Factory stereo distorted until it "warms up"

I've noticed something strange about my stereo - when I first turn it on, the sound is distorted (sounds like if you cranked up the distortion on a guitar amp), but the distortion goes away after a few minutes. It occurs in both speakers, the distortion is present if I turn the balance to one side or the other. After it warms up everything works as it should.

I'm thinking it's the head unit, and most likely the capacitors on their way out. It almost seems like the output stage doesn't have enough voltage for the signal that's driving it, clipping the signal. Has anyone experienced anything similar? Is there a parts list for replacing the capacitors on the head unit?

Send it to Brian K

Try rebuilding your amps first. Successful repair of the head unit is rare.

Best if you open the unit and check the actual capacitor spec because Alpine changed the circuit board design over the years and while the cap spec was the same, the actual number of each caps used were different depending on the year model, country spec, extra modifications applied, etc.

Depending on the level of damages, you will be forced to replace extra caps, the OP AMP, surface mount Tr, diode, Zenor, etc as well.

Examples here; http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=44


Kaz

Kaz-kzukNA1 said:

Best if you open the unit and check the actual capacitor spec because Alpine changed the circuit board design over the years and while the cap spec was the same, the actual number of each caps used were different depending on the year model, country spec, extra modifications applied, etc.

Depending on the level of damages, you will be forced to replace extra caps, the OP AMP, surface mount Tr, diode, Zenor, etc as well.

Examples here; http://www.nsxcb.co.uk/blog.php?1811&blogcategoryid=44


Kaz

Click to expand...

Thanks, Kaz! I plan on repairing the SRS unit in a few weeks, and I'll go ahead and pull the head unit at the same time. Better to catch it now while it still works. I'll take some pictures and post them here for others to reference. My car has the USA-spec adapter, which I saw on your site will cause extra stress on the head unit.

Regarding the USA SPEC PA11-HON, you only need strengthening the ACC line on the bottom circuit board at the CD changer port if you have European spec OEM (single antenna) head unit.

The JDM and Acura spec (two antenna, diversity system, both country specs are basically the same, just the cassette door label difference) circuit boards already have huge ACC line track that you won't see smoke coming out from the centre console area.......
My NSX is the everyday car and I have been driving with the PA11-HON for years now.


Kaz

Kaz-kzukNA1 said:

Regarding the USA SPEC PA11-HON, you only need strengthening the ACC line on the bottom circuit board at the CD changer port if you have European spec OEM (single antenna) head unit.

The JDM and Acura spec (two antenna, diversity system, both country specs are basically the same, just the cassette door label difference) circuit boards already have huge ACC line track that you won't see smoke coming out from the centre console area.......
My NSX is the everyday car and I have been driving with the PA11-HON for years now.


Kaz

Click to expand...

Interesting! I didn't know that, thanks for the info. Strange that they used a different PCB for JDM\Acura and EDM markets.

With the unit off, try Turning the volume knob back and forth for a minute at a fast rate. I have to do this if the radio isn't regulary used and it works quite well.

Eric Von Prescott said:

With the unit off, try Turning the volume knob back and forth for a minute at a fast rate. I have to do this if the radio isn't regulary used and it works quite well.

Click to expand...

I'll give it a shot, but I'm not sure it's related to the volume potentiometer.

crxguy52 said:

I'll take some pictures and post them here for others to reference...

Click to expand...

@crxguy52 Please do!

The headunit failure appears to be endemic-it will happen to everybody eventually. I'd rather keep my car 100% stock, and I would love to see a DIY approach to repair.

I believe that @Kaz-kzukNA1 is the only person currently doing any level of repair on these units; we need more information/expertise in this area.