General Diagnosis - Speakers
TOOLS REQUIREDJ 39916 CD and Cassette Diagnostic Kit
IMPORTANT: Always compare the front speakers to the front, and compare the rear speakers to the rear. Do not compare the front speaker to the rear speaker for the following reasons:
^ The front and the rear speakers could be different speakers.
^ The front and the rear speaker mounting environments could cause a sound difference.
The tones test and evaluate the following components:
^ The coaxial speakers
^ Other complex speaker system
Three basic tones are used:
^ 50 Hz sine tone
^ 500 Hz warble tone
^ 9 kHz spectral tone
The combination tone is a blend of the above 3 tones.
Bass/Sub-Woofer Test (50 Hz Sine Tone)
The 50 Hz sine tone evaluates the following items:
^ The bass response of an audio system
^ Audio Systems that have separate sub-woofer amplifiers and speakers
Midrange Speaker Test (500 Hz Warble Tone)
The 500 Hz warble tone evaluates the midrange speaker response. The 500 Hz warble tone qualifies as a warble tone because of the different audio characteristics present as opposed to the sine tone. The 500 Hz warble tone produces a warble sound. At midrange frequencies, use a warble tone instead of a sine tone because the location of a warble lone source, such as a speaker, is easier to identify. A normal sine tone can set up a standing wave within a vehicle. A standing wave may cause difficulty in determining the source location.
Tweeter Test (9 kHz Spectral Tone)
The 9 kHz spectral tone is used for the following evaluations:
^ Tweeter
^ High frequency
The 9 kHz spectral tone is a section of frequencies of equal amplitudes ranging from 8.5-9.5 kHz. The tone sounds like a group of crickets chirping. The 9 kHz spectral tone is used for 2 reasons:
^ In order to locate the source, much like the warble tone.
^ For easier identification, for those people with high end hearing loss problems.
All Speaker Test
The combination tone is used for numerous audio problems, such as the following conditions:
^ Distorted sound from the speakers
^ No sound from the speakers
When using the combination tone, comparative AC voltage measurements can be made on the speaker terminals provided that the following controls are in the detent position:
^ FADE
^ BALANCE
With these voltage measurements, a determination can be made in the diagnosis of the following components:
^ A speaker
^ An amplifier
Speaker/Grill Rattle Test (50 Hz-8 kHz Swept Sine)
The next portion of the diagnostic tape rattles in the following components:
^ The speaker
^ The grille
The first test is 2 tones played back-to-back. The second test is a variable frequency tone, but frequency change is at a much slower rate. Both tests can be used in order to repair the following conditions:
^ A speaker rattle
^ A speaker buzz
If the condition has already been identified, complete the following steps:
^ Set the following controls to the proper location:
- FADE
- BALANCE
^ Play the test tones in the specific problem area.
Motor Speed Test
A 2-minute time period is marked in this section of tape for the purpose of inspecting the cassette tape motor speed. This portion of the diagnostic tape can be used to verify complaints of abnormal sound from the cassette tape player. In some cases, improper tape motor speed can cause audio abnormalities. If the time taken for the motor speed test is between 116-121 seconds, the tape motor speed is within tolerance.
Noise Diagnosis (Dead Space)
This portion can be used for diagnosis such as alternator whine and switch pops, which can be more easily detected during dead space. Dead space is blank space between songs. This portion of the diagnostic kit may be used in conjunction with the noise diagnosis in Radio in Electrical Diagnosis.