n t l l l tlI ARE THEANSWER,S: HER.E The WBsrox Model 787 is the only service Oscillator which reads 40 kc. per division at 40 mc. This precise tuning is absolutely essential to test the band width of F.M. receivers. Each instrument is individually hand calibrated at 2 mc. intervals. (The broad frequency coverage of Model 787 ...from 22 to 150 mc. fundamental frequencies...safeguards against obsolescencein the event of changesin assignedchannels.) t t' W E S T O NM o d c l 7 8 7 U . H . F .
RADIO ond TelevisionRETAILING'S Senuire S/rr'nf errJr "Tricks the Trade" 1940Editionof of - - Enlargcd, Reviced, Renamed "bread Practical and butter" tips for radio dealersand servicemenon how to fiindand repair the most common troubles peculiarto specificmodelsof receivers plur ReferenceCharts of PermanentValue and Use o T' H I S m a n u a lm i g h t p r o p e r l yb e n a " ' e d M O N E Y M A K I N G S H O R T C U T S f o r t h e r a d i od c a l e r and rerviceman.
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O R A D I O R E T A I L I N G ' 5, , , eUie AC.DC SETS AC.DC SETS HUM IN AC,/DC SETS \\'lrt'rr :tlnornr:rlly high hum nrodulation is prr.rser-rt in a-c/cl-c rcccivers, it is suggcste
z R A D t o R E T A I L I N G 'ttSerrorioe 5 AIRLINE62.89 Rider Manuals? TellYou..." Last i.f. transformer Insensitive defective. Replacewith part #P5127; other transformers unsatisfactory. AIRLINE62.99 Iuoperative Poor 32 oscillator tube. Try several tubes. A slight readjustnrent of plate attd screett voltages is sontetirtteshelPful. A|RLINE62-103 shorted or Weak, low volume open screen bypass or open screen -reopen 415 ohm sistor. Inoperative flexible wire-wound resistor, shorted screen bypass on 6D6 r.
rrSevuie OR A D I O R E T A I L I N G ' S AfRL|NE 62:2126 Dead open secondary of anterrna coil. f,oil rrust be renroved to 6nd tr-ouble. AIRLINE Alc:andcr. If you can't align check center-tap resistor of 2l-volt winding. It should be 150-ohms but sometimes changes valrre enough to cause osciJlation. AIRLINE 64. Inoperative tuning meter and weak signals. Place finger on control grid cap of first r.f. 58. If volume increases meter is burned out.
O R A D I O R E T A I T I N G ' S, , , eh{tice APEX 11, 42 Oscillation over entire scale. Try 2,000 ohm resistor in second r.f. grid lead. APEX.16 Distortion at low volume. This trouble can be overcome by replacing the old control and connecting in a slightly different fashion. The old control is simply a series resistor in the catl.rodecircuits of the 24 tubes.
? R A D T O R E T A t L t N G ' S" , .ARVIN 35. Poor tone . . Replace both .01 mfd. audio 'with mica moulded coupling condensers typel oisame value. ARVIN 41, 51. Distortion at low v o l u m e c o n l r o l s e t t i n g s ,o n s t r o n g s i g _ nals Due to oueibias of 6F/ cria. Remove 100-ohm resistor from catfrodi o f t h i s t u b e a n d c o n n e c t t h e c a t h o d ei o g:ound .through an 800-ohm resistor. I he volume control, in other words. should affect bias on the 6.
O R A D I O R E T A I L I N G ' S" , ezZdm A.K. 46 Distortion replace .5 mfd condenserfrom B plus end of first audio plate resistor. The original condenseris in a oack. AK 37-60. New, double-spring contact arms are available at the factory and make it ururecessafyto change entire volume controls rmless the wire is shot. Clean the winding with alcohol. AK 37, 40, 41, 12, 43, 44, 53,51, 55, 55C, 60 Installing volume control strips Connect replacement strip across ll0 volt, a. c.
