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Fujitsu M255XK Customer Engineering Manual page 56

5 1/4" mini-flexible disk drive
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Table of Contents
4.4.13 Head Load Inspection and Adjustment
Tools Required:
Phillips Screwdriver, M3
Allen Wrench, 1.5mm
Oscilloscope
Scratch/Work Disk
Exerciser (AVA 409 or equivalent)
Screw Lock Liquid
Intraconnector 34-pin
1.
Set the Head Load jumper selection to HS and set Drive Select to DSO, refer
to Figure 4-1, Table 4-5.
2.
Set the oscilloscope as follows:
Channell: Connect to TP4, AC mode, 0.2V
Channel 2: Connect to TP5, AC mode, 0.2V
Trigger:
Connect to pin-4 of intraconnector
Set Trigger mode to External, on the negative edge
3.
Start the Spindle Motor and load the alignment disk.
4.
Record a pattern of IF (all zero's) on Track 04 (Write Data frequency of
125kHz for the M2552K and 500kHZ for the M2553/54K).
5.
Adjust Channel 2 output waveform, using the oscilloscope's ranges and variable
gain controls, until the amplitude of Level "A" as shown in Figure 4-16 is
equal to 5 divisions.
A - - - -
Figure 4-16 Head Load SignallA"
6.
Refer to Figure 4-17. While selecting and deselecting the drive, measure the
time from head unload to head load. Ensure that the time, from scope trigger
to 90% of maximum amplitude (Leve1
I
B") is less than 50 milliseconds.
DRIVE
SELEC.I
Si&Da1l
100
~.---------------------
~~=========+~------
B
lO.=;======;;;;:;;:;:~
_ _ _
CO,.
!fax.
so.sec.
Figure 4-17 Head Load Interval and Signal "8"
TS-021-013087 ••• 01
4-24

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