The second common source of radio interference is the ignition system. In this case, you should connect a 1.0 μF capacitor between the ground and the "SW" or "+" terminal of the ignition coil (see B/Figure 10.11). This will eliminate the ticking sound from the speakers.
Another source of interference is spark plugs. The Peugeot 305 uses special ignition wires with built-in radio interference suppression, but if they are replaced with regular ones, problems may arise.
To suppress radio interference from spark plugs, you can install special resistive caps on them (see B/Figure 10.12), whose resistance ranges from 10,000 to 15,000 ohms. If space is limited and resistive caps cannot be installed, linear radio interference suppressors can be used (see B/Figure 10.12) (if the noise is not too strong, it is enough to install one suppressor on the wire between the coil and the distributor. If this does not help, suppressors must be installed on all ignition wires).
Check the grounding of the radio and antenna. If possible, keep the length of the radio receiver's power cable to a minimum.
If all common sources of radio interference have been checked and "neutralized" and the noise persists, all electric motors, light switches, and appliances should be checked. The solution to the problem in this case is shown in Figure 10.13 (not very strong interference from the electric motor) and 10.14 (interference from operating devices). Interference from the light switch is generally not suppressed. Recently, when a radio receiver is factory-installed, a choke has been installed on its power supply line in addition to a fuse, which also helps suppress radio interference. If you do not have such a throttle, install it as shown in B/Figure 10.15.
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In the case of a transistor radio, a 2 A choke is sufficient. If you have an electric clock in your car, interference from it can be eliminated using a 0.5 μF capacitor installed as shown in Figure 10.13 for an electric motor.
If the interference does not disappear even after all the measures taken, check whether it is passing through the wires. You can try replacing the regular power cable with a shielded one.
In the worst case scenario, check whether interference is caused by interference from metal parts of the car rubbing against each other (if the fasteners are not tightened properly). Interference of this kind is removed by shunting the "noisy" connection with a wide ground bus with a braid. The most likely sources of interference may be the mounting locations:
- a. muffler
- b. exhaust pipes (at the point of contact with the cylinder block)
- in. air purifier
- front and rear bumpers
- steering column
- e. hood and trunk lids (their locks)
Interference of this kind is most noticeable (1) at idle, (2) under engine load.
A pulsating grinding noise when driving can be caused by static electricity building up on the wheels or tires. To remove them, it is necessary to "inject" a special antistatic powder into each tire.
Interference in the form of a shrill howling sound that changes its tone as the car moves and appears and disappears can be caused by the antenna (especially telescopic). To remove them, simply place a small rubber ball on the end of the antenna. If interference occurs during braking, it is caused by static electricity build-up in the brakes (especially noticeable in hot, dry weather). Such interference can only be removed by installing a special, very expensive brake kit.
(Data published on the website: PEUGEOTBOOK.ru)
Car radios are less susceptible to interference, but if it does occur, it's important to eliminate interference from the generator and ignition system and install a 3-5 A choke on the power supply wire. In the most severe cases, shielding the power supply wire and the wires leading to the speakers can be helpful.
Note: In case of electronic ignition system, it is not recommended to install resistive caps on spark plugs or a capacitor on the ignition coil. because this may result in damage to the system. Most electronic ignition systems have built-in radio interference suppressors.