RCAVICTOR Radiola 86 Operating and maintenance manual

RCA
Radiola 86
SERVICE NOTES
VOLUME
CONTROL LOCALDISTANT
SWITCH
TONE STATION
CONTROL SELECTOR.
OPERATING
SWITCH
First Edition-30M
Copyright October, 1930
RCA Victor Company, Inc.
RADIOLA DIVISION
Camden, New Jersey
REPRESENTATIVES IN PRINCIPAL CITIES
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Property of the RCA Victor Company, Inc. Confidential and to be used only by its
Authorized Distributors and Dealers in furnishing service in connection
with its apparatus
Copyright 1930-RCA Victor Company, Inc.
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CONTENTS
Page
Electrical and Physical Specifications 5
Electrical Description of Circuits 5
PART I-INSTALLATION
9 Jerky Action of Station Selector 9
g Use of Local-Distant Switch 9
Radiotrotis y Precautions for Excessively Loud Signals 9
Removal of Shipping Blocks 9
Location 9 Blown Fuse 9
Adjustment of Line Voltages 9 Adjustment of Lid Mechanism_ 10
Antennas
Ground
PART II-SERVICE DATA ON RADIO RECEIVER
Antenna System Failures 10
Radiotron Sockets and Prongs 10
Noisy Volume Control 10 Adjustment of R. F. Line-up and Oscillator
Broken Condenser Drive Cord 10 Trimming Condensers 10
Excessive Hum 10 Adjustment of I. F. Tuning Condensers 10
Acoustic Howl 10 Line-up Adjustments of Gang Condensers 10
Low Volume 10 Dial Scale Reading Incorrectly 10
PART III-ELECTRICAL TESTS
Electrical Tests 10
PART IV-MAKING REPLACEMENTS
Making Replacements in Receiver Assembly or S. P. U. 11
PART V-SERVICE DAT
Adjustment of the Armature
Replacing Rubber Pivot Supports and Damp-
ing Block
PART VI-PHONOGRAP
Lubrication of Motor
Speed Regulation
Governor
Phonograph Motor Service Data Chart
Noisy Operation
Heating
Service
Distorted Reproduction 10
Audio Howl 10
Oscillation 10
A ON MAGNETIC PICK-UP
11 Replacing Coil 13
Replacing Armature 13
Testing Magnetic Pick-up and Tone Arm 13
12 Magnetic Pick-up Service Data Chart 13
H MOTOR SERVICE DATA
151515
17 Replacing Motor Spindle, Disc or Governor
18 Driving Gear 20
19 Replacing Motor Spindle Ball Bearing 20
Continuity of Motor Circuits 19
To Remove Motor 19
Replacing Motor Coils 19
Replacing Motor Governor Parts 20
PART VII-SERVICE DATA ON MICROPHONE
Data on Microphone 21
PART VIII-SERVICE DATA ON AUTOMATIC SWITCH
MECHANISM
Pick-up Switch Failure 22 Automatic Switch Mechanism Service Data
Motor Switch Failure 22 Chart 23
ILLUSTRATIONS
Cabinet View
Rear Interior Cabinet View
Schematic Circuit Diagram of the Radio-
Phonograph Instrument
25-Cycle and40-CycleMotor Condenser Changes
Audio Circuits
Phonograph Parts
Magnetic Pick-up
1 Adjusting Pick-up 12
4 Phonograph Motor 13
Lubrication of Phonograph Motor 15
6 Assembly Wiring Diagram of Radio Phono-
7 graph Combination Instrument 16
8 Top View of Phonograph Compartment 18
9 Details of Microphone 21
11 Automatic Switch Mechanism 22
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RECEIVER ASSEMBLY
S. P.U. - REPRODUCER
ASSEMBLY
Rear interior cabinet view of the radio-phonograph combination instrument
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RCA RADIOLA 86
SERVICE NOTES
Electrical Specifications
Voltage Rating 105-125 Volts
Frequency Rating 50-60 Cycles, or 25-30 Cycles
'Power Consumption (Radio Alone) 60 Cycles-120 \Vatts; 25 Cycles-125 Watts
Power Consumption (Phonograph) 60 Cycles 155 Watts ; 25 Cycles-200 Watts
Type of Circuit A. C. Screen Grid Super-Heterodyne
Type and Number of Radiotrons...4 UY-224, 2 UY-22;, 2 CX-245, lUX-280-Total, 9
Number of Radio Frequency Stages 1
Type of First Detector Tuned Input Grid Bias
Number of Intermediate Stages 2
Type of Second Detector Power Grid Bias
Type of Tone Control-Variable resistance in series with condenser across output of
2nd detector
Number of Audio Stages (Radio) 1 (Push-Pull)
Number of Audio Stages (Phonograph or Recording) 2
Type of Magnetic Pick-up Low Impedance
Type of Tone Arm Inertia
Diameter of Turntable 12 Inches
Type of Rectifier Full Wave, UX-280
Type of Loudspeaker Electro-Dynamic
Wattage Dissipation in L. S. Field 10 (110 V., 85 M. A.)
