General Instruments Corp. 700R Schematic

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Product Information:
Model:700R
Manufacturer:General Instruments Corp.

Schematics Content:

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(C)John F. Rider
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___ __ __ __ __ _ _ RCD. CH, GEN 1Ns'r PAGE 195
GENERAL INSTRUMENT CORP. MODELS YOOF, 'ZOOR
All Series 700 Record Changers are of the single post, fully
automatic drop type, featuring single button control and eccen-
tric spindle cam record selection. The series 7OOR Record
Changer has the record support platform in the left rear corner.
Series 7OOF has the record support platform in the left front
OPERATION
Starting - when the switch Button (58-75096) is moved to the
ON position, power is connected to the Motor (56-75555)
causing the Turntable Assy. (66A74682) to rotate, and automatic
cycling, which is required to drop the first record, is accom-
plished by pulling the Switch Plate (lO-74368) in the direction
indicated by the arrow. When automatic cycling is started the
Manual Trip Lever (55-75102) is advanced until it contacts the
Cam Trip Lever (55A74B55) mounted on the Main Cam (45-75159)
which moved sufficiently to permit the spring loaded Pinion
Actuating Lever (55A748l5) to function, which, in turn, lifts
the floating brass Pinion Assy. (2BA75704) directly beneath the
spindle so that a projection on this floating Brass Pinion is
caused to engage a finger on the adjustable collar (65-75595)
fastened to the Turntable Hub.
The combination of the foregoing causes the turntable to become
connected with the Main Cam which through its single revolution
performs all of the required change cycle functions. It is to
e noted that, except during the change cycle, the motor power
is used only to revolve the Turntable.
Cycling - As the Main Cam rotates, the spring loaded lever which
actuates the Floating Pinion is automatically depressed and th s
reset for the next change cycle.
At the end of the change cycle the Motor power is disconnected
from the change mechanism when the Plastic Washer mounted on
the Floating Brass Pinion drops into a depression on the top
edge of the rim of the Main Cam. This position, called home
position of the Main Cam, is retained by a Leaf Spring (55-72965)
detented in the cam hub.
Record Selection - Record Selection is accomplished during one
complete revolution of the Eccentric Cam Assy (45A7296O) at the
top of the lower section of the spindle. This portion of the
change cycle is accomplished when the extended section of teeth
of the Main Cam engages and rotates the Spindle Cam Pinion
(28-VSOB4). The home, or in line position of the Record Select-
ion Eccentric Cam is retained by a Leaf Spring (55-75155) which
detents into a slot in the underside of the Spindle Cam Pinion.
Successive record drops are accomplished by a repetition of
this action.
(C)John F. Rider

