Voltage Regulator Noise; Hood And Trunk Lid Noise; Other Electrical Noises - Motorola Radius CM200 Installation Manual

Noise Reduction Techniques
10.4

Voltage Regulator Noise

This type of interference is characterized by erratic popping noises which change only slightly with
changes in engine speed. The noise is generated by arcing in the vibrating breaker contacts of the
voltage regulator. It can be suppressed by connecting a 0.5 µF coaxial capacitor (Motorola Part No.
0882571B01) in the battery and armature leads of the voltage regulator (see Figure 10-4).
CAUTION: Disconnect the battery ground terminal before attempting to connect components
!
to the voltage regulator.
Step 1.
Mount Capacitor
(0.5 F Coaxial Type)
to vehicle chassis
using lockwasher and
self-tapping screw.
Step 2.
Disconnect wire (dashed)
from battery post and
connect to capacitor
using lockwasher and nut.
10.5

Hood and Trunk Lid Noise

This type of noise is characterized by irregular popping sounds. It is caused by friction in poorly
bonded automobile hoods or trunk lids. This friction causes static electricity to build up until arcing
occurs. This type of noise is suppressed using a Motorola Hood Wipers and Mounting Hardware Kit
(part of the TLN5277 Noise Reduction Kit) which provides electrical bonding of the hood or trunk to
the vehicle body while permitting them to be opened.
10.6

Other Electrical Noises

Other elements of the electrical system which can generate noise are listed below. These can be
suppressed by connecting a 0.5 µF bypass capacitor between the noise source and ground.
1. Ammeter-to-battery lead
2. Gauges (oil, fuel, temperature)
Vehicle
Battery
Post
A coaxial capacitor can
be added here, if required.
Figure 10-4. Voltage Regulator Noise Suppression
Armature
Step 3.
Add lead from battery
post to capacitor using
lockwasher and nut.
FL0830265-O
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