Page 254
3.
If the noise has a "whine" characteristie and changes
in pitch with varying engine speed and is still present
with the ignition off, then the generator is the major
source of interference.
4.
A
distinct
but
irregular clicking noise, or "hash" as
it
is sometimes called, that disappears with the engine
idling, indicates the voltage regulator
is
at fault.
5.
A
steady
popping noise that continues with the
ignition off indicates wheel or tire static interference.
This is more pronounced on smooth
roads
6.
The same
type
of interference
as
in step 5, but more
irregular when on bumpy roads, particularly at slow
speeds, indicates body static.
Refer to the Troubleshooting Chart and Figure
2-9
(fold-out
from Page
252), to help determine how to suppress most
noise interference. Naturally, not all vehicles will require
suppression to the extent shown in Figure
2-9,
but some
stubborn cases may require all the suppression components
shown, plus shielding of the ignition system.
Grounding
A
good ground to the automobile body
is
essential.
Recognize that a layer of paint between adjoining parts and
panels may cause
a
discontinuity
in the ground path. A
jumper between the parts may be required.
It may be necessary to bond various parts and body panels
of the automobile to each other, starting from the hood and
continuing to the trunk. This may include bonding of the
transmission line every few feet.
Noise Suppression Troubleshooting Chart
RECOMMENDED
REMEDY
1.
Replace plugs with resistor type
(recommended).
2.
Loose crimped connections should be clean-
ed and soldered.
3.
Place resistors in distributor system.
1.
0.1
!.IF coaxial type capacitor in series
with the armature (A lead).
2. Clean commutator.
3.
Replace brushes.
4.
Ground generator shaft
5. Parallel trap
(#lo
w~re-coil and suitable
capacitor) in
serles with armature A lead,
tuned to
operating
frequency.
TYPE
OF NOISE
Loud popping increasing
to buzz with increased
engine speed.
Whine
-
varies with
engine speed.
POSSIBLE
CAUSE
Ignition system.
Alternator or
generator.
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