Hi-Line Sound System Channels Dropping Out

[Oztourer]

I have an MY05 D3 HSