Tandberg-64X-tape-al 维修电路原理图.pdf

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1、January 1967TANDBERG TAPE.RECORDERModels 64x and 62xAlignment instructionforheads and electronicsPrefaceThe models 64x and 62x are improved versions of has been introduced to improve the frequency re-the earlier models 64-62 and this alignment instruc- sponse and the signal to noise ratio.tion is an

2、 appendix to the service manual for model The oscillator has been redesigned and fully transis-64:-62. lt covers the special head alignments and torized. Certain minor changes have been introducedelectrical adjustments necessary for model 64x and in the equalization circuits, mainly changes of com-6

3、2x. ponent values. A microswitch is further introducedin the bias circuit to reduce the bias in 1.7/e i. p.s.The models 64x and 62x have the same operation tape speed. This switch is operated automatically byfacilities as 64-62. A new, and separate bias head the speed selector mechanism. See fig. 3.

4、Ti.d.*.qr=r=rErlEr/TANDBERGS RADIOFABRIKK A/S OSLO NORWAYRadioFans.CN 收音机爱 好者资料库1.0 AlignmentIt is important that the contact between the tape andthe heads on the tape recorder is good. To obtainthis contact the tape should be run through the taperecorder 5-10 times at normal speed to have thetape p

5、olished before measuring the frequency re-sponse and the signal to noise ratio.1.0.1 DemagnetizingDemagnetize the heads and adjacent parts beforealigning the heads.1.0.2. The mounling plate lor the headsThe height of the mounting plate for the heads (15.4)is aligned by the adjustment screw at the re

6、ar of theplayback head. Move the operating lever slowly tonormal forward drive with a tight tape inserted. Alignthe height of the mounting plate for the heads untilthe tape runs equidistant from the flanges of the tapeguide (79,2).1.0.3 The adjustable tape guideSet the operating lever in normal forw

7、ard drive withtape inserted and depress the push-button lll. Alignthe adjustable tape guide (79.3) until the tape runsequidistant from the flanges of the adjustable tapeguide. Repeat 1.0.2.2.O Adjustment of the oscillator and bias headcircuits.2.0.1 Insert one 10 ohm resistor in series with eachbias

8、 head half to ground and connect a V.T.V.M.across each resistor.2.O.2 R 609 and R 612 is turned up to 1 oclock posi-tion while R607 and R610 are set to approx. 11oclock. Rel. fig. 3.2.0.3 Set the tape recorder to stereo recording andthe speed selector to 7tlu i.p.s.2.0.4 Use a calibrated long wave r

9、eceiver, frequencymeter or frequency counter for the indication andadjust the oscillator frequency by C 610 until f/osc.= 85.5 kc/s.2.0.5 Set the tape recorder for mono recording CH 1and the speed selector to 7tlz i.p,s.2.0.6 Adjust the oscillator frequency with L601F/osc. will then be 85.5 kc/s.2.0

10、.7 Set the tape recorder for mono recording CH 2.2.0.8 Readjust L 601 to compromise if necessary. Theosc. frequency deviation between mono recordingCH 1, CH 2 and stereo should be less than 2 kc/s.The deviation should be indicated with frequencymeter, long wave receiver or frequency counter.2.0.9 Ad

11、just C 602 and 604 to max. reading on theV.T.V.M. (between 100 mV and 400 mV).3.0 Head alignment and track control with TandbergTest Tapes, Model 64x3.1. The playback head3.1.1 Connect one V.T.V.M. to each CATHODEFOLLOWER output.3.1.2 Height alignment:Play back the test tape No. 1. This is a full tr

12、ackpre-recorded tape with 1000 c/s recorded atTt/zi.p.s.tape speed. The record level of the exact areacorresponding to track 3 is reduced 30 dB. Adjustthe height of the playback head until minimum outputis botained on a V.T.V.M. from track 3 (ch. 2).3.1.3 Azimuth alignment:Play back the test tape No

13、. 2. This is a full trackpre-recorded tape with 10.000 cls al 71lz i.p.s. tapespeed. Adjust the azimuth position of the playbackhead until maximum reading is obtained on bothoutput meters.3.1.4. Lateral alignment:Check the lateral position of the playback head bypulling the pressure pad (59.5) away

14、from the erasehead when the test tape No. 2 is played back. Theoutput level should not decrease more than 3 dB.Adjust the lateral position of the playback head, isnecessary, by turning the head mounting plate. Re-adjust the azimuth position.3.2 The record head.3.2.1 Adjust the horizontal position of

15、 the bias headuntil the head is in center of the record head. Ref.fig. 1.3.2.2 Adjust the height of the bias head until the taperuns freely in the groove in front of the bias head.3.2.3 Height alignment:The record head is set in a preliminary position whereapprox. 0.1 mm (.0025) of the lamination fo

16、r theupper track is visible above the tape. The position ofthe record head can be inspected by using the ironpowder method (Magna-See). Record all four trackson the tape and dip the tape in the solution. Thepattern on the tape will show il the position of thehead is correct. Readjust if necessary.3.

