Audio Head Unit Service 202412

Over the Christmas time, started servicing another head unit.

The owner mentioned that he observed significant imbalance between the L and R channels.
He had to turn the balance knob like 80% more towards the R-side.

On the bench with oscilloscope, while the RR and RL channels were pretty much even, for the Front channels, it was actually the FR at much higher output than the FL.
So, opposite of what the owner said.

Then, connecting to the real Bose AMP and speaker cone, to my ear, all 4ch sounded evenly when tested one at a time so not conclusive.


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Probably one of the most clean face plate that I have ever seen for this year model.
Almost no scratch or faded white text.




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The usual capacitor leakage but since I couldn’t recreate the same issue that the owner mentioned, going to replace these capacitors on the tone/balance control board as well.


The AMP at the R-door is believed to be the one that was previously serviced by someone using the wrong parts.

Later, I refurbished it but had to replace so many components.

I will be testing this head unit using my NSX at the end of the service to put some mileage.



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More than 7 months ago, started testing the spare AMPs using my NSX.

All 3 x speaker boxes have them.

Already covered more than 2,500miles and went through scorching hot summer and recent freezing cold weather.

I would rather replace the owner’s R-door AMP with my spare one installed at the same side so that when the owner puts everything back in place,
exactly the same setup between the audio head unit and the R-door AMP will be established.

More to follow.


Kaz

Finally, managed to make some progress with this head unit.

Now carrying out the final test driving session using my NSX.

Some of the photo to show what has been done.




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Didn’t like where the leaked acid was heading to.

Ended up replacing so many extra capacitors.

Replaced the caps on the balance/tone controller as per post #1.



The extra wires installed for the dissolved track and the usual ACC line reinforcement for the CD Changer emulator if used on the European spec audio head unit.




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Volume module cleaned using the contact cleaner, re-installed with blue loc-tite and alignment checked.



Cassette deck head, pinch roller, etc cleaned.




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Although the display module was very clean, standard procedure for me to check and clean inside.




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In order to check each signal output from all 4 channels, you really need proper audio analysis environment and equipment.

I use condenser mic with audio interface and DSP mixer for other purpose so can do basic analysis but nothing like the sound deadening environment or other equipment for the scientific measurement.

Mobile phone mic is not ideal at all but since it’s handy to use the basic App, just used the sound level meter.




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The owner felt that his audio head unit has imbalance between the L and R-ch when listened inside the cabin.

He said he had to set the balance knob fairly towards to the R side to get somewhat evenly balanced output.


You can’t judge the sound level between R/L channels inside the NSX cabin using one’s ear due to so many factors.

Your body and the skull even affect the hearing, let alone your ear sensitivity to each frequency range.

Some mobile phone allows you to check your hearing against wide frequency band so give it a try.


Tested another audio head unit and got exactly the same result.

Checked the signal level on each channel one at a time on the bench and confirmed all 4ch to be at the same level under exactly the same condition.

When installed inside the cabin and if used one’s ear, both unit resulted in the same setting.




Managed to tune into minimum of 8 radio stations even with the JDM half height antenna.



Already covered more than 30miles of test driving session under all sorts of EMI, thermal shock, vibration, etc environment.

Will take it out from the cabin this week and return it to the owner.


Kaz