HP 7925D Service Manual page 241

Appendix A
7925
Table A-II. HP 7925H Motherboard PCA-A7 Signal Distribution List (Continued)
SIGNAL
MNEMONIC
DEFINITION
A1*
DATA PCA
A2*
MICROPROCESSOR
PCA
A3
SERVO PCA
A4
DRIVE CONTROL peA
AS
TRACK
FOLLOWER PCA
A6
R/W
PREAMPLIFIER
PCA
A7
MOTHERBOARD peA
COMMENTS
XA1P1 XA1P2 XA2P1 XA2P2 XA3P1
XA3P2 XA4P1 XA4P2 J1 J2
XA5P1 XA5P2 XA6P1 J1 J2 J3
"Not" Decrease Write Current •
C (3.25 mA)
~ - - - - - + - - - - + - - - - - + - - - - - + - - - - - + " .......---~
ECS Energize Carriage Solenoid
F
To Power and Motor
Regulator ·peA pin
A9J1-50.
FLT Drive Fault F
"Not" Drive Fault Lamp
T
To DRIVE FAULT
lamp via indlcator peA
pin A 11 J 1-6.
FMT Format Pack 13 J
From FORMAT
switch -S4.
.
HSO
Head Select Bit 0
.
.
12
HS1
Head Select Bit 1
,
.
13
.
:
HS2 Head Select Bit 2
R
HS3 Head Select Bit 3 .
. .
.
. .
3
. • . . . .
.
....__ I_C_A _ _...._ _ II_le_g_a_I_C_y_l_in_d_e_r_A_d_d_re_s_s_....
-+ .....
- 6 - - + - - - - - + " " " " _
----01-----+-----+----+-----+----+----+-------~~---+-----1----+_-----------1
ICI5 Interlock Chain In AS
17
Interlock chain source
from -24V supply.
15
IC05/ICI6 Interlock Chain Out A5/ln A6
~ '
.
a--------1------------~----t_----_I_---_+----+_---
..... ----t_---+-----t'----t----...,.. --.....
----+---.-.------~.I----+---~----+-----------
...
IC06 Interlock Chain Out A6
ICll
I nterlock Chain I n A 1 13
..
::
I . .
ss
I·,A'
.
.;.
.
. .
..
To pack chamber
interlock pin J2-7.
From Spindle Logic
peA pin A8P1- T .
DENOTES SIGNAL SOURCE
• WHEN DSU IS INSTALLED, SLOTS A1 AND A2 CONTAIN HEAD
ALIGNMENT PCA AND I/O SECTOR PCA, RESPECTIVELY.
A-68