTS TAKEN IN "RECORD .. POSITION.
32ND TO MT
111F T 511 RSKD NT
AM; ° UNIT
REPRODUCE
HEAD
FOR MEA ?LIT C JI N gERTÉg NS
ELECTRICAL PARTS LIST
Ref.
No.
Part
No.
Description
Ref.
No.
Part
No. Description
VI
12AU7, Oscillator C8 Fixed Trimmer, 2500 mmf. C) 500 V
Cl
Solenoid Filter, 4 mfd, C)250 V C9
Indicator Coupling, 50 mmf.C)500 V
C2
Motor Starting, 4 mfd. C) 330 V CIO
Indicator Coupling, 50 mmf. C) 500 V
C3 Audio Coupling, 5 mfd. C)600 V
C4
.
Bias Oscillator Grid, 2000 mmf.
RI Oscillator Grid, 221Q -4 1/2 W
C) 500 V
R2 Oscillator Grid, 22Kn, 1/2 W
C5 Bias Oscillator Grid, 2000 mmf.
R3
Isolation, 10Kit, 1/2 W
C6
® 500 V
Chassis Isolation, .01 mfd. C) 400 V
R4 .
Ll
Surge Limiter, 470, 1/2 W
,
Bias Oscillator Coil
C7 Bias Oscillator Decoupling, .1 mfd.
C) 400 V
M1
,
Selenium Rectifier .
Page 7‘

MECHANICAL PARTS LIST
Ref.
No.
Part
No.
Description ,
Ref.
No.
Part
No.
Description
1
91A5 Reel
Retainer, Knob and Spring
42
91A31
Safety Shaft
2
91A82
Rewind Flange Assernbly
43
77A6
Tension Springs for Pressure
3
71D1
Panel, Only
Roller Pivot Bracket
3A
CARRYING HANDLE
ASSEMBLY
44
87A15
Control Knob
78A7
Chromeplated Handle
45
75A67
Mounting Spacers
77A1
Handle Spring
46
91B83
Rewind Motor Assembly
67X1
Handle Spring Cotter
Pin 47
91A45
Rewind Pawl and Pawl Bracket
63X14
Handle Spring Washer
48
6110B6S
Motor Mounting Screws
4
614B5
4-40 x 5/16" Roller Mounting
(Supplied with Motor)
Screw
49
91A43
Rewind Hub and Tube Assembly
5
63A5
Tape Roller Washer
50
63A9
Friction Felt
6
91A9
Tape Guide Roller Assembly
51
74A70
Bushing
7
76A8
Guide Roller Shaft 52
75A86
Ratchet Disc
8
75All
Spacer
53
77A2
Rewind Pawl Spring
9
91A17
Erase Head for PT6
54
63A9
Friction Felt
9A
91A205
Erase Head for PT63
(See #78)
55
63A10
Brass Washer
10
91A13
Recording Indicator plus
56
63All
Rubber Pressure Disc
Lead Wires 57
75A70
Knurled Adjusting Nut
11 91A18
Head Shield for PT6
58
61CS8
Adjusting Screw
11A 91A112
Record Head Shield for
PT63
59
91A379
Fast-Forward Control Shaft and
11B
91A111
Reproduce Head Shield for PT63
.
Wire (See Item #69)
12
612F12
Mounting Screw 2/56 x 3/A
60 91A26
Drive Puck Mounting Bracket
Fillister Head
.
Assembly
13 91A57
Record-Reproduce Head for PT6
61
91A86
Drive Puck Wheel 2-1/2"
13A 91A187
Record Head for PT63 (See #78)
62 71D40
Back Panel
13B 91A188
Reproduce Head for PT63 (See #78)
63 91A28
Drive Puck Mounting Bracket
14
614K5
Knurled Retainer Screw
for .
