HP 7925D Service Manual page 244

7925 Appendix A
Table A-II. HP 7925H Motherboard PCA-A7
Signal Distribution List (Continued)
From Indicator PCA pin
A 11Jl-9.
COMMENTS
From Spindle Logic PCA
pin A8Pl-M.
From Spindle Logic PCA
pin A8Pl-L.
To Fault Indicator PCA
pin A12Jl-3.
From Spindle Logic PCA
pin A8P1-11.
From UNIT SELECT switch -
53. Also,to Unit Select Display
via Indicator PCA pin A 11 J1-
17.
From Velocity Transducer.
From Velocity Transducer.
From UN IT 5E LECT switch -
53. Also, to Unit Select Display
via Indicator PCA pin A 11 J 1-
15.
From UNIT SELECT switch-
S3. Also, to Unit Select Display
via Indicator PCA,pin A11J1-
16.
J3
5
J2
A7
MOTHERBOARD PCA
P
E
S
6
B
8
5
15
Jl XA6Pl
A6
R/W
PREAMPLIFIER
PCA
XA5P2
AS
TRACK
FOLLOWER PCA
XA5Pl J2 Jl XA4P2
A4
DRIVE CONTROL PCA
XA4Pl
2
XA3P2
A3
SERVO PCA
XA3Pl XA2P2
17
A2*
MICROPROCESSOR
PCA
2
XA1P2
Al*
DATA PCA
XA1Pl
DEFINITION
Unit Select Bit
2
Unit Select Bit 1
"N ot" Seek I nh ibit
US1
US2
SOF Set Offset N T
SPi5"
liN ot" Speed Down 15
SP1T
"Not" Speed Up
C
STF
"Not" Self Test Failed
STOP
"Not" Stop
TEe
"Not" Timeout Count Clock
TAC Tachometer B
TAC
"Not" Tachometer C
fC5F[
"Not" Timeout Fault LED 3
URG Unselected Read Gate
K K
usa
Unit Select Bit 0 A
SIGNAL
MNEMONIC
DENOTES SIGNAL SOURCE
• WHEN DSU IS INSTALLED, SLOTS A1 AND A2 CONTAIN HEAD
ALIGNMENT PCA AND I/O 5ECTOR PCA, RESPECTIVELY.
A-71