O R A D I O R E T A I L I N G ' S , , . a,ui@ AK 55 (Early). lntermrtrenr operation after a few minutes of use, reception gradually fading out completely with a buzz . . Open sccondary in second r.f. transformer. Plate lead, of.24 comes through this coil and as fault is intermittent it is usually difficult to hit the open period when checking socket voltages. Application of heat from a 60 watt lamp will hasten the opening if this condition exists. A-K 55. O""0, or almost inaudible.
@R A D I O R E T A I T I N G ' S"Squie A . K . 3 r 7 , 3 3 7 ,6 3 7 No broadcast reception check voltage on oscillator section of 6A,8. This should be approxinratcly 185 volts. If lorver replace 30,000 ohm platc dropping resistor. AK .tl6-{.f&l16 Intermittent or weak . . . shorted .l mfd. condenxr (marked No. 102) between 6F6 cathode and .1 meg. resistor, replace. A.K. a35 Dead, constant hunr. Check for open .05 mfd. bypass in 6K7 i.f. grid circuit. This condenser is C5 in schematic. A.K.
O R A D I O R E T A I L I N G ' 5, , , q\dee BRUNSWICK BRUNSWICK ACIO. Weak signat, all voltages ok . Voice coils commonly blow. B R U N S W T Cl K t , t 2 , 1 5 ,3 3 Weak or no reception on low frequency end of dial look for open 910 mmf. condenser locatecl betrveen stator of oscillator tuning condenserand high side of oscillator plate coil. B R U N S W T Ci K l, t2, t5, 23 Iiading, poor selectititv or sensitivitv Tighten screq' f:rstening 10 ntmf .
O R A D I O R E T A I L I N G ' S"Setuie BOP CHEVROLTT. Pronounced vibntor bvzz . .. Removc 75 tube. If troise ltops rcplece tubc end rhort scrcwdriver ecrou grid to ground. If buzz continucr cqurlly toud ptece tl mike condenser ecrogs B ptur to ground. Troublc ir due to opening up of 6ltcr output condenscr. CHEVROLET. Intermittent spark noise, not traceable to faulty supprcssion . . .
; R A D I o R E T A t L t N G ' sr r ,eh.n@ C-995. A hi-lo sensiCOLONIAL tivity switch,which will cut down'interstation noise when tuning locals with this a.v.c. model, may be added by removing wire lead betwecn lugs 1 and 2 of the Candohm reststors, connecting a 100 ohm type between the lugs, cutting the ground connection to lug I and gounding lug 2.
O R A D I O R E T A I L I N G ' 5"Squire CROSLEY58 CROSLEY I24 Dead. . Suspect metal cased condenser containing r.f. plate, screen and It cathode bypass (part #W7753). frequently shorts out, sorrretimesburning one or both of the Candohm resistors at the back of chassis. As a safety first measure solder the speaker plug to its socket connections under' chassis. This is a constant source of noise and intermittant reception as plug often works loose.
A R A D I O R E T A I T I N G ' S" , e)'de c R o s L E YA - r 5 7 . . Set stops playing when jarred install new tube socket for the 6A8G as original unit does not grip the prongs tightly enough. CROSLEY 158. Local stations barely audible rvith volunre on full Look for open 750 ohrn resistor connecte
o R A D I O R E T A I L I N G ' 5. " S e ' z u i e , CROSLEY 555 Loss of volume . . . leaky condenser No. 14 in schematic connected between anode grid of converter and primary of oscillator coils. CROSLEY 60l. Filanrent rheostat shaft shorts to metal panel, heatir-rgwire and destroying fiber insulation without damaging wire itself. Equip shaft with insulating bushing, 6ll in between wire turns where charred with heat resisting cement and pulverized asbestos,smearing mixture on wire to hold it firmly.
ORADIO R E T A I L I N G ' S f f , erde CROSLEY Showbor. No r.f. platc voltage. Shorted 5 mfd. condenser bypassing B-rupply lead is reported as most common cause. CROSLEY SHOWBOX. Fading. Try soldering a piece of wire on bottom of aerial lug and fastening the other end under the screw at the top of the aerial and ground strip. Distortion or dead set. Apply heat with soldering iron to the case of the a,f. condenser. Then push back high potential terminals. CROSLEY.
O R A D I O R E T A It I N G'i_J7, EMERSONMAC-7 Dead . . . look for open 2000 . ohm 1-rvatt cathode resistor on 5g. r{unr, after S Y P BnS Os-crvice II. M-AC-7. Derlg several rrrorrths,""4;;; to opel filter or other conrnron causes . - . Check iigh voltage *i.airg ".i porter transformer wittr an ohlunleter. . n c w t n d t , ) g s o n r e t i n r e sp a r t i a l l y shorts, .t lllt',r11.jpg the !$ensoN center_tap zoA, zs!.. om. .Excessive os- curatlon .... Remove antenna wire coil rrom. Instde case.
O R A D I O R E T A I T I N G ' S" . eZdre FAIRBANKS MORSE FAIRBANKM S O R S E4 2 Motorboats when volume is advanced on strong stations suspect 8 nrfd condenser or resistor connected to volume control. FAIRBANKSMORSE.I.I Loud howl that disappears whcn tone control is set to bass Replace bias cell in grid circuit of output tube. Before replacing, clean all contacts thoroughly. FAIRBANKS.MORSE 238T32. Noisy reception Due to vibrator unit being tightly mounted to the chassis.
O R A D I O R E T A I L I N G ' S" , enuie FORD PHILCO I937 6E &r0. RCA Ml4 G.E. L-50 Male end Ignition interference of antenna lead making poor contact in set socket. Solder short heavy braid to shield on male cap and fasten securely under edge of junction box after 6rst cleaning off paint. If some noise still persists, bond the middle screw on set cover to dash. also junction box to emergency brake bracket screw.
"Sq>uie OR A D I O R E T A I T I N G ' S G.E. F63 G.E. M65 Distortion on strong signals. Resistor (R3 in diagram) conducted to 'lug wrong on terminal strip. when volume control Oscillation turned on full . . . Check all filter condensers. Replace 8 mfd section with red leads with new unit. G.E F63 Anterrna coil burnecl out . . . . defective rvale bancl srvitch rvl'rich goes beyond stop positior.r ancl places 98 volts on the rvinding. GE F 63, 55, 65 A squeal rising in pitch as volun.
@R A D I O R E T A I L I N G ' S , , , e&i@ G.E. A-85 I-orv volrrnre or no reception check voltage across 3000 ohm 6rst audio cathode resistor. If less than 2 or 3 volts replace electrolytic bypassina' this section with 5 to 10 mfd. 25 volt unit. e. E. 16 Static but station cannot be tuned in. Shorted condenser in sentry box . un&r 6A8 tube. To replace, unsolder all leads on sentry box, remove front dial screws, lift up dial assembly, pull out band shaft, remove front section of sentry box from bottonr. G.
." ,,. R A D I O R E T A I L I N G ' S eh'ui@ G . E . E r 5 5 ,r l 2 6 Before Noisy volurne control. replacing volume control, replac-e6C5 firit A.Ir. In models E86, E95' and E , 1 0 5t r v r e p l a c i n g 6 F 5 f i r s t A . F . GE I937MODELS insert 150 Pilot light burnouts ollnr r€sistor in centertap of high voltage winding, also l5 olrru resistor irt ser-ieswith colorattra liglrts. Tlris offsets hieh line voltage. G.E. I93.
O R A D I O R E T A I T I N G ' S" . ehuia GRUNOW 8A Low volume, high plate current on output tube . Low resistance short of the output tube's bias resistor due to leakage from 6lter condensers through fibre protective covering to close-fitting can. G R U N O WI I A Distortion a iter 1.5 nrinutcs oneration c l r t . c k c o u l r l i r r gc o r r , l i , r r r e r b e t r v e e n8 5 s e c o n c l c l e t e c t o r - a n d 7 6 push pull clrives. GRUNOW llA. Oscillation . .
O R A D I O R E T A I L I N G ' S, ' , e/rui@ KADETTE KADETTEK634 Present \\'a\-e trap is rrot sufficient to stop code irrterfercrrce.Disconnect wave tlap entireh- irrd corrnect it's coil in series rvitl-r rerl s ire fronr band switch to antenna coil. Connect it's trinrrner d i r e c t l v a c r o s st r a p c o i l . KADETTE IOI9 Takes too long to warnt up, poor tone. Condenser pack leaking to cltassis, replace.rvhole pack. KADETTEI2OO.ST. REGIS22OO Hard to align, distortion on locals.
I O R A D I O R E T A I L I N G ' 5" , e2de MAJESTIC 50. Set dead, no plate voltage on second detector but all other voltages only about l5 volts below normal Do not remove bottom plate from chassis. Instead, relnove the small plate at back of chassis directly below the deck upon which is mounted the 80 and 45 tubes. Look for a charred 25,000 ohm resistor. Replace it and the associated I mike condenser. which has shorted, causing the resistor to turn out.
.O ,,, R A D I O R E T A I T I N G ' 5 atui@ MAJESTIC 66. Normal voltages, vibrator ok but s€t don't play . . ' Try removing shield of i.f. coil, placing insulating paper around coil framc. Intermittent oPeraMAJESTIC 66. tion when car is operated over rough roads . . Look for broken shielded ground wire leading inside o,f plug at iear of set. Take oft plug and unscrery, soldering wire. MAJESTIC 66. No screen voltages.
O R A D I O R E T A I T I N G ' S" , a,ui@ MAJESTIC Internuttent 908. reception Sometimes defective choke in r.f. lead. To renredy, short out choke. Performance is not noticcablv imoaired. MAJESTIC eoB.. Fading...Replace detector cathodebypass condenser. Check 27's. MAJESTIC 9OB. No plate volt- age,trouble apparently in powerpack .. . Disconnect leads between pack and set, turn current on for 45 seconds. UAJESTIC 90, 908.
@R A D I O R E T A I T I N G ' S" , qZuie MAJESTIC3OO Overload with volume all on, still not enough volume . . . high resistance leak in coupling condenser connecting to tube side of volume control. MAJESTTC3OO Motorboating u'hen volume is atlvanced . replace l0 rufd electrolytic. C3 in schematic MAJESTIC 300 SERIES. Weak signals, heard only at critical point of volume control Condensir can marked C and D houses two capacitors, C17 a .l mfd. and C24. a .25 mfd.
lrERIquRRIERs TORTHE ]IN EsT TUBES RRIIIO '.% RUTHORIIRIIUE IETHNItRl tnI0RmRIl0n t Ih.ough its achievements in the development and manufacture of the finest radio tubes, Sylvania has logically become headquarters for authoritative technical information. Sylvania service to the radio industry is always "at your service.
NBVBRBDBI{AITYTHIITG THBRB'S TIKBTIIBM! € Third, Edition R . A D I OS E R V I C E ENCYCTOPEDIA THE SUPPLEMENTAI SBBVICB TBCIIITICAT ITYBMOI{TITIY i"'t''iliu ' " ' ;;il;.;;;;;i"r"i-"i1i'" series.It hai hell'ed.thcnr solve l.arfffu;',ai# :r4:18:,'i:>" prob.lemsnot covcred bv anv other an4 of. utst ' servtce regardless, there are still-manvinvaluableissuesto come' You can still get-theentire series fo date " ' i.
'.,i."ii'i::i " ^: "'1!j ;,.,- S A Y! R B A DW I I A TU S B N S "I wich to compliment you on the excellent work you are doing and the service you are rendering the Radio Servicenran." -Rohert F. ,lones Spr inttield. I llirtois "Send me the M Yll Supplenrente ao far prrblished aa ao()n as posaible. After eeeing thenr, I think I'm miscing out on sornething." -[}al Dumberk Pork- Quebet CrenJield "l have received the supplernent that goes with the third Mallory manual.
SITICON .ZINC T U N G S T E N . G L A- S S5 O A E 1 M A T E R I A I .USS E D' N R A D I O T U A T S :- a ; n F r' d I I = C, W h y T u b e ss h o u l d b e t e s t e d z :) o every six months o ah u.l f- c z. c F 'Tl z o c !o d. o 2 (J I m f, P m o 2 o VI z z n UI T IN YWIR E S TVARP II{ TIMI 9 : z. { - {t} m : : ? rn HEATINJURES INSUTATI()N r! o x o -{ I r t2l (J t- rl = c o : N tfEtDtDJ0|l{Ts ARESTRAII{ED TEMPERATURT AFTECTS SEAI.
a I O R A D I O R E T A I T I N G ' S" , "2de MIDWEST MTDWIST t6-t{. Poor selectivity and weak reception . . . This model does not hold its alignment due to shifting of windings on coils. Coat all coils with wax or liquid cement and realign all trimmers. Go over all trimmers a number of times to uncover interaction between circuits. Before realigning install a 3 or 4 plate variable midget condenser in place of the tone control assembly. Tone control assembly can be mounted on the side of the cabinet.
O R A D I O R E T A I T I N G ' S , , , e/f/ui@ 'Loud whistle 77A. MOTOROLA and distor.tedreception in early nrotlels . . Generally caused by breaking of solid wire cottnectiotrbetweetr tone control and small fixed condenser mounted on chassis directly behind control. The wire is covered with cotton braid and frequently appears to be ok' Continuity test shovvs up defect. Replace with flexible wire, such as is. used in later Suspect the vinrodels. Dead set . brator first.
I R A D I O R E T A I T I N G ' S" , "/ruifu PHILCO TI. Set blows fuses and vibrator is found to be ok . . . Check for short between speaker field housing and on-off switch mounted on volume control. Tape section of field close to volume control and also cover switch assembly with insulating material. PHILCOT.I I Boonrv torre replace 0.1 nr.f.d. tone control condenser with .01 m.f.d. P H I L C OC T I I Noisv, unstable . . .
A R A D I O R E T A I L I N G ' S , , , ehuie PHILCO 20. Bad tone, pitchco higher than normal. Rcplace old cone using solidified disc with new spider tyPe conc. P H I L C O2 0 connect.l rnfd Oscillation condenseracross entire.voltageclivider. P H T L C O2 0 'is Oscillation n'hen volunre increased . cl-rcck.05 nrfcl screen bypass on 2-1 r.f. for open. Tuning shaft PHILCO 20, 70, 90. wears grooves where bathtub serves as end bearing for rotor . . .
? R A D T O R E T A t L t N G ' S" , PHTLCO39-307 Oscillation as volunre control is advanced replace .0002-5nrfd plate bvpass on 75 first audio with .0l tnfd. P H T L C O3 9 - 3| Extrenrely high pitchetl tone with tone control set at "high" . . reverse line plug. If condition still persists, change position of wires around volume control leads and srid lead to 75. PHTLCO39-3s If pushbuttons will not stay in remove chassis and take out the two small blocks at the front inside.
O R A D I O R E T A I L I N G ' Sf I eUioo ?H[CO 60 Intermittent or low volume . . . Check for high resistance opcn in secondary of antenna coil. PHILCO 60. Intermittent loud buzzing similar to outside motor intcrference but originating in set . . . Replace 6A7 oscillator-first dctector even though it tests ok. PHTLCO60, s05 Noisy check .18 nrfd cathocle bypass on 6.47 tube. PHttco 65 Fading intermittent open in speaker field. This field should have a resistance of approximately 3000 ohms.
Y i O R A D I O R E T A I L I N G ' S" . ehde PHTLCO 80 PHILCO 84 PHTLCO90 Wc:rk C l r c c l r r r i r c l c ; r t l r o t l cr . c : i . t , n ' [ , , t ' c l t ; r t t g ci t t r e r i r l r r r r c , ' . Loud hunr check rivet that holds 42 socket, lug from 42 cathode grounding on rivet. P H T L C O8 4 Noisy. Check for loose oscillator coil shield. Crimp edge to make tisht fit or solder to chassis. PHTLCO90 Impossible to turll volume off on locals . shield first detector tube.