Assembly
Pressure Rollers
64
77A4
Tension Spring for Drive Puck
14A
614K6
Knurled Retainer ScrIw
Capstans
for
•
(Some Models Use Two Springs
in this Application. )
15
91A14
60 Cycle Pressure Roller 7-1/2"/ 65 91A130
Forward Idler Wheel
Sec. (Std. Equipment)
66
91A27
Forward Idler Wheel Bracket
91A15
60 Cycle Pressure Roller 15"/ and Solenoid Plunger
Sec. (Std. Equipment) 67 77A4
Tension Spring (For Item #65)
91A19
50 Cycle Pressure Roller 7-1/ 2"/ 68 77A4
Tension Spring (For Item #63)
Sec. (Special Order)
(Some Models Use Two Springs '
91A20
50 Cycle Pressure Roller 15"/
in this Application)
Sec. (Special Order) 1
FOLLOWING NOT SOLD SEPARATELY
16 87A4
Fast-Forward Control Knob
ORDER COMPLETE 93C3 ASSEMBLY
17
75A37
Fast-Forward Control Shaft
69
Fast-Forward Pivot Arm
Bearing ,
70
Mounting Bracket for Pivot Shaft
18
91A53
Take-up Shaft Assembly (Includes
71
Main Support Bracket
—
Items #19 through #27)
72
Fast-Forward Wheel Mounting
19
91A52
Bearing Housing
Bracket
20
91A36
Take-up Hub and Tube
73
91A85
Fast-Forward Drive Wheel 2-1/z"
21
63A9
Friction Felts
74 77A35
Tension Spring Fast-Forward
22
91A35
(Includes Items #20 through #27)
75 35B5
Main Drive Motor (1800 rpm)
23
63A9
Friction Felts
22A2
4mf. Condenser for 1800.rmp
24
63A10
Brass Washer
Motor (Not Shown)
25
63All
Rubber Pressure Disc i
75
35S2
2-Speed Motor (900-1800 rmp)
26
75A70
Knurled Adjusting Nut
22X8
6mf. Condenser for 2-Speed Drive
27
618C58
8-32 x 1/2" Adjusting
crew
Motor (Not Shown)
28
63X34
Internal Tooth Lock Washer
76
91A39
Thrust Housing
29
62-43H20
Loclçnut for Item 17
77
91A30
Switch Control Arm and Pin
30
74A21
Capstan Shaft Bearing
78 91A121
PT63 THREE HEAD ASSEMBLY
31
63A8
Felt Pad and Bearing
Retainer
(Heads Not Sold Separately)
(78A22)
91A205
Erase Head (PT63)
32
91All
Complete Pressure Arm
Assembly
91A187
Record Head (PT63) -
32A
74A13
Roller for Pivot Bracket
91A188
Reproduce Head (PT63) ' '
33
91Al2
Capstan Shaft Assembly
79
Fast Forward Switch
34
78X28
Ball Bearing
80
Rewind Switch
35
78A22
Bearing Retainer
81
Forward Switch
35A
36
624E4
31S1
4/ 40 Elastic Stop
Solenoid (Less Plunger)
CAPSTANS (NOT SHOWN IN EXPLODED VIEW)
37 74A21
Capstan Shaft Bearing
75A15
15"/ Sec. Capstan for 60 Cycle AC
38 63A8
Felt Pad
75A16
7-1/ 2" Sec. Capstan for 60 Cycle AC
39
67X13
Tru-Arc Retaining Ring
75A21
15"/ Sec. Capstan for 50 Cycle AC
40 91A32
Switch Control Shaft
75A22
7-1/2"/ Sec. Capstan for
41
77A1
Spring for Safety Shaft
50 Cycle AC
:MC

P HOTOFACT* Folder
_
ente r MAGNECORD MODELS ,
PT6-A, AH, AHX, AX, PT63-A, AH, AHX, AX
Figure 1
GENERAL INFORMATION
The Magnecord PT6 Series and PT63 Series Tape Recorders are mechanically similar. The
PT6 Series is designed for use with the amplifiers and other units of the PT6 Series while the
PT63 Séries recorder mechanism is designed for use with all PT63 or PT? Magnecord ampli-
fiers. Other variations are as follows:
.1"
PT6-A. Basic recorder in portable carrying case. * Includes 15" and 7-1/2" per second
capstans pressure rollers, four mounting bolts, oscillator tube, one empty reel and no
connector cables.
case.
PT6-AX. Same as above, less case.
PT6-AH. Same as PT6-A, plus Hi-Speed Forward for fast cue ing in. Complete with
PT6-AHX. Same as above, less case.
•
PT63 -A. Same as PT6-A, but has t three heads for.monitoring from the tape. Separate
erase, record and playback heads, • •••
11 •+ .; 4 4: •
PT63-AX. Same as above, less•case.
PT63-AH. Same as PT63-A, plus Hi-Speed Forward.
•
PT63-AHX. Same as above, less c'ase - .. 24 -
. • • ,.
.; •
These units derive their power from the .e ,Magnecord Amplifier used - 117 volt, 60 cycle (or 50
cycle) AC.
