HP 7925D Service Manual page 116

7925 Troubleshooting
8 10 11 12 13 14 15 16
17 18
D
C
A
4-39
4-41
4-43
4-45
4-47
4-49
4·51
SERVO
CODE
VARIABLE GAIN
DIFFERENTIAL
AMPLIFIER
Mainframe Assembly
I/O Control System.
Spindle Rotation System
Head Positioning System
Sector Sensing System
Read/Write System . .
Fault Detection System
FIXED GAIN
DIFFERENTIAL
AMPLIFIER
DUAL
ANALOG
SWITCH
L
TAC
CRB
____________ --.J
LMC
"1" = ODD CYLINDERS
"0" = EVEN CYLINDERS
I
3
MOTOR
.1
LMC
I
CURRENT
SAMPLE
I
RESISTOR
I
J1
I
1-----< 28 f - - - - - -....- - - - - - "
I
o
7920
I
,-"p
7925
J
W41 ------
SEE NOTE 1
PROGRAM-
MABLE
VOLTAGE
REGULATOR
SERVO HEAD
SIGNAL FILTER
POSITIVE
I
PEAK DETECTOR.....,
+5V REF
+36V
-PEAK
RETRACT
TIMER
-36V
+36V
LINEAR MOTOR
POWER AMPLIFIER
+10V
1-----+12V
r------------------
I LINEAR
MOTOR
flELAY
TAC
CRB
.;-8
COUNTER
UNITY GAIN
INVERTING
AMPLIFIER
WINDOW
GENERATOR
POSITIVE
NEGATIVE
DIGITAL
TO
ANALOG
CONVERTER
OUTPUT
SUMMING
AMPLI FI ER
6 MAGNITUDE
CLEAR
OFFSET
MAGNITUDE
REGISTER
CLEAR
.........
__
.....
~
Uf----I----+---__e
T ~-+---
..
r--;2--T~~O;PC~
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - , - - - - - - - - - - - - - - - - - - - - -
13
1
16 DIFFERENTIAL P2
. . . - - - - - PREAMPLIFIER STAGE I
~---~20
I
SEE SECTOR
I
SENSING SYSTEM
I
DIAGRAM (B5)
+
~r-I
. •
P2 PHASE
~
6 53,760'" /REV LOCKED 6720'" /REV
I
I
AGC
I
COMPARATOR LOOP REF :
,
<l=------.---------------+-4-------------;--;-------S;.~~O
- __
-J
(
P1 -5V REF
.....-----~
16
#--..-------<0\--------------- r - - PHA::MS~II~T~:BLE
- - - - - - ,
- -12V REF + PEAK
r--+----.-----(. 18 ~~----........,~------'l"
I
I
I
I
_--------~ 22
I .,
PSF
I
SEE NOTE 2
L _
...... -----+-----~ 14
) - f - - - - - - - - - - - - - - - - - - - - - - . . t
SEE FAULT
DETECTION
SYSTEM
DIAGRAM
SEE READ!
WRITE
SYSTEM
DIAGRAM
(09)
LSB
TAC
CC
~
t' '--
~
___
~
SUMMING -;;<f ,
AMPLIFIER
\
VELOCITY
CURVE
GENERATOR
~
L>f
[ill
~~ig~~
+ ....- ........
UNITY GAIN
INVERTING
AMPLIFIER
I
ANALOG
SWITCH
DIGITAL TO
ANALOG
CONVERTER
-
DIRECTION
CORRECTION
(
1 PRESENT NEW
"1" = CYLINDER < CYLINDER
ADDRESS ADD RESS
PRESENT NEW
"0" = CYLINDER ~ CYLINDER
ADDRESS ADDRESS
~
DIFFERENCE
'--4--------------+-------------+--+......t.~---------------;r-)~
16
"",4
10 ....
UP/ON
"1"= ON
"0" = UP
10
",'"
MATCH +SKI
(C7)
CYLINDER
CO~~~~~~SOR
I----+_t--P.... OSITIVE
CLEAR
. . ._.....01. . . ._ . . . .
DISABLE
t----t-----il----------il------+---------------II
ANALOG
I
I
SWITCH
I
CRB CRB
MATCH-l'~'
(Ala)
-
1!4 TRACK DETECTED ---..
FINE POSITION
lSi<
-4'"'_~lcK
PRESENT
r - - -
0 S
Qt-------~ j_~. J r-L--/
CYLINDER
J
FIRST
~g~~~~~
CLOCK
INHIBIT
FF
CYLINDER
PULSE
GENERATOR
I
TCDle-- ()
-Jr TRACK
CENTER
DETECTOR
MATC~H
SKH--.
MATCH+SKI~--n
(A 10) MATCH + SK I r-------R-ET-ar-----....' (C7) _ ...... - - t _ I t - - - - - - - ' +6V
4> SKI_ (C6 & C9)
' . I
r7l
- SKH (
-.L!..J
SKI ~
....
-~
MATCH + SKI
rr
D S Q -
~
SKH • AGC + SLEW ( F O R W A R : D @ 3 . 5 I P S ) , A N A L O G ( )
AGC (B8 & B9)
I
I
SEEK SWITCH C7
"'-----------+----------_~L
C
H~~E ,~
1'::/
[ill
~
SKI
V
R Q
~---o
- - . SKH • AGC _ _ SLEW -6V LI NEAR MOTOR •
(C12)
T
SKH
J
(REVERSE@3.5IPSI CURRENT COMMAND CURRENT
T
/P2 SKI _
=--..,/
RET
J
AMPLIFIER COMMAND
~ I)
1
13 " I RET
~
- LIMITER
I
I AGC }SEE FAULT
I , SKH ...--.. .-
I~
I '" ) AGCF.. DETECTION
~ ' - COF SRH
S SYSTEM
/ I SK J
I ./ I
DIAGRAM
N " -
,W
(A7)
L
~u
J
AGC 16 /P1
"I
I
I
I
I
I
I
U~~
I
MATCt+SKI _ I
(C7)
FROM~
2 ./P2
~
D$U
I -.. ,
~/
....
