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Model
8904A
Replaceable
Parts
Section
6
REPLACEABLE PARTS
6-1.
INTRODUCTION TO THIS SECTION
This section contains information for ordering parts. Table 6-
1
lists reference designations, and
Table 6-2 lists abbreviations that are used in the Replaceable
Parts
List. Table 6-3 lists all replaceable
parts in the instrument. Table 6-4 contains the names and addresses that correspond
to
the
manufacturer’s code numbers listed in Table 6-3.
Also
included in this section are drawings to aid
in identifying and ordering chassis mounted parts and mechanical parts.
6-2.
REFERENCE DESIGNATIONS AND ABBREVIATIONS
USED
IN
THIS
MANUAL
Table 6-1 lists the reference designation letters
for
electrical
parts
in the instrument. The letter
designations found in Table 6-1 are coupled with numeric designations to provide a unique reference
designation for each part in the instrument.
For
example A3R1
is
the reference designation
of
a
particular resistor
R1
on assembly A3. Designators with no letter are mechanical parts.
Table 6-2 lists abbreviations used in the parts list and on schematics.
6-3.
REPLACEABLE PARTS LIST
Table 6-3 is a list
of
replaceable parts and is organized as follows:
a. Electrical assemblies and their components with reference designations in alphanumeric order.
b. Chassis-mounted parts with reference designations in alphanumeric order.
c. Mechanical parts with reference designations
in
numeric order.
Ordering
Parts.
Instrument Serial Numbers.
Attached to the rear
of
the instrument is
a
serial-number plate. The first four digits and the letter
are the instrument serial-number prefix. The last five digits (serial-number suffix) are unique to each
instrument. When parts in the instrument are changed, the serial-number prefix of the instrument may
also change. This means that sometimes a part will be listed more than once in the the replaceable
parts list along with a serial-number prefix
or
range of serial-number prefixes. Find the serial-number
prefix on the serial plate of your instrument and order the part listed under the corresponding prefix
in the table. If no serial prefix information is listed, the part is compatible in instruments of all serial
numbers.
NOTE
It is possible that some assemblies
in
your instrument have been updated
(through service
or
retrofitting) to reflect changes made to instruments with
serial-number prefixes later than that shown on
your
instrument serial-
number tag. Be sure to note the printed circuit board number
of
the
assembly
being repaired
or
replaced when ordering parts
for
your
instrument.
6-
1