Page 1: ...y T oW q r r f rr5r Service manual MNDBERG Tape recorder modell 12...
Page 2: ...rate recordand playbackpreamplif iersand sepa rate power amplifiersfor each channel The power outputamplifiers are ratedfor l0 wattseach The model 12 2 is the two trackversionwhile the model I 2 4 is...
Page 3: ...n r e c o r d p o s i i i o n 2 5 5 1 5 The equolizing omplifier in ploybock position 26 5 1 6 The equolizing omplifier in omplifier posilion 27 5 1 7 lhe power oulput omplifier 28 5 1 8 The ploybock...
Page 4: ...l I2 2 Half track eraseheao Half track combinedrecordand playbackhead Air gap 003 mm 00012 Frequency response 7 l i p s 30 20 000 c s l 2 dB 40 16 000c s 33 ai p s 30 I 3 000 cls r 2 dB 50 I 0 000c s...
Page 5: ...playbackpositionand amplifier position AMP is maximum 3 volts open circuit One standardtelephoneiack in parallelwith one DIN loudspeaker contactare furnishedfor connection to head pnones Powerouipul M...
Page 6: ...and in AMP position Conirolsthe recordinggain in record mode and the output volume in playback mooe Upperknob Channel1 Upper track Lowerknob Channel2 Lowertrack lndicatesthe recording level Optimum re...
Page 7: ...peaker terminals Theoutputfrom CHI is connected to both internalspeakers Indicates the positionof the tape Activatesthe mechanismin the lape recorderfor the different modesof operalion Re sets the tap...
Page 8: ...ns have the same specification Inpul impedance200 ohms unbalanced input sensitivity 150trv F i g 4 F i g 5 A t t cH2 V c H t 200 n M t c 4 0 Themechanism detaileddescription andadiustment instruction...
Page 9: ...the operatinglever ref fig 7 The switch is con nectedin serieswith lhe motor currentand is activated by the operatinglever 54 i to shut off the motor in neutralor free position The motor switch also...
Page 10: ...4 1 3 The pressurewheel assembly The pressurewheel assembly 51 3 is guided into operatingpositionby the eccentricsegment 59 17 when the operatinglever 54 1 is moved to normal forward drive Thepressure...
Page 11: ...A Z I M U T H oii J Jil u Fig Il Mounling of the heods with the pressure wheel ossembly tr uc t E sriQ Lb l 3 xfx r iatg 4 s 1 t Fig 12 The lower mounting plote wi lh the turntobles removed...
Page 12: ...p lever to the left position The tape brake 5 9 shouldbe completelydisengaged Adiustthe screwF until the spacingbetweenthe tape brake 5 I 9 and the record playback headis approx 2 mm 08 4 1 5 Thetrip...
Page 13: ...insertthe turn table 65 2 Ref fig 15 Move ihe operating lever 54 l to the fast wind posi tion Thiswill allow the supplyturntable 65 2 ro rest on the f lange 72 2 Insertone teflon washer M355 on the t...
Page 14: ...er 59 8 all the way down by usinga screwdriver The spacebetween the two clutch levers 59 7 59 8 will now be approx 6 mm 1t7o 1 Turn the cartridge 61 1l 90o clockwise and make sure that the two delrin...
Page 15: ...th the tape threadedon the recorder Thetape shouldnot touch the edges of the plastic reels in any mode of operalion Theturntablesare raisedor lowered if necessary by adding or subtractingturbax washer...
Page 16: ...on the turntable 65 1 is approx 0 5 l mm 02 04 Recheck all other po sitionsof the operatinglever and finally sealthe ad iustmentscrew B f 4 3 3 Fastwind Fig 23 The supply turntable Thesupply turntable...
Page 17: ...lrin button 59 19 on the upperclutchlever 59 2 is in the middle posiiion pressing down the springloadedlowerclutch lever 59 8 The delrin lugson the cartridge 61 l are releasedfrom any tension and the...
Page 18: ...r i p s Adiustments Theverticalpositionof the motor pulley 62 1 is ad_ justed withthe operatinglevertS fl in neutralposi_ tion Thedividing rib of the motorpulley 62 1 should be sef 0 5 mm O2 below an...
Page 19: ...ween the upperandthe lowermountingplates Zl 2 71 1 The jfj n iT ll t8 islinked t i iri esrn nt Jy t wntte the parallelarm 53 2 is connected be_ tween the lifting arm 59 lg and the tia nsfer wheel hold...
Page 20: ...3 Thetwo screws M l25 are loosened and correctposi tion of the capstan 66 2 is obtainedwhen all three legs of the tool No 5 touchesthe upper mounting plate 71 2 4 7 1 The brake for the flywheel The br...
Page 21: ...th the pressurewheel iSt l away from the capstan 66 2 and activates the tape brake 51 9 Adiustments Move the operating lever to normal forward drive position and set the momentary start stoplever in t...
Page 22: ...m 02 in f rontof theimaginary linex x whentheactuating spring 79 17 ismovedfromtherestposition lowards thefrontof theuppermounting plate 71 2 The actuatingspring shall run free inside the tape guide s...
