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Page 1: ...tion November 1926 RADIO CORPORATION OF AMERICA 326 Broadway New York City Prepared by NATIONAL SERVICE DIVISION 233 Broadway New York City DISTRICT SERVICE STATIONS 10 South La Salle Street Chicago I...
Page 2: ...A has prepared a series eef Service Notes of which this booklet is a part containing technical information and practical helps in servicing Radiolas This information has been compiled from experience...
Page 3: ...re overloaded by an abnormally strong signal being forced through the amplifiers distortion will follow If it is definitely established however that the distortion or rattle complained of is not due t...
Page 4: ...Fig 1 Moving part of motor Fig la End view of motor Method of adjusting armature clearance...
Page 5: ...irmly Figure 8 shows the method of tightening the upper screw with the spacers in place After the two screws have been tightened the spacer tools should be removed and the Loudspeaker tested If the ra...
Page 6: ...otor in place These screws thread into the spacer bushings E 7 Place a piece of iron on the ends of the horseshoe magnet and slide the motor off The piece of iron takes the place of the motor and acts...
Page 7: ...ghtly and when the spacer tools are removed the strain causes the armature to spring out of the central position Remove the spacer tools and note care fully whether or not the armature is centered bet...
Page 8: ...e cone 1 Remove the small nut that holds the cone to the connecting rod 2 Remove the four screws a b c and d shown in Figure 13 When these screws are removed the entire aluminum frame may be removed f...
Page 9: ...upports and lay the casing on them in a horizontal position 10 Allow the aluminum frame to rest on the four cleats O Figure 13 on the front edge of the casing 11 Center the frame in the center of the...
Page 10: ...Fig 14 Cylindrical filter type lo Fig 15 Square filter type...
Page 11: ...t points are shown in capital letters in the circuit diagram and illustrations Figs 14 15 and 16 Before starting the click test disconnect terminal D from the binding post at B This free terminal D wi...
Page 12: ......
Page 13: ...100A RADIO CORPORATION OF AMERICA Prepared by Service Division of the Production and Service Department 233 Broadway New York City 326 Broadway New York City DISTRICT SERVICE STATIONS 1412 Monroe Stre...
Page 14: ...the RCA has prepared a series of Service Notes of which this booklet is a part containing technical information and practical helps in servicing RCA Loudspeakers and Radiolas This information has bee...
Page 15: ...dspeaker Connections 10 Service Data Chart 15 PART II MAKING REPLACEMENTS Replacing Magnet Coils 11 Replacing Armature and Drive Pin 12 Replacing Thrust Lever and Driving Rod to Cone 13 Replacing Moto...
Page 16: ...AGNET COILS THRUST LEVER SOFT SOLDER MAKE ADJUSTMENTS WITH SOLDERING IRON SILVER SOLDER DRIVE PIN DRIVING ROD CONE SEATING NUT CONE Figure 1 Diagram showing constructional details and operating princi...
Page 17: ...s used in conjunction with receivers using plate voltages passing current in excess of 10 milliamperes some method of coupling the out put of the receiver to the Loudspeaker should be employed A choke...
Page 18: ...If a signal of good quality and volume is being delivered by the receiver the loudspeaker will have to be examined for the cause of any imperfect repro duction that may occur 2 PROCEDURE TO REMOVE HO...
Page 19: ...it may be necessary to adjust the armature to check on this condition In any case an adjustment of the armature is necessary To adjust the armature a set of spacer tools are necessary Figure 4 illust...
Page 20: ...ly Poor reproduction is the result and inspection of the armature drive pin may indicate a slight torque or twist This is most likely to occur when replacing a cone The new cone should be carefully se...
Page 21: ...will cause distortion Defective magnet coils will also cause imperfect reproduction The circuit and correct connections are shown in Figure 8 The reference letters in the circuit diagram refer to the...
Page 22: ...roduction As there is not much wear and tear on the coil connections the most likely place to find trouble of this nature is in the connecting cord The point where the cord enters the loudspeaker hous...
Page 23: ...otor mechanism with supporting screws S T V and bush ings X Z Figure 9 may now be removed from the supporting frame and separated by releasing the bushings X Z and removing the supporting screws S T V...
Page 24: ...en cone lock nut and seal with seal ing wax Seat screws around edge Place spacer tools in position to adjust the armature as indicated in Fig ure 5 and tighten screws A and B Resolder drive pin to thr...
