Hi Mini community!

I am a new owner of a 2008 Cooper Hatch with HiFi package installed.

A great car in almost every way, and has been looked after well, except for a problem with the stereo.

There is a constant white noise whenever the unit is turned on.
I first thought it was a problem with the HiFi amplifier, but I disconnected the cable to it and made some bypass jumpers between the inputs and the outputs to the individual speakers. As expected there was some frequency loss due to the component nature of the speakers, however the white noise remained.

The white noise is present no matter what input the head unit uses, CD, radio, auxillary.

Another part of this strange problem is the "gong" setting under audio options. When turned up to +3 and more, all speakers suddenly emit a very load machine gun noise which continues until the volume is clicked off.

In the course of my diagnostics, I accidently touched two of the input wires coming into the amp together, or maybe touched the body of the car, suddenly there was a short - 5 or 6 machine gun sound "burst".
After this the white noise was gone when I turned the radio on!

To tempt fate, I thought "I wonder if the 'gong' setting problem is still there?" Of course it was, it went into machine gun mode and then the white noise was back!

So I think the problem is in the head unit, not so much in the amplifier, but now I am totally confused and looking to appeal to any of you good people to shed light on this issue. Any ideas? It does not seem to have been mentioned on the forum before.

Thanks

 

White noise is broad spectrum (white noise is equal energy per frequency, pink is equal energy per octave), so it makes sense you'd hear it regardless of which speakers you disconnected/bypassed - each speaker is still going to reproduce its part of the spectrum.

With what you are describing, I would definitely suspect the headunit. We've found them to have a pretty high failure rate.

 

Thanks Kevin for the repsonse,

My investigation has started to lead me to the same conclusion. I wondered if there was a grounding problem for the head unit, so I investigated the famous X9331 connector as it is more easily accessible than the head unit itself. I successfully removed the ground wire pin from the female side of the connector (pin 9 I believe is the ground wire to the head unit) and made a ground from there to the chassis. There was no magic solution to the white noise. The strange thing is that the sound can go and then come on again. After fiddling with the connector, disconnecting and reconnecting the battery, the sound magically vanished and beautiful clear sound was heard. After a few minutes it came back on again, and expletives were heard!

The mystery continues

 

Sadly I don't think it's a ground issue, at least not external to the HU. We've found the quality control to be pretty poor on these HU's. Likely a component failure within the HU itself. Not the answer you were hoping for, I'm sure.

 

Yes you are right Kevin - I just found an earlier post of yours from 7 years ago regarding the nature of the signal ground vs power ground.

224845-getting-static-noise-through-speakers-after-speaker-amp-upgrade.html


Don't suppose you know of a way to fix the floating signal ground issue apart from replacing the head unit?

 

There isn't anything to "fix" with that - that's the way it is designed, not a flaw. The issue in that post is a little different, the OP there had upgraded elements of his system, and likely connected signal and power ground without realizing it. You're audio is all factory? Or you have upgraded something?

 

Yes all factory HiFi setup.
I pulled the fuse for the radio in the kick panel yesterday. On putting it back in, white noise gone again - it was terrific. After a little while - 45mins? Static noise came back again.

Thanks for your input Kevin.

 

Sure thing, happy to help. Wish the answer/outcome was better for you...

 

Just wanted to chime as I was having a similar issue. My noise was present whenever the cabin occupation relay was energized. I removed my head unit and speedometer unit, contact cleaned and dielectric greased my connectors and re-assembled. Upon powering back up, it seems to be resolved. I also had loud cracks and ear splitting noises happening when adjusting my aux cable and 12v socket appliances before doing this, and they seem to be gone. I am chocking it up to a corroded ground pin in the radio harness or one of the coax connectors (which may have been acting as noise antennas).

https://www.northamericanmotoring.co...ml#post4680731