Page 23: ...54 2 s3 4 79 34 T m M 321 32 2 4 M130 4l 3 2ry 73s...
Page 24: ...e two channels and only the amplifiersfor the upper track are therefore explainedin the following discussions Pr omp output CH1 P r e o n p o u l p u l C B 2 S w i l c h e s o o n d b i opgn rn mono o...
Page 25: ...for the equalizingamplifier in record position is shown in fig 42 The recordamplifier is a four transistor amplifier Ql06 and QIOT is a compound connectedstage Darlingtonconnection Thiscircuithas a h...
Page 26: ...3l is introducedto preventtransientoscil lations in thetransistor Q109 The components are referred to 7Yz i p s tape speed Theequalization switch is linked to the speed selectorknob and correctequaliz...
Page 27: ...lifiervia the switch Al3 Thefrequencyresponse of the equalizingampli fier in AMPLIFIER positionis flat within the audio ran9e 100 200 500 1000 2000 s000 Fig 45 The response curves for the equolizing o...
Page 28: ...from the output of the amplifier to the emitter of e301 The poientiometer R4 together with C3O2forms the treble control while the potentiometer R5 together with C303formsthe basscontrol The temperatu...
Page 29: ...oUAL AME R 603 t50K 1W R 502 100K 01 c 605 8op D601 c 602 02 5 1 9 The record level indicator circuil The schemaiicfor ihe record level indicatorcircuit is shown in tig 49 The EAM86is a combinedrectif...
Page 30: ...ed by the threetransistors Ql Q50I and Q502 and the zenerdiode D501 Ql worksasa variableresistor When the linevoltage load increases the impedanceof transistorQ1 will decrease to stabilizethe line vol...
Page 31: ...of the levers has the following three positions RECORD PLAYBACK and AMp Thetwo le_ vers can be operated individually An interlocksys tem has been introduced between lhe operating lever and the two lev...
Page 32: ...T E R C H A N N EL SPEAKERCH 2 R IG H T C H A N N E L R 1 7 5 Z 4 n NII P05lTlONS l ftg g 2 PL AYB 3 A M P R 2 1 1 8 2 5 2 3 Monauralrecordingon ch I or ch 2 Ref blockdiagramfig 39 We presumethai we...
Page 33: ...he input of the equalizing amplifier ch 2 in amplifier position the signalis then fed to the power output amplifier ch 2 The pro gramme will be reproducedthrough both internal speakers and through bot...
Page 34: ...einstabilityand oscillations The tape speed 71 z i p s is recommended for this purpose Soundon sound recordingscan only be completelysatisfactory on a taperecorderwith separaterecord and playback head...
Page 35: ...he upper edge of the tape shall run flush with the upper part of the airgapfor ch l Ref chapters5 5 tand 5 6 2 for track controlof the record playbackhead Theazimuthalignment Play back a standardazimu...
Page 36: ...the VTVM reads lV at 000 c s Set the FM MX filter switchto positionON Setthe generatorto l9Kc s and adiust L4 ch I 15 36 ch 2 to min deflection on ihe VTVM Theattenua tion between the signal levels at...
Page 37: ...TVM shows65 mV Thereadingfor the two trackversionshouldbe 95 mV Checkthe frequency to be 85 5 kc s and readiustCl20 if necessarv Set the function selectorswitch ch 2 to PLAYBACKposi tion and adiust L3...
Page 38: ...M have the same reading 5 7 14 Adiuslmeni of the equalizationcoils Ll and L2 Connect the audiogenerator to the HIGHLEVEL inputs ch I and ch 2 and setthe frequencyto f I 8 000 c s Set ihe speed selecto...
Page 39: ...M con nected to both preamp output terminals with the speaker swiich in position EXT and both function selectorswitchesin position PLAYBACK Check the frequency responsefor all speedsaccordingto the sp...
Page 40: ...1 0 0o h m sy 2 W 1 O t pF25 0V 20 1 pF 250 V20 BCIt4 BCIr4 BC ll3 Modificationsintroducedto the 1 5KohmsyzW 10 1 5K o h m s V 2 W1 O 43 KohmsYzW 10 43 KohmsVzW 10 150ohmst 4W 5 68 KohmsVzW 10 l 5 0...
Page 41: ...can be connectedfor eilher 220 volts or ll0 volts 50 60 c s 220v 50y t 6 0 Partslist To improvethe equipment minor changes and modi 3 ficationshave been introducedon the models The complele referencen...
Page 42: ...2 yellow yellow Elecironic beom indicotor boord withoul lubes Brocket for indicotor boord Tube socket for EAM86 Spring for indicotor tubes Spring for indicotor tubes Rubber tube for indicotor boqrd Vo...
Page 43: ...er for orm for equolizofion switch Piloi lomp Socket for pilot lomp Shield for pilcf lomp Microphone contoct DlN Microphone iock for 1l5 V version only Input conioct for CR PHONO ond RADIO DrN Externo...