Page 25: ...motor mechanism is replaced 4 REPLACING MOTOR ASSEMBLY COMPLETE When replacement of the complete motor mechanism is necessary remove mechan ism assembly from housing as described in Part I Sec 2 Then...
Page 26: ...e the diagonal position of the cloth pattern as originally installed The reassembly is a reversal of the foregoing procedure Rear Grille To replace the rear grille the mechanism assembly and front gri...
Page 27: ...er from ture action mechanism Sec 3 Weak Loose thrust lever mounting Tighten screw and resolder Reproduc tion screw drive pin Sec 6 Sec 3 Improperly aligned cone Align cone correctly Sec 5 Drive pin p...
Page 28: ...Printe in L S A 1927...
Page 29: ...right October 1928 Radio Corporation of America SERVICE DIVISION OF THE PRODUCTION AND SERVICE DEPARTMENT 233 BROADWAY NEW YORK CITY DISTRICT SERVICE STATIONS BROOKLYN N Y CHICAGO ILL SAN FRANCISCO CA...
Page 30: ...of the RCA has prepared a series of Service Notes containing technical information and practical helps in servicing RCA Loudspeakers and Radiolas This information has been compiled from experience wi...
Page 31: ...Service Data Chart 15 PART II MAKING REPLACEMENTS Replacing Magnet Coils 11 Replacing Armature and Drive Pin 13 Replacing the Thrust Lever and Driving Rod 13 Replacing the Motor Assembly Complete 14...
Page 32: ...AFFLE METAL MOUNTING FRAME _ METAL MOTOR SUPPORT nr art a THRUST LEVER 4 WITH MAGNET DRIVING ROD ARMATURE WITH 4 DRIVE PIN t MOTOR MECHANISM FILTER ftrkR INPUT CORD n iKtri 1 ra4 Y Figure 1 Rearview s...
Page 33: ...tied over this frame to give an artistic finish and provide easy access to the mechanism when necessary Some method of coupling the output of the receiver to the loudspeaker should be employed when L...
Page 34: ...for the cause of any imperfect reproduction that may occur INNER EDGE DRAW STRING OUTER EDGE DRAW STRING Figure 4 Location of draw strings used to fasten silk cover over canopy 2 PROCEDURE FOR REMOVIN...
Page 35: ...e Division Stock No 2321 The material obtainable on the open market should be phosphor bronze strip 010 thick and 25 wide It is bent as illustrated and soldered to hold the ends fairly rigid The two e...
Page 36: ...ge of the cone 23 m o rer o I Figure 6 General appearance and correct dimensions of armature spacing tools can now be lined up with those of the metal frame and the outside frame lightly attached with...
Page 37: ...n the coils or in the filter unit A pair of headphones and a 41 2 volt battery connected together in series or a voltmeter and sufficient battery to give a full scale deflection should be used ARMATUR...
Page 38: ...nuity of the leads and also for a short between the leads Shake the cord while conducting the continuity test to disclose any breaks which will be indicated by interrupted clicks Figure 8 Drive pin th...
Page 39: ...frequencies can be indicated to run such a test A test of this kind is quite conclusivefor quality and volume of reproduction and will indicate if further repair work or adjustments are necessary Figu...
Page 40: ...occupied by the old ones 11111 11111 LOUDSPEAKER COILS Figure 10 Schematic circuit of Loudspeaker 103 coils and filter and photo of filter unit b Reassemble the motor mechanism and replace the thrust...
Page 41: ...Removing reproducer assembly from baffle 3 REPLACING THE THRUST LEVER AND DRIVING ROD Ordinarily the driving rod and thrust lever are not likely to become damaged or require replacement However shoul...
Page 42: ...nd magnet and install the new motor The reassembly will be a reversal of the foregoing procedure 5 REPLACING CONE When replacing a cone re move the old one as described in Part II Section 1 The in sta...
Page 43: ...tapestry proceed in the following manner a b c d e f The Remove the mechanism by removing the six machine screws that hold it to the baffle board and remove the baffle board by removing the eight woo...
Page 44: ...se thrust lever mounting screw Improperly aligned cone Drive pin poorly soldered Weak magnet Examine receiver Part I Sec 1 Remove foreign matter from mechanism Part I Sec 3 Tighten screw and resolder...
