Diagnostic Switch; Diagnostic Mode - HP 7936 Support Manual

Troubleshooting and Diagnostics
7936 and 7937
Time Mode) or a Diagnostic Mode which adds
Read-Only Error Rate Tests (RO ERT) to the
sequence. The results of the diagnostics are passed
to the front panel LED display, providing a visual
indication of the operational status of the drive.
The external exerciser program can also be used to
initiate the self-test diagnostics and retrieve the
resultant status/error information.
8-5. DIAGNOSTIC SWITCH
Diagnostic switch Sl is one segment of the
4-segment Channel Address/Diagnostic switch as-
sembly, located on the rear panel of the drive. See
figure 3-2. Two diagnostics can be selected by the
switch: RUN TIME MODE and DIAGNOSTIC
MODE. The selected switch position is read each
time the drive is powered on.
8-6. RUN TIME MODE. When switch Sl is set
to the R UN TIME MODE position, a series of
hardware tests are performed at power-on.
Following successful completion of the hardware
diagnostic routines, the drive comes on line. The
diagnostic normally takes approximately
10
seconds to complete. During this time the front
panel LEDs sequence through the following
display:
RED
ON
OFF
OFF
YELLOW
ON
ON
OFF
GREEN
ON
ON
ON
DURATION
8 seconds
2 seconds
cont;nuous
Successful completion of the diagnostic is indi-
cated by the Green LED remaining lit at the end
of the sequence. If the drive fails the hardware
diagnostic, the Red LED will remain lit and the
Yellow and Green LEOs will be coded to indicate
the malfunctioning assembly. A power supply
failure or loss of input power is indicated by all
LEOs extinguished.
The coding for the LEOs is shown on a la bel on
the rear panel. See figure 3-2.
8-2
NOTE
A drive fault condition (Red LED il-
luminated) does not necessarily mean
that the controller is incapable of com-
munication with the host. In most cases,
details of the fault condition (over and
above the information encoded by the
LEDs), can still be obtained by using the
external exerciser to retrieve status and
error information.
8-7. DIAGNOSTIC MODE. If Sl is set to the
DIAGNOSTIC MODE pO~1tion, the same hardware
diagnostic executed in RUN TIME MODE is in-
voked when power is applied. However, the con-
troller does not bring the drive on line following
the completion of the hardware diagnostic
routines. Instead, the drive performs a full-volume
RO ERT (7.5 minutes) followed by a continuous
loop of random RO ERTs.
When the drive successfully completes the
hardware diagnostics and begins the RO ERTs,
both the Yellow and Green LEDs will be
il-
luminated. If any uncorrectable or marginal data
errors occur during the RO ERT, the Green LED
is extinguished leaving only the Yellow LED lit.
A hardware diagnostic failure will be indicated by
the Red LED remaining lit and the Yellow and
Green LEDs coded to indicate the source of the
most likely malfunctioning assembly. A power
supply failure or loss of input power is indicated
by all LEOs extinguished.
The coding for the LEOs is listed on a label on the
rear panel. See figure 3-2.
NOTE
Failure information gathered during this
time will be logged in the internal error
logs. To retrieve this failure information,
Diagnostic switch Sl must be returned
to the RUN TIME MODE position and
the power cycled. After this. the infor-
mation can be obtained by using the ap-
propria te external exerciser command.