HP 182C Operating And Service Manual page 66

Model 182C
8-30.
SEMICONDUCTOR REPLACEMENT.
8-31.
Semiconductor
devices are
available
in a
wide
variety
of
shapes
and
sizes.
This can
make
it
confusing to
identify
the
leads.
Examples
of
some
of
the
most
common
con-
figurations are
shown
in
Figure
8-1
8-32.
When
removing a semiconductor, use a
pair
of long
nose
pliers as a
heat
sink
between
the device
and
the
soldering
iron.
And, when
replacing a
semiconductor,
ensure
sufficient lead length to dissipate soldering heat
by
using the
same
length of
exposed
lead as used for
the
original part.
8-33.
DETAILED TROUBLESHOOTING.
8-34.
The following troubleshooting
tips
are categorized
according to the various areas of the instrument.
These
tips
can be helpful only
after a
trouble
Is
localized to
one
of these
areas.
Read
the theory of operation
in
Section IV
to learn
how
a circuit
should
operate.
With the
aid
of this
information,
it is
easier
to discover
why
a defective
circuit
Service
is
inoperative.
Finally,
make
resistance checks
to uncover
the faulty
component.
If it
appears
necessary to
calibrate
the
instrument,
refer to Section
V
for the proper
procedures.
8-35.
LOW VOLTAGE POWER
SUPPLY.
&-36. Fuses, test
points for measuring
regulated output
voltages
arKi
voltage adjustment
controls are located on
the low voltage regulator
assembly. Access
to the assembly
is
obtained by removing
the instrument
rear panel,
Each
tow
voltage
supply
is
fused.
The
fuses are
in series
with
the
regulator transistors,
ar>d
all
regulated output
power
flows through the
fuse for the respective supply.
8-37.
Since the
+100V and
-100V
supplies are current
fold-back
limited,
and the
-HSV
and —12.6V
supplies are
current
limited,
an
open
fuse generally
indicates that
trouble
exists
in
the
regulator portion of the supply.
If
a
fuse
is
open, <^eck
the
series regulator
transistor, driver
transistor
and comparator.
8-3