And Replacement; Etched Circuit; Recommended; List Of - HP 182C Operating And Service Manual

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