ESI 250-DA - Checking the Standard Capacitor; Removing the Bridge Chassis from its Case; Procedure for Removing the Chassis; Procedure for Replacing the Chassis

6.
2.
11
CHECKING
THE
STANDARD
CAPACITOR
Check the
standard
capacitor by
measuring
a capacitor
of
known
value*
We
recommend
the
0*1
pf
standard
capacitor listed
in
6*2*1. If
this
test
indicates that
the standard capacitor is unsatisfactory,
remove
the
bridge
from the
case* Disconne
ct
the standard
capacitor
and
check
it
with
a
capacitance
bridge, (The
leTsI
i
I Model
270
Capacitance
Bridge
is
recommended*)
The
value
should be
99,880
ppf
±0.1%.
6*3
REMOVING
THE
CHASSIS FROM
THE
CASE
6.3*1
REMOVING
THE CHASSIS
Prepare
a
soft,
clean place
to
set
the instrument.
Be sure
that no
projections
or
pointed
objects will
be underneath the bridge
panel.
See that
there are
no
metal filings near the exposed
wiring and parts
of
the
bridge;
filings
which accidentally
get into
the chassis can cause
short
circuits.
Loosen the
four
panel screws, lift
out
the
chassis
and
place it
carefully on
the prepared surface with the panel
down.
6.3.2
REPLACING
THE
CHASSIS
Be
sure
that
the
interior of the case is thoroughly
clean. Position
the bridge in
the case.
Replace the panel
mounting screws
and tighten
them in
place
.
6,4
REPAIRING THE
BRIDGE
Repairs
are
limited to
mechanical
adjustment
and
replacement
of
parts*
When
trouble
shooting
indicates
that
a
component is defective, replace
that
component*
Lejs-IM
250-DA
7/59