Undistorted Output 3 0 Watts
Physical Specifications
Height 48 Inches
Depth 27 Inches
Width 18 Inches
Weight Alone 150 Lbs.
Weight Packed for Shipment 210 Lbs.
ELECTRICAL DESCRIPTION OF CIRCUITS
This instrument is a combination radio receiver, similar to Radiola 82, an electric
phonograph employing an improved type of magnetic pick-up and tone arm and a
home recording mechanism by which either a radio program or sound production in
the home may be recorded on the Victor home recording record blanks. The frontis-
piece shows a rear interior cabinet view.
Radiola 86 incorporates the tone contrcl of Radiola 82 and when the rotary switch
is in the "Radio" position, it is electrically the same as Radiola 82. The schematic
circuit is shown in Figure 1. Its operation in the other positions follows:
Phonograph-When the rotary selector switch is in the "Phonograph" position, the
radio portion of the receiver is made inoperative and the second detector is used as
an audio stage together with the power amplifier. The magnetic pick-up is suspended
by the new "inertia" type tone arm. This name originates from the method of weight-
ing and then counter-balancing so as to have sufficient weight and mass present for
best reproduction. This weight prevents the tone arm and pick-up from vibrating with
the record variations and provides true reproduction, due to the needle following
exactly the record variations. The phonograph parts are shown in Figure 4.
5
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The output of the pick-up is fed into an auto-transformer which in turn applies
this voltage to the grid of the second detector. The grid bias of this tube has been
changed in order to have it operate as an audio amplifier. The output of this tube
is then applied to the two UX-245's, acting as a power amplifier, the output of which
is in turn delivered to the reproducer unit. The volume of output is controlled by a
60-ohm potentiometer connected across the magnetic pick-up.
Radio Recording-Any radio program may be recorded on a Victor Home record-
ing blank with this instrument. The additional material required is a record blank and
a special home recording needle.
The electrical functions of recording a radio program are the same as that of re-
ceiving such a program with the exception that the pick-up is substituted for the cone
coil of the reproducer unit. The cone coil is then connected across the output with
a 150-ohm series resistor in the circuit and the reproducer is used as a monitor. When
acting as a cutter greater pressure is required on the record than when reproduction
is in progress. Therefore a small weight is provided for placing on the pick-up head
while recording.
After making a record, it may be played either on the present instrument or any
other phonograph in the usual manner with the exception that the special needle used
for recording must also be used for reproducing. If the present instrument is used, it
is important that the weight on the pick-up head be removed, otherwise the record
will be damaged.
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Figure 2-Circuit changes for 26-cycle and
40 -cycle operation
Home Recording-A small hand microphone is provided for recording the voice
or other programs originating in the home. This microphone is connnected in series
with the bias resistor of the first detector and across a tap on the pick-up input trans-
former. About 10 milliamperes then flows through the microphone. The circuits then
function as in "Phonograph Reproduction" except that the output of the UX-245 is fed
into the pick-up instead of the reproducer unit. The weight must be used on the
pick-up as in radio recording.
The operation of the audio circuits with selector in its various positions is shown
in Figure 3.
Models are also available for 25-30-cycle operation and these may be adapted to
40-cycle operation by means of a special motor condenser. The differences between the
25-cycle and the 60-cycle models are : the power transformer ; the additional filter
capacitor ; the rotary switch : and the motor condenser. These parts are shown in
Figures 1 and 2.
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SCHEMATIC AUDIO CIRCUIT DIAGRAMS
2,9 DE ECTOR
UY 27.
MAGNETIC
PICK-UP
0..F
CHOKE.
