Maintenance
WARNING
THESE
SERVICE
INSTRUCTIONS
ARE FOR USE
BY
QUALIFIED
PERSONNEL
ONLY. TO AVOID
ELECTRIC
SHOCK,
DO NOT
PERFORM
ANY
SERVICING OTHER
THAN THAT
CONTAINED
IN
THE OPERATOR’S
MANUAL
UNLESS
YOU ARE QUALIFIED
TO
DO
SO.
INTRODUCTION 3-1.
This
section contains
maintenance information for
the
performance
testing,
calibration,
general maintenance,
and
troubleshooting of the
70, 73, 75, 77,
21,
and 23 Series II
Multimeters
(collectively
called the
Series n meters). For
operator
maintenance and
instrument
specifications,
refer
to the Users Manual.
The
performance
tests are
recommended as
a
preventive maintenance
tool
to
verify
proper
instrument
operation. A one year
calibration cycle is
recommended
to
maintain
the
specifications given
in the
Users Manual. Test equipment
required for
the perfor-
mance tests and
calibration is listed
in Table
3-1.
If the
recommended equipment
is not
available,
instruments with
equivalent specifications may
be used.
PCA
ACCESS AND
GENERAL
MAINTENANCE
3-2.
WARNING
TO AVOID
ELECTRICAL
SHOCK, REMOVE THE
TEST LEADS
BEFORE OPENING
THE
CASE, AND CLOSE THE
CASE
BEFORE
OPERATING
THE
METER. TO
PREVENT FIRE, INSTALL
FUSES
WITH
THE RATING
SHOWN ON BACK OF THE
METER.
CAUTION
To avoid contaminating
the pea with oil from
the
fingers,
handle
it by the
edges or wear gloves. PCA
contamination
may not
cause immediate instrument failure
in controlled
environments.
Failures
typically show
up
when
contaminated units
are oper-
ated in
humid areas.
Use
the
following procedure for removing
the
pea
(printed
circuit
assembly)
from its
case:
1.
Set
the function switch
to
OFF,
and disconnect
test leads if they are installed.
2. Remove the four Phillips
screws from the
bottom
cover.
3. Turn the meter face
up, grasp the top cover,
and pull
the
top cover from
the
meter.
4. Some Series II meters have
a fuse on the lower
portion
of
the
pea.
This
fuse must be
removed to access the screw that holds
the
pea to
the
case bottom.
NOTE
Be
careful
not
to lose the spring located directly under the
screw
on the
back side
of
the
pea.
5. The
pea
may now
be
removed from the
bottom
cover.
3-3
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