Magnecord PT6-6 Series Operating instructions

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Figure 1. RearView of TapeTransport.
GENERALINFORMATION
The ‘Magnecord” Model PT6-6A Tape Recorder
is designed for use with the “Magnecord” Amplifier
Model PT6-6J.
The “Magnecord” Model PT6-6A Tape Recorder
features Stop, Forward, Fast Forward, and Rewind
modes of operation by merely turning a knob. Play-
back or Record is selected by switch on PT6-6J
Amplifier. Any reel up to 7 inches can be used. New
recordings can be made on previously recorded tape,
since erase head is automatically connected when
switch on amplifier is in “Record” position.
Tape Speed Switch on PT6-6A will change speed
from 15 ips (FAST position) to 7 l/2 ips (SLOW posi-
tion) when 15 ips capstan and pressure roller (large
capstan and small pressure roller) are used. Speeds
will be 7 l/2 ips (FAST position) and 3 3/4 ips (SLOW
position) when 7 l/2 ips capstan and pressure roller
(small capstan and large pressure roller) are used.
SPECIFICATIONSPT6-6ATAPETRANSPORT
Tape Speeds - 3 3/4 ips, ‘7 l/2 ips, and 15 ips are
interchangeable with no tools required. Tape speed
selection is made by switch and/or change of capstan
and pressure roller.
Rewind Speed - 1200 ft. of tape (full ?-inch reel) re-
wound in 40 seconds.
Flutter - Less than 0.3%.
Tube - Bias Oscillator tube 12AU7.
Motors - 1500 RPM rewind motor. Hysteresis Syn-
chronous 2 speed, 900 RPM and 1800 RPM, drive
motor.
Frequency Response - 50to 7500 cps with tape speed
of 7 l/2 ips, 40 to 15,000 cps at tape speed of 15 ips.
SPECIFICATIONSPT6-JORPT6-6JAMPLIFIER
Frequency Response - 50 to 15KC, f 2 db equalized
for tape speeds of 7 l/2 and 15 ips. 3 3/4 and 7 l/2
ins equalizer available.
Input Level - Sensitivity -105 dbm for zero level re-
cording.
Maximum Level - 35 dbm.
Input Impedance - 50 or 250 ohms, balanced or un-
balanced. High impedance unbalanced bridge (Phone
Jack).
Noise - 65 millivolts maximum at 600-ohm output
(switch at “AMP”); 20 millivolts maximum at 600-
ohm output (switch at “PLAYBACK”). Ret-PB over-
all signal-to-noise ratio 50 db from 3% third harmonic
distortion point.
Total Harmonic Distortion -- Less than 2% with 10
watts output.
Output Impedance - 600 ohms balanced, 16 and 4 ohms.
Output -- 10 watts with less than 2% distortion.

Figure 2. View of Right Sideof TapeTransport.
Tubes - (1) Type 5879
(1) Type 12SJ7
(lj Type ~SL?
(2) Type 5881
(1) Type 5Y3
Dimensions - Amplifier; 8” deep, 7” high, 19” wide
without carrying case. 13” deep, 8” high, 20” wide
with carrying case. Transport Mechanism; ll”deep,
7” high, 19” wide without carrying case. 16” deep,
8” high, 20” wide with carrying case.
Weight - Amplifier; 20 lbs. without carrying case,
34 lbs. with carrying case. Transport mechanism;
26 lbs. without carrying case, 40 Ibs. with carrying
case.
INSTALLATION
PT6-6A and PT6-6J units may be mounted in
portable cases ‘or standard 19” racks without adapter
panels.
OPERATINGINSTRUCTIONS
PT6-6A motors and oscillator tube receive their
power through male Jones connector on rear of unit.
See schematic for terminal designation. This power
is supplied by Magnecorder PT6-6 Jamplifier. Female
Cannon connector on rear of PT6-6A is connected to
male Cannon connector on rear of PT6-6 Jamplifier by
an interconnecting cable. This cable couples Record-
Reproduce head of transport mechanism to the play-
back amplifier input in the playback mode, and couples
the output of the Record amplifier to the Record-
Reproduce head in the record mode.
1. Make sure oscillator tube located in rear and
at right side is secure in its socket.
2. Set control knob (30) to STOP.
3. Make sure correct capstan andpressure rol-
ler for desired speed and knurled retaining screws
are firmly in place. For speed and speed changts see
“General Information”, page 2. Make sure taper-
shaped capstan shaft is completely free from dirt or
foreign particles before installing capstan,
Threading the Tape
1. Before a reel of tape can be placed on spindle,
reel retaining knob (1) must be removed. To remove
reel knob, push in and turn counterclockwise to re-
lease bayonet pin.
2. Place empty reel on take-up spindle (36), and
replace reel retaining knob (1).
3. Place a reel of tape on rewind spindle (2),
withtape paying off in clockwise direction, and replace
reel retaining knob (1).
4. Pull off about 2 ft. of tape, thread over and
around top tape guide roller (23), then around lower
tape guide roller (9), over erase head (15), and Record-
Playback head (29), between capstan (33) and pressure
roller (35). Then thread on right hand empty reel.
