Table of Contents
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Model
1331A
Service
SECTION VIII
SCHEMATICS AND
TROUBLESHOOTING
8-1. INTRODUCTION.
8-2.
This
section contains schematics,
repair
and
replacement information,
component-identification
il-
lustrations, waveforms,
and test conditions.
Table
8-1
defines
symbols and conventions
used
on
the
schematics.
A disassembly procedure
for removing
the
CRT
is
also contained
in
this
section.
8-3. SCHEMATICS.
8-4.
Schematics
are printed
on foldout pages
for
easy reference to
the text
and
figures in other sections.
The
schematics are
drawn to
show
the
electronic
function of the
circuits.
Any one
schematic
may
include
all or
part
of
several different physical
assemblies.
Non MIL-standard symbols
and con-
ventions
used in the
schematics are
defined in table
8-1.
8-5.
The schematics
are
numbered in
sequence
with
a
bold number
at
the lower right-hand
corner of each
page. These numbers
are
used
to cross reference signal
connections
between the
schematics.
At
each circuit
breaking point,
a
number in
a circle
is
shown, followed
by
another
number in bold type. The
circled
number
indicates the
signal
or
circuit and
the bold number
indicates the associated schematic that
contains
the
source
or
destination of
the signal.
To find the
source
or destination
of
the
signal,
turn to the indicated
sche-
matic
and
find the
circled
number in question.
8-6.
A table
on each
schematic
lists
all components
shown
on the schematic by reference designation.
Component reference
designators that have been de-
leted
from
the schematic
are listed below the table.
8-7.
All
components
within the inclosed
areas
of the
schematic are
physically
located
on
etched circuit
boards.
Components
not physically located on an
etched
circuit board
are
shown in the uninclosed
areas of
the
schematic.
8-8. REFERENCE DESIGNATIONS.
8-9.
The unit
system of
reference designations used
in this manual is in accordance with the provisions
of USA
Standard Y32. l 6-1968, Reference Designations
for
Electrical
and
Electronics Parts and Equipments,
dated March
1,
1968. Minor variations from the
standard,
due to design
and
manufacturing practices,
may be noted.
8-10.
Each electrical
component is
assigned
a class
letter
and
a
number.
This
letter-number
combination
is
the
basic reference designation.
Components
which
are
part
of an assembly
have, in
addition
to
the
basic
designation,
a
prefix designation indicating the
assembly of which
the
component
is
a
part. For in-
stance,
resistor R23
on assembly
Al is
called
A1R23.
8-11.
Assemblies
are
numbered
consecutively.
If
an
assembly reference designation
is
assigned and later
deleted, that number
is
not
reused.
8-12. COMPONENT LOCATIONS.
8-13.
Locations
of components on assemblies and
s ubassemblies are
illustrated
on
photographs
adja-
cent
to the
schematics.
Since the
schematics are
drawn to
shown function,
portions of
a
particular
assembly
may
appear on several
different sche-
matics. The
component-location
photograph is printed
next to the
schematic that shows most
of
the circuit-
ry
on
the
assembly.
In
some cases, a
particular
com-
ponent-location
photograph may
appear adjacent
to
more than
one
schematic.
8-14.
The
locations of all adjustments are shown
in
Section
V.
8-15. PREVENTIVE MAINTENANCE.
8-16.
Preventive maintenance
consists
of periodic
performance checks,
calibration,
mechanical in-
spection, lubrication, and other services designed
to
prevent breakdown
and
failure. Performance checks
and
calibration
are covered
in Section V of this
manual. The
other
preventive maintenance
services
are covered in
the
following paragraphs.
8-17.
MECHANICAL INSPECTION.
8-18.
Periodically inspect the instrument
for
dam-
aged components, excess
grease, dirt, and
corrosion.
Look for
loose and
misaligned
assemblies.
Ensure that
all screws and fasteners are
tight and serviceable.
8-19.
Refer to the paragraphs in this section on
repair
and
replacement
for
instructions on replac-
ing damaged
components.
8-20. CLEANING.
8-21.
Painted,
glass,
and plastic surfaces
can
be
cleaned
with a commercial, spray-type, window
8-1
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