Tascam 122 Service Manual Download

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Summary of Contents for 122

Page 1: ...TASCAM TEAC Production Products SERVICE MANUAL MASTER CASSETTE DECK Effective April 1981 810041 5704008406...

Page 2: ...Record circuits 34 7 12 Dolby Noise Reduction effect 50 3 14 Dolby HX circuit 37 7 13 Dolby HX effect 50 4 Parts location 41 7 14 Headphones output level 51 5 Essential maintenance 7 15 Bias trap adju...

Page 3: ...mm 19 x 5 13I1S x 13 9 1S 19 13 1S Ibs 9 kg net 50k ohms unbalanced 10k ohms or less 14 dBV 190 mV 24 dBV SO mV 25k ohms or more unbalanced 3 5k ohms or less 10 dBV 0 3 V 7 5 dBV 0 42 V 100 mW Maximu...

Page 4: ...on If the REC MUTE button is pressed while a re cording is being made only an erase signal is applied to the tape To release the record muting mode press either the play or PAUS E button INPUT LINE 2...

Page 5: ...panel LINE IN j3cks LI NE 2 Selects the signals applied to the front panel LIN E 2 jacks TEST Use this position when setting the bias and recording level calibration controls using a separate signal...

Page 6: ...eter amplifier PCB CONTROL SECTION 3 1 SYSTEM CONTROL IC 3 1 1 Pin assignments Output Control input Ir r 8 F FWO FAST REW PLAY PAUSE AR US01 M54410P TO P VIEWI PLAY STOP f fWO MEMO REW PAUSE REt GNO _...

Page 7: ...SE PLAY REW FAST F FWD Operating mode PLAY L L H L L L PLAY mode STOP L L L L L L STOP mode F FWD L L L L H H F FWD mode REW L L L H H L REW mode PAUSE L H L L L L PAUSE mode REC and PLAY H L H L L L...

Page 8: ...s and voltages are given below 8 Note A diagonal line indicates that the current mode remains unchanged and PAUSE are combined the record reproduce or record pause mode wiH be enabled regardless of th...

Page 9: ...O which is the state entered when the stop button is depressed In this way the deck enters the stop mode when power is turned on 2 When a cassette is loaded When a cassette is loaded cassette in swit...

Page 10: ...rd pause modes to per form the following mechanical functions Raising the head base to bring the erase and record reproduce heads into close contact with the tape 10 Lifting the pinch roller to the pa...

Page 11: ...s cut off I As 0605 is off 0515 turns off as its base current is cut off m As 0515 is off the solenoid is reset because its holding current which was flowing via path CD is cut off At the same time C5...

Page 12: ...y circuit The positive side of capacitor C526 is con nected to the output of the 23 V voltage regulator This regulated 23 V is used as the power source for the amplifiers and also as a reference volta...

Page 13: ...Reproduce delay circuit The circu try is designed so that in the repro duce mode the pinch roller solenoid operates after the head base solenoid has completed operation The reproduce delay circuit del...

Page 14: ...122 Depress PLAY bunon Head basa solenoid is held 13V Pinch roller solenoid is held 13V Reproduce mode signal is held Reproduce mode Fig 3 7 Flowchart of solenoid operation lin reproduce mode 14...

Page 15: ...itted from the reel motor to one of the reel disks during the reproduce fast forward and rewind modes by the processes shown in Fig 3 9 3 11 as seen from the front of the deck As seen from Fig 3 9 and...

Page 16: ...creases since its base level falls from 13 V divided by RS10 REW 0 OUT R622 U601 F 1 5 V iv R6ZO and RS09 This results in a decrease in OSOS s collector current the current supplied to the motor and i...

Page 17: ...1 R519 R520 CD 0518 e 691 REEL I g MOTOR L 0509 R50 8 0521 ROLLER T 1 I I I R694 PI Ol I I I 6 I I I I I L L HIJ L 6 0 041 r f I 0 0 OUT P S i 0602 I i do U601 Fig 3 12 Reel motor drive circuit repro...

