Tandberg 62 X Service Manual
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Extracted text from Tandberg 62 X Service Manual (Ocr-read)
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1.0 Alignment It is important that the contact between the tape and the heads on the tape recorder is good. To obtain this contact the tape should be run through the tape recorder 5-10 times at normal speed to have the tape polished before measuring the frequency re- sponse and the signal to noise ratio. 1.0.1 Demagnetizing Demagnetize the heads and adjacent parts before aligning the heads. 1.0.2. The mounling plate lor the heads The height of the mounting plate for the heads (15.4) is aligned by the adjustment screw at the rear of the playback head. Move the operating lever slowly to normal forward drive with a tight tape inserted. Align the height of the mounting plate for the heads until the tape runs equidistant from the flanges of the tape guide (79,2). 1.0.3 The adjustable tape guide Set the operating lever in normal forward drive with tape inserted and depress the push-button lll. Align the adjustable tape guide (79.3) until the tape runs equidistant from the flanges of the adjustable tape guide. Repeat 1.0.2. 2.O Adjustment of the oscillator and bias head circuits. 2.0.1 Insert one 10 ohm resistor in series with each bias 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 o'clock posi- tion while R607 and R610 are set to approx. 11 o'clock. Rel. fig. 3. 2.0.3 Set the tape recorder to stereo recording and the speed selector to 7tlu i.p.s. 2.0.4 Use a calibrated long wave receiver, frequency meter or frequency counter for the indication and adjust the oscillator frequency by C 610 until f/osc. = 85.5 kc/s. 2.0.5 Set the tape recorder for mono recording CH 1 and the speed selector to 7tlz i.p,s. 2.0.6 Adjust the oscillator frequency with L601 F/osc. will then be 85.5 kc/s. 2.0.7 Set the tape recorder for mono recording CH 2. 2.0.8 Readjust L 601 to compromise if necessary. The osc. frequency deviation between mono recording CH 1, CH 2 and stereo should be less than 2 kc/s. The deviation should be indicated with frequency meter, long wave receiver or frequency counter. 2.0.9 Adjust C 602 and 604 to max. reading on the V.T.V.M. (between 100 mV and 400 mV). 3.0 Head alignment and track control with Tandberg Test Tapes, Model 64x 3.1. The playback head 3.1.1 Connect one V.T.V.M. to each CATHODE FOLLOWER output. 3.1.2 Height alignment: Play back the test tape No. 1. This is a full track pre-recorded tape with 1000 c/s recorded atTt/zi.p.s. tape speed. The record level of the exact area corresponding to track 3 is reduced 30 dB. Adjust the height of the playback head until minimum output is botained on a V.T.V.M. from track 3 (ch. 2). 3.1.3 Azimuth alignment: Play back the test tape No. 2. This is a full track pre-recorded tape with 10.000 cls al 71lz i.p.s. tape speed. Adjust the azimuth position of the playback head until maximum reading is obtained on both output meters. 3.1.4. Lateral alignment: Check the lateral position of the playback head by pulling the pressure pad (59.5) away from the erase head when the test tape No. 2 is played back. The output level should not decrease more than 3 dB. Adjust the lateral position of the playback head, is necessary, by turning the head mounting plate. Re- adjust the azimuth position. 3.2 The record head. 3.2.1 Adjust the horizontal position of the bias head until the head is in center of the record head. Ref. fig. 1. 3.2.2 Adjust the height of the bias head until the tape runs freely in the groove in front of the bias head. 3.2.3 Height alignment: The record head is set in a preliminary position where approx. 0.1 mm (.0025") of the lamination for the upper track is visible above the tape. The position of the record head can be inspected by using the iron powder method (Magna-See). Record all four tracks on the tape and dip the tape in the solution. The pattern on the tape will show il the position of the head is correct. Readjust if necessary. 3.2.4 Azimuth alignment: Connect a signal generator to the HI-LEVEL inputs CH1 and CH2, and two V.T.V.M. to the CATHODE FOLLOWER outputs CH1 and CH2. Make a stereo recording in B-test al 7t/z i.p.s. of a 15.000 c/s signal. Adjust the azimuth of the record head to max. reading on the output meters. The out- put level should now be approx. 100 mV with the playback volume controls to max., readjust the record gain controls until this is obtained and check the azimuth position of the record head. 3.2.5 Lateral alignment: Check the lateral position of the record head by pulling the pressure pad (59.5) away from the erase head during the recording. The output level should not decrease more than 3 dB. Adjust the lateral position of the record head, if necessary, by turning the head mounting plate. Recheck the height and azimuth position of the head. Ref. para. 3.2.3 and 3.2.4. 3.3 The bias head. 3.3.1 Heighl alignment: Connect two V.T.V.M. directly across the recording heads. Set the tape recorder to stereo recording at 71 lz i.p.s. and turn both playback volume controls down to 0.
