MITSUBISHI HSU748
Manual de Servicio

3-4. Phase Adjustment
1. Play back an alignment tape (NM3KE6 : 859C339O50). 2. Preset the tracking. 3. Loosen the Screws D and E shown in the Fig. 3-4-1. Insert a screw driver (+) into the Hole in the MAIN PLATE ASSY (Part A) and move the A/C PLATE to the right and left to set the amplitude level of the FM Waveform to maximum. 4. Tighten the Screws D and E. 5. Play back an alignment tape [NMX : 859C568O60]. 6. Confirm the Missing Portions of the FM Waveform and Audio Waveform are as shown in the Fig. 3-4-2. 7. If the Missing Portions differ from the Fig. 3-4-2, repeat the procedure 3. 8. Adjust the tracking so that the amplitude level of the FM Waveform will be at the maximum. And set the oscilloscope so that the Waveform will be 5 divisions of the oscilloscope. 9. Preset the tracking. 10. Confirm that the FM Waveform on the oscilloscope is 4.8 divisions or more. 11. If the FM Waveform is below 4.8 divisions, preset the tracking and repeat steps 3~10. 12. Push the A/C HEAD to the right and left (in the direction of A-A' in the Fig. 3-4-1) and release it. Confirm that the amplitude of the FM Waveform does not change, compared to before the A/C HEAD was shifted. 13. If the amplitude level of the FM Waveform changes, check the set position of the A/C HEAD. If the A/C HEAD is installed incorrectly, correct the position according to the Item 2-8. "A/C HEAD UNIT" and 3-3. "A/C HEAD Adjustment", and then repeat this item from the beginning. 14. Alternately load and unload the tape several times. Confirm that the amplitude of the FM Waveform does not change.

Screw D

A
Tape

Part A

a A'
Screw E
Fig. 3-4-1

FM Waveform

Audio Waveform Output

b

Missing Portion

Fig. 3-4-2

3-5. Tape wrinkle check
1. Confirm that there is no wrinkle at the lower edge of GUIDE POLE(TU) in PB/FS mode with T-160 tape beginning and ending. 2. Confirm that there is no wrinkle at the upper edge of GUIDE POLE(TU) in RS mode with T-160 tape beginning and ending.

Tape

GUIDE POLE (TU)

GUIDE PIN (TU)
Fig. 3-5

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