JRC JMA-9923-7XA - 8.2 TROUBLESHOOTING

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8.2
TROUBLESHOOTING
ln
case of semiconductor
circuits, it
is
deemed that there
are
few
cases
in which the used
semiconductor devices
have inferior
quality
or
performance
deterioration
except due to
insufficient
design or inspection
or by other external and artificial
causes.
In
general,
the relatively
many
causes
are disconnection
in
a
high-value
resistor due to
moisture, a defective
variable resistor and
poor
contact of a switch
or
relay.
Some troubles are
caused by defective
parts,
imperfect
adjustment
(such
as tuning
adjustment) or
insufficient
service
(such
as
poor
cable
contact).
lt
will also be
effective
to check and
readjust these
points.
Melted fuses are
caused by any
clear
cause. When
a
fuse is
replaced,
it is
necessary to check the
related
circuits even
if there is no
trouble.
In this
case,
noie that
there is some
dispersion
in
the
fusing
characteristics.
Table 8.7
shows
a list of fuses
used
in the
equipment.
Table 8.7 Fuse List
Location
Parts
No.
Nominal
Current Protection
Circuit
Type
Display Unit
(NSK)
F1to
F4
0.5A LOG.NSK
circuit
PC4201 MF6ONR-0.5A
8-17