17、2.4 Azimuth alignment:Connect a signal generator to the HI-LEVEL inputsCH1 and CH2, and two V.T.V.M. to the CATHODEFOLLOWER outputs CH1 and CH2.Make a stereo recording in B-test al 7t/z i.p.s. of a15.000 c/s signal. Adjust the azimuth of the recordhead to max. reading on the output meters. The out-p

18、ut level should now be approx. 100 mV with theplayback volume controls to max., readjust the recordgain controls until this is obtained and check theazimuth position of the record head.3.2.5 Lateral alignment:Check the lateral position of the record head bypulling the pressure pad (59.5) away from t

19、he erasehead during the recording. The output level shouldnot decrease more than 3 dB. Adjust the lateralposition of the record head, if necessary, by turningthe head mounting plate. Recheck the height andazimuth position of the head. Ref. para. 3.2.3 and3.2.4.3.3 The bias head.3.3.1 Heighl alignmen

20、t:Connect two V.T.V.M. directly across the recordingheads. Set the tape recorder to stereo recording at71 lz i.p.s. and turn both playback volume controlsdown to 0.RadioFans.CN 收音机爱 好者资料库Adjust the height of the bias head by the heightadjustment screw (ref. fig. 1) until max. reading isobtained on b

21、oth V.T.V.M. Check that the tape runsfreely in the groove in front of the bias head andthat there is sufficient clearance between the biashead and the mounting plate for the record head.The height position of the bias head is not critical,and if the clearance between the bias head and themounting pl

22、ate for the record head is insufficient,raise the bias head slightly.3.3.2 Horizontal alignment:Connect two V.T.V.M. to both CATHODE FOLLOWERoutputs, and connect a signal generator to the Hl-LEVEL inputs CHI and CH2. Set the tape recorderto stereo recording al 71lz i.p.s. and turn both play-back vol

23、ume controls to max.Record a 1000 c/s signal.Untighten the fixing screw for horizontal adjustment(ref. fig. 1) and move the bias head from the extremeIeft position towards the recording head until max.reading is obtained on both V.T.V.M. The output levelshould now be approx.5V, readjust the record g

24、aincontrols until this is obtained and check the horizon-tal position of the bias head. After one has assuredthat the horizontal position is correctly adjusted,tighten the adjustment screw making sure thatthe head is not being moved. This is eventuallyindicated by a loss of the output level.A fine-a

25、djustment of the bias current is obtained bythe pot.meters R609 (CH1) and R612 (CH2). AdjustR 609 and R 612 until max. reading on the optputmeters are obtained.3.4 The erase head.3.4.1 Height adjustment:The erase head is set in a preliminary position whereapprox. 0.25 mm (.01) of the ferrite core fo

26、r theupper track of the erase head is visible above thetape. Insert the test tape No. 9 and record a 1000 c/ssignal from the generator on ch. 2 at maximum re-cording level. Dip the tape in the Magna-See solutionand check that the re-recorded track lies in centerof the erased track. Make sure that th

27、e erase headdoes not erase any part of the adjacent tracks.3.4.2 Azimuth alignment:Align the azimuth position of the erase head by theazimuth adjustment screw. The erase head should beparallel with the mounting plate for the heads (15.4).The azimuth position of the erase head is not critical.3.4.3 L

28、ateral alignmenl:Turn the head mounting plate for the erase head, untilthe front of the head is parallel to the pressure pad.3.5 Model 62x.10 000- 5000 - 1C00 - 100- 50-250 c/s recorded at71/ti.p.s. tape speed. The tape conforms with the N.A.B.standards. The output tolerance is -+ 2 dB for allfreque

29、ncies. The difference in level between the twochannels should be less than 3 dB.4.2 Adjustment of the playback amplifiers:Play back the test tape No. 4 with the output volumecontrols to maximum. This is a full track prerecordedtape with 400 c/s at71/z i.p.s. tape speed. Ad.just thepotentiometers R23

30、3 (CH 1) and R234 (CH 2) until thereading on the output meters are 1.3V.5.0 Adjustment of the record current (A-B test) andthe electronic beam indicators.Make sure that all adjustments under paras 1.0, 2.0and 3.0 are made before proceeding with these ad-justments.Connect a signai generator to both H

31、l-LEVEL inputsand two V.T.V.M. to both CATHODE FOLLOWER out-puts.Record a 4O0 cls signal in stereo A-test, with bothplayback volume controls to max. at 7tlz i.p.s. Adjustthe record levels by the record gain controls untilthe output levels are 1.5 V. Depress the push-buttonslV and V (stereo B-test) a

32、nd adjust the record currentby R115 (CHl) and R116 (CH2) until the readingson the output meters are 1.5 V.Adjust R 137 (CHl) and R 138 (CH2) until the elec-tronic beam indicators are closing. Release the push-buttons lV and V (stereo A-test) and check that thereadings still are 1.5 V on the output m

33、eters.6.0 Head alignment without Tandberg Test Tapes.6.1 The playback head.6.1.1 Height alignnnent:The height of the playback head is aligned by theheight adjustment screws. The upper edge of the tapeshall run flush with the upper part of the airgap forchannel 1.6.1.2 Azimuth alignmenl:Play back a s

