Dejur-TMB820-tape-sm 电路图 维修手册.pdf

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1、F.*toToFACT* FolJt DEJUR MODEIS TK-82O, TMB-82O qR Eo aq 3= cd E(ll -l 6 llra ay l- GENERAL I NFORMAT ION The DeJur Dual Professional Tape Recorder Models TK-820 and TMB820 use standard I/ 4 magnetic tape and dual track recording. Two sets of erase and rbcord-playback heads are provided thus elimina

2、ting the necessity of stopping and reversing the tape reels at the end of each track Control is by pushbuttons which includes a momentary hold button for tem- porarily stopping recording or playback. Complete facilities for all types of inputs and outputs are provided as well as remote controls, Rev

3、ersing time at 7 L/ 2 io p. s. is 4 seconds and at 3 3/ 4 i. p. s. is I second. Using both tracks of the tape the recording time is approximately as follows: 3 3/ 4 Speed (6rg 19c pu IE btr I i/f ReeI Size 5 (600 ft. ) ? (1200 ft. ) I hour 2 hours 7 L/ 2 Speed L/ 2 hour I hour These units are design

4、ed to operate on 60 cycle ll5 volts AC supply only. Before con- necting to a line supply be absolutely certain it agrees with the above specifications. Supplied By: DeJu r Amsco Corporation Northern Blvd. at 45th. St. Long lsland City I, New York fhis moleriol compiled ond published by HOWAnD W. SAn

5、S Radio-Phono-TV, Microphone plus re- empty reel and reel of tape from the storage com_ mote control (2 high, I low impedance). partment. Outputs: 2. Depress the stop bar. This releases all buttons except the track buttons. Depress the Track I Built in speakers, phone-speaker, power button. amplifie

6、r. 3; Set speed control switch to the extreme right Page 2 RadioFans.CN 收音机爱 好者资料库 or left position, 7 l/2 i.p.s. or 3 3/4 i.p.s. re- spectively. 4. Plug the AC line cord into the receptacle in the back of the recorder and into a convenient power supply being certain that outlet supply is 110 volts

7、AC. Speed Change Knob: The speed change knob is an electrieal slide switch and must be kept at the end of its slide/either right - 7 I/2i.p.s., or left - 3 3/ai.p.s. toinsure proper electrical contact. Threading The Tape: l. Place empty reel on right hand spindle with reel slots engaged on protrusio

8、ns on reel pan. 2. Place full reel of tape on left hand spindle with gtossy side of tape out. Unwind about 14 of tape from reel. 3 Insert section of free tape into tape slot. 4. Insert end of tape into slot in empty reel. Turn reel by hand 2 or 3 turns to secure tape. To Record From Microphone: l. I

9、nsert microphone cable plug into jack marked Microphone on back of recorder. 2. Turn Input Selector Switch to Micro. 3. Turn on-off-loudness control cloekwise until click is heard and allow about 30 seconds for unit to warmup. Lightundertape counter dial will glow when set is turned on. 4. Press Tra

10、ck I button. (Feeds from left to right) 5. Depress Locking button, and while holding lock button down, depress Recording button. 6. While holding down Locking button, set correct recording level by adjusting loudness control until Magic Eye just closes on the loudest notes ?. To start recording rele

11、ase Locking button. NOTE: The tone control does not function during re- cording. To Record From Radio-TV-Phonograph: l. Insert the phonograph pickup plug into the Radio-TV-Phono input jack. 2. Set selector switch to Radio. 3. Proceedasdescribedunder To Record From Microphone. NOTE: On phonographs ha

12、ving a standard pin plug a telephone type plug adapter will be required. 4. For Radio or TV recording, connect patch cord to the voice coil of the radio or TV speaker by means of the alligator clips. Plug into Radio-TV- Phono input jaeks. 5. Set selector switch to Radio. 6. Proceedas describedunder

13、To Record From Microphone. ?. Remove patch cord when recording is com- pleted. To Use Second Track: 1. Depress Stop Bar. 2. Depress Track II Button. 3. Proceedas describedunder To Record From Microphone. NOTE: Track II may be used without stopping the motor by merely depressingthe Track II button wh

14、ile the unit is operating. The unit takes about 4 seconds to reverse at ?.5 i.p.s. and one second at 3 3/4 i. p. s. To Play Recordings: l. Turn on unit with Loudness control knob Depress Stop Bar. 3. Set the Speed Control Switch to the speed at which the recording was made. 2. Place tape on left han

15、d reel as described under Threading The Tape. 4. Depress Track I button. 5. Depress Play button. 6. Adjust Tone and Loudness controls to desired listening level. High Speed Forward Or Reverse: When it is desirable to play a certain portion of the tape it is not necessary to rewind or play the en- ti

16、re tape. Bydepressing the Forward or Reverse button the tape will advance (or reverse) at a rapid speed. Several minutes of normal recording can be skipped in a few seconds by this procedure. Tape Timer: The tape timer provides complete selectivity and immediate location of any part of the recorded