Manufactured by:
Magnecord Incorporated
Sales Office: 360 North Michigan Avenue
Chicago 1, Illinois
Plant: 225 West Ohio Street
Chicago 10, Illinois
This material compiled and published by
HOWARD W. SAMS & CO., INC., INDIANAPOLIS, INDIANA
Copyright 1953 • All Rights Reserved
•
DATE 1-53 SET 190 FOLDER 6

•••t• •
Speed Change -
Two sets of capstan-pressure r oiler combinations
are furnished with each unit; the large capstan and
small pressure roller provide for 15" per 'second tape
speed and the small capstan and large pressure roller
for 7-1/2" per second tape speed, using the - standard
1800 rpm motor.
If the recorder mechanism is provided with a two-
speed m ot or (900-1800 rmp) the larger capstan and
smaller pressure roller may be used for 15" and
7-1/2" per second, while the smaller capstan and
larger pressure roller are used for 3-3/4" and
7-1/2" per second tape speed.
NOTE: When changing speeds, if an equalizer switch
is not provided on the amplifier being used, it
will be necessary to change equalizers in the
amplifier accordingly. •
OPERATING INSTRUCTIONS
1 Insert the power cord into a receptacle of
the proper rating.
2. Set control knob (44) in the "Stop" position.
3. Before a reel of tape can be placed on the
spindle, reel retaining knob (1) must be removed To
remove the reel knob, push it in and turn counter-
clockwise to release the bayonet pin.
4. Place an empty reel on the right (take-up)
spindle (18), and replace the reel retaining knob.
5. Place a reel of tape on the left (rewind)
spindle (2).
NOTE: This recorder uses Type "A" wound tape i.e.
g tlie dull magnetic coated side faces inward. If
e the tapeito be used is Type "B" (coated side
.'facing outward), place the reel of tape on the
right (take-up) spindle (18) so that the tape will
lead off in a clockwise direction. Thread the
tape on to the left (rewind) spindle (2) as des-
cribed in paragraph "To Rewind". Place con-
trol knob (44) in "Rewind" and allow the full
reel of tape to wind on the empty reel. The
magnetic side of the tape will now be facing
inward.
6. Unwind about 18" of tape and thread it
through the normal tape path of the recorder.
7 Insert the end of the tape in one of the radial
slots of the take-up reel and wind at least two full
turns of tape on to the reel.
To Make a Recording -
1. Turn power switch, on amplifier being used,
to "On" This provides the necessary power for both
amplifier and recorder mechanism.
2. Place the "Play -Record" control on the
amplifier in "Record" position.
3. De-press safety button (42) and, simultane-
ously, turn control knob (44) to "Forward". This
sets the tape in motion.
4. The red bias indicator will glow when the
oscillator is operating properly. This indicates a
new recording is-being -made and any previous record-
ing on the tape will be erased.
5. When the recording is completed, turn con-
trol knob (44) to "Stop".
To Rewind a Tape -
I. Before rewinding, lift the tape clear of the
pole surfaces on the record/playback head and place
it on top of the head shield (11). This prevents excess-
ive wear of the pole surfaces during the rewind opera-
tion. The balance of the tape may remain in its nor-
mal path.
2 The tape may be 'rewound at any time by
placing control knob (44) in "Rewind"
3. Control knob (44) may be turned to"Stop"
at any time without danger of tape spillage. These
units will rewind 1200 feet of tape (7" reel) in less
than forty seconds.
CAUTION:W h e n switching ft om "Rewind" to "For-
ward", always pauée in the "Stop" position
long enough for the, tape to come to a com-
plate stop. Failure to do so will result in
tape breakage due o the tight grip the cap-
stan and pressure roller exert on the tape
when control kn,:.1 b (44) is in "Forward"
position.
To Playback a Tape -
NOTE: A PT63 three head assembly contains both a
record head and a eproduce head. They
should be used for these functions alone. (In
PT6 units the head may be used for record or
playback as necessary. )
1. Place the "Play-R l ecord" control on the
amplifier in "play" position. U this is not done, the
tape will be erased when set in forward motion.
It I
2. De-press safety button (42) and place con-
trol ) knob (44) in "Forward" p sition.
3. Adjust volume and tpne controls to suit.
Hi-Speed Forward -
On units so equipped, the Hi-peed Forward mechan-
ism is actuated by de-pressing control knob (16). In
this position, the tape is driven at a rate of four times
the normal capstan or drive, speed. It permits fast
cue ing or editing of any recorded tape. Since the
Hi-Speed Forward mechanisrn is spring loaded, the
farther down control knob (16 1) is pressed, the faster
the Hi-Speed Forward action. I
MECHANICAL oppRATION
Flywheel and Capstan -
The balanced flywheel and capstan (33)., which is
driven by two rubber-tired wheels (61), provide a
constant speed for the tape.
Page 2