Sector Sensing System, Functional Diagram - HP 7925D Service Manual

7925
Troubleshooting
10
4-39
4-41
4-43
4-45
4-47
4-49
4-51
SEE
READIWRITE
SYSTEM
DIAGRAM
(D5)
Mainframe Assembly .
I/O Control System.
.
Spindle Rotation System
Head Positioning System
Sector Sensing System .
ReadlWrite System . .
Fault Detection System
SEE
I
I/O CONTROL
SYSTEM
DIAGRAM
(C15 & C4)
-----1
I
I
I
SEE
STROBE I/O CONTROL
I
TO UNIT SYSTEM
(IDENTITY LOGIC) DIAGRAM
(C21
I
I
I
I
I
SECTOR
----.~ COMPARE
(STATUS BIT 8)
..-
~/-6-- ~~~T~E~S
7
DO-D5
W6
ADDRESSED
SECTOR
I
I
I
I
I
I
1=D f------------rP2~)
K
>-
URG -----.
READ-
I
W R I T E - - = D
)1
9
) - U W G -
I
_________ ---l
SEE
I/O CONTROL
SYSTEM
DIAGRAM
(A4)
[£]
SEE{ •
I/O CONTROL, AT
SYSTEM
DIAGRAM HOI
(C31
+5V
LOOK- AHEAD
COMPARATOR
pn
LOOK-AHEAD
JUMPERS
(0-+ 15)
IN = "0"
OUT="1"
SECTOR
ADDRESSED
COMPARATOR SECTOR
SECTOR
SEE
ADDRESS
I/O CONTROL
CHECK
SYSTEM
DIAGRAM
(84 & C4)
COMPARE
PRESENT
=
ADDRESSED
SECTOR SECTOR
W
SECTOR
,
COMPARE
FF
D Q SC
J
C
SEE{
I/O CONTRO L ~ /6
SYSTEM ~
DIAGRAM
(A15)
PRESENT
I -_ _ .c--......-
SECTOR -----L-"'7I'----I~
SEE {READ. SEL
I/O CONTROL
SYSTEM·
DIAGRAM
(A4) WRITE. SEL
;CLOtK
SECTOR
COUNTER
1088(7920)/
817 (7925)
1120 (7920)/840 (7925)
SECTOR
COUNT
DECODER
7920 0 W5
7925
6--
SECTOR
COUNT
.- .-
..
-
..
- .-
-
. -
-
. -
...
-
.-
-
- . -
INDEX
DETECTOR
I/O SECTOR PCA-A2
JUMPER LOCATIONS
W5
E:!l .
L!TII!O!..!..!..!.-!I II:Z:Il m
C'::: :5' 1 :' ; :: :9:J~~!~
,=JUMPERS.
~
.•cy:.
0··· -
• • • tt. _
[;:::::5"C;;:::;:5
q'
.
.
..
C::::::~'i::'::::5
1::::::,:5" "
[:::::3'
p,
,c:::3'
E:::!J l!::!l
( . . . . . . . ::::. . . . . . . . :::5:
c::3 c:J
MUST BE IN W 4 · · • ~ ENABLE RPS
PLACE FOR
~.
• W.6
~
DISABLE R.PS
PROPER OPI:IIATION
~
•• . _ ·cr·c:J
0·· :-
"I
SE~ORO
I
LOW-PASS
FILTER
AGe}
SEE
L
HEAD POSITIONING
SYSTEM DIAGRAM
(C18)
tNDEX PATTERN
0*
I
1
I
I
I
I
L _
ID~~~~-----------------------------------~
I
~----.~, ~.8
I
WINDOW
GENERATOR COUNTER
I
I
DIFFERENTIAL
PREAMPLIFIER STAGE
I
07925-60005
I
FIXED GAIN
, ~
ONLY
I
rscL1
DIFFERENTIAL
~
AMPLIFIER PHASE
I ,
SERVO HEAD LOCKED P21
SIGNAL FILTER LOOP 1--_f--------4--4.....,..4· 6
>-_
SCL
-<
6
~(
.....
~-2------Io----
....
....- - - - . . I ,
II
53,760 "'/llt:V
I
I :
2.42 Mill
I
3)-
I:
\ - I '
1 : w
e
IP IP I
I ,
I
I INDEX PULSE I
y : ~IIER
.~I 31~~
Pl I
v~
I __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ----1
C~P
I :
}
: --<
L'!
SEE r - NDPS D
I"
FAULT
I
DETECT.ION,
_J
I
SYSTEM
DIAGRAM
lBB)
I
I
I
I
I
L , _
L - -_ _
-+-_ _ S~~ci~
- - - - - « 1,3
SECTOR· 63
1
I
*0 FOR AN HP 13356A DISC PACK
1 FOR AN HP 13357 CE DISC PACK
PRE
REF
TEST
POINT
ACTUATOR
ASSEMBLY
,----,
I
I
L __ ---l
C
D
A
SECTOR SENSING SYSTEM TIMING DIAGRAM
7311-29C
10
Figure 4-27. Sector Sensing System, Functional Diagram
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