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' by the Sweep Lever Assy. (55A75045
RCD. CH, PAGE 19-6 GEN INST
MODELS 70017, '/ooa GENERAL 1NsTRUM`i:NT?oRP_ ` ` `
Picku Arm Movement - The movement of the Tone Arm Assy.
A 50 during cycle is controlled entirely by the surface
movements are picked up
and grooving of the Main Cam. These
). After a record has been
played or when it is rejected, the Trip mechanism causes the
Main Cam to rotate which, in turn, lifts the Tone Arm off the
records sweeping it clear to permit a record to drop and re-
turning it to the edge of the record. The Tone Arm Support
mechanism is so designed to permit the Tone Arm to be handled
during any part of the change cycle without damage to the
mechanism. This is accomplished by two spring loaded Mating
Cams (45-75069) (45-75115) which disengage when any restraint
prevents it from following the motions of the Sweep Lever.
The Tone Arm is also vertically spring loaded allowing it to
be lifted upward to an almost vertical position to permit
ready changing of needles or cartridge.
Automatic Trip - This trip is so designed that it will start
the automatic cycling mechanism when the Tone Arm moves toward
the Spindle at a rate of speed greater than 1/8" per revolution
of the Turntable. This Trip, therefore, is practically uni-
versal as it will operate on any center leading groove or
center eccentric circle groove records conformin g to RMA
specifications. However, the Trip does not become operative
except within a distance of approximately 5" from the Spindle.
Thus, manual resetting of the Tone Arm is possible at distances
greater than 5" from the Spindle.
The Velocity Trip is composed of three major elements: The Trip
Lever Assy (55A73C42), the "V" Lever (55-72966) and the
Crescent Lever (55-75066). The Trip Lever and "V" Lever work
together through a Friction Clutch (10-72955), the tension
for which is maintained by a Coil Spring (55-75534) which is
one of the elements in the assembly of these two parts. As
the Tone Arm moves toward the spindle center, the sickle
shaped section of the Sweep Lever comes into contact with one
leg of the "V" lever causing the tip of the Trip Lever to move
toward the center of the Turntable by energy transmitted
through the Friction Clutch. This movement continues until
the tip of the Trip Lever is in the range of the Finger of the
adjustable Collar mounted on the Turntable H ub. Once this
position is attained and so long as the movement of the needle
toward the Spindle is less than L/8" per revolution the tip
of the Trip Lever will be retarded from further movement by
being pushed away once during each revolution of the Turn-
table. This retarding movement means that the Friction
Clutch slips a corresponding amount. When the needle moves
into a fast spiral or an eccentric center groove of the record,
the tip of the Trip Lever will move
center of the Spindle it will allow
Lever to slide off the flat surface
engage itself behind the Lever. In
Turntable the finger on the adjusta
so rapidly toward the
the tip of the Crescent
of the Cam Trip Lever and
the next revolution of the
le Collar will force the
Trip Lever outward causing the Crescent Lever to move the Cam
Trip Lever far enough to unlatch the Floating Pinion Actuating
Lever, thus setting up the change cycle as previously described.
(C)John F. Rider _

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_ _ RCD. CH. GEN INST PAGE 19 7
GENERAL INSTRUMENT CORP. MODELS TOOF, 'YOOR
10" and 12" eration - The lO" and 12" indexing is determined
y the main cam y allowing the sweep lever pin to enter either
the 10" or l2" indexing track. This switching is controlled
by means of a Frog (12-75060) which is moved from one side to
another by the Frog Actuating Lever Assy. (55A73886 Rear) or
(55A74605 Front) extending from the Record Support As?y.
(62A75l29 Rear) or 62A7472O Front). This lever shunts the
sweep lever pin into the indexing track dependent upon whether
the record support is pushed toward or away from the spindle
for 10" or 12" records.
ADJUSTMENTS
Tone Arm Index - The tone arm should be indexed at the start
of every record approximately l/8" from the edge for both the
10" and 12", If the needle index is too far in or out, this
this may be corrected by loosening one of the two set screws
found in the lower cam located in the bottom of the tone arm
approximately ?" above the top of the motorboard, andaadvancing
the other set screw sufficiently to bring about proper indexing
The proper setting having been obtained, both screws should be
locked tightly. This action is accomplished by means of the
two screws contacting a flat on the vertical shaft at an angle
that will cause the shaft to turn with any movement of either
Aggustment of Record Suggort - When the record is centralized
w h the lower part of e spindle, the record support plat-
form in both 10" and 12" position should clear the edge of the
record by approximately .Ol5" (l/64). To move this setting
for the 12" record, it is necessary to advance or retract the
set screw nearest the spindle on the upper part of the support
beneath the motorboard. The screw farthest away from the
spindle will adjust the 12" position in a similar manner.
S indle Ali nment - If the spindle eccentric cam is not lined
up per ectly w th the lower part of the spindle while out of
cycle, the main cam should be moved to its home position as
determined by its detent spring and the spindle pinion gear
should also be moved to its home position as determined by
its detent spring. Loosen the set screws in the hub of the
spindle pinion gear and line up the eccentric with the spindle,
then tighten set screws.
The spindle cap should be positioned so that the slide is point-
ing towards the center of the record support. This may be
positioned by loosening the screws on the square retaining bar
found in the lower bracket. There should be approximately
.OO5 total vertical play in the spindle assembly after both
adjustments to prevent binding.
(C)John F. Rider