17、tape. By setting the tape indicator to zero when be- ginning each reel, the numerals on the indicator will act as a ready reference to any desired portion ofthe recorded tape. Permanent records may be kept on the tape box allowing pin-point selection of any re- cording. To Edit And Splice Tape: NOTE

18、: Recordings to be edited should be limited to one track because it is impossible to edit one track without affecting the other track. l. The tape may be edited by cutting out un- wanted portions or by joining selections in another sequence. Announcements may be inserted between -l AU 6DE |9C 9u _3

19、Fg Ftr B i/r Page 3 RadioFans.CN 收音机爱 好者资料库 Figure 2 selections, etc. Unused sections of tape may be spliced together for re-use. 2. Best results are obtained by cutting the tape at a slight diagonal. Join ends together with splicing tape ontheglossyside, and cutting off any excessive width. Erasing

20、 Recorded Material: The erase head operates automatically when the Record button is depressed erasing any previous recording while a new recording is being made. To erase material without making a new recording depress the Record button and turn the loudness control to the minimum position. To erase

21、 the second track de- press the Track II button and proceed as above. Motor Drive Circuit Operation: The motor is an inside-out HYSTERESIS SYN- CHRONOUS motor, exceptionally heavy to insure con- stancy of speed. Reversal is obtained by PHASE SHIFT. Themotor containstwopairs of contact blades (Gl and

22、 G2) both being closedwhenthe motor is stopped. With Track I depressed, all other buttons up, switch off, 7 L/ 2 i. p. s. speed, the motor circuit is as follows: 1. Contact M21-2 closed on 165 V. line. 3 Page 4 Contact M15-5 closed for clockwise rotation Contacts M19-1 and Ml9-2, closed. 4. Contact

23、bridge 28-18, 2C-lC, 8I-?I, 8K-7K closed on motor relay circuit. 5. Governor contacts Gl and G2 closed 6 Contact M19-3 open. When the unit is turned on motor relay M-19 energizes through bridge contacts, closes contact M19-3, and opens contacts M19-l and M19-2. This stops motor and releases prssure

24、solenoid. NOTE: Depressing any of the other buttons breaks bridge contact string (4 above) but motor re- lay remains energized due to contact M19-3 being closed. For this reason buttons must be pressed all the way down to close shorting contacts 4A-3A, 4C-3C, 5H-4H, or 5J-4J. These contacts temporar

25、ily short the power to the motor relay opening contact M19-3, and closing contacts M19-1 and M19-2, allow- ing motor to start. Recording Button Depressed : 7 L/ 2 i. p.s. 1. Contacts Gl and UIII closed. 2. Relay M21 energizes shifting contact MZL-L to 260 VAC supply to motor. 3. Just below normal sp

26、eed centrifugal switch Gl opens, de-energizes relay M21, changes contact 2. Spindle And Upper Shell Solenoid Coil Felt Wisher Clutch Disc Washers Lower Shell SPindle Drive Belt Fiber Washer Steel Washer Steel Washer Hexagon Adj. Nut Frame Hexagon Adj. Nut r+U + MUIING Sw STOP BAR F GUIDT PINS ,M0T0R

27、 B0ARD i l I l- 30y 5h4W 0st0 lr ONLY PA( PAGE 8 Figure hl rH c t9 F o;i vl tK 30 idu IFJ H Bb M2I-2 from 260 vAC to 165 VAC suppry. FigUfe 4 3 3/ 4 i.p. s. Relay M2l does not operate at 3 g/ 4 i.p. s setting due to contact U3 being open. Motor starts on l6b VAC. Changing From Track I to Tk II Witho

28、rt Stoppiry With Track I depressed head relay Ml? is not energized. When Track II is depressed relay (Ml?) operates switch (Mlb) as follows: l. M15-5 changes motor return circuit shifting phase of motorl motor reverses. 2. M15-1 changes power supply from left clutch to right clutch. 3. Ml5-2, Mlb-3

29、and Mlb-4 change the corre_ sponding ERASE, and RECORD-PLAYBACK heads. 4 Contacts IF-2F are closed temporarily when Track II button is completely depressed. This en_ ergizes changeover assisting relay MIZZ, closingcon- tact Ml6-t and opening contact Ml6-2. This bpens motor circuit. (Shown in heavy l

30、ines on schematic). 5. When motor stops centrifugal switch closes closing contact Gl. This energizes relay M2l which changes contact MZI-? from l6b VAC to 260 VAC lotor supply, and closes contact MZI-I. Relay M22 falls out closing contact Ml6-2 completing motor cir- cuit. 6. Motor comes up to speed

31、and shifts to l6b VAC supply as described earlier. NOTE: Tooverride any previously set operation it is necessarytopush the button completely to the bottom. The unit may betemporarily stopped by depress_ ing the momentary Stop button (black top). When this button is released the unit immediately rest

32、arts. For permanent stops depress the Stop Bar. Fast Forward Or Fast Rewind: When the Fast Forward or ,Fast Rewind button is.pressed, current through the pressure solenoid (M20) is interrupted by contacts jA-tA o 1D-2D respectively. In Fast Forward the right clutch magnet is energized through contac