10,000
SECONDARY OF
39 L P TRANS.
SECONDARY OF
39 I. F TRANS..,
re DETECTOR
UY-227,
J
to,o00.11
TON CONTROL,'
40 000.11
00445 .025 MFD
MFD.
-E IS GROUND
R. F.
CHORE
R.
CHOKE
tTONE CONTROL-'
40,000 A
`.000746 02S MFD.
UFO
PUSH-PULL
POWER AMPLIFIER
USN -PV Lt
POWER AMPLIFIER
PIC( -UP USED
AS CUTTER.,
CONE OF
REPRODUCER UNIT
(REPRODUCER USED
AS MONITOR)
Figure 3A-
Radio
Recording
PUSH-PULL
POWER AMPLIFIER
PUSH-PULL
POWER MANNER
-6 IS GROUND +8 +8
CONE OF%
REPRODUCER UNIT
Figure 3B-
Phonograph
Reproduction
7ALA-LIP USED
AS CUTTER`,
? l
7
CONE OF%
REPRODUCE* UNIT
(REPRODUCER UFER
AS MONITOR)
Figure 3C-
Home
Recording
-1
IV
CONE OF
REPRC)UCER UNIT
Figure 3D-
Radio
Reproduction
8
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PART I--INSTALLATION
The reader is referred to the Radiola 80 Service Notes for the following data on
installation.
Antenna (Outdoor type ). Location.
Antenna (Indoor type). Adjustment for line voltages.
Special antenna installations for noisy Jerky action of station selector.
locations. Use of local-distant switch.
Ground. Precautions for excessively loud signals.
Radiotrons. Removal of shipping blocks and screws.
HOME RECORDING
RECORD
COMPARTMENT
USED NEEDLE
MICROPHONE CUP CASE CLIPS
NEEDLE NEW NEEDLE
CUP
MICROPHONE INPUT TERMINALS PICK-UP WEIGHT (USED FOR RECORDING)
Figure 4-View of phonograph parts
TONE ARM
SELECTOR
SWITCH
SPEED
ADJUSTMENT
SCREW
PHONOGRAPH
VOLUME
CONTROL
(1) BLOWN FUSE
A blown fuse may be caused by the following:
(a) Connecting the set to a D.C. line.
(b) Plate to plate short of Radiotron UX-280.
(c) Shorted condenser in capacitor pack.
(d) Shorted filament or heater contacts or dial lamp socket.
(e) Defective power transformer.
Any of the above causes must be cleared up before a new fuse is installed other-
wise the new fuse will blow as soon as the old one is replaced and the power turned
"On."
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(2) ADJUSTMENT OF LID MECHANISM
A spring mechanism is provided that balances the lid at any opening position. (See
frontispiece.) Failure of proper operation is indicated by the lid either continuing to
open or close after the hand is removed. If this condition is present adjust as follows :
(a) If the lid continues to open after being released, too much tension is present
on the spring. Reduce the tension by turning the adjusting screw counter-
clockwise gradually until normal operation is secured.
(b) If the lid closes upon release of the hand insufficient tension exists at the
spring. Increase the tension gradually by turning the adjusting screw clock-
wise until normal operation is secured.
If the spring has lost its tension it must be replaced. If a replacement spring is not
available try removing a turn from the old spring.
PART II-SERVICE DATA ON RADIO RECEIVER
The receiver assembly and S. P. U. of this receiver is very similar in both mechanical
and electrical characteristics to that used in Radiola 80. For service information on
these units other than that contained herein the reader is referred to the Service Notes
on Radiola 80. This includes :
Antenna system failures.
Radiotron sockets and prongs.
Noisy volume control.
Broken condenser drive cord.
Excessive hum.
Acoustic howl.
Low volume.
Distorted .reproduction.
Audio howl.
Oscillation.
Adjustment of R. F. line-up and oscilla or trimming condensers.
Adjustment of I.F. tuning condensers.
Line-up adjustments of gang condenser.
Dial scale reading incorrectly.
PART III-ELECTRICAL TESTS
The electrical tests given in RCA Radiola 80 Service Notes are all applicable to
the present instrument when the rotary switch is in the "radio reproduction" position.
There is one slight difference to remember, however, and that is the 1300-ohm choke
and .000745 mfd. condenser in the plate circuit of the 2nd detector in the present in-
strument that is not in the Radiola 80.
