Service
Model
182C
8 19.
PRELIMINARY CHECKOUT.
8-20. To help isolate
malfunctions, perform the following
checkout procedure:
a.
Check for improper
control settings (refer to Section
III).
b. Check
for
proper operation
of accessory equipment.
c.
Visually Inspect instrument
for
loose
wire and cable
connections. Check wiring to all
board assemblies for
proper connections.
d. Visually inspect
for burned, broken or
chafed
wires,
charred or
discolored components;
and any other indi
cation of physical damage.
e. Check
for proper power supply voltages and deter-
mine
that fuses are not open.
8-21. DETAILED CHECKOUT.
8 22.
If the trouble cannot be
located using the prelimin-
ary
checkout procedures, a detailed
check of the circuits
will be necessary.
Troubleshooting charts, waveforms, and
voltages are provided to
help in locating problem areas
and
components. The
troubleshooting charts and wave-
forms
are
to
be used to isolate the problem to a
specific
area. The voltages can then be
osed
to
locate the
faulty
component within the
problem area.
When taking
waveform
or dc
voltage
measurements,
use
extreme care to
avoid shorting
supply voltages
or com
ponents;
8-23. Oc voltages
are shown on the schematics
near active
components
such as
transistors. Waveforms are
also placed
on
the schematics at
points which
will assist in determining
proper
circuit
operation As an
aid to locating measure-
ment points, a small dot is
etched on the circuit
board
next to the emitter lead
of each
transistor, the source lead
of
FET's, the
cathode end
of diodes and the
positive end
of electrolytic
capacitors. Use these points
to assist
in
voltage and
resistarKe
measurement tests
arKl
as
guidance
in properly replacing
components.
8-24. TROUBLESHOOTING
TABLES.
8-25. Troubleshooting tips
are
given in several
tables. The
tables are not intended as a
fool-proof tool for pin-pointing
every
possible trouble;
only some
of
the
most common
symptoms and
probable faults are
given. Before doing the
checks, be sure that the symptom
is valid by
checking
control settings. For
example, what may at
first
appear
as no
display may
really be a no sweep
problem.
8-26. REPAIR
AND REPLACEMENT.
8-27. The following
paragraphs contain recommended
procedures for repair and replacement of defective
com-
ponents. A complete list of
components, with Hewlett-
Packard
part numbers and ordering information,
is in
Section VI. Contact the nearest HP Sales/Service Office
listed at the rear of this
manual
if satisfactory
repair or
operation cannot be achieved.
8-28. SERVICING
ETCHED CIRCUIT BOARDS.
8-29.
Etched circuit boards in this instrument have com-
ponents mounted on one side of the board,
conductive
surfaces on both sides, ar>d plated through
component
mounting holes.
Hewlett-Packard
Service Note M-20E
contains
useful information
on servicing etched circuit
boards. Some important
considerations are as
follows:
a. Use a 37 to 47.5 watt chisel tip soldering iron with
a tip
diameter of
1/16 to
1/8
inch, and
a
small
diameter
rosin core solder.
b. Components may be removed
by
placing the solder-
ing
iron on the
component leads on either side of the
board
and pulling
the component straight away from the
board.
If heat
is
applied
to the component side of the
board, greater care
is
required
to avoid damage to the
comportents, especially semi-conductors. Heat
damage
may be minimized by gripping the lead with long nose
oilers
between
the soldering iron and
the component,
thereby
forming
a heat sink.
c. If a
component is obviously
damaged or
faulty, clip
the leads close to the
component
and
then unsolder the
leads
from the board.
d.
Large components, such as potentiometers, may be
removed by
rotating the soldering iron from lead to lead
and
applying steady pressure to
lift
the part
free.
The
alternative is to clip the
leads of the
damaged
part and
remove them individually.
e. Excessive heat or
force
will
destroy
the
laminate
bond between the metal plated surface (conductor) and
the board.
If this problem should
occur,
the lifted
con
doctor may be cemented down
with
a small amount
of
quick-drying acetate-base cement
having
good insulating
properties. Another method
of
repair is to
solder
a section
of good
conducting
wire
along
the damaged
area.
f. Before replacing
a
component, heat the remaining
solder
in
the component hole and clean
it out
with
a
toothpick or
"solder
sucker".
Sharp pointed metallic
tools are not recommended since they may loosen eyelets
in boards or remove
plating from the inside of holes
on
plated-through etched circuit boards.
g.
Tin and shape replacement component leads to
fit existing holes.
h. Install the replacement component in the same
position
as
the
original.
8-2
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