33、ts 9A_gg while , in Fast Rewind the left clutch magnet is en_ ergized through contacts ?C-?D. When the clutch magnet is energized a practically solid coupling exists between the upper and lower halves of the clutch as_ sembly. Relay Mlg is de-energized by contacts 3A- 4A or 3C-4C respectively and co

34、mpleies the motor circuit. ADJ USTMENTS Disassembly Instructions : 1. Remove the two control knobs, the speed change knob and four round brass screws from the cover plate. Remove cover plate. PAGE 9 2. Unscrewsixsmall nuts holding chassis to the cabinet. 3 Carefully lift the chassis partially out of

35、 the cabinet being careful not to damage fuses on the back of the chassis or contacts on the front of the chassis. 4. Unplug speaker leads and remove chassis completely from cabinet. NOTE: Do not lift chassis by clutch assemblies as serious damage to the clutches will result. SeparationOf The Tape T

36、ransport Mechanism And The Amplifier: 1. Unplugthree Sprong plugs leading to the head mounting plate, the 12 prong plug on top of the trans- former, and the two prong plug from the program in- dicator. 2. Unscrew 14 screws along the rim of the top frame. 3. Carefully lift off the top frame being car

37、eful not to damage the push button switches. NOTE: The external cage of the motor rotates - Be absolutely certain tat it is well clear of any obstructions before switching on. Clutch Replacements: 1. Unsolder the two leads to the clutch solenoid and remove the upper clutch spindle (1) 2. Insert a sc

38、rew driver into the slot in the solenoid and unscrew the bottom locking nut (12). 3. Lift out the clutch assembly. 4. Install the new assembly in the order shown in Figure 3, starting with piece 11. The axial play of piece (6) should not exceed /64th inch. 5. Tighten the bottom lock nut (12) lightly

39、. 6. Place two gauge washers between the clutch solenoid and the upper clutch shell. Rotate the shell and check the clearance between the felt insert on the upper shell and the top surface of the drive pulley. The upper shell should be just clear of the drive pulley. If so, remove one gauge washer a

40、nd again check the clearance. The upper shell should just touch the drive pulley causing a smooth friction. Proper spacingcan be obtained by turning the solenoid clockwisetodecreasethe space between the shells and counterclockwise to increase the spacing. 7. Make sure both clutch shells are level wi

41、th each other. 8. Remove both gauge washers and tighten the lock-nut (12). 9. Installupperclutch shell (1) and replace shell holding bracket. Resolder the sorenoid leads. 10. Thread a tape and check the unit for correct mechanical operation of the tape transport mechanism. Record-Playback Head Adjus

42、tment: The position of the Record-Playback and erase Page I0 heads is very critical. The adjustment should be made using a tape on which a 6000 c. p. s. note has been re- corded on a standard machine. The adjustment is accomplished by altering setting of the three serews mounting the Record-Playback

43、 head sockets to the chassis. Use a VTVM connected into the high im- pedance output. Adjust for maximum output. The heads are then adjusted to bring the gap of the heads in close contact with the coating of the tape. Adjustthe top edge of the LEFT Record-Playback head about l/ 64th inch above the to

44、p edge of the tape with the tape running. Adjust the bottom edge of the RIGHT Record-Playback head below the bottom edge of the tape. The edge of the pole pieces of the erase heads should line up exactly with the corresponding edge of the tape. The tape should run between the tape guide posts in an

45、absolutely straight line. This is very important, and correct adjustment of the tape guide posts is therefore critical. Pressure Solenoid, Pressure Roller, And Pressure Slider: The pressure roller and slider transport the tape over the head assemblies at an even speed and is operated by the pressure

46、 solenoid. The pressure roller should exert pressure against the tape equiva- lent to about one pound pull on the tape To adjust loosen the lock-nut on the back of the solenoidandrotate the core until the desired pressure exists. Tighten lock-nut. A screw-driver slot is provided for turning the core

47、. Hum Control Adjustment: The hum level is adjusted by R6 to a minimum on each Playback channel. The level should not exceed l/ 100th of a 1000 c. p. s. recording made at full modulation level on both tracks and at both speeds on Playback at the maximum setting of the loudness control. This correspo

48、nds to a hum level of minus 50 db. R6 is finally adjusted to a compromise setting that does not exceed this level at either speed on either track. Adjustment For Slow Tale-Up Reel: Make adjustment for proper setting of the two shells as outlined under Clutch Replacement. Bias Adjustment: Bias curren

49、t to each recording head is approxi- mately I ma. when recording. To check insert a 100 ohm 1/2 W carbon resistor in series with the head to chassis return lead. The voltage drop across the resistor should be 100 mv l0% Adjust C38 to obtain correct bias. Highfrequencycurrentto erase head is approxi- mately 50 ma when recording.-Ti-ace a l0 ohm l/ 2 watt in series with the head to chassis return lead. The voltage drop across the resistor should be 500 mv. The core of the oscillator coil (L-2) is adjusted to obtain this reading. NOTE: If the erase head current is adjusted th