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6.2
WAITE
GATE
WRITE OPERATION: PC BOARD 20243-XXX.
FIGURE 21:
Write Operation
PC Board
20243-XXX
REDUCED
CURRENT
HEAD
SELECT
PULSE
GENERATOR
&.2.1
WRITE GATE
A write sequence is initiated when
~rite
Gate is activated and applies
+
12 Volts
to the center tap of the selected head. At the same time, data is sent to the line
receiver 7L.
&.2.2
LINE RECEIVER
DifferentiaI Write Data (precompensated MFM) is received from the controller
and changed to single line. It is then fed into the pulse generator (7K) which
changes square wave data to pulse data. Depending on whether plus or minus
data is to be written, either pin 7 or pin 9 of 7H is activated. The amount of
current to be written is primarily established by R53. When writing to the inner
heads, 2 and 3, Write current is reduced by adding R52 in parallel which reduces
the problems of pulse crowding.
24
ST212 PRODUCT MANUAL/Rev. B
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