A RADIO RETAITING'S PHILCO 9lX. Hun.r, developing aftcr few hours of use, accompanied by distortion . . . Replaceinput push-pull audio transformer. Secondariesare sometimes faulty. 95. I ntermittent recrption volume increasesto high level and drops back to normal when test instruLook for inments shock circuit termittent trouble in bypasscondenseron low side of volume control. The lead to this condenser goes from control, through a cable, and connects to filter block.
@R A D I O R E T A I L I N G ' S" , ehui@ P H I L C O2 Z t , 2 2 tA , 2 t , z t { Dead; sometimes distorted, tunes sharply . replace Cathode bias resistor of 24A detector with 200 ohm 2 watt carbon. PHILCO 511, Excessive hum. Where parts check ok hum can be removed by shielding the detcctor, grounding the shield. PHILCO 5ll. "Quivery" reception . . . Check for partial open in voltage divider sectionfeeding the r.f. plate. PFTTLCO 600 Fading . . . leaky twin .09 mfd.
O R A D I O R E T A I L I N G ' S"Sqtcde PHILCO TRANSITONE. When installing set in 1934 Chevrolet do not mount on right side near coil if this is avoidable as it is practically impossible to remove motor noise due to chassis pickup. The battery lead on th€ model 10, cut to fasten to the ammetcr or starter, is the guilty wire. Shielding don t help, Lengthen the lead, shield it and thcn run it directly to the battery, connecting the lead to the negative and the shield to the positive post.
O R A D I O R E T A I L I N G ' S , , , qr,ui@ RCA T7.5 RCA 9KI RCA Ril-eE 62 Distortion, high plate current in 6F6 output stage Increase bias resistor to its normal value and distortion rvill clisappear. L-utoff on str(xrg signals Check nrica condenscr coupling r.f. st:lge to 6rst detector-. Intermittent. . . replace C l8 a.l mfd. condenser in A.V.C. network.
O R A D I O R E T A I T I N G ' S"Seutie R A D I O L AI 7 VICTOR RE 20 RCA 26 No reception look for open section in voltage divider located on chassis sub-base of socket power unit. From where output of rectifier feeds into divider, value of sections in their order are 580, 4,000, 2,500, 200 and 1,900 ohms. Loud hum open .1 mfd condenser from cathode of. 27 second detector to one side of ] watt 1 meg resistor. This condenser is in condenser pack and has two blue leads. Oscillation over entire dial . . .
@R A D I O R E T A I L I N G ' S" , q'de VICTOR 32. Open speakerfields are often easily repairable. Remove cover and look for burned or broken wire. Usually these are accessible. vtctoR R32 Noisy volume control when replacing controls in this set use a 10,000 ohm unit. Disconnect the brown resistor that biases the 26 r.f. tubes and connect to one side of new control. Connect antenna to other side, ground center arnt. This change *'ill increase selectivitv ancl give the control longer life. RCA-VICTOR R32.
O R A D I O R E T A I T I N G ' S"Sauie RADIOLA {.t, 46 Difficulty in aligning Probably due to shorted turns on the small, universal-wound plate coil. Replace this coil. RADIOLA 44, 46. Set plays on one or two stations but it seems impossiblb to align tuning condenser . Replace the first, unshielded, r.f. coil, which is frequently affected by moisture and climatic conditions. RCA 44, 46. To tune in poiice calls . Trlmmers may be adjusted to pick ap l7l2 kc.
RADIOLA64 O R A D I O R E T A It I N G'i_7', Fading. intenrrittent reception, . sta_ tions rece'ivetl below trr"i, o.'ig.i;;f s"i_ tlng' connecting tabs on oscillator series trinrnrer condenser h";; snapped. RADIOLA66 Dead, loud hunr shorted bypass c o r r d c n s ea r .c r o s s 1 r l : L t ae n . l c a t h o d ei u e s unucrneath socket of second detect6r tube. Replace with a .OOZ+niiO. RADIOLA66 . P"1d, except for loucl hurn look tor shorted .002 mfd. bypass fronr plate to cathode lugs oI i..
l : O R A D I O R E T A I L I N G ' S"Sqzuie RCA 96T4.96T5.9616 Pushbutton antenlla trinrruers rvill not tune look for sholt to livet 'back between back to band srvitch terminals. Both are indicated as 8 in the diagram although there should be no electrical connection. RCA TMV-97-C. When using this oscillator be sure the shielded lead from the output connection is fabric-covered or the Bbattery will run down in the event the shielding touches the outout iack.