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Adjust the height of the bias head by the height adjustment screw (ref. fig. 1) until max. reading is obtained on both V.T.V.M. Check that the tape runs freely in the groove in front of the bias head and that there is sufficient clearance between the bias head 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 the mounting plate 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 FOLLOWER outputs, and connect a signal generator to the Hl- LEVEL inputs CHI and CH2. Set the tape recorder to stereo recording al 71lz i.p.s. and turn both play- back volume 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 extreme Ieft position towards the recording head until max. reading is obtained on both V.T.V.M. The output level should now be approx..5V, readjust the record gain controls until this is obtained and check the horizon- tal position of the bias head. After one has assured that the horizontal position is correctly adjusted, tighten the adjustment screw making sure that the head is not being moved. This is eventually indicated by a loss of the output level. A fine-adjustment of the bias current is obtained by the pot.meters R609 (CH1) and R612 (CH2). Adjust R 609 and R 612 until max. reading on the optput meters are obtained. 3.4 The erase head. 3.4.1 Height adjustment: The erase head is set in a preliminary position where approx. 0.25 mm (.01") of the ferrite core for the upper track of the erase head is visible above the tape. Insert the test tape No. 9 and record a 1000 c/s signal from the generator on ch. 2 at maximum re- cording level. Dip the tape in the Magna-See solution and check that the re-recorded track lies in center of the erased track. Make sure that the erase head does not erase any part of the adjacent tracks. 3.4.2 Azimuth alignment: Align the azimuth position of the erase head by the azimuth adjustment screw. The erase head should be parallel with the mounting plate for the heads (15.4). The azimuth position of the erase head is not critical. 3.4.3 Lateral alignmenl: Turn the head mounting plate for the erase head, until the 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/t i.p.s. tape speed. The tape conforms with the N.A.B. standards. The output tolerance is -+ 2 dB for all frequencies. The difference in level between the two channels should be less than 3 dB. 4.2 Adjustment of the playback amplifiers: Play back the test tape No. 4 with the output volume controls to maximum. This is a full track prerecorded tape with 400 c/s at71/z i.p.s. tape speed. Ad.just the potentiometers R233 (CH 1) and R234 (CH 2) until the reading on the output meters are 1.3V. 5.0 Adjustment of the record current (A-B test) and the electronic beam indicators. Make sure that all adjustments under paras 1.0, 2.0 and 3.0 are made before proceeding with these ad- justments. Connect a signai generator to both Hl-LEVEL inputs and two V.T.V.M. to both CATHODE FOLLOWER out- puts. Record a 4O0 cls signal in stereo A-test, with both playback volume controls to max. at 7tlz i.p.s. Adjust the record levels by the record gain controls until the output levels are 1.5 V. Depress the push-buttons lV and V (stereo B-test) and adjust the record current by R115 (CHl) and R116 (CH2) until the readings on 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 the readings still are 1.5 V on the output meters. 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 the height adjustment screws. The upper edge of the tape shall run flush with the upper part of the airgap for channel 1. 6.1.2 Azimuth alignmenl: Play back a standard azimuth alignment tape with a V.T.V.M. connected to each cathode follower output. Adjust the position of the playback head by the azimuth adjustment screw, until maximum reading is obtained on the output meters. 6.1.3 Lateral alignment: Pull the pressure pad (59.5) away from the erase head when the standard azimuth alignment tape is being played back. The output level should not decrease more than 3 dB. Adjust the lateral position of the playback head, if necessary, by turning the head mounting plate. All the alignments specified in chapters 3.1, 3.2, 3.3, 6.2 The record bead. and 3'4 are valid for model 62x with the exception-o1 iorro*'in"l instructions given under para3.z. paragraph 3.1.2 which is superseeded by 6.1.1 and paragraph 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 3'3' with Tandberg test tapes. 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 height recorded tape with the following frequencies:250- adjustment screws. Approx.0.25 mm (.01 ") of the