5
Troubleshooting
This
chapter
provides
troubleshooting
information
on
the
HP
70001A
mainframe
.
Problem
isolation
and
diagnosis
related
to
the
front-panel
fault
indicator
lights
,
fan
operation,
fuse
replacement,
and
power-on
light
are
discussed
as
operator-level
repairs
.
Turn
On
When
the
HP
70001A
as
part
of
an
HP
70000
Modular
Measurement
System
is
turned
on,
the
mainframe
monitors
its
condition
as
it
brings
power
and
cooling
air
up
to
specication.
Once
power
and
cooling
is
established,
the
modules
begin
their
self-test
sequences
.
The
power
ON
light
should
come
on
and
stay
on.
The
V
OL
T/TEMP
and
I/O
fault
indicators
should
blink
on
and
then
turn
o.
The
CURRENT
fault
indicator
should
not
light.
The
fan
noise
will
be
noticeable
.
During
this
self-test,
the
module
A
CT
and
ERR
lights
of
all
the
modules
in
the
instrument
will
be
turning
on
and
o.
After
about
a
minute
these
lights
should
settle
down
to
a
steady
state
.
After
the
module
self-test
is
complete
,
the
power
ON
indicator
is
the
only
mainframe
light
that
should
remain
on.
Note
Some
older
models
may
have
a
fourth
fault-indicator
labeled
AIR
FLOW
.
This
indicator
should
not
light.
The
circuitry
for
this
function
should
be
disabled.
Line
Fuse
A
6.3
A,
250
V
line
fuse
is
located
inside
the
power
receptacle
on
the
back
of
the
instrument.
The
most
common
reason
for
an
open
fuse
is
improper
setting
of
the
line
voltage
selector
,
however
,
internal
problems
can
also
cause
a
fuse
to
open.
See
Figure
2-2
for
fuse
removal
and
replacement
information.
Refer
to
the
HP
70001A
Service
Manual
for
troubleshooting
information.
T
roubleshooting
5-1
