Inspection Procedure 11

Inspection Procedure 11: Excessive Noise On AM And FM.

DIAGNOSIS
Radio reception can be affected by Radio Frequency (RF) emissions from a variety of sources. The disturbance is even greater if the station is weak or poorly tuned. FM reception is not as sensitive to disturbances as AM. AM reception is sensitive to electrical disturbances such as power lines, lightening and other types of similar electrical phenomena.

STEP 1. Check if the customer heard the noise under any of the following conditions.

- A motorcycle was passing.
- Lighting was flashing.
- Passed beneath a power line.
- Passed beneath a telephone line.
- Passed by a signal generator.
- Passed by any other sources of electrical noise.
- Passed under a bridge or through a tunnel.

Q : Did the noise occur during any of the circumstances listed above?

YES : The observed noise is normal.

NO : Go to Step 2.

STEP 2. Compare the customers radio to another identical model.

Operate the radio in a vehicle with a known good audio system of the same type as the customer's.

Q : Is there more noise on the customers radio?

YES : Check all power and ground connections. If all connections are in good condition, consult the radio manufacturers service center.

NO : The observed noise is normal.