In addition to the tests already mentioned, special tests may be necessary on the
parts special to Radiola 86. These tests are included in the Service Data Sections (see
page 11, etc.) on these parts.
The receiver assembly and S. P. U. of Radiola 86 are exactly the same as those
used in the Radiola 82. The Radiola 82 Service Notes should be referred to when-
ever wiring diagrams are necessary for Radiola 86. Some models of Radiola 82 and
all models of Radiola 86 have a slight change in wiring from that shown in the dia-
gram of Radiola 82 receiver assembly, namely, the .025 mfd. condenser of the tone con-
trol connects to the positive plate supply instead of to ground. This change is made by
replacing the bus bar from the .025 mfd. condenser to ground as shown in the diagram
by a red lead from the condenser to the terminal strip to which five red leads are al-
ready attached. This is located on the under side of the chassis between the center
1. F. transformer and the chassis front.
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PART IV-MAKING REPLACEMENTS IN RECEIVER
ASSEMBLY OR S. P. U.
Making replacements of parts in the receiver assembly and S. P. U. of Radiola
86 is very similar to that of Radiola 80. The reader is therefore referred to Radiola
80 Service Notes for information on the following:
To remove receiver assembly.
To remove S. P. U. Reproducer Assembly.
Replacing reproducer cone.
PART V-SERVICE DATA ON MAGNETIC PICK-UP
Service work on the magnetic pick-up may be divided into the following classes:
1. Adjustment of the armature.
2. Replacing rubber pivot supports and damping block.
3. Replacing coil.
4. Replacing armature.
Figure 5-Disassembling the magnetic pick-up
ai'
T 1
I
.2 .0175".-L14-.0i73'IF-.0175'
Figure 6-Magnetic pick-up
armature spacing tool
(1) ADJUSTMENT OF ARMATURE
Adjustment of the armature consists essentially of having it in its electrical center
between the two pole pieces. Need for this adjustment is usually evidenced by dis-
tortion during phonograph reproduction with blasting, especially on the low notes.
The following procedure should be adopted when making this adjustment:
(a) Remove screws A and B (See Figure 5) from the pick-up, and remove the cover
thereby released.
(b) Mark the magnet poles and the pole pieces so that when they are replaced they
will be in their original position. The magnet may now be released. Place a
keeper such as a large nail across the magnet poles and remove the magnet
from the pole pieces. Another way is to slide the magnet over the pole pieces,
until it is on the opposite side of the armature adjusting screws. (See Figure 5.)
If the magnet is released from the pole pieces or keeper even for an instant the effici-
ency of the pick-up as a record cutter is seriously impaired. Be careful not to let this
happen and if it does, remagnetize the magnet before and after reassembling.
(c) With a small screw driver loosen screws C and D. The small piece of metal
that holds the damping block may now be moved either way until the arma-
ture is approximately between the two pole pieces. Judging the center by the
eye is sufficiently accurate for this adjustment.
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(d) After the center has been located the two screws, C and D should be tight-
ened. The magnet may now be replaced, the keeper removed and the pick-up
re-assembled in the reverse manner of that used to remove it. While re -assem-
bling be sure that all dirt is completely removed from any part of the magnet,
armature or other parts of the pick-up.
(2) REPLACING RUBBER PIVOT SUPPORTS AND DAMPING
BLOCK
After considerable time, or due to climatic conditions, the rubber pivot supports
and the rubber damping block may become hardened and require replacement. Such
hardening is usually evidenced by the armature being set to one side and not moving
easily. As with other rubber articles, these parts give best life when used frequently.
ARMATURE SPACING TOOL F \
TIGHTEN VICE AND
z THEN TIGHTEN NUTS E&F
Figure 7-Magnetic pick-up in vise
The pick-up should not be supported, when not in use, by the needle resting on
the record or turntable as such use will tend to set the armature to one side. The pick-up
should hang free.
Usually the rubber pivot supports and damping block will require replacement at
the same time, and are therefore supplied in sets of three. When a replacement is
necessary such a set should be procured. If such a set is not available and a repair is
urgently needed, the damping block may be cut from a piece of automobile inner tube.
The rubber strips for the pivot support may be cut from the thin portion of a baby's
rubber nipple.
