Index Burst Verification And Adjustment; Track 0 Sensor Adjustment - Panasonic JU-475-4 Service Manual

9.8 Index Burst Verification and Adjustment
(1) Insert an alignment diskette. Seek to the track specified in the index burst column of Table
8-1.
(2) Set the oscilloscope in the same conditions as in section 9.7, and set horizontal deflection to
SOps I division.
(3) Check that the time from oscilloscope start to the first data meets the index burst
specifications of Table 8-1.
(4) If the specifications are not met, adjust as follows.
• Loosen the index detector mounting screws enough to free the assembly.
• Adjust the timing to meet the specifications of Table 8-1 .
• Retighten the screw.
• Check the timing again.
Fig.9-5 Index Timing
9.9 Track 0 Sensor Adjustment
(1) Set the oscilloscope as follows.
Fig. 9-5-1 Index Detector
TRIG SYNC CH 1 CH2
VERT HORIZ
(2) Step between specified tracks at in the track 0 item of Table 8-1. (Turn the seek delay switch
on the exerciser to adjust 3 ms seek.)
(3) Loosen the track 0 sensor screw and adjust until the waveform on the oscilloscope appears as
shown in Fig. 9-6.
Fig.9-6 Track 0 Waveform
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Fig. 9-6-1 Track 0 Adjustment