Tools Required
J 39916-A Audio System Diagnostic Kit
Important: Always compare the front speakers to the front and the rear
speakers to the rear. Do not compare the front speaker to the rear speaker
for the following reasons:
• The front speaker and the rear speaker may be different speakers. • The speakers mounting environment could cause them to sound different. • 50 Hz tone • 500 Hz warble tone • 9 kHz spectral tone
Bass/Sub-Woofer Test (50 Hz Sine Tone)
The 50 Hz tone is used to evaluate the bass response of an audio system. This tone is helpful in evaluating audio systems which have separate subwoofer amplifiers and speakers.
Midrange Speaker Test (500 Hz Warble Tone)
The 500 Hz warble tone is used for the evaluation of midrange speaker response. This tone is qualified as a warble tone because it has different audio characteristics than a sine tone. The warble tone produces a warble sound. It is best to use a warble tone than a sine wave at these tone midrange frequencies, because 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 which can make it difficult to determine its source location.
Tweeter Test (9 kHz Spectral Tone)
The 9 kHz spectral tone is used for tweeter or high frequency evaluation. This tone is a section of frequencies of equal amplitudes, ranging from 8.5-9.5 kHz. The 9 kHz spectral tone sounds similar to a group of crickets chirping.
The 9 kHz spectral tone is used for the following reasons:
| • | It is easy to locate the source of the 9 kHz spectral tone. The tone sounds much like a warble tone. |
| • | The 9 kHz spectral tone is easy to identify, especially for people with high-end, hearing loss problems. |
All Speaker Test
The combination tone can be used in order to diagnose numerous audio conditions, such as the following conditions:
| • | Distortion from the speakers |
| • | No sound emitting |
You can use the combination tone in order to make comparative AC voltage measurements on the speaker terminals. Before you make these measurements, ensure that the fade and balance controls are in the detent position. A determination can be made in the diagnosis of the speaker or the amplifier.
Speaker/Grill Rattle Test (50 Hz to 8 kHz Swept Sine)
The next portion of the tape can be used in order to diagnose rattle noises in the speaker and the grill. This portion of the tape has 2 tests:
| • | Two tones played back to back. |
| • | Variable frequency tone. |
| Frequency change is at a much slower rate than the two tones played back to back test. |
Both tests can be used in order to repair a speaker rattle or a buzz sound.
If you have already identified the specific problem area, you may complete the following actions:
| • | Set the fade and balance controls to the correct location. |
| • | Play the test tones in the problem area. |
Motor Speed Test
There is a 2 minute time period marked in this portion of diagnostic tape for the purpose of evaluating 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. Improper tape motor speed can cause audio abnormalities, in some cases. If it takes 116-120 seconds in order to plat this portion of the tape, the tape motor speed is acceptable.
Nose Diagnosis (Dead Space)
This portion of diagnostic tape can be used for noise diagnosis, such as alternator whine, switch pops, etc. These conditions can be easily detected during the dead space (the blank space in between subsequent songs). This portion of the diagnostic tape may be used in conjunction with Speaker Noise - General .