Use the following procedure when making replacements :
(a) Procure magnetic pick-up armature spacing tool. This is listed in the spare
parts catalog, or it may be easily constructed by referring to Figure 6.
(b) Remove the pick-up case and the magnet from the pole pieces as described in
Part V, Section 1.
(c) Unsolder the leads to the coil at the terminal strip inside of the pick-up case.
Remove nuts E and F, Figure 5, and release the pole pieces from the back
support. Now remove screws C and D and disassemble the pole pieces. arma-
ture and coil. The old rubber should be completely removed from all parts, and
the parts should be scraped clean with a knife.
(d) Place the new rubber pivot supports in their proper place. This may be either
tubing or strips. Reassemble the pole pieces and coil, and new rubber damping
block in place with armature spacing tool in place as shown in Figure 7. Now
place in a small vise and clamp the pole pieces together, as shown in Figure
7, with the spacing tool in place. Tighten nuts E and F, remove pick-up
from vise and remove spacing tool.
(e) Reassemble the magnet and cover as described in Part V, Section 1. making
sure the small magnet clamp is in place at the top of the magnet.
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(3) REPLACING PICK-UP COIL
The pick-up coil may be replaced in the same manner as the rubber supports and
damping blocks, the difference being that the coil is replaced instead of the rubber
pieces.
(4) REPLACING PICK-UP ARMATURE
The pick-up armature may be replaced in the same manner as the rubber supports
or coil, the difference being that the armature is the part replaced. All adjustments
are the same. In some cases replacement of the armature is made necessary due to
rust. If a new armature is not available, the old one may be temporarily repaired by
removing all rust with sandpaper. This is not a permanent repair due to the fact that
the sandpapered surface will quickly rust, so therefore a new armature should be in-
stalled as soon as available.
RESISTOR AND
REACTOR CONTAINER
SELECTOR
SWITCH
PHONOGRAPH
VOLUME
CONTROL
MOTOR 4.5 MFD.
CONDENSER.
Figure 8-Bottom view of the phonograph motor mounting
board, showing various parts.
(5) TESTING MAGNETIC PICK-UP AND TONE ARM
After a magnetic pick-up has been repaired it is good practice to test it on actual
records. The following Victor records are very desirable for test purposes.
For testing the ability of the pick-up and tone arm to track the record groove use :-
FUNERAL MARCH OF A MARIONETTE-No. 6639
ZAMPA-No. 35985.
For a voice as well as low frequency test at the saine time :-
A GAY CABALLERO-No. 21735
For dance music which has an evidence of high frequency as ,yell as low frequency
response use:-
BULL FIDDLE BLUES-No. 2155.
For checking low frequencies mainly use :-
ALOHA 0E-No. 21121.
which at the very end has about 50 cycles recorded on it, also
ANDANTINO-No. 35843.
For testing rattle of pick-ups use :-
MY CAROLINA SUNSHINE GIRL.No. 10094.
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MAGNETIC PICK-UP SERVICE DATA CHART
Indication Cause Remedy
No reproduction
Poor volume control contact between
arm and resistance Clean volume control resistance with a
pipe cleaner and any of the various
cigarette lighter fluids
Open pick-up coil or connections Repair any loose connections by resold-
ering or replace an open coil as de-
scribed in Part V, Section 3
Weak or distorted
reproduction
Loose needle Tighten needle in socket with needle
set screw
Dirty contact in volume control Clean volume control resistance and con-
tact arm
Armature out of adjustment Center armature as described In Part V,
Section 1
Defective rubber damping block or
pivot supports Replace rubber damping block and pivot
supports as described in Part V, Sec-
tion 2
Dirt in armature air gap Clean all dirt from air gap by means of
a blower or disassemble pick-up and
clean. Remove rust from armature if
necessary
Weak magnet Remagnetize magnet by taking to mag-
neto repair shop. Place keeper across
pole faces until magnet is again in
place in the pick-up. Making repairs
without placing a keeper on the mag-
net is the easiest way of having the
magnet lose its magnetism.
Needle holder rattle If the needle hole of the pick-up cover
touches the set screw that holds the
needle, a rattle will result.
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PART VI-PHONOGRAPH MOTOR SERVICE DATA
The phonograph motor used is of the induction disc type and is unusually rugged
in construction. (See Figure 8). The following text covers the details of any service
that may become necessary.
