Table of Contents
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Model 8414A
Section VIII
Service
SECTION VIII
SERVICE
8-1.
INTRODUCTION.
8-2.
This section contains principles of operation,
circuit descriptions, troubleshooting procedures,
schematic diagrams and repair procedures.
8-3. PRINCIPLES OF OPERATION.
8-4.
A description of the simplified block diagram
and general principles of operation are presented
on the first foldout. A detailed block diagram
description is presented on the back of the foldout
preceding the diagram. Schematic circuit descrip¬
tions are given on the back of the foldout preced¬
ing each schematic diagram.
8-5. TROUBLESHOOTING.
8-6.
An equipment setup and preliminary instruc¬
tions for all troubleshooting procedures are given
in Figure 8-4. Troubleshooting procedures for the
block diagram and each schematic are on the back
of the foldout preceding the block diagram and
each schematic.
8-7.
RECOMMENDED TEST EQUIPMENT.
8-8.
The test instruments and accessories required
for troubleshooting are listed in Table 8-1. Test
instruments other than those listed can be used
provided their performance equals or exceeds the
Critical Specifications listed.
8-9.
REPAIR.
8-10. Part Location Aids.
8-11.
The
locations
of
adjustments,
chassis-
mounted parts and major assemblies are shown on
the last foldout. The locations of individual com¬
ponents mounted on a printed circuit board are
shown opposite the related schematic diagram. The
part reference designator may be found from the
schematic diagram, then located on the board.
8-12. Circuit Board Repair.
8-13.
The printed circuit boards in the 8414A are
of the plated-through type consisting of metallic
conductors bonded to both sides of insulating
material. Soldering can be done from either side of
the board with equally good results. Table 8-2 lists
required tools and materials. Following are recom¬
mendations and precautions pertinent to printed
circuit repair work.
a.
Avoid
unnecessary
component
substi¬
tution; it can result in damage to the circuit board
and adjacent components.
b.
Do not use a high-power soldering iron.
Excessive heat may lift a conductor or damage the
board.
c.
Use a suction device
(Table
8-2)
or
wooden toothpick to remove solder from compo¬
nent mounting holes. Do not use a sharp metal
object such as an awl or twist drill for this purpose.
Sharp objects may damage the plated-through
conductor.
d.
After soldering, remove excess flux from
the soldered area and apply a protective coating to
prevent contamination and corrosion. See Table
8-2 for recommendations.
8-14.
A broken or burned section of conductor
can be repaired by bridging the damaged section
with a length of tinned copper wire. Allow ade¬
quate overlap and remove any varnish from the
conductor before soldering wire into place.
8-15. Component Replacement.
8-16.
A general procedure for replacing a com¬
ponent is as follows:
a.
Remove defective component from circuit
board.
b.
Remove solder from mounting holes using
a suction desoldering aid (Table 8-2) or wooden
toothpick.
c.
Shape leads or replacement component to
match mounting hole spacing.
d.
Insert component leads into mounting
holes and position component as original was posi-
8-1
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Table of Contents
Troubleshooting
