Roberts-1640-tape-sm 电路图 维修手册.pdf

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1、SERVICE MANUAL 1B40-1B50-1BBDD-1B70 TAPE RECORDERS _;. ,IMJ $2.50 RadioFans.CN 收音机爱 好者资料库 MODELS 1640, 1650, 16600, 1670. !KEYED TO ILLUSTRATION AT RIGHT! 1. Supply Reel Holder 2. Supply Reel 3. l eft Channel Spcocr (Not in 1660D. Outboard In 1670) 4. Tope Guide Roller 5. Automatic Shut-Off lever 6.

2、 Drive Cop1tan Storage Post 7. Index Counter 8. Editing Guide 9. Take-up Reel Holder I 0. Toke-up Reel I I . Right (ronnel Speaker (Not in 1660D. Outboard in 1670) 1 2. Drive Capstan 13. Pinch Wheel 14. Paue lever 15. Rewid/ Fasl Forward Control 16. Stop/ Storl Con1rol 17. l eft Channel Miaophonc In

3、put, 18. Right Channel Microphone Input 19. l eft Channel Volume Control 20. left Channel VU Meter (Oual Purpose Meter on Madel 1640) 21. Modl!l 1640: left/ Righi VU Meier Switch Model. 1650 and 1670: Monilor-NormaiMule Speqkcr Switch Model 1660D: R/ l - NOII!IOI l / R Channel Transfer Switch 22. Ri

4、ght Channel VU Meter (Not in Model 1640) 23. Right Channel Volume Control 24. Left Channel Play/ Record Switch 25. Right Channel Ploy/ Record Switch 26. Tone Control 27. Power Switch 28. Record Indicator light 29. Power Cord Connection 30. Stereo Headphone Jock ( 1650 t forward operations. This also

5、 mules the ound during these modes. Stop-Start: Starts tape movement i11 Play or Record position. Stops tape movement when moved lo the Stop position. Rewind-Fast Forward: Fast Forward position advances U1e tape onto the take- up reel at a fast rate of speed. Rewind position winds the tape onto the

6、feed reel at a fast rate of speed. Pause Lever: In t.he Up posilion, pinch roller is moved away from capstan, and take-up torque is removed from take-up spin- dle. Tape stops instantly. This permits an adjustment of the record level without tape movement. Vhen lever is re- tmned to Down position, th

7、e tape movement begins. Index Counter: Provides a means of locating desired selections on a reel of tape without skipping and hunting. Hum Adjustment Controls: On Lhe lear paneL next to lhe A.C. Receptacle are two openings, these are the Right and Left Channel hum ad- justing Potentiometers. They ar

8、e screw driver adjustment. Without tape on the unit, turn the volume up full and ad- just the controls for minimum hum on each channel. Auto-Stop Switch: When tape holds the auto-stop switch Up, the motor circuit is completed and the motor runs. If the tape breaks, runs out, is of insufficient tensi

9、on, the switch lever fails, breaking the circuit, shutting off the motor. INPUT AND OUTPUT JACKS Microphones: A micropho11e input is provided for each channel. These input jacks are located on the front panel to the left of the left channel volume control. Note: When using the Phone-Radio inputs, th

10、e mi- crophone plugs must be removed from the mi- crophone jacks. Phono-Radio Input: Each channel is provided with a Phono-Raclio input for making direct recordings from a radio. phonograph, or tuner. These inputs are located on the rear panel. Outputs: 1660D . There are two high and two low level p

11、reamp outputs. each adjustable by the volume controls. These out- puts are used to collllect the 1ecorcler playback system to an external power amplifier. The output jacks are located on the rear panel. The high level outputs are used with standard tube type amplifiers that have tu_ner, auxiliary or

12、 other high level inputs. The low level outputs are for solid state amplifiers. Te5ts will show which is best for each individual case. The high and low level outputs are low impedance cath- ode follower outputs allowing for lvnger interconnecting c.:ables without line losses. 1640 . On the rear (Ja

13、nel are two external speaker jacks and two high impedance preamp outputs. 1650 ; the record switches down in record mode. 7. Start signal source to set recording level. VU Meters should read -3 to - 7 on the average. 8. Release the Pause Lever (down) to start tape. Tracks 1 and 3 are now being recor

14、ded. 9. When recording is completed, or when the end of the reel of tape is reached, return start/stop control to Stop position. Record switches are automaticaUy re- leased to return to play position. 10. To record tracks 2 and 4, remove full reel from take-up spindle. turn over and place on supply

15、spindle. Proceed as in steps 2 - 9. To Play a Stereo Recording: 1. Connect recorder to proper power source with power cord provided. Turn power switch to Power On. 2. Thread the tape. Set Index Counter to zero. 3. Locate desired starting point by using Fast Forward- Rewind knob while observing Index

16、 Counter. 4. Turn Start-Stop knob to Start position. Adjust volume for each channel. Both tracks of a 2-track stereo tape or tracks 1 and 3 of a 4-track stereo tape will now be played. 5. Tape may be advanced rapidly or rewound, after Start- Stop knob is placed in stop position, by using Fast Forwar

