HP 7925D Service Manual page 79

7925
Table 4-1. Visual Indication of Drive Status (Continued)
Troubleshooting
ACTIVE STATE
INDICATOR!
FUNCTIONAL
INDICATION
DIAGRAM
LOGIC EQUATION CIRCUIT DESCRIPTION
W. AR LED WRITE. ACRY Indicator is lit when the following conditions are met:
Fault Detection
Indicator
a. Drive in write mode.
System, figure 4-29.
b. ACRY (Access Ready) signal inactive.
R. W LED URG. WRITE Indicator is lit when the following conditions are met:
Fault Detection
Indicator
a. URG (Unselected Read Gate) signal active.
System, figure 4-29.
b. WRITE (Write) signal active.
W. AC LED WRITE. ACW Indicator is lit when the following conditions are met:
Fault Detection
Indicator
a. Drive in write mode.
System, figure 4-29.
b. No data signal present.
SPU LED Indicator - - - Indicator is lit when spindle motor is operating at correct
Spindle Rotation
speed.
System, figure 4-25.
OFF LED Indicator - - - Indicator is lit when power is removed from spindle motor.
Spindle Rotation
System, figure 4-25.
SPFLT LED
- - -
Indicator is lit when an overcurrent condition is sensed in
Spindle Rotation
Indicator spindle rotation system.
System, figure 4-25.
Spindle starts to
PIP. DL • ILF • RUN. Spindle rotation occurs when the following conditions are
Sp ndle Rotation
rotate from a CRB. TOF met:
System, figure 4-25.
stationary state.
a. Disc pack in place.
b. Disc pack access door locked.
c. No IL drive fault.
d. RUN/STOP switch set to RUN.
e. Carriage fully retracted.
f.
No time-out fault.
Spindle continues CRB. ILF
Once started, the spindle motor continues to rotate as
Spindle Rotation
to rotate. long as the follow ing conditions are met:
System, figure 4-25.
a. Carriage not fully retracted. [CRB (Carriage Back)
signal inactive.]
b. ILF (Interlock Fault) signal inactive.
Heads seek to RET. SPU
During a power-up operation, the heads seek home when
Head Positioning
cylinder 0 (home) the RET (Retract) signal becomes inactive. This occurs
System, figure 4-26.
from the retracted
when the spindle reaches operational speed (SPU signal
position.
active).
Heads seek from ACRY • SK • ICA
The heads seek from one cylinder to another provided the
Head Positioning
one cylinder to following conditions are met:
System, figure 4-26.
another.
a. Heads settled on any legal cylinder. [ACRY (Access
Ready) signal active.]
b. The SK (Seek) signal from controller is present.
c. The address to which the heads are to seek is not an
illegal one (
>
823).
4-5