HP 7925D Service Manual page 126

7925 Troubleshooting
Table 4-4. Motherboard PCA-A7 Signal Distribution List
(Continued)
COMMENTS
J3
A7
J2
MOTHERBOARD PCA
J1 XA6P1
A6
RIW
PREAMPLIFIER PCA
XA5P2
A5
TRACK
FOLLOWER peA
XA5P1 J2 J1 XA4P2
A4
DRIVE CONTROL PCA
2
XA3P2
A3
SERVO PCA
u
XA3P1 J1
A2
XA2P2
I/O SECTOR PCA
XA2P1 XA1P2
A1
HEAD
ALIGN MENT peA
XA1P1
DEFINITION
"Not" Seek Home
"Not" Seek Inhibit
SIGNAL
MNEMONIC
SOF Set Offset
N T
SPD "Not" Speed Down From Spindle logic PCA pin A8P1-11 •
15
SPU "Not" Speed Up From Spindle logic PCA pin A8P1-L.
C
STB "Not" Strobe From Controller.
13
STF "Not" Self Test Failed
15
STOP "Not" Stop
From Indicator peA pin A11J1-9.
U
TCC
"Not" Timeout Count Clock From Spindle logic PCA pin A8P1-M.
V
TAe Tachometer From Velocity Transducer.
S
TAC "Not" Tachometer From Velocity Transducer.
C
TBUSO "Not" Tag Bus Bit 0
One-way tag bus from controller._
37
TBUS1 "Not" Tag Bus Bit 1 One-way tag bus from controller.
39
TBUS2 "Not" Tag Bus Bit 2
One-way tag bus from controller.
41
TBUS3 "Not" Tag Bus Bit 3 One-way tag bus from controller.
43
TOFl "Not" Timeout Fault lED
To Fault Indicator PCA pin A12J1-3.
SKH
SKI
DENOTES SIGNAL SOURCE DENOTES BIDIRECTIONAL SIGNAL
4-59