(1) LUBRICATION OF MOTOR
The various bearings and gears of the motor should be kept clean and should be
lubricated at least once every six months. Phonograph motor oil and motor grease
should be used and applied to the points indicated in Figure 9. Should phonograph
motor oil and grease not be available, any high grade light engine oil may be substi-
tuted for the oil and vaseline for the grease. Before lubricating it is desirable that the
parts. first be cleaned with carbon tetra-chloride (Carbona), and all dirt and old
grease removed. In addition to the regular lubrication all bright metallic parts, except
the motor disc, should be covered with a light film of oil to prevent rusting.
OIL UPPER SPINDLE BEARING
AND GOVERNOR SHAFT BEARING
WITH MOTOR OIL
LUBRICATE SPIRAL OF SHAFT
AND GEAR WITH MOTOR GREASE
OIL GOVERNOR SHAFT BEARING,
GOVERNOR SLIDING SLEEVE AND
LOWER SPINDLE WITH MOTOR OIL.
Figure 9-Lubrication points of the phonograph motor
(2) SPEED REGULATION
A stroboscope disc is included with each instrument which makes speed adjust-
ments very easy. The instructions for its use are printed on each disc and will not be
repeated here. If a stroboscope disc is not available the following method may be
used for correct speed adjustments.
(a) Place a record on the turntable and insert a small piece of paper under the
edge of the record to serve as an indicator.
(b) Play the record in the normal manner and count the number of revolutions
made by the turntable for one minute. The speed should be 78 revolutions per
minute.
(c) Turning the speed regulating screw (Figure 4) clockwise allows the motor to
run faster, and counter-clockwise, slower. Adjust by trial until the speed is
78 revolutions per minute as determined from a full minute's count.
NOTE-The speed of the machine should be checked at least four or five times a
year. Improper speed will cause distortion.
(3) GOVERNOR
The governor will maintain a constant speed of the motor within a range of sudden
voltage changes of 20 volts, providing all the parts are correctly adjusted. Any ad-
justment made on the motor (including lubrication), will have a certain effect on the
regulation of speed and the speed adjustment should be checked as described in Part
VI. Section 2, before the unit is again placed in service.
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SOOOR
MQN ' S
INTERNAL CONNECTIONS OF
REMSTOR AND REACTOR UNIT
NIAIDOD
J SHIELDS
MONOGRAPH
VOLUME
CONTROL
SSUTSMER
TO PICK-uP
SNORT MINTING
SWITCH
RESISTOR AND
REACTOR UNIT
cucúñcmL coi
S. P. U.- REPRODUCER
ASSEMBLY
POWER
TRANSFORIAER
I
TO ADTOM.nC
SWITCH Kam
MCUNEITC PHONOGRAPH MR AN
T MAGNETIC PICK-UPOTOASSEMBLY
li
_... Ci* A,.
ROTARY SWITCH
STATION TONE LOCAL. DISTANT
«LECTOR., CCOONTROL\ SWITCH ;CMTROU
411'e.E!4 DT.SET Y.EEI SV-224 W.T,.._.
2 5NCOs ° a
VEG
RECEIVER ASSEMBLY _á á
OPERATING SWITCH
o eas u.-aS
- TOIINueLE
.-MONOGRAMS MOTOR
-.NA[A HrtN MOTOR COHOENSER.
MICROMONE
INPUT JACKS
SICHOPTONE AND
MAGNETIC Flow-
MFUT TRANSFORMER
S 5X1110$
USINER
A o. IX TUT
Figure 10-Assembly wiring diagram of the radio-phonograph combination instrument
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(4) PHONOGRAPH MOTOR SERVICE DATA CHART
The following Service Data Chart indicates the cause and remedy for any difficulties
which may be encountered in the operation of the phonograph motor. These are listed
according to their indications :
Indication Cause Remedy
Failure to run
Operating switch or record switch
"off" or defective Turn switches "On" or repair any de-
fective switches
No A.C. power at socket outlet Check with a 0-150-V. A.C. voltmeter
Loose or open connection in the con-
nector cord or plug Repair any defective connections
Wrong or open connections of motor
coils Check wiring and make any repairs nec-
essary
Jammed motor Rotate turntable by hand with power
on. If jammed examine motor and re-
place or repair part causing jamming
Shipping wedges not removed Remove paper wedges if used between
disc and coils to hold motor during
shipment
Motor fails to main-
tain correct speed
Low line voltage Check line voltage with a 0-150 Volt
A.C. voltmeter while motor is run-
ning and phonograph is in operation.