Page 44: ...eie Delrin butfon for clutch lever Shqft for clutch levers Tronsfer brocket Brocket for com disc orm shoft Shqft for com disc orm Toke up pulley disc right Supply pulley disc left Mylor sheet for toke...
Page 45: ...eodcover Brocket for front heodcover Top cover Top cover with interlock l l5 V _ 60 c s Top cover Top cover with interlock l l5 V _ 6e c s Mounting slrew 4 x24 mm Rubber mounting front Wqsher for moun...
Page 46: ...sislors Ql l2C Tronsislor T13030 Qror l2c Bclo9B Ql02 r2c Bcrt4 u3962 Ql03 l2c Bcr13 sE400l Ql04 l2c Bclo9B Qr05 i2c Bclo9B Ql06 l2C BCIO9B Ql07 l2c Bcto9B Qr08 r2c Bcr13 sE400r Ql09 l2C BCIO7B Ql l0...
Page 47: ...W r Wr t zW 1 zW 1 zW t wr 1 z N Chongedfrom seriqlNo 742326 Chongedfrom seriolNo 742326 Chcngedfrom seriolNo 738926 Chongedfrom seriolNo 739900 5 1 o h m 22 Kohm 22 Kohm 100 Kohm 100Kohm I Mohm Mohm...
Page 48: ...20ohm 1 2Kohm 100ohm l0 Kohm I Kohm 4 7 Kohm I 20 ohm 68 ohm 33 ohm 1 5Kohm 33 ohm 9 1 0o h m 33 Kohm 5 1 0o h m 43 Kohm 220 Kohm 10 Kohm 30 ohm l Kohm 5 1 Kohm 3 Kohm I Kohm 33 ohm 150ohm 68 Kohm I 5...
Page 49: ...hm 5 I Kohm 5 1 0o h m 300Kohm 100Kohm 150Kohm I0 Mohm 100Kohm 150 Kohm l0 Mohm 1 t tN t t W z i t 1 t W 1 z W 1 t N 1 z W 1 z W 1 z W r r wrl 1 zW 1 zW 1 zW 1 tW t h w 1 z N 3 W Wirewound 3 W Wirewou...
Page 50: ...V 2 5 V 20v 1 2 5V 160v 500 v 6 4 V 2 5 Y 125 V 125V 250Y 250 v 80 pF 022 ptF 1 5p F 047 ptF 015pF ol pF l p F 15pF 2 5 ytF 2 5lrF 500 pF l p F 80 pF 2 5IF 01trF 5000pF 5000pF 1000pF 1000pF 25 prF 25...
Page 51: ...1 2 5V 5 o l o 125V 5 o o Electrolytic Elecfrolylic Tonlolum Styroflex Metolized poper Electrolytic Electrolyiic Polyester Polyester Electrolylic Polyester Polyesier Polyester Polyester Melolized pope...
Page 52: ...tr n isz F tt il q b m s F 5 __ Fr l x 106 l Rr l flB s Gl l r rlE I l I 4 s t u t x I fl rF Fig 58 Amplifierboord printedside 52...
Page 53: ...9 The power outPUi omplifier boord component side Used on tope recorders below seriol No 749500 c 308 53 Fig 60 The power outPut omplifier boord component side Used on tope recorders qbove seriql No 7...
Page 54: ...on tope recorders below seriol No 749500 R309 l t rq R320 ffiA n i T d la f__Lsrf 4li n V r C3 0 3 a ni l i_ l lAl I dlU L lul I r l ro I I lr o c 308 fr l 1 t 0 305 o B Fig 60 The power outpuf ompli...
Page 55: ...Record ploybock heod circuit boord input boord ond erose heqd circuii boord componenl side AAA An 7 t vqruc u 2848 t BC115 AC127 AC128 u 28t8 2 5E6001 AC152 sE6002 Fig 63 Conneclion of the lronsislor...
Page 56: ...O 5 8 K x R 1 0 5 1op t j g R 1 2 5 O l 6 2 0 R 1 0 6 2 7 A l 0 l I 5 c tor 100 c 2 c H l O Ul P U T c H 2 H G H L E V E L t ADJ 8tas AOJ L O w L E Y E L M X F I L T E R t9 kft F L I E R i n s 2 2 K _...
Page 57: ...c 4 0 4 r 3 0 NIC r l9 t 0 J 111 l 5tl r o2 c 407 t 0 M o D E L 1 2 2 t w o t r o c k s Sp cilicotions os Mod l 12 4 fo kocks xept l o r t h i o l l o i R r 4 8 R 1 4 9 R r 5 0 l 0 0 6 h m C 1 1 1 0 0...
Page 58: ...the flywheel and ihe speedtransfer wheel are mounted in self lubricating bearingsand shouldusuallynof be lubricated lf however it should be necessary to lubricafe the bearingsfor any reason useTeresso...
Page 59: ...Tandbcrgs Radiofabrikk A S Kjelsas TAND BER GS RADIOF A BRIK K AZS P O 8 9 Korsvoll Oslo 8 Norway T a n d b e r g sR a d i o f a b r i k kA S d i v K j e l l e r...
