Delco Audio System Dignostic Kit
Use the J 39916-A Audio System Diagnostic Kit in order to test and evaluate coaxial speakers or other complex speaker systems.
Test Tones
| • | 50 Hz sine -- Sub woofer test |
| • | 500 Hz warble tone -- Midrange speaker tests |
| • | 9k Hz spectral tone -- Door tweeter test |
| • | Combination tone -- All speakers |
| • | 50-8k Hz swept sine -- Speaker buzz and rattle test |
| • | Timed section in tape -- Motor speed test |
| • | Instructions on tape cleaning |
| • | Dead space -- Noise diagnosis |
Bass Speaker Test
Use the 50 Hz tone in order to evaluate the bass response of an audio system.
Use the 50 Hz tone in order to evaluate audio systems which have separate subwoofer amplifiers and speakers.
Midrange Speaker Test
Use the 500 Hz warble tone in order to evaluate midrange speaker response.
The warble tone has the following characteristics:
| • | The tone has different audio characteristics than a sine tone |
| • | The tone produces a warble sound |
Use a warble tone rather than a sine wave at midrange frequencies. The location warble tone source, such as a speaker, is easy to identify. A normal sine tone is able to set up a standing wave within a vehicle. This action may make it difficult to determine the source location.
Tweeter Test
Use the 8.5k-9.5k Hz spectral tone in order to evaluate tweeter or high frequencies. This tone is a section of frequencies of equal amplitudes ranging from 8.5k-9.5k Hz. The tone sounds like a group of crickets chirping. The tone is used for the following reasons:
| • | The source of the tone is easier to locate |
| • | People with high end hearing loss may easily identify this tone |
All Speaker Test
The combination tone is a blend of all three test frequencies. When the tone is in use, you will hear three distinct sounds. Use the following procedure in order to determine if there is a speaker malfunction:
| • | Listen to the sounds. |
| • | Compare the left front speakers. |
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 for the following reasons:
| • | The front speakers and the rear speakers may be different types of speakers |
| • | The mounting environment may change the sound of the speakers |
Use this section of tape for audio difficulties such as distorted sound or no sound from a speaker or speakers. When using the combination tone, you may make comparative voltage measurements on the speaker terminals. Ensure that the fade and balance controls are in the detent positions. Use these voltage measurements in order to diagnosis a speaker or amplifier.
Speaker and Grille Rattle Diagnostics
Use this portion of the tape in order to diagnose speaker and grille rattles. Use the two test tones for the purpose of diagnosing speaker and grille rattles.
Use the first tone for two variable frequency tones played back to back.
The second tone is a variable frequency tone, but the frequency change is at a much slower rate. Use the second tone in order to repair a rattle or a buzz. If the problem has already been isolated by the customer, play the fade and balance controls in the specific problem area.
If a distorted or strange sound is coming from the speaker during certain sections of music, the technician may use this portion in order to verify and repair some conditions associated with this type of occurrence.
Motor Speed Diagnostics
There is a two minute time period marked in this section of tape in order to check the cassette tape motor speed. The tape will tell you when to mark the time on a watch in order to start the timing event. There is about one minute and fifty seconds of music. Instructions at the end of the tape tell when to mark the time for the end. If the time taken for this test is between one minute and fifty seconds to two minutes and one second, the tape motor speed is within specs.
Use this portion of the diagnostic tape in order to verify or resolve abnormal conditions. In some cases, improper tape motor speed may cause audio abnormalities.
Dead Space
Use this portion of the tape in order to diagnosis the following noises:
| • | Alternator whine |
| • | Switch pops |
Use this method in order to confirm noises between songs on a tape. Use this portion of the diagnostic tape in conjunction with Radio/Audio System Schematics .
