Wirecorder Corp. PA Schematic

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Product Information:
Model:PA
Manufacturer:Wirecorder Corp.

Schematics Content:

Page 1:

The Model PA WiRecorder is a precision-built, professional type high fidelity magnetic recorder-reproducer unit for adaptation to any " public address " type amplifier.

The amplifier with which the Model PA WiRecorder is used should have an overall gain of not less than 100 db. Less than one watt of power is required for recording. Hence the power output of the amplifier is not important.

An advanced design in the wire recorder field, the Model PA is capable of continuous recording or playback for a period of 65 minutes, and spoole may be changed at any time, without rewinding, in a matter of seconds.

It is EXTREMELY IMPORTANT that the owner familiarize himself with the operational instructions contained In this manual.
TO UNPACK WARNING: The Model PA WIRecorder is shipped with special packing devices to insure safe de llvery. The unit cannot be operated until these precautionary devices are detached from the mechanism.

First, remove the WiRecorder from the cabinet by removing the four chassis screws from the bottom, and the two panel screws from the upper left and upper right hand corners of the front panel. Now, by grasping the large WIRE CONTROL knob from the front, and pushing the chassis from the rear the unit will slide forward from the front of the cabinet.

Now, referring to Figure 3, a rear view of the chassis and Wi Recorder shows the retaining wire 29, and the two separator blocks 27 and 31 all of which must be carefully removed. The wire should be severed with wire cutters, and withdrawn, and the two small blocks pulled out. Care should be taken in this operation to guard against forcing the two rear clutches against the left and right brake arma, and thus bending them.

Next the WIRE CONTROL knob must be removed, using the ALLAN WRENCH which will be found attached to the inside of the front cover of the cabinet. Reference to Figure 4 will show fiber coller 32 behind this control knob which must now be removed, and the WIRE CONTROL knob replaced securely on the shaft.

Screws 28 and 30 must now be removed, and the large washer under each screw discarded. screws themselves should then be replaced.

The removal of the washers and the fiber collar permits the W1 Recorder to float freely on the four shock mounts, dampening vibration.

Before replacing the unit in the cabinet it is advisable to actually operate the mechanism with the wire spools in place.
HANDLING AND APPLYING THE SPOOLS One set of spools, containing some 7500 feet of. 004 " stainless steel recording wire sufficient for more than one hour of continuous recording or playback, is included with each Model PA WiRecorder, and will be found packed in an individual container.

Note that the recording wire is attached to both spools and will remain so except in event of mishandling or accidental wire breakage. An automatic trip trigger on the rear flange of both spools stops the mechanism before the wire leaves either spool.

To apply the spools to the two shafts, first lift the front guide wire extending below the recording head. This wire is hinged at the head and will swing upward with the application of slight pressure at the bottom of the wire.

Now place the full spool on the left shaft and the nearly empty spool on the right shaft, pushing both spools firmly against the locking springs until they snap into position.

KEEP WIRE STRETCHED TIGHTLY BETWEEN SPOOLS DURING THIS PROCEDURE. ALWAYS MAKE SURE WIRE IS STRETCHED TIGHTLY BETWEEN THE TWO SPOOLS BEFORE STARTING WIRECORDER EITHER IN FORWARD OR REWIND. Any slack should be removed manually by turning either spool counter-clockwise.
With the spools securely in place the hinged wire guide may now be swung downward, and snapped into place against the rear guide, with the recording wire held between them.
MECHANICAL OPERATION Forward and reverse travel of the wire is controlled by the single large knob marked " Wire Control. "
To start the wire moving forward (from left to right) for recording or playback, first make sure power switch is " on ". Now turn wire control. knob clockwise until it locks in position. Note that the wire has been lifted into the recording head by the neoprene pinch idler and by the guide arm to the right of the head, and the motor turned on.

To stop the motion of the wire, merely press the red button marked " Stop ".. Now, to rewind, turn wire control kob counter-clockwise until it locks in position.

