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Страница 1: ...Radio Corporation of America 233 BROADWAY NEW YORK CITY DISTRICT SERVICE STATIONS BROOKLYN N Y CHICAGO ILL SAN FRANCISCO CAL Bld No 19 168 39th St 2001 West Pershing Road 274 Brannan St DALLAS TEX ATLANTA GA Santa Fe Bldg Unit No 2 Monroe Bonded Warehouse Spring and Peters Sts ...
Страница 2: ... in promoting this phase of the Dealer and Distributor s business the RCA Service Division 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 been compiled from experience with RCA Dealers and Distributors service problems and presents the best practice in dealin...
Страница 3: ...14 Refinishing Marred Surfaces 14 Continuity Tests _ 14 Continuity Test Chart 15 Important Precautions 15 Service Data Chart 20 PART II MAKING REPLACEMENTS Replacing Antenna Coil 16 Replacing Radio Frequency Coils 16 Replacing Gang Sockets 17 Replacing Main Timing Condensers and Drive 18 Replacing Large By pass Condensers 18 Replacing Audio Transformers 19 Replacing Condenser Drive Cable 19 Replac...
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Страница 5: ...ifier Radiotron easily capable of handling the signal delivered to the last audio amplifier Service work in conjunction with RCA Radiola 16 should be small since all construc tion is of a simple character See Figure 1 and of fool proof design However for the guidance of those called upon to locate and remedy any trouble that may occur the following notes are presented PART I SERVICE DATA 1 RADIOTR...
Страница 6: ...e and effective method of overcoming any oscillating tendency of the radio frequency amplifiers 6 A fixed resistor is used in the filament circuit instead of a variable rheostat This eliminates an extra control on the panel and safeguards the filaments of the Radiotrons against excessive voltage 7 A plate voltage of 135 volts is used on both audio stages in conjunction with a negative grid bias of...
Страница 7: ...pe Where the installation of an outdoor antenna is not practical satisfactory results may be had by using an indoor antenna consisting of about 50 feet of insulated wire strung around the picture molding The size of the wire is not particularly important though No 18 B S bell wire is suggested In buildings where metal lathing is employed satisfactory results are not always possible with this type ...
Страница 8: ...he grating continues the service man can soon determine whether or not the cause of complaint is within or external to the receiver and plan his service work accordingly 7 RADIOTRON SOCKETS The sockets in Radiola 16 are of the standard gang UX type The three gang socket is fer the radio frequency amplifiers the single socket is a cushioned socket for the detector and the two gang socket is for the...
Страница 9: ...cable and drum operating mechanism 10 ADJUSTMENT FOR SLACK DRUM CABLE The main tuning condensers are controlled by a cable and drum arrangement giving a smoothly acting vernier movement that has no back lash See Figure 1 After considerable wear or extreme changes of temperature the cable may become slack To take up this slack open lid of cabinet and turn the cable adjusting screw with clamp until ...
Страница 10: ...TANCE RESISTANCES 800 OHMS 600 OHMS 3 o GANG CONDENSERS VOLUME CONTROL GROUND TO FRAME 12 BROKEN CABLE Should a cable become broken due to considerable use or excessive tightening the proper remedy is to replace the cable The procedure for making this replacement is described in Part II Section 7 However if a new cable is not immediately available a temporary repair may be made in the following ma...
Страница 11: ...LOW TRACER GREEN WITH RED AND BLUE TRACER O 8 67MAROON LED o B 45MAROON l c 9 BLACK WITH GREEN TRACER and wiring color scheme for making battery connections reducing them to 67 volts Off hand it would seem that a series resistance could be used to drop the voltage but when we realize the plate voltage varies in practically all of these devices except in the case of the RCA B Eliminator Duo Rectron...
Страница 12: ...r should then be readjusted so that no clattering occurs on the greatest volume desired In RCA Loudspeakers Models 100 100A 102 and 104 however the polarity is not an important factor They should accordingly be connected in the manner that gives the most pleasing reproduction 15 UNCONTROLLED OSCILLATIONS Should Radiola 16 oscillate or regenerate at any point in the tuning range the trouble is prob...
Страница 13: ...the loudspeaker production is poor test the loudspeaker input from the receiver A pair of phones or a loudspeaker of known quality may be used for this purpose If the output of the Radiola is of poor quality the distortion may be due to any of the following causes 1 Excessive voltage on R F amplifiers 2 Excessive filament voltage 3 Defective Radiotrons The Radiola may be operating properly but a p...
Страница 14: ...t which together with a camel s hair brush should be a part of the service man s kit when servicing Radiola 16 This tlronze paint can also be used on the RCA 100A Loudspeaker 21 CONTINUITY TESTS The following tests will show complete continuity for the circuits of Radiola 16 The volume control should be adjusted so that half its resistance is in the circuit the antenna lead disconnected and the ba...
Страница 15: ...ring Defective switch or connections Open detector grid resistance Defective 1 mfd by pass condenser Defective 1 2 mfd by pass condenser Open ground connection to chassis frame Open secondary of radio frequency transformers or grid resistances Defective A F by pass condenser Defective grid leak or detector grid resistance Open volume control Open filament resistor Open primary 1st R F Transformer ...
Страница 16: ...is located at the left end viewed from the rear of the cabinet the end that has the condenser drum and scale See Figure 9 To remove the coil unsolder the two leads and remove screw and nut that passes through center of coil The new coil is then placed in the position occupied by the old one The nut and screw are replaced and the Radiola is reassembled in the reverse of the foregoing order Before b...
Страница 17: ...6 Give Radiola an operating test before replacing in cabinet to determine that replacement has been properly made 7 Return chassis assembly to cabinet and replace all screws and control knobs 3 REPLACING GANG SOCKETS The sockets of Radiola 16 are of the gang variety using one detector socket a two gang A F socket strip and one three gang socket strip for the radio frequency amplifier tubes These s...
Страница 18: ...ency transformers and color scheme of connections 5 REPLACING LARGE BY PASS CONDENSERS These condensers located on the under side of the chassis frame are held together by means of clamps that form part of the condenser case fastened to the frame A step by step procedure when making replacement is as follows 1 Remove chassis from cabinet as described in Part II Sec 1 2 Remove condenser assembly as...
Страница 19: ...drum 4 Now bring cable over the large drum Turn drum so that cable adjusting screw is on top Pass cable over groove until point is reached where there is a slot in the drum for passing cable to the other side of drum to the other track 5 Follow on around other track in same direction until point is reached where cable is directly above front grooved drum 6 Starting on the third groove back from th...
Страница 20: ...tive By pass con densers Replace main tuning condenser assembly Sec 19 Sec 8 Sec 1 Sec 2 Sec 6 Sec 5 Sec 4 Poor Quality High plate voltage on R F amplifiers Defective A F transformer Defective By pass condenser Reduce plate voltage to 67 on R F amplifiers Replace A F transformer as sembly Replace defective condenser Sec 13 Sec 6 Sec 5 Noisy or Intermit tent Reception Dirty Radiotron prongs Loose v...
