Tools Required
J 39916-A CD and Cassette Diagnostic Kit
Important: Always compare the front speakers to the front, and the rear speakers to the rear. Do not compare the front speakers to the rear speakers because the speakers may be different or their mounting environment could cause them to sound different.
The tones are used to test and evaluate coaxial speakers or other complex speaker systems. The following three basic tones are used:
| • | The 50 Hz sine tone |
| • | The 500 Hz warble tone |
| • | The 9 kHz spectral tone |
| The combination tone is a blend of the three tones. |
Bass/Sub-Woofer Test (50 Hz Sine Tone)
The 50 Hz sine tone is used in order to evaluate the bass response of an audio system. This tone is also helpful in evaluating audio systems which have separate sub-woofer amplifiers and speakers.
Midrange Speaker Test (500 Hz Warble Tone)
The 500 Hz warble tone is used for the evaluation of midrange speaker response. The tone is qualified as a warble sound. At midrange frequencies use a warble tone rather than a sine tone. The location of a warble tone 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 difficulties in determining the source location.
Tweeter Test (9 kHz Spectral Tone)
The 9 kHz spectral tone is used for tweeter or high frequency evaluation. The tone is a section of frequencies of equal amplitudes ranging from 8.5 kHz to 9.5 kHz. The sound is similar to crickets chirping.
This type of tone is used for the following reasons:
| • | Much like the warble tone the source is easy to locate. |
| • | The spectral tone is easier to identify for those people with high end hearing loss problems. |
All Speaker Test
The combination tone can be used for numerous audio problems, such as distorted or no sound from speaker(s). When using the combination tone, comparative AC voltage measurements can be made on the speaker terminals provided the fade and balance controls are in the detent position. With these voltage measurements, a determination can be made in the diagnosis of a speaker or amplifier.
Speaker/Grill Rattle Test (50 Hz to 8 kHz Swept Sine)
A portion of the tape can be used to diagnose speaker and grille rattles. The first test is two tones played back-to-back. The second test is a variable frequency tone, but the frequency change is at a much slower rate. Both of the tests can be used to repair a speaker rattle or buzz. When the problem has been isolated the fade and the balance controls can be set to the proper location. The test tones can be then be played in the specific problem area.
Motor Speed Test
There is a two minute time period marked in this section of tape for the purpose of checking 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 this is between 1 minute and 56 seconds to 2 minutes and 1 second, the tape motor speed is within tolerance.
Tape Cleaning Procedures
The recommended time for cleaning is every 15 hours for best performance and every 50 hours to prevent damage to the tape head. The perferred type of cleaner is available as part of the J 39916-A CD and Cassette Diagnostic Kit.
Noise Diagnosis (Dead Space)
This portion can be used for noise diagnosis such as alternator whine, switch pops, etc., which can be more easily detected during dead space (blank space between songs). This portion of the diagnostic tape may be used in conjunction with, refer to Audio Preliminary Diagnosis .