P ~1~-+-+_
...
---------_+_-~_U_--------------___t ~~~;~~L
V "POS COMPENSATION
CARRIAGE
_ _ _ _ - - , UNLATCHED
r- - - - - - - - - - ~;;~T~E~T;M;;;:;;-
- - - - - - - - - - - - - - - J1
I
SOLENOID
r---------------------------------------------------------- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7
5~)Jl [>0
(49 f-(__ C_SO_L
--1Q--
+10V
I
LMV
I
I
r
AcTU~OR
..,
• I
ASSEMBLY
I
T
J3 LMV
P2
P1
58
~--------~
17
>--+---+-------"""<
Q ......- -.......
SERVO
ENABLE
FF
D-.... --------u---_+_----.;...~ U
AGC
~--.JI---------------------+-----~17
R
Q
DRIVE
READY
FF
SEE
DRDY
}~O
CONTROL(B14)&(B15)
FAULT DETECTION (B8)
SYSTEM DIAGRAMS
SEE I/O
CONTROL
SYSTEM
DIAGRAM (B10)
~
....... 0 _R D_Y . .. --I Q
AGF
CBF
ILF
DWF
TOF
SEE
}
I/O CONTROL (B, 10)
-READ!WRITE (D6),
&
FAULT DETECTION
(B9) SYSTEM
DIAGRAM
ACRY
I
I
I
SEE FAULT
I
DETECTION
SYSTEM
DIAGRAM
I
(89)
SEE FAULT{ R Q SEN 7 I
DL. PIP DE, TEC ..T. 10 . . N,. . TOF { PSF
~
I
SEE SPINDLE (B4)
DI~~~;~
ILF SEE FAULT (D5)-----r7 N
I
ROTATION SPU -(B-9) DETECTION I
I
SYSTEM DIAGRAM (C5) SYSTEM DIAGRAM CRB I
(B7) I S
I
STOP
(C4) P2
I
~--------------------------~ 13
L
~
10
6791011r;:-R~A~----
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
p;-1 )~~~ •
CYLINDER '
J' ,
' 1 --. ')
F
_--A-D-D-R-E-SS-------------------------------- DO - D9 --_--1~-------------+-_+----H-,
_,K_,_L' " ",<M
<
P1 CYLINDER ADDRESS ,/10
_I
CYL
I.
,~
I
1
1 - - - - 0 - -. . . MATCH -1
10
S~)
MATCH -- (C7)
I
~
ILLEGAL LOGIC _ _ MATCH
~
CYLINDER I C A . . - .
J
NEW
I
(C7)
DAE~~~~~SR
SR ] "' CLoCK
~DL6~~~:
p£!:5AR , 10 •
~
I
CYL
- - R E G I S T E R " P2, (B7)
" ' - - - - - - - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -.....
/11
~
rvcl I
0~
.A.
~ ~_o------P'T"11)'" ~8
) DWA •
1.1 -
~~o------"""""I~)
13
~
k
I
DWC ~~o--------a.~/
12
~
I
TACHOMETER
I
@fJ,
BUFFER
I
~--.J
A N A L O G J L <...
----..,P21""",~
--lSWI~H
. /
..!..
SB
(B6)
POS
pas
7,9,10,11,
I :
AGC AGC J L M 1 07 OFFSET
COF
~
COF
~
SIGN
" J
REGISTER '--------------------------------------DO~::
&
D7-------l......-----------------------------------------
- - - : ~ : ; . ; ~ ; . . ~ ; ; . D 5 : : . . : : : & . . : D : . . : . 7 ~-------------- ~ . . . ; . ~ _ - ~ . . . . ; 5 . . . . ; & ~ D . . . ; . 7
___'
L -- -- -- -- - -- -- -- -- -- - -- -- -- --
F~~~----------------------------------l
")--D_R_D_Y_L_+-----<;8 P1
H P2
I
I
1
; }SEE FAULT
SK I SK DETECTION
> - - - - - + - -..... --< 12
~
SYSTEM
I DIAGRAM
1 (A8)
1
I
SOF I
>-------iI---4.---+---< N
fl---
OFFSET
MAGNITUDE
AND SIGN
' I
INDICATOR
;C;:;:::;;111
DRIVE
I
I
READY
((\\ J1- I
1+12V~7
L _ _
---I
SEEK
NOTES:
1. RELAY SHOWN IN THE DE-ENERGIZED POSITION.
2. PROPER POSITION OF PMR JUMPER SHOWN BELOW.
I
SEE I/O
I
CONTROL
SYSTEM
DIAGRAM I
(B4)
I
I
SET OFFSET SOF • SEL P1 T
SEL -....-----
L
---l
FROM
CONTROLLER - - : ! J 1
3,5,6,~~8~9~1_~(L,
21,23,25,27
F
---- --- ---------
-,7891011
I!OSECTOR PCA-A2 J1Y ,
c{>
F'ri
K
L'M'
_ ~ _ 00-09 P1 ' , , ,
CONTROL
I)
BUS :
I
I ACRY
A
D
C
7311-280
6 8 10 11 12 13 14 15
16 18
Figure 4-26. Head Positioning System, Functional Diagram
4-45/4-46