Model
8901B
Adjustments
Section
5
ADJUSTMENTS
5-1.
INTRODUCTION
This
section contains adjustments and checks
that
assure
peak
performance
of
the
iModulation
Analyzer.
The
instrument should
be
readjusted
after
repair
or
failure
to pass
a
performance
test.
Allow
a
30
minute warm-up prior
to
performing
the
adjustments. Removing
the
top cover
is
the
only
disassembly
required
for most adjustments.
To
determine which performance
tests
and adjustments to perform
after
a
repair, refer
to
paragraph
5-5,
Post-Repair Tests, Adjustments, and Checks.
5-2.
SAFETY CONSIDERATIONS
This
section contains information, cautions, and wa-nings which must
be
followed for
your
protec-
tion and to avoid damage to the equipment.
Adjustments described in
this
section are performed with power supplied
to the instrument and with protective covers removed. Maintenance should
be performed only by service trained personnel
who
are aware
of
the hazard
involved (for example, fire and electrical shock). Where maintenance can be
performed without power applied, the porixr should be removed.
Removal of the Modulation Analyzer's
bottom
cover
is
not necessary to
perform these adjustments. However,
if
the bottom wver is removed.
hazardous voltage
(~120
Vac) is nccessiblc.
A
pin-to-pin coltage difference
of
55
Vdc
may bc found
on
man?
of
thc
Modulation Analyzer's circuit board conimtors. Be careful while uorking
on the circuit boards with power supplicd
to
the instrument.
If
a circuit board
is
placed
on
uri exteridcr
board,
the possibility
of
coming
in contact uith
55
Vdc is greatly increased. Be curefiil while working
on
the circuit boords with
porcer
supplicd.
Work
uith
one
hand.
DO
not toiich
the extendcr board.
5-3.
EQUIPMENT
REQUIRED
Each adjustment procedure contains
a
list
of
required
test
equipment. The test c;uipment is
identified
by
callouts
in
the
test
setup diagrams where included.
If
substitutions must be made for the specified test equipment,
refer
to Table
1-3
in
tlx
Operating
Mcinual
for
the minimum specifications. It
is
important that the test equipment mea
the
critical
specifications listed in the
table
if the Modulation Analyzer is to meet its pciformance riquirements.
5-
1
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