I/O
This
circuitry
senses
the
readiness
of
the
external
HP-MSIB
.
If
the
indicator
is
on,
HP-MSIB
communications
are
inhibited.
The
I/O
fault
indicator
light
will
be
on
if
one
of
the
following
conditions
is
true
.
The
external
HP-MSIB
loop
is
not
complete
.
Check
that
both
ends
of
all
HP-MSIB
cables
are
securely
connected.
2
Not
all
the
elements
on
the
external
HP-MSIB
loop
have
the
power
turned
on.
V
erify
that
the
power
is
on
to
all
mainframes
and
stand-alone
instruments
on
the
external
HP-MSIB
.
The
mainframe
is
in
need
of
repair
.
HP-MSIB
communication
will
resume
as
soon
as
the
problem
is
corrected.
If
an
I/O
light
fault
is
indicated,
the
following
steps
will
help
isolate
the
problem.
Disconnect
both
HP-MSIB
cables
from
the
mainframe
at
the
mainframe
connectors
.
Is
the
I/O
fault
indicator
still
on?
NO
The
problem
is
either
with
the
cables
,
or
the
element
that
was
connected
to
the
mainframe
with
the
cables
.
Loop
each
cable
\IN"
to
\OUT"
to
the
mainframe
HP-MSIB
connectors
.
If
the
I/O
light
comes
on,
that
cable
is
faulty
.
If
the
light
does
not
come
on
for
either
cable
,
then
the
element
connected
with
these
cables
is
faulty
.
Refer
to
the
service
manual
for
that
element
for
troubleshooting
information.
YES
The
HP
70001A
Mainframe
or
one
of
the
installed
modules
is
probably
faulty
.
Remove
all
the
modules
.
Does
the
light
still
come
on?
Y
es
The
mainframe
is
faulty
.
Refer
to
the
HP
70001A
Service
Manual
for
troubleshooting
information.
No
Replace
the
modules
one
at
a
time
until
a
faulty
module
or
slot
is
located.
Try
the
module
in
a
dierent
slot.
If
the
problem
only
occurs
in
one
slot
the
mainframe
or
connector
is
faulty
.
If
the
problem
follows
the
module
the
module
is
faulty
.
Refer
to
the
faulty
module
service
manual
for
repair
instructions
.
Note
It
is
possible
that
a
module
may
disrupt
all
HP-MSIB
communication
with
no
mainframe
fault
or
no
module
error
lamp
turned
on.
2
If
more
than
one
mainframe
is
used,
or
if
other
elements
are
connected
to
the
HP-MSIB
,
all
cables
must
be
connected
otherwise;
the
HP-MSIB
will
not
operate
.
If
a
single
mainframe
with
no
external
elements
is
used,
there
should
be
no
HP-MSIB
cables
connected
to
the
external
HP-MSIB
connectors
of
that
mainframe
,
although
a
single
cable
looped
from
the
input
connector
to
the
output
connector
will
allow
the
mainframe
to
operate
.
5-4
T
roubleshooting