The voltage must be between 105-125
for proper operation.
Improper lubrication Examine moving parts, bearings and
gears. If oil and grease is gummy
clean and lubricate as described in
Part VI, Section 1.
Motor improperly mounted or jarred,Loosen
in shipping the three motor mounting screws
and tighten alternately while motor is
running. Do not tighten any screw
sufficiently to cause binding or slow-
ing down of the motor
Worn motor spindle ball bearing Replace a worn ball bearing
Weak motor coils After checking all the above causes and
the motor still fails to maintain speed
replace one or both of the motor coils
as described in Part VI, Section 9.
It is possible for them to test elec-
trically O. K. but be weak in opera-
tion
Noisy operation See Part VI. Section 5 for the cause and remedy of defects or improper ad-
justments that may cause noisy operation
Hum
Loose coils or coil laminations Tighten screws that hold coil cores to-
gether. If this does not correct the
hum place a small wooden wedge be-
tween inside of coil and core
Cabinet hum Tighten motor mounting screws or re-
place the rubber between motor and
cabinet
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(5) NOISY OPERATION
There are several causes of motor noise other than hum, which is discussed in the
Phonograph Service Data Chart.
(a) Governor Springs.-A noise or rattle may sometimes be caused by loose or
broken governor springs. Tighten all the governor spring screws. If this
does not stop the noise, loosen the screws on the gear end of the governor
springs and allow the motor to run for a minute or two to allow the springs
to assume their correct position. Stop the motor and retighten. the screws.
If any of the springs are broken or badly out of balance, they should be
replaced.
Figure 11-View of motor board with turntable removed
(b) Governor Bearings.-The thrust bearing at the gear end of the governor may
cause noise while the motor is running. Hold one finger over the end of the
bearing and loosen the set screw which holds the bearing in position. Adjust
the bearing to the most quiet running position and retighten the set screw.
If this procedure is not successful the position of the governor spiral relative
to that of the governor drive gear should be shifted slightly until a condition
of minimum spiral to gear noise is obtained.
To do this the set screw holding the thrust bearing at the gear end of the governor
spindle is loosened and the bearing shifted slightly and re-clamped (loosening the
bearing on the opposite end of the shaft first if necessary). Now, with the bearing at the
disc end of the spindle loosened and one finger against it to prevent it from slipping
out, start the motor. While the motor is running, press lightly against this bearing
and clamp the set screw to hold it in place. The center of the worm should be approxi-
mately opposite the center of the worm gear. If this is not the case for the position of
minimum noise a defective or poorly lubricated worm or worm gear is indicated. A
bent governor spindle may also he the cause.
(c) Governor Spindle.-A bent governor spindle will cause binding in the gears
and bearings as well as noise. The bent spindle should be replaced with a
new one. Removal of the governor can be accomplished by loosening the
two governor bearing screws, one at each end of the governor shaft, and lifting
the governor from the frame.
(d) Governor Driving Gear.-Remove the motor spindle as described in Part VI,
Section 10, and examine the gear for wear. If the wear on the teeth is uneven
on opposite sides of the gear the turntable spindle is bent and both gear and
spindle should be replaced.
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(e) Turntable Spindle and Disc.-A bent turntable spindle, or a bent or improp-
erly adjusted disc will cause noise. The bent spindle may cause the disc to
rub against the iron core of òne of the coils. A bent spindle can be detected
by placing a pencil flat on the motor board with the point against the spin-
dle ; if the pencil point touches the spindle on one side only while the motor
is running, the spindle is bent and should be replaced. If the disc is bent
and rubs against the cores of the motor coils the lower spindle bearing should
he adjusted as described in Part VI, Section 11, or the disc should be replaced,
depending upon the extent of the damage.
(f) If the motor "bumps" (turntable jumps up and down), it may be due to a faulty
or worn gear or worm ; insufficient grease or poor grease on the worms ; or not
enough turns on one of the upper motor coils.
(6) HEATING
Normal operation of the motor will produce more heat than can comfortably be
tolerated while touching any of the coil units. This is mentioned in order that the
service man will not misconstrue this heating as an indication of a defect.