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RCD. CH. PAGE 19-8 GEN INST _ __ __ _ __
1110131555 7QOF, 7005 - GENERAL INSTRUMENT CORP.
Main Cam Frog Movement - When the record support is in the 12"
position, the phosphor bronze spring that actuates the 10" or
12" selector Frog pin should be high enough to clear the frog
pin. When the record support is in the 10" position this
spring should cause an interference with the frog pin enough
to move it into position to shunt the sweep lever pin into the
10" indexing track. This spring is slit for the purpose of
easy adjustment. If this spring does not move the frog enough,
it should be rebent to do this. It should be remembered that
the frog is so constructed that as the sweep lever pin goes
past it, it will automatically reset the frog in the 12" posi-
tion, and to play a 10" record this pin must be reset by the
spring everytime.
Removin Turntable - To remove the turntable for any reason,
remove t e small orseshoe-like spring found around the spindle
near the turntable top. Then make sure that the trip lever
is moved tar enough away from the turntable center to allow
it to clear the extremities of the bakelite washer of the
floating pinion. The turnablemay then.be removed by lifting
up. In replacing the turntable care should be taken to see
that the idler tire is properly positioned within the I.D. of
the turntable and that the trip lever is also out of the way
so that it will not be bent by the bakelite pinion gear washer.
Adjustment of Tone Arm Height - If tone arm needle does not
clear a stack of records, loosen the set screw securing the
vertical tone arm shaft underneath the motorboard and raise
the shaft up. In some extreme cases the zinc sweep lever
itself may be bent. If the needle is set too high to play
the first record, retract the set screw found on the top of
the motorboard directly behind the tone arm.
DIFFICULTIES
Failure to Feed Record - This could be caused by the spindle
eccentric cam not lining up with the lower spindle sleeve at
the end of its cycle. First determine whether the detent
spring is in the pinion depression. If this is so, and it
is still out of alignment, loosen the screw and adjust as
previously explained under SPINDLE ALIGNMENT. Secondly, check
the position of the record support as previously explained.
Check the record thickness for a maximum of .10" at center
hole (RMA maximum thickness).
(C)John F. Rider

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~ RCD. CH. GEN INST PAGE 19 9
GENERAL INSTRUMENT CORP. MODELS TOOF, 'YOOR
Drops two or more Records at Once.- Check thickness of record
at center hole. Record should be not less than .ovo" at this
point. If the records are within this RMA minimum, check the
spindle slide. It should be flush to .o2o" below the bottom
of the spindle cap. If it is too low file it off, if it is
too high remove the pin in the cap and file the slot to get
the proper dimension. This pin is held in the cap by a light
knurl fit and can be easily replaced. Be careful not to bend
the spindle rod during this process.
If two records still drop, check the record support setting
(see above). N ote:` Proper record diamenter for all settings
of the record support should be:
9-'7/8" 1 l/52 for the 10" record
11-'7/8" if 1/52 for the 12" record (RMA STANDARDS)
Continuous Tri - This is caused by the floating pinion not
dropping ar enough away from the projection of the collar
on the turntable hub. Make sure the main cam is in home posi-
tion and that the floating pinion falls in the depression of
the cam edge and remains there until the record is completed.
Rotate the turntable to make sure that the collar clears it
by approximately l/52. Reject the changer and check to insure
approximately 5/64 or better engagement with the collar finger
Check the manual trip lever to make sure it clears the cam
trip lever.
No Tri in - If the changer wont trip manually, check the
manual tr p lever to make sure it moves the cam trip lever
enough to unlatch the pinion actuating lever. This action _
should occur before the switch plate reaches its maximum allow
able rotation.
No Automatic Trip - Check the pickup lead to make sure it is
not binding the tone arm movement, particularly as the needle
approaches the spindle. Check the V lever to make sure it
rotates freely and the clutch has movement. Put the cam in
home position and make sure the crescent trip lever is free
and contacts the flat side of the cam trip lever. Move the
V lever and make sure the clutch imparts enough force to
the trip lever to allow the crescent lever to move along the
flat and drop behind the trip lever. There should be no
friction or binds in any of these mechanisms. Non-tripping
can be caused by any binds or by too tight or light a spring
load on the crescent. This spring load is adjustable by
anchoring the crescent lever spring in any one of three holes.
(C)John F. Rider

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