IBM System/34 Maintenance Manual page 278

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6.
7.
8.
9.
Select a recalibrate and, for this example, a seek
to track 24 from the diskette exerciser test 1
command menu (enter an E after selecting the
cylinder number).
Use the default option to execute the commands.
Press the Attn key (three times) to return to the
diskette exerciser test 1 command menu.
Select the READ LOOP command and, for this
example, select M FM mode, cylinder 24, head 1,
and sector 11 from the displays (enter an E after
selecting the sector number).
10. Select the LOOP ON CMND TABLE option and,
for this example, set Address/Data switches (CE
panel). to 6093 to display byte 93.
The loss of amplitude can be seen on the oscilloscope.
.
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I' .. ' ' -
I_"_~.I.~
:1,
II :
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. . . . : . . . . 1 . . . . ' . . ''-
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Example 2: To scope a damaged track (contains all
ones in the
10
field), the following changes must be
made to the preceding procedure:
1.
2.
3.
4.
5.
Set the Times Per Division on the oscilloscope to
20 ms/cm.
Connect the trigger to test pin TPB-9 (+index).
In step 6 of example 1, seek to the damaged
cylinder.
In step 9 of example 1, select the READ SECTOR
command (select the head, sector number, and
cylinder number that you want to scope).
In step 10 of example 1, select the SCOPE LOOP
A CM N 0 option.
The following oscilloscope screen image shows the
damaged area of the diskette.
1
Track
Damaged Area
25-995
53FD Diskette Drive 59
•