Make sure oxide coating on tape is toward heads. See
illustration on front cover.
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Figure 3. BottomView of TapeTransport.
ToMakea Recording
1. Flip power switch, on amplifier being used,
to “ON”. This provides necessary power for both
amplifier and recorder mechanism.
2. Turn selector switch on amplifier to “Record”
position.
3. Push VU meter switch in to connect meter,
if PT6-6J amplifier is used with PT6-6A tape trans-
port mechanism.
4. For headphone monitoring, insert plug of
phones in amplifier front panel Monitor Jack. For
speaker monitoring, turn speaker volume control up
to desired position.
5. Vary volume level with Gain Control. Turn-
ing control clockwise increases amplifier gain. VU
meter should move with program material and should
read a peak value of “0” once every few seconds to a
minute, depending upon nature of program being
recorded.
6. To place tape transport mechanism in ‘Re-
cord” position, depress safety button (19) and simul-
taneously turn control knob (30) to “Forward”. This
sets tape in motion.
7. Red bias indicator will glow when oscillator
is operating properly. This indicates a new recording
is being made and previous recording on the tape will
be erased.
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8. When recording is completed, turn control
knob (30) to “STOP”.
To Rewinda Tape
1. To rewind tape, turn control knob (3) to
“Stop”, then place tape over guide roller (23) from reel
to reel. Turn control knob to “Rewind”. Rewind mech-
anism, driven by shaded-pole motor (102), will com-
pletely rewind 1200 ft. of tape (full ‘7” reel) in approxi-
mately 40 seconds.
2. Control knob (30) may be turned to ‘Stop”
anytime during rewind without danger of tape spilling.
3. To rewind tape without unthreading, tape
should be placed on top of Record-Reproducer head
shield. Be sure tape is returned to its normal position
on the heads before recording or reproducing.
Caution:
When switching from “Rewind” to “Forward”
always pause in “Stop” position long enough for tape
to come to a complete stop. Failure to do so will re-
sult in tape breakage due to tight grip which capstan and
pressure roller exert on tape when control knob (30)
is in “Forward” position.
To Playbacka Tape
1. Make interconnections and correct soeed as
described under “Operating Instructions” on page 3.
2. Set selector switch on amplifier (PT6-6J
amplifier) to “PLAYBACK” position.

Figure 4. TapeTransport with Front Panel Removed.
Pressure Roller
3. Turn speaker volume control clockwise; pull
meter switchout for “Off” if volume level on playback
makes it necessary to prevent meter damage. Pressure Roller (35), actuated by control knob
(30) through switch control shaft (93) and pressure
roller arm assembly (79), with the tension spring keeps
a positive pressure against tape and capstan, main-
taining constant rate of tape travel.
4. Depress safety button (19) and place control
knob (30) in “Forward” position.
Hi-SpeedForward
“Hi-Speed Forward”contro1 is theknob on right
side of front panel. This control will function only
with Main Control Knob in ‘Stop” position. To place
machine in ‘Hi-Speed Forward”, turn control to right
and hold. To stop machine, release control.
If you have rewound tape too far, turn Hi-Speed
Forward knob to reel tape rapidly forward until begin-
ning of recording is reached.
RecordingIndicator
Recording Indicator lamp will glow when plate
supply voltage is supplied to oscillator tube. This
indicates any previous recording on tape is being
erased and a new recording may be made.
MECHANICALOPERATION
Flywheeland Capstan
Balanced flywheel, drive hub and capstan shaft
assembly (83), driven by two rubber-tired wheels (67
and 70), provide constant speed for tape.
Hi-SpeedForward
Hi-Speed Forward is put into operation by rotat-
ing Hi-Speed Forward control knob (1’7A) in a clock-
wise direction. This, in turn, actuates control shaft
and wire (126), pivot arm (53), wire (52), and fast
forward wheel mounting bracket (50), pulling fast for-
ward wheel (56) into contact with drive motor shaft and
take-up hub (39). Simultaneously, pivot arm (53) moves
against fast forward actuating switch, starting main
drive motor (121).
Rewind System
When control knob (30) is placed in “Rewind”,
switch (125) is actuated, starting rewind motor (102).
A DC operated solenoid is also energized during re-
wind, pulling forward idler wheel (61) away from take-
up hub (41), allowing bearing mounted take-up shaft
(36) to turn freely. When rewind operation is com-
pleted, and control knob (30) returns to ‘Stop”position,
solenoid is de-energized. This allows forwsrd idler
wheel (61) to contact take-up hub (41), applying a
braking force sufficient to stop reel.
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Figure 5A. ExplodedView of Parts AboveFront Panel.
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Figure 5B. ExplodedView of Parts BelowFront Panel.
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Figure 5C. ExplodedView of Parts BelowBackPanel.
ADJUSTMENTS
The “one way” pawl-actuated clutch on rear
shaft extension of rewind motor (102) operates so that,
as tape is unwound from payoff spindle (2), a certain
amount of drag is imparted to motor shaft, which is
then transmitted to tape as tension. When rewinding,
pawlis disengaged from ratchet disc (111) by direction
sensitive rewind paw1 spring (llO), allowing motor
shaft to turn freely. A rapid rewind results.