17、d-Rewind knob. 6. To play tracks 2 and 4 of a 4-track stereo recording after tracks 1 and 3 have been completed, do not rewind tape. Remove full ree from takeup spindle, turn it over. and place on feed spindle. Proceed as in Steps 2-5 above. Monaural Recording and Playback: Proceed as indicated for

18、stereo operation but use only jacks. controls and switches for one channel. Volume con- trols for the unused channel should be set at zero. To record four monaural tracks. use left channel first. recording track 1. Reverse tape by removing full reel from Lakeup spindle, turning it over. and placing

19、it on the feed spindle. Continue to use left channel while recording track 4. Reverse tape and use right channel to record track 3. Rever.se tape again and continue to use right channel in order to record track 2. To play back four monaural tracks. use the same sequence of tape sides and recorder ch

20、annels as when recording. 5 6 SOUND-WITH-SOUND RECORDING This is a procedure by which you may record yam favorite orchestra on one channel, and then play or sing with the re- cording in such a manner as to make the playback sound as though you were right there . with the orchestra. Or it may be used

21、 for language study. with the teachers voice on one channel and your responses which may be erased and re-re corded as often as desired) on the other channel. ROBERTS Language Laboratory Tapes. available from your Roberts dealer, have tne instrucors voice pre-recorded in this manner in four differe.

22、nt languages. PROCEDURE: 1. Make a master recording on Track 1. using Left chrumel only. Turn Right channel volun1e controls to zero and fol low procedure m1der To Make a Stereo Recording, using Left channel only. 2. Rewind tape. 3. Record on Track 3, using Right channel only while listening to Trac

23、k 1. 4. Rewind t.ape. 5. Play back recording, as in stereo play. Master recording will be heard on Left channel and added recording will be heard on the Right channel. 6. Track 3 may be erased and rerecorded without disturbing master track by repeating Steps 2 through 4. SOUND-ON-SOUND RECORDING (16

24、60D ONLY) 1. Make original recording on Track 1 using Left channel only. Turn Right channel volume control to zero and follow procedure under, To Make a Stereo Recording. 2. Rewind tape to beginning of original recording. 3. Set Channel Transfer Switch io L toR position. 4. Push Pause Lever up to St

25、op position. 5. Hold Righi Record Switch depressed and turn Start-Sto p knob to Start position. 6. Connect Right challllel microphone. Apply sig11al to microphone and adjust the Right channel volume control for ap- proximately half the normal recording level reading on the Right channel VU Meter. 7.

26、 DO N01 READJUST THE RIGHT CHANNEL VOLUME CONTROL AFTER PRESETTING FOR THE MIC- ROPHONE RECORDING LEVEL. (V:! Jormal) 8. Releae Pau:e Lever and make a tdal recording of the Left cbael trSllSfer and the Right channel microphone added. 9. Adjust the Left channel volume control only, while watching the

27、 Right channel VU Meter reading. The Right chan- nel VU Meter should be reading full normal. Half of the reading will be the Left cbrumel transfer ru1d the other half. the Right channel microphone. 10. Rewind the tape. play the trial recording. If the test run was satisfactory. proceed with the fina

28、l recording by re- peating Steps 2 !hrcugh 9. 11. Playback recording. Sound-On-Sound recording is on Track 3 (Right channel) so volume controls for Left channel should be set to zero. (NOTE: The original Track l recording of the Left amplifier is still intact at this point, so Steps 2 through 9 may

29、be repeated if the final recording was not satisfactory.) 12. The aboe process may be repeated, using Track 3 as the original recording and add more material to it for a rnul- tirle recording. In this case the Channel Transfer Switch should be set at R to L position, and the Left channel microphone

30、input will be used. ASSEMBLY -DISASSEMBLY Assembly (mounting): (1660-D) 1. Check for dearance, (deck - -: -J- I RIGHT I RIGHT H l(ioH LOW L.li.VEL L.EVIi.e head. (2) Defective erase head. (3) Low erase voltage. (4) Defective head elevation. 4. HIGH BACKGROUND NOISE LEVEL ON TAPE. (hiss, scratchy) (a

31、) Hiss. (1) Magnetized beads. (2) Defective tape. (3) Hash on oscillator output waveform. (4) Direct current leakil1g to heads. (b) Rumbling. (1) Defective tape. (2) Distorted oscillator output waveform. (3) Excessive tape pressure against heads. (4) Exces!iive tape wrap around beads. 5. LOSS OF HIG

32、H FREQUENCIES. (a) No sparkle. (1) Dirty heads. (2) Record bias incorrect voltage. (3) Wnrn beads. 6. LOW SENSITIVITY. (a) VU Meter reads normal. (1) Dirty heads. (2) DefeciJve heads. (3) Defective record current circuit component. (4) Defective tape. 7. LOSS OF LOW FREQUENCIES. (a) No bass. (1) Mismatch of impedances of input. (2) Incorrect sped. (fast) 23