Page 18: ...12 R612 OUT PAUSE II R613 OUT U601 HEAD BASE T 0694 SOLENOID L692 3 6 TAPE END DETECTION CIRCUIT See Fig 3 15 The ring magnet shown in Fig 3 15 is mount ed on the counter pulley shaft and rotates whil...

Page 19: ...ts to charge C610 as soon as U601 P LAY 1 2 R6 11 OUT FAST 1 4 0 6 10 I STOP I OUT 606 2 STOP F N IN L693 C60 6 L _4_ME_MO _ _ _ _w _____ SO_L_EN_O_ D 662 Q613 cu rrent from path completes charging C6...

Page 20: ...cally R601 r C60l I I STOP R606 r 2 4 C606 PLAY IN REW 13 OUT U601 R502 0504 STOP IN MEMO IN rC507 h If the MEMORY switch is set to PLAY when 0691 has turned on a reproduce mode signal L level is outp...

Page 21: ...e a rise of the output voltage results in an increase in the current of 0520 an increase of the current on path and a decrease of the cu rrent on path CD in this sequence POWER RECTIFYING SMOOTHING TR...

Page 22: ...s POWER TRANSFORMER 0533 Fig 3 18 DC power supply system R527 VOUT Q512 x 23V VBE R526 R527 R530 VOUT Q513 x 23V VBE VOUT Q507 where VBE is 0 6 UNREG 39V to 0534 R517 0 2 I 0531 UNREG 19V J C506 R516...

Page 23: ...ON DIRECTION CONTROL 1 TORQUE CONTROL CAPSTAN MOTOR MS92 RSI8 c J HEAD BASE RSI2 SOLENOID I brNlAY 6 uA f r lS92 esol I REEL MOTOR MS91 DELAY CIRCUIT DRIVE CIRCUIT U601 o e 0509 RSI9 i 1EM RYJ RStt SO...

Page 24: ...14 turns on and the reproduce amplifier is released from muting Fl60Z PAUSE 6 IN II PAUSE OUT C602 l U601 PAUSE R613 r 5 R614 3 9 2 Pause mode To explain operations in the pause mode we divide the sys...

Page 25: ...of fast forward mode r r STOP r R601 I C601 1 R604 C604 1 R606 2 4 C606 J PLAY IN IJ R501 REEL MOTOR REW DRIVE CIRCUIT OUT R50Z 0501 0505 REW IN 0504 R518 COUNTER SWITCH S696 FAST 14 STOP OUT IN 1 C5...

Page 26: ...n As Ql04 is on the signal line of the moni tor ci rcu it is shorted to ground to prevent the generation of click noise when power is switched on e When C521 is fully charged Q522 turns off as its bas...

Page 27: ...e As 0112 is on the base current of 0103 flows via path and it is on so the reproduce equalizer amplifier is muted Because the signal level is low in the 0103 circuit its collector is grounded to red...

Page 28: ...through the loop consisting of C135 the emitter of Qll0 the base of Qll0 and C135 As the discharging of C135 proceeds the discharging current the base current of Q110 decreases and Q110 turns off slow...

Page 29: ...r I REC MUTE I R640 r CONTROLLEO 8 t23V R622 kRI97 6 BIAS OSC UI03 6 RI6Z Q R623 0604 RI66 VI Rch R266 CI44 REC WUTE FLIP FLOP r 1311 R647 R641 R643 R645 R646 R653 L LEVEL ONLY DURING RECORD REPRODUCE...

Page 30: ...1 drops to L level 0604 turns off as its base current is cut off while 0611 turns on as base current is applied to it Therefore even if 0609 turns off with the REC MUTE flip flop reset 0610 remains on...

Page 31: ...e f In the Dolby decoder L102 and C112 form a low pass filter with a cutoff frequency of ap proximately 22 5 kHz Ll03 and Cl13 form a band elimination filter These filters remove undesirable frequency...

Page 32: ...rated output level at the OUTPUT terminal is 7 dB when the level at TP1 is 580 mV Dol by level At this time the VU meter reads 3 VU 3 12 2 Phone amp lifier The deck is provided with PHONES control R7...