HeadAlignment
1. The primary purpose in head alignment is to
provide maximum frequency response.
(NOTE: Before attempting to align record-reproduce
head, make certain difficulty is not due to an accumu-
lation of tape coating residue on pole surfaces.)
Drive System
The drive system is driven by main drive motor
(121) throughtwo rubber-tired idler wheels (67and 70),
mounted on sliding suspension arm supports (85 and
87). Idler wheels (67 and 70) are held in contact with
hub of flywheel assembly (83) and drive motor shaft
(121) by springs (71). This, in turn, drives capstan
(33), which is secured to flywheel shaft and, with
pressure roller (35) conveys tape at aconstant speed.
Take-UpSystem
Take-up shaft (36) is driven by forward idler
wheel (61), making contact with drive motor shaft and
take-up hub (41). Take-up hub (41) is concentrically
mounted on take-up shaft (36) and is coupled to the
shaft through a clutch assembly (39 thru 46) similar
to that in the rewind system. With tape properly
threaded on recorder and mechanism in “Forward”,
take.-up shaft (36) slips a certain amount due to pres-
sure applied on tape by slower running capstan and
pressure roller. Consequently, tension imparted to
tape causes tape to move from one reel to the other
without throwing or stalling.
2. The right mounting screw of the record -
reproduce head is drawn up securely. This side of
head holder is provided with a rocker action. Left
adjustment screw (14) is associated with a compres -
sion spring. Rotating this screw changes gap align-
ment with respect to tape. Proper alignment is
achieved when maximum signal, at a given setting of
the gain control, is reproduced from alignment tape,
as alignment screw (14) is turned in or out.
SolenoidAdjustments
The Plunger of Solenoid (72), energized during
rewind, should pull against springs (64) and lift idler
wheel (61) away from drive motor shaft by l/16”, but
maintain contact between idler wheel (61) and the
take-up wheel (41). When mechanism is switched from
“Rewind” to “Stop” the solenoid relaxes, spring (64)
returns idler wheel (61) into contact with drive motor
shaft. This shaft is not turning and in turn, idler wheel
(61) is prevented from turning: This stops free ro-
tafion of Take-up Wheel (41), acting as a brake on the
take-up shaft.
Solenoid (72) should be positioned to accomplish
the above. The solenoid is mounted by two screws in
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Figure 6. TopView of Bias Oscillator Chassis.
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Figure 7. BottomView of Bias Oscillator Chassis.
slotted holes in back panel above drive motor (121).
When readjusting solenoid, be careful plunger does not
bind within tube. To check this, place recorder in its
operating position and operate control knob (with power
applied to mechanism) between “Rewind” and ‘Stop”.
Return springs (64) should have enough tension to re-
turn idler wheel (61) to normal position when there
is no binding of solenoid plunger.
Clutch Adjustments
Tape tension is maintained by two friction
clutches. Their correct adjustment causes tape to
move from one reel to the other in either direction
without throwing tape or stalling and applies proper
tape tension for tape contact on heads.
1. Clutches are located on rear ends of supply
reel spindle (2) and take-up reel spindle (36). Supply
reel spindle clutch is located at right side (facing rear
of unit). It consists of a felt washer (112) lubricated
with silicone fluid pressing against a ratchet (ill),
free to rotate in a clockwise direction but prevented
from turning in opposite direction by a spring-loaded
paw1 (105). Pressing against opposite side of felt
washer is a brass washer (113) and a sponge rubber
washer (114). On the other side of the ratchet(ll1) is
a silicone lubricated felt washer (109) which also ex-
hibits a clutch effect. To remove complete friction
assembly, loosen screws (107) and (116) and slide
assembly off shaft. A split knurled adjustment lock-
nut (115) bears against sponge rubber washer (114)
and is loaded in place by a set screw (116). Set screw
must be backed off before adjusting locknut (115) can
be turned. Rotating adjustment locknut clockwise in-
creases clutch friction.
2. The supply reel spindle clutch adjustment
should maintain a drag as supply reel rotates when
recorder is in “Forward” operation. This drag should
be sufficient to stop supply reel without permitting
tape to loop, or to be thrown when control knob switch
is turned from “Forward” to “Stop”. The amount of
friction should be minimum necessary to accomplish
this, (3 to 4 inch ounces).
3. Too much clutch friction will increase tape
drag to a point where tape speed will cause flutter
and wow.
4. Take-up reel (36) friction clutch is located
on left side (facing the rear). This is similar in ap-
pearance to the other clutch but employs no pawl. It
is also necessary to back off set screw (46) before
adjusting this clutch. +.
5. Take-up reel spindle friction clutch couples
spindle to synchronous drive motor, when control knob ,
is set to “Forward”, and acts as a brake on take-up
reel when control knob is set to “Stop”. Clutch ad-
justment shouldprovide sufficient friction for take-up
reel to take up tape at normal speed forward when
take-up reel is almost completely full and supply
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