Audio Problem Diagnosis - How To Get Started (ASN 1194-06)

AUDIO PROBLEM DIAGNOSIS - HOW TO GET STARTED

TECHNICAL SERVICE BULLETIN

AUDIO PROBLEM DIAGNOSIS: HOW TO GET STARTED

Model(s): 1986-95 Acura Vehicles

Group: Accessories

Bulletin No.: ASN 1194-06

Date: November, 1994

SERVICE INFORMATION

You can "fix" some audio unit problems without replacing the unit. In this issue, we'll look at some tips for your initial diagnosis of an audio problem.

PREPARATION FOR DIAGNOSIS

Learn how to operate all the audio unit types in the Acura product line. Learn what level of performance is normal for each type.

Keep a high-quality music cassette at hand to double-check whether a problem is radio reception or really the audio unit itself. Also keep a head cleaning cassette handy.

If your service area is noisy or has its own sources of radio interference (fluorescent lights, metal roofing, etc.), find an area near the dealership that has less interference for testing or demonstrating radio performance.

Note one strong AM and one strong FM station near the dealership; note one weak-but receivable AM and one weak FM station (preferably stereo). Use the strong stations to check whether the customer's radio is truly malfunctioning. Use the weak ones to demonstrate unavoidable reception characteristics like fade-out.

DIAGNOSIS OF AUDIO PROBLEMS

Hopefully, the service adviser had the customer demonstrate the problem. If a problem cannot be demonstrated, run the radio and tape player through a quick "performance check," comparing its sound quality to other Acura cars.

Regardless of the symptom, the first thing you should do is clear the unit's microprocessor by disconnecting power from the unit. (Voltage spikes can sometimes cause the microprocessor to "flip-out," causing any number of symptoms.) Make sure you have the anti-theft code, and record the customer's preset stations, then disconnect the battery or the audio unit connector for at least 20 seconds. If this doesn't eliminate the symptom, then continue with your diagnosis.

If the problem is distorted sound, static, or no sound from one speaker, try playing a music cassette. If you get the same symptoms, then it's not a reception problem, and you'll need to do some more troubleshooting.

If it appears to be a reception problem, double-check by tuning the very weak and very strong stations you found in "Preparation" above. If the problem is only on the weak station, it's probably due to radio signal strength and is not repairable (the radio station is just too far away). If it's a stereo station, a weak signal is easy to confirm: the stereo sound will fade in and out to monaural or switch completely to mono.

If the problem is static, check using the strong and weak stations. If the static is only on the weak station, it's another symptom of a weak signal to the radio. Generally, static is a constant "hiss" on a weak FM station and crackling "waves" on a weak AM station.

If the static is the same on all stations, it's probably a bad ground at the antenna, a faulty antenna lead (coaxial cable), or a loose coaxial cable connection at the antenna or the radio. Antenna-caused static is also more in-time with the ignition system or other electrical components like the blower motor, the power window motors, or the hazard warning lights.

A quick way to determine if it's an antenna ground problem is to tune to a weak AM station or a "no-station" frequency between two AM stations. While on this frequency, start the engine and operate other electrical components to see if you get corresponding "crackles" and "pops." If you get electrical interference, check the resistance between the antenna collar and body ground, and between the antenna tube and the antenna jack, as described in Service Bulletin 94-011 .

If the problem is with the tape player try playing the high-quality music cassette. If the sound is still bad, try using the head cleaning cassette. Wait a couple of minutes for the alcohol to evaporate from the tape head, then play the known-good music cassette again. If the sound is no better, the unit must be replaced. If the sound is slightly better, the tape head needs to be professionally cleaned (the head cleaning cassette may not do enough. If the sound is good, the head cleaning cassette solved the problem.