Page 33: ...l by the same amount so that meter sensitivity is raised by 20 dB 2 Peak indicator circuit See Fig 3 28 and 3 29 Semi fixed resistor R72 determines the operating level of the peak indicator When the s...

Page 34: ...1 Line input circuits See Fig 3 30 The deck has two line input circuits LINE 1 is provided at the back of the deck and LIN E 2 on the front panel The INPUT switch deter mines which line input is used...

Page 35: ...304 R309 4 6 2 RI9 R316 I INPUT 3 MPX C310 NR 2 FILTER R315 NR HX 6 U305 OUTo 1 L L _ _ _ _ L ___ MONITOR I CIRI UIT r j 1 C305 SYSTEM Fig 3 30 Line input circuit LINE AMPL UI04 RI79 RIB7 C14 0 RI93 O...

Page 36: ...onance circuit becomes infinitely large preventing bias current from entering the record amplifier if this should happen the ampli fier would be saturated and the Signal distorted The record signal ou...

Page 37: ...mid range components into consideration sacri ficing frequency response at high frequencies However for maximum sensitivity at bass and mid range frequencies bias should be much higher than at high fr...

Page 38: ...zation is that of curve shown in Fig 3 37 With curve the amount of boost at high frequencies is very large but the level of high frequency components of the input signal is low Therefore distortion wi...

Page 39: ...itions NR SYSTEM switch NR HX SPEED switch STANDARD BIAS switch Co Cr02 or NORMAL 2 Variable bias circuit The output of the selector circuit is applied to pin 2 of U303 d a U303 d is an inverting ampl...

Page 40: ...R329 R327 30 I SEND I R304 N R S 7 Y S TE M 1 r TO DBX ENCODER _____ J HX OOL8Y SYS TEM t I 3 OUT db IEXTI Rc _ JL VARIABLE EOUAlIZER CIRCUIT L ______________ _ _________ _ ___________ J L _______ i...

Page 41: ...WER TRANSFORMER I N OUT PCB ASSY JOINT PCB ASSY LEVEL SWIT REEL MOTOR COUNTER ERASE HEAD TENSION ARM PINCH ROLLER CAPSTAN MOTOR REC PLAY HEAD CASSETTE HOLDER FAST FORWARD SOLENOID HEAD BASE SOLENOID P...

Page 42: ...668B or equivalent Hewlett Packard Model 204C or equivalent Range 0 to 1 MHz Sensitivity 0 1 V RMS Impedance More than 1 MD less than 25 pF Range BO to 40 dB Impedance More than 1 MD less than 25 pF 1...

Page 43: ...location 6 2 MICROSWITCH A ASSEMBLY CLEARANCE 1 Insert a blank cassette and close the cassette holder 2 Loosen the two screws on the microswitch A 3 Move the switch so that actuator of the switch cont...

Page 44: ...eel taking up the tape in each mode so that the measurement is not influenced by the tape s inertia The fast for ward torque must be in the range 90 160 g cm 1 3 2 2 oz inch and the rewind tor que mus...

Page 45: ...reproduce method Record a 3 kHz signal on blank tape rewind the tape and re produce the recorded signal NOTE When measuring using the record re produce method the recorded section should be reproduce...

Page 46: ...122 46...

Page 47: ...a VTVM to the OUTPUT terminals as shown in Fig 7 1 Play test tape MTT 150 to check that the phase dif ference between the Land R channels is less than 45 Reproduce the 10 kHz 10dB signal from test tap...

Page 48: ...r the setting of the reproduce and bias levels 7 1 and 7 4 and VU meter 7 2 is complete The following items 1 5 indicate the standards levels and setting orders of each control METAL 1 Connect the mea...

Page 49: ...Record an input signal of 14 dBV 400 Hz on blank tape and play it back to measure the distortion of the output signal 3 The value should be less than 1 0 for any of the tapes used For the tapes to be...

Page 50: ...t the EQ and BlAS switches to match the blank tape used and the MONITOR switch to SOURCE 50 3 Load the blank tape and put the deck in the record pause mode 4 Apply a 14 dBV 1 kHz signal to the LI NE 1...

