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
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