T.O f f , ehun@ RADIO RETAITING'S R C A2 8 1 RCA VICTOR867 ntake sut'e l)istortion on locals 76 and 6D6 tubes ir.r special a.v.c. I{um check circuit are O.K. 42 output tubes for plate current balance. Phonograph PlaYs but RCA 321. not the radio . . . Check for short in condenser having blue lead to terminal near oscillator padding condenser.Whcn replacing be sure to include 30,000 ohm resistor in original position' Use 4 mike unit with 500 volt rating.
O R A D I O R E T A I L I N G ' S, , , ehui@ SILVERTONE SILVERTONE data: field-coil Number King-made Silvertone 90 94 95 100 111 lllB l12 C o l o n i aNl o . 3 6 . . . . . . I 1 5 0 4 l. . . . . .rr52 4 1 C . . . .I.1 5 4 3 8 . . . . . lt70 4 l. . . . . .t t 7 4 4 2 . . . . . tt74 . 3 9 . . . . .1250 4 9 . . .. . . 1252 4 1 P . . . . .zffi 3 6 P . . . . 260 J/ . . . . . . 310 3 7 . . . . . .312 4 7 . . . . . .320 4 7 . . . . . .322 4 7 . . . . . . 324 4 7 . . . . . .326 3 7 P . . . . 330 4 6 . . . . .
O R A D I O R E T A I L I N G ' S" . eZuioe 16,t{r. Blurping at SILVERTONE high volume tevels . . Reverse trangformer secondary leads to grids of 46's. SILVERTONE I640 Motorboating check .2 mfd screen bypass for open. poor SILVERTONE rOS2, 1654. selectivity in models equipped with .005 condenser in i.f. stage . Remove second i.f. untuned transformer under. ncath chassis and replace with part R64l5A, a tuned,i.f. iransformcr. Realign both i.f. stages.
ORADIO R E T A I L I N G ' S f f , A/uie SPARTON SPARTON I. F.'T MODEL MODEL MODEL 9-X t72.5 '5 172.5 75 {56 |0 t 72 . 5 t 6 t 72 . 5 7 r A 156 t2 t72.5 {+P 172.5 75-L)( 156 t3 t72.5 15 t72.5 75-B 156 f{ 172.5 {GP 172.5 76 15al l+A t72.5 5t 156 77 t1t 15 t72.5 56 172.5 7E t72.5 ftx t72.5 57 {56 E0 155 16 t72.5 5E 156 El {56 t6AW. tt2.5 60 900 Et-a 156 t7 172.5 61 156 156 C2 fE 172.5 62 156 63 156 25 172.5 6t 156 ta {56 2rx 172.5 61AX 156 EtX 156 25 t72.5 65 156 E6-X 156 2G.LW. t72.
O R A D I O R E T A I L I N G ' S"Sezuire SPARTON 69, 79, 79A, E9. (Number terminal strip posts I to 9, from front to back.) Detector plate voltage, terminals I to 2, should be 180 with pickup inserted in jack . . . If 90 to 135 check 20,000 ohm resistor and its bypass between a.f. transformer primary rnd 6lter choke. Detector bias, terminals 2 to 9, should be 14 to 20 . . . If not check 1,200 ohm resistor from phono jack to terminal 2. With pickup in use voltage should be frgm 3 to 5 . . .
r r i O R A D I O R E T A I T I N G ' 5 , , , "htti@ SPARTON600 X{otorboating Check the bias resistor on the 183 output tubes. The resistance should be 1,250 ohms but changes to 700 ohms often a few minutes operation. Replace with a wire rvound unit. SPARTON5OO Strong hunr when set is tuned to resonance rvith a signal replace .006 mfd condenser connected fronr one side of porver transforruer to ground with a .5 or I mfd rrnit. It is importarrt that this condenser is of the non-inductive type.