WARNING: In going from " forward " to " rewind " or vice versa or to stop wire motion, STOP button MUST be pushed before turning wire control knob to new position.
AUTOMATIC STOP The specially designed WiRecorder spools include an automatic trip trigger which stops the wire before it leaves either spool, either in forward or rewind. Thus threading or handling of the wire is unnecessary at any time.

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BRAKE ACTION With the WiRecorder removed from the cabinet, note the mechanical operation of the patented " Magneflo " clutches at the rear of each spool shaft,

If the adjustment of brake arms 12 and 13 (figure 1) has not been disturbed in the process of removing the special shipping devices, the following action will be posted:

When the wire is moving forward, for recording or playback, the entire clutch assembly and shaft 6 (figure 1) is swung against brake arm 12, stopping rotation of outer clutch hub 25 (figure 2.)

When the wire is rewinding the clutch assembly and shaft ? (figure 1) is swung against brake arm 13, stopping rotation of outer clutch hub 16.

If these brakes are operating as described, the wit may be replaced in the cabinet and is ready for service. If slippage of the clutch hubs is taking place, reference to brake adjustment in the serviciog section of this manual will indicate the remedy.
CONNECTIONS TO AMPLIFIER Two simple connections to any standard public address type amplifier are all that is required. In addition to the power cord extending from the rear of the Model PA chassis, two other cables will be found. One, a shielded cable terminated with a female Amphenol connector, is to be connected to the high impedance microphone input of the amplifier. The other, & twisted pair, must be connected to the voice coil output of the amplifier at any impedance between 3.2 and. 16 ohms. The black lead should be connected to the grounded side of the output on the amplifier.

The speaker itself is to be disconnected from the amplifier, and plugged into the phone jack at the rear of the Model PA chassis.

Likewise, a high impedance microphone for voice recording is to be connected to the Model PA chassis, using the Amphenol male connector provided.

A feed from a record turntable or radio may be connected in normal fashion through the phonoh channel of the amplifier itself.
RECORDING PROCEDURE To make a wire recording on the Model PA, the following steps must be taken:

1. Turn selector switch at lower left hand corner of panel to " record " position.

Ad just volume control on public address amplifier until level indicator neon light flashes on peaks. NOTE: Best results will be obtained with a minimum of flash. Constant flashing indicates too much volume. Amplifier tone controls should be set at " flat " position, with no treble or bass boost, or attenuation.

3. Turn wire control clockwise to a locking position, thus starting wire forward. You are now recording.
TIME INDEX The time scale across the top of the panel is calibrated in minutes. With a full spool on the left and the index set at zero, the time scale will indicate the length of each recording. As the wire is rewound, the indicator motion is reversed thus making it easy to return to any desired spot in & recording.

The indicator carriage is movable manually along the feed screw by twisting the carriage knob slightly to the right or left and sliding. This is of special advantage when changing spools.
PLAYBACK PROCEDURE To play back & wire recording, the following steps must be taken: 1. Having completed the recording, the STOP button must be pushed. The wire must now be rewound to the start of the recording. Turn wire control knob counter clockwise to a locking position, and watch time indicator for rewind to proper spot in wire.

Push stop button.

Turn selector switch at lower left hand corner to " Listen ".

Turn wire control knob clockwise to locking position, thus starting wire forward.

5. adjust volume of playback with volume control on the public address amplifier.
Any tone controls on the amplifier may also be adjusted to suit the listener's ear.
OPERATING SUGGESTIONS Always make sure wire is taut between two spools before turning wire control knob.
If wire is loose turn either spool counter-clockwise by hand to remove slack.

Is going from " forward " to " rewind or to stop unit, STOP button must be pushed before wire control knob is turned to new position.

When turning wire control knob clockwise into recording or playback position, too rapid a motion is not advisable. Smooth, even, turning pressure will assure positive action.

Always allow spools to come to a full stop before turning wire control to new position.

