HP 7925D Service Manual page 118

7925 Troubleshooting
10 11 12
13 14
A
TO/FROM
CONTROLLER
{
DATA
DATA
SELECT
SEL
(C6)
A
URG
(D7)
c
WRITE
(07)
ZERO
CROSSING
DETECTOR
DATA
AGC
CIRCUIT
LOW-PASS
FILTER
SEE
FAULT
DETECTION
SYSTEM
DIAGRAM
(C8)
>-
ACW - - - - .
/
/
WEN
DECREASE
CYLINDER
DWA DWB DWC IN WRITE
2 9 2 8
2
7 CURRENT
(mAPEAK)
0 127 0 0 0 0
128 255 0 0 1 2.1
256 383 0 1 0 4.2
384 511 0 1 1 6.3
512 639 1 0 0 8.4
640 767 1 0 1 10.5
768 822 1
1 0 12.6
...
... ..,
..,
~<¥
AC
WRITE CURRENT
DETECTOR
:-
MULTIPLE
HEADS
::
SELECTED
DETECTOR
=
C
o
>-
DCW - - - .
NOTE: All D-Type flip-flops are
clocked on the rising edge
of the clock signal.
Mainframe Assembly .
I/O Control System. .
Spindle Rotation System
Head Positioning System
Sector Sensing System .
Read/Write System . .
Fault Detection System
4-39
4-41
4-43
4-45
4-47
4-49
4-51
o
7311-30C 10 11 12 13 14
Figure 4-28. Read/Write System, Functional Diagram
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