Page 51: ...etting the MONITOR switch to TAPE 4 While recording and reproducing the signal turn the BIAS LlR R35 R45 clockwise to obtain the maximum value Lmax of the VU meter When observed at the OUTPUT terminal...

Page 52: ...122 I 8 EXPLODED VIEWS AND PARTS LISTS EXPLODED VIEW 1 52...

Page 53: ...6000 Cord AC Power EJ Cord AC Power IU K J 2 50 5800059201 Bracket Switch 5350oo8300 Cord AC Power iAJ 2 51 5124022000 Jack PHONES 2 52 5200013700 PCB Assy SW IMEMORYI UI 5534660000 Strain Relief AC P...

Page 54: ...J l 03f 10 33 1 I 110 0 2 1 2 6 V 0 I t1 1 i x a lx 2 j I 5 J I or 0 1 9 O A J I E 2 I OJ l Oiog f r f 9 E r cg M 6 1 cj x Q I 1 e 3 2 N I I l 7 t W 04 IO SA 291 9 26 l KZ S 3 1 2 A AUSTRALIA EI EURO...

Page 55: ...BOARDS AND PARTS LISTS PC Boards shown viewed from foil side LEVER SWITCH PCB ASSY I o 3 o IOo OO56J IOOV it 114h 52 0 R46J 130 wv 4360 0068I1COV II I C431 o D0821100V 460 8 2_ Wr Jt4 9 82k R4 8 910 M...

Page 56: ...I 122 EXPLODED VIEW 4 57...

Page 57: ...2 1 r o o 001 0 1 1 CI XlIr1rcx I t o JJ o O 6 il 1 1n n 1t C u C I I 1 1 1 1 i I OO loOO o 11 0 1 if i f 1 l 4 C 3 if 0 0 2 a C I O G J e W O O U o e o uJOQ t C204Q 111 Wi W I w IlUJ n o ocnr cov il...

Page 58: ...10J lF 16V R305 W 05 5183066000 220P C3 20 C420 5172996800 Elec 2 2uF 50V R306 5183066000 220n C321 5170425000 Mylar O Ol uF 100V 5 R307 5183086000 1 5kP C322 C422 5054330000 Dip M ica 150pF 50V 10 R3...

Page 59: ...064000 180n Rl17 R217 5183064000 180n Rl18 R218 5183082000 lkn Rl1 9 R219 5183118000 33kn Rl20 R220 5183058000 loon UI u s A A AUSTAALIA REF NO PARTS NO R121 R221 R122 R222 R123 R223 R124 R224 R125 R2...

Page 60: ...00 Connector Plug 6P B LK 5122130000 Connector Plug 6P WHT 5122185000 Connector Plug 4P BLK 5122127000 Connector Plug 3P WHT 5122131000 Connector Plug 7P WHT 5 5 5 5 5 5 10 10 10 10 10 I I REF NO PART...

Page 61: ...RTS NO DESCRIPTION CARBON RESISTORS All resistors are rated 5 tolerance and 1 4 watt R501 5183112000 18k 1 R502 5183086000 1 5k 1 R503 5183094000 3 3k 1 R504 5183142000 330k 1 505 5183100000 5 6k 1 R5...

Page 62: ...0000 15kn R720 R820 5183082000 lkn R721 R821 5183040000 18n U U S A Parts marked with require longer delivery time than regular parts REF NO PARTS NO DESCRIPTION C701 caOl C702 ca02 C703 C803 C704 ca0...

Page 63: ...8 8 9 8 9 2SA733P 2SA933LNS 2SC1327T 2SC1684S 2SC1841 E 2SA934R 2SC2060Q 2SB750 2S0880Y 2SC1844F C B E 2SC945AK 2S0655E C B C B E C C C B B B E E E E r v E C B B C E 2SC1636 2 2SC1636 C B Q E E C B 2S...

Page 64: ...A Round Head Tapping Screw A Type B Binding Head Screw F RTB Round Head Tappin Screw B Type mma F Flat Countersunk I Head Screw SETSCREW SF Hex Socket Setscrew Flat POint D 0 Oval Countersunk Head Scr...

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