When new spools and wire are placed on your WiRecorder for the first time it is advisable to run the entire hour spool through a complete cycle (forward and rewind) to " phase " the wire for best level winding action.

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SHELF LIFE OF WIRE RECORDINGS Wire recordings made on the Model PA may be stored indefinitely without loss of magnetism in the wire, Or, wire recordings may be played back thousands of times without appreciable wear, loss in quality or change in background noise.

It is entirely practical to " edit " wire recordings just as one might edit home movie film, taking portions from one spool and adding to another. Empty spools are available for this purpose, And wire may be spliced at will simply by tying an ordinary square knot to secure the ends. DO NOT USE HEAT ag this weakens the wire. Ends of the wire should be cut off as close to the knot ag possible.
SERVICING The following service information covers such adjustments and lubrication recommendations that may easily be taken care of by the owner of the Model PA WiRecorder.

In event of major repair or adjustments not covered in these pages it is advisable to return the unit to the factory.
LUBRICATION Oilite bearings throughout the Model PA WiRecorder make frequent lubrication unnecessary and undesirable.

011 wicks adjacent to these bearings may be lubricated every 100 hours, with a light machine oil. USE OIL SPARINGLY. In addition to the oil wicks readily visible from the top of the WiRecorder, the following points may be lubricated:

Shaft bearings behind spools. Remove spools and apply one drop of oil to each bearing.

Neoprene idler bearing. (3, Fig. 1). Remove idler retaining screw, slip idler from bearing and apply one drop of light oil. Great care must be taken to guard against oil creeping to surface of this idler.

Apply small amount of vaseline.

Worm gear on right hand shaft, fiber gear and heart cam.

Motor. Apply one drop through ducts, front and rear, appearing at top of casing.

Use vaseline.

Time indicator feed screw and end bearings.

WARNING: Oil on any of the driving surfaces, such as the clutch hubs, the rear drive wheel, the front drive wheel, the neoprene idler, or capstan roller (5), capstan flenge (10) or felt brake pads will cause serious slippage, resulting in varying wire speed. Oil creepage caused by centrifugal force or capillary action should be guarded against, and all driving surfaces kept clean,
LEVEL WIND ADJUSTMENT In event of uneven level wind either in " forward " or " rewind " position, the recording head should first be checked. The head may have become bent with relation to the brass drive shaft. If it is not at right angles to this shaft from all positions, it may be straightened by light finger pressure If this fails to rectify the level wind trouble the spool shafts may have to be moved forward or backward. To move these shafts a single # 8 Allan wrench is required to loosen the set screws in clutch hubs 23 and 24, figure 1.

When set screws have been loosened, ends of shafts may be tapped lightly for placement.
BRAKE ADJUSTMENT If the brake action as described on page 2 is not functioning properly, the following adjustments may be made:

With the wire moving forward (in record or playback position) note that the right hand clutch assembly 16, figure 2, remains in contact with rear drive wheel ll, while the left hand clutch assembly 25 is swung against felt-padded brake arm 12. In this position brake arm 12 should be adjusted by mears of two adjustment screws on the rear of the base so that it exerts just enough pres sure on clutch hub 25 to stop rotation and thus furnish the proper amount of drag to stop wire whip,

Now set the wire control in rewind position. Note that clutch assembly 25 is in contact with the rear drive-wheel, while right hand clutch assembly 16 1s swung away, bearing against brake arm 13. In this position brake arm 13 should be adjusted to give just enough braking pressure to stop rotation.

IMPORTANT: Brake pressures should always be set at a minimum to stop rotation of the hub against which they are bearing.
CAPTAN FLANGE BRAKE ADJUSTMENT When the WiRecorder is in STOP or REWIND position, the capstan flange in is pushed away from front drive puck 9, braking against arm 2 to stop rotation of the flange. This brake arm is adjustable by means of screws 22. IT MUST NOT contact the flange when the unit is moving the wire forward for recording or playback.
AUTOMATIC SHUT - OFF LEVERS Immediately below the wire spools will be found trip levers 14 and 15. These are actuated by trigger wires in the spools themselves, released as the last layer of wire begins to unwind.

