Model 1707B Service
SECTION Vlll
SCHEMATICS AND TROUBLESHOOTING
8-1. INTRODUCTION. 8-10. Each electrical component is assigned a class
letter and a number. This letter-number combination
8-2. This section contains schematics, repair and is the basic reference designation. Components which
replacement information, component-identification are part of an assembly have, in addition to the basic
illustrations, waveforms, and test conditions. Table designation, a prefix designation indicating the as-
8-3 defines symbols and conventions used on the sembly of which the component is a part. For instance,
schematics. A disassembly procedure for removing the resistor R23 on assembly A1 is called AlR23.
CRT and instrument modules for repair and replace-
ment is also contained in this section. 8-11. Assemblies are numbered consecutively. If an
assembly reference designation is assigned and later
8-3. SCHEMATICS. deleted, that number is not reused.
8-4. Schematics are printed on foldout pages for 8-12. COMPONENT LOCATIONS.
easy reference to the text and figures in other sections.
The schematics are drawn to show the electronic 8-13. Locations of components on assemblies and
function of the circuits. Any one schematic may in- subassemblies are illustrated on photographs adjacent
clude all or part of several different physical assem- to the schematics. Since the schematics are drawn to
blies. Non MIL-standard symbols and conventions show function, portions of a particular assembly may
used in the schematics are defined in table 8-3. appear on several different schematics. The com-
ponent-location photograph is printed next to the
8-5. The schematics are numbered in sequence schematic that shows most of the circuitry on the
with a bold number at the lower right-hand assembly. In some cases, a particular component-
corner of each page. These numbers are used to location photograph may appear adjacent to more
cross reference signal connections between the sche- than one schematic.
matics. At each circuit breaking point, a number in
a circle is shown, followed by another number in 8-14. Components located on the chassis are identi-
bold type. The circled number indicates the signal fied in figures 8-4 and 8-5. The locations of all adjust-
or circuit and the bold number indicates the associated ments are shown in Section V.
schematic that contains the source or destination of
the signal. To find the source or destination. of the
8-15. PREVENTIVE MAINTENANCE.
signal, turn to the indicated schematic and find the
circled number in question.
8-16. Preventive maintenance consists of periodic
performance checks, calibration, mechanical inspec-
8-6. A table on each schematic lists all components tion, lubrication, and other services designed to pre-
shown on the schematic by reference designation.
vent breakdown and failure. Performance checks
Component reference designators that have been de- and calibration are covered in Section V of this
leted from the schematic are listed below the table.
manual. The other preventive maintenance services
are covered in the following paragraphs.
8-7. The physical locations of components on etched
8-17. MECHANICAL INSPECTION.
circuit boards and assemblies are identified by dashed
lines. Refer to illustrations 1, 2, and 3 on table 8-3. 8-18. Periodically inspect the instrument for dam-
aged components, excess grease, dirt, and corrosion.
Look for loose and misaligned assemblies. Ensure that
8-8. REFERENCE DESIGNATIONS.
all screws and fasteners are tight and serviceable.
8-9. The unit system of reference designations used 8-19. Refer to the paragraphs in this section on re-
in this manual is in accordance with the provisions
pair and replacement for instructions on replacing
of USA Standard Y32.16-1968, Reference Designat- damaged components.
ions for Electrical and Electronics Parts and Equip-
ments, dated March 1, 1968. Minor variations from 8-20. Painted surfaces can be cleaned with a com-
i
the standard, due to design and manufacturing prac- mercial, spray-type, window cleaner or with a mild
tices, may be noted. soap and water solution. Excess grease can be re-
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ACEC