O R A D I O R E T A I L I N G ' S , , . ehube & STEWART.WARNER STEWART-WARNER, Loss of volunle or sensitivity after defectiveby-ptrss condenseris replaced Sets are critical as to by-pass condenservalues. IJse exact original value of tubular type condenser,avoiding mctal-casedreplacement units. STEWAR,T-WAR,NER. Some models of auto-radios have loud hum when volume control is at Looser. the r.f.
O R A D I O R E T A I L I N G ' S, , , a,uhe STEWART WARNERRI8OA fnsensitive, dial off calibration, impossible to align at lorv end of dial . . . . add .0025 nrid. conclenserto the .0054 unit which is alreadv across tlre padder. STEWART-WARNER R301, R3OIA, R30lB, R30lE. Inoperative, especially on high frequency . . . . Check voltage of 27 oscillator. If less than 100 converter is probably cutting out.
o RADIO RETAItlNG'S "Sezuiu SlNOMBERG STlOMltlG ro, n. FedinS, making it necessary to operrtc rolume control well up . . . Sevcn hundred ohm scctim of voltage divider olrcns commonly. Replacc with lG wttt unit. 48, 49 STROMEERG Dial slips causedby the U rvashers olr tlrtl friction drive rtrechanisrrr binding to tlre shaft openiug of the cab'fo irret. renterl-r' : raise front of <:hassit slightly anrl ilrsert thin rubhel strilr between chassis atrrl n oorlctt clt:tssi. support.
O R A D I O R E T A I L I N G ' 5 f f , ehde TRUETONE 5K Crackling, vibrator and ignition quiet. . . Antenna transformer shield can ungrounded. This condition may be remedied by removing chassis and inserting a phosphor bronze spring between the coil can and chassis bracket with a long-nose pliers. Most stores hatdling this set have these springs on hand. UNITEDMOTORS4037 Weak or inoperative . . . . this trouble can often be traced to shorted turns on the primary of the vibrator transformer.
r O R A D I O R E T A I L I N G ' S" . qZdre WELLSGARDNER5E Noisy replace con
O R A D I O R E T A I L I N G ' S" , e)'de ZENITH BATTERYMODETS 1F227, EFa?I, 5F25| "B" battery life Complaints of short and poor tone quality after battery voltage has dropped below 120 volts may "C" batbe corrected by eliminating tery and converting circuit to automatic bias. Also by bypassing plate voltage with 4-8 mfd electrolytic condenser. To accomplish this, disconnect nega"B" lead where it tive connects inside chassis and connect a 300 ohm I watt carbon resistor in series to chassis.
fI I I l l z I I I J | I I I I I I I I I I J J I I I I I I - ORADIO @ R E T A I L I N G ' S" , e)de ZnNffH S0 Scricr. To simulate r,v.c. , . In re-sctting thc automatic tuning levers first throw the antenna tsimming controt to the extreme left rnd leave it there. Tune the weakest rtrtion of the selection as sharpty as gossible and set the volume control until the volume is barcly audible, about one or two db. Leave the volumc control atone from then on.
O R A D I O RETAILING?S rrSenuie ZENITH 5528 zENITH'5902 Dead or rveak on automatic tunittg check C2, a 50 ntmf. condenser for open (part No.22-289) Oscillation or audio howl. ground the 56 detector cathode right at the socket, remove original black ground wire. Reroute the second i,f. plate wire from the lug around the 8 rurfd condenser and connect to the other side of the choke. ZENITH 56,t7 before reBlown ballhst tube placing tube check C9, a 4O mfd condenser connected to cathode of.2526.
A R A D I O RETAItING'S "Seufiw ZENITH I93' MODELS zENtTH CHASSTSs709 Strong motor-boating with switch in distance position . . . replace screen grid and plate bypass condensers marked C 4 in schematic. Dead on broadcast band, alright on l0 mmf . condenser short waves shorted in antenna transformer. This is part #22-601, CZl in diagram. zENtrHs t938 Z E N I T HA U T O M A T I CS E T S Noisy tuning on short wave band . . remove dirt and grease insulating the condenser drive shaft from ground.
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