If the trigger wire from the spool fails to hit the lever the automatic shut-off will fail. These levers may be bent into proper position with ordinary pliers if care is taken to avoid fracturing the metal.

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GUIDE ARM Guide arm 4, figure 1, has a specially treated smooth surface. It may show slight wear after many hours of use, causing the wire to slide across its surface irregularly. In this event the guide arm may be rotated a few degrees to expose a new surface to the wire.

CLEANING THE HEAD Dirt, dust, and wire lubricant sometimes collect in a recording head, resulting in loss in high frequencies and level. If the accumulation becomes too severe actual jamming of the wire may take place.

To clean the head quickly and easily, lift the front wire guide and run a small piece of stout silk or lined thread through the wire groove, back and forth several times. Dipping the thread in a cleaning fluid such as carbon tetrachloride may prove helpful.

NEOPRENE IDLER If lubricant from the wire collects on the neoprene idler 3, the idler may be removed and cleaned with soap and water.. NEVER use carbon tetrachloride, gasoline, benzine or other types of cleaning compound on this roller, as such products may be injurious to the neoprene.

Watch for excessive wear on this idler, apparent from roughness of the surface. For perfect speed control of the wire the idler surface must be smooth, free from dirt or pock marks.

CAPSTAN YOKE SPRING ADJUSTMENT The yoke supporting the capstan (5, figure 1) and capstan flange (10, figure 1) pivots on a bearing in the base, moving against drive puck 9 when the wire is moving forward, and against brake 21. when the wire is rewinding, or when the WiRecorder is shut off.
An adjustable spring on the left hand side of the base casting immediately below brake arm 21 controls the amount of pressure between the capstan flange 10, and the drive puck 9.

If th wire a tendency to " loop " between the recording head and the neoprene roller when the control knob is turned clockwise for recording or playback, this pressure may be too great.

On the other hand, if the pressure is too light the flange will slip on the drive puck thus failing to drive the wire at a constant speed of 2'per second, causing " wows ".

It should This spring adjustment is critical, and has been properly made before shipment. not be tempered with unless adjustment is absolutely necessary.

VOLUME INDICATOR ADJUSTMENT The volume indicator adjustment controlling the flash of the neon bulb is located on the right hand side of the chassis. Set at the factory, this adjustment is regulated to flash the neon bulb at peaks of. 3 of a volt, measured across the voice coil of the recording head, with the 50L6 Oscillator tube removed from its socket. The voice coil leads are the two right hand leads on the terminal strip on top of the motor, looking down on the unit.

ERASE VOLTAGE In event of incomplete erasure the voltage across the erase coil which is incorporated in the head itself should be measured. Erase coil leads are the two left hand leads on the terminal strip above the motor. This voltage should be between 3.5 and 4, measured with a vacuum tube voltmeter, and must be measured with the selector switch in record position. The frequency of the erase volt age is between 30 and 40 KC.

FREQUENCY RESPONSE The frequency response of the Model PA WiRecorder, when used with an amplifier capable of delivering flat response from 105 to 10,000 cycles for recording, and delivering in db of bass boost for playback, will be flat + 5 db from 100 to 6000 cycles.

The response curves off the wire with constant current input, equalizer curve and recommended amplifier playback curve are shown in Figure 6.

YARNING Before turning the selector switch to " record " position, make sure microphone volume control on amplifier is at a low setting. Incrcase volume control slowly until level indicator on Mi scorder flashes occasionally. Failure to follow this procediire may result in damage to recording head and level indicator.

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FIG. 3 - REAR VIEW MODEL PA WIRECORDER

FIG. 4 - SHIPPING WASHER INSERT FRONT PANEL

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FIG. 5 - WIRING DIAGRAM, MODEL PA WIRECORDER

FREQUENCY IN CYCLES PER SECOND

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