(7) CONTINUITY OF MOTOR CIRCUITS
Due to the absence of a motor terminal board it is best to disconnect the motor and
test for continuity of circuit directly at the motor coils. This may be done by any
of the methods used for regular continuity tests. Associated circuits should be checked
by referring to the diagram, Figure 10.
(8) TO REMOVE MOTOR
If it is necessary to remove the phonograph motor, it may be done in the following
manner :
(a) Place the pick-up and tone arm to the side, clear of the turntable. Remove
needle from pick-up and remove turntable.
(b) Gain access to the rear and remove all wiring to the motor.
(c) Remove the three nuts, washers and rubber pieces from the motor supporting
bolts, being sure to hold the motor so that it will not drop. It may now be
moved to a place convenient for work.
When replacing the motor, care should be exercised to see that the motor speed
adjustment arm lines up properly with the speed adjustment screw.
(9) REPLACING THE MOTOR COILS
Should the necessity arise for replacing the coils of the induction disc phonograph
motor proceed as follows :
(a) Remove the motor as outlined in Part VI, Section 8.
(b) Open the lugs holding the black power leads to the motor frame and remove
these leads to one side.
(c) Release the round head machine screws holding the coil unit, which is to be
replaced, to the motor frame.
(d) Put the new coil unit in place and replace the coil unit mounting screws, tight-
ening them carefully.
(e) Replace the black power leads under the lugs and reconnect the power leads
to the proper points on the terminal board as shown in Figure 10. Lubricate
motor if necessary.
(f) Replace motor and turntable and test for operation and speed.
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(10) REPLACING THE MOTOR GOVERNOR PARTS
If it becomes necessary to remove the governor, to replace the governor spindle or
springs use the following procedure :
(a) Remove the motor as outlined in Part VI, Section 8.
(b) Unscrew governor bearing screw.
(c) Push the governor spindle against this hearing so as to start it out of its
socket, and remove this bearing.
(d) Remove the governor spindle with its associated parts.
(e) All governor parts are now readily accessible and it may be disassembled. The
governor spring holding collar is fastened to the governor spindle by means
of a small set screw, and the spindle is "spotted" to facilitate proper replacement.
(f) Replace the governor spindle and its assembled parts by placing the outer tip
of the spindle in the outer thrust bearing socket first, and then inserting the
inner tip into its bearing, after which the outer bearing is replaced, and its set
screw tightened, being careful to leave a little play in the bearings.
(g) It is usually a good plan to lubricate the unit whenever service work is done.
(h) Replace motor and turntable, and test for operation and speed.
(11) REPLACING THE MOTOR SPINDLE, DISC OR GOVERNOR
DRIVING GEAR
(a) Remove motor from cabinet as described in Part VI, Section 8.
(b) Open the lugs holding the power leads to the motor frame and move these
leads to one side.
(c) Remove the three mounting screws from the coil unit on the opposite side
of the motor from the governor, and remove this coil unit.
(d) Press down on the speed regulating arm so as to release the pressure on the
governor friction disc, and turn the motor disc so that the set screws in the
hub of the motor disc and the governor driving gear are readily accessible.
(e) Loosen both set screws far enough to back them out of the recesses provided
for them in the motor spindle and draw out the spindle.
(f) The motor should now be reassembled in the reverse of the above procedure,
making any necessary replacements.
NOTE-Care should be taken to see that the ball bearing under the lower end
of the motor spindle is not lost.
After assembling the motor the lock nuts around the spindle adjusting screw
should be loosened and the spindle adjusting screw should be adjusted until
the motor disc turns freely in the center of the air gap of the coil units.
Tighten the spindle adjusting screw lock nut.
Replace the motor and turntable.
Lubricate the motor (Refer to Part VI, Section 1).
Reconnect, following the wiring diagram, Figure 10, and test operation and
speed (Refer to Part VI, Section 2).
(g)
(h)(i)(j)(k)
(12) REPLACING THE MOTOR SPINDLE BALL BEARING
A worn motor spindle ball bearing will cause slow or varying speed and should be
rep:aced as follows :
(a) Place the pick-up and tone arm clear of turntable, remove any needle which
may be in the pick-up and remove the turntable.
(b) Loosen the spindle adjusting screw lock nut and remove the motor spindle ad-
justing screw. The ball bearing may now be removed.
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