34、tandard azimuth alignment tape with aV.T.V.M. connected to each cathode follower output.Adjust the position of the playback head by theazimuth adjustment screw, until maximum reading isobtained on the output meters.6.1.3 Lateral alignment:Pull the pressure pad (59.5) away from the erase headwhen the

35、 standard azimuth alignment tape is beingplayed back. The output level should not decreasemore than 3 dB. Adjust the lateral position of theplayback head, if necessary, by turning the headmounting plate.All the alignments specified in chapters 3.1, 3.2, 3.3, 6.2 The record bead.and 34 are valid for

36、model 62x with the exception-o1 iorro*inl instructions given under para3.z.paragraph 3.1.2 which is superseeded by 6.1.1 andparagraph 3.2.3 is superseeded by 6.6.2. 6.3 The bias head.4.0 control and adiustment ol playback amplifiers, Follow the instructions given under para 33with Tandberg test tape

37、s. 6.4 The erase head.4.1 Control of the playback amplifier:6.4.1 Height alignment:Play back the test tape No. 3. This is a full track pre- The height of the erase head is aligned by the heightrecorded tape with the following frequencies:250- adjustment screws. Approx.0.25 mm (.01 ) of the1 /z.B.all

38、WOmeedihe:hend2.0rd-uIsut-)thustntil,nsentlgsec-sh-theferrite core for the upper track of the erase headshould be visible above the tape.6.4.2 Azimuth alignment:Align the azimuth position of the erase head by theazimuth adjustment screw. The erase head shouldbe parallel with the mounting plate for t

39、he heads(15.4). The azimuth position of the erase head is notcritical.6.4.3 Lateral alignment:Turn the head mounting plate forthe erase head, untilthe front of the head is parallel to the pressure pad.6.5 Track control, model 64x.6.5.1 The record head:Record a 1000 c/s from a generator at maximum re

40、-cording level in stereo A-test on track 1 and 3 (push-buttons l, ll and lll depressed) for approx. 5 seconds.Turn the tape around and make a similar recordingon track 4 and 2. Cut the tape and dip it in a mixtureof iron powder and alcohol (Magne-See) to make therecording visible. The spaces between

41、 the recordedtracks should be distributed equidistant across thetape. Readjust the height position, if necessary, andrecheck the azimuth alignment.6.5.2 The erase head:Insert a full-track pre-recorded tape and record a1000 c/s signal from a generator at maximum record-ing level in mono A-test on tra

42、ck 3 (push-buttons lland lll depressed). Cut the tape and dip it in theMagne-See solution. Check that the re-recorded trackis in the center of the erased area. Adjust the verticalpos. of the erase head if necessary.6.5.3 The playback head:Record a 1000 c/s signal on track 1 (CH1) and a 500c/s signal

43、 on track 3 (CH2) at maximum recordinglevels. Turn the tape around and play back track 2(push-buttons lll and V depressed) at maximum vo-lume. No signal should be heard. Raise the playbackhead if the 1000 c/s signal is heard. Lower the play-back head if the 500 c/s signal is heard. Re-checkthe azimu

44、th position.6.6 Track control, model 62x.6.6.1 The erase head:The height of the erase head is aligned by the heightadjustment screws. The tape shall run equidistantfrom the upper and the lower edge of the ferrite core.6.6.2 The record head:The height of the record head is aligned by the heightadjust

45、ment screws. Record a 1000 c/s signal in stereo(push-buttons l, ll and lll depressed) at maximumrecording level on a full-track pre-recorded tape. Dipthe tape in the Magne-See solution and check thatthe tracks are distributed symmetrically across thetape, and that the recorded zone remains in thecen

46、ter of the erased zone. Readjust the erase andthe record heads, if necessary.6.6.3 The playback head:The height of the playback head is aligned by theheight adjustment screws. The tape shall run flushwith the upper edge of the lamination for channel 1.Readjust the azimuth in necessary.7.0 Adiustment

47、s of the amplifiers, vuithout TandbergTest Tapes.A V.T.V.M. is connected to each output terminal. Thesignal generator is connected to the high level inputsof both channels and tuned to 400 c/s.The tape recorder is set up for stereo recording A-test(push-buttons l. ll, and lll depressed with the oper

48、at-ing lever in normal fonvard drive position) at 7tlz i.p.s.tape speed. Insert a good quality recording tape.Adjust the recording gain controls until the readingson the output meters are 1.5V with the playbackcontrols to maximum.Replace the V.T.V.M. for channel 1 with a distortionmeter and depress

49、the push-button lV (B-test CH1).Adjust the recording current by R 115 until the read-ing shows 3 o/o distortion.Replace the V.T.V.M. for channel 2 with the distortionmeter and depress the push-button V (B-test CH2).Adjust the recorder current by R 116 until the read-ing shows 3 o/o distortion.Adjust

50、 R 137 (CH1) and R 138 (CH2) until the electro-nic beam indicators are closing.Connect a V.T.V.M. to each output terminal and pro-ceed the recording as described above in stereo B-test with all push-buttons depressed.Adjust the R 233 (CH1) and R 234 (CH2) until thereading on the output meters are 1.