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Fujitsu M255XK Customer Engineering Manual page 48

5 1/4" mini-flexible disk drive
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4.4.8 Read Level
Tools Required:
Work Diskette
Exerciser (A V A 409 or equivalent)
Dsc illoscope
Proceed as follows:
1.
Connect the oscilloscope channels to TPI and TP2.
Set the oscilloscope to
AC mode, both channels to 0.2 volts per division, and 1 microsecond per
division time base.
Put one of the channels in invert mode, and put both channels to ADD.
2.
Start the Spindle Motor and load the level diskette.
3.
Seek the Read/Write heads to the innermost track.
4.
Record and then read a constant "2F" on the entire track (2F is aI's only
WRITE DATA frequency of 250kHz for M2552K and 500kHZ for M2553!54K).
5.
Measure the average Read Level value (Vp-p), refer to Figure 4-9.
ADD
Yp-p
Figure 4-9 Average Read Level Measurement (2F)
6.
Ensure the Read Level (true value) is within the range shown below:
Innermost track Read Level
=
200mvp-p or more (all M225XK Models).
7.
Repeat steps 4 through 6 for side 0 and side 1.
B.
If the results are not within the indicated range, the following items are
probable causes:
(a) Faulty diskette. Replace the diskette if it is bent or damaged.
(b) Abnormal disk speed. Refer to paragraph 4.4.5.
(c) Faulty head contact. Refer to paragraph 4.4.6.
(d) Faulty Read/Write head. Refer to paragraph 4.5.1.
(e) Faulty circuit card. Refer to paragraph 4.5.6.
TS-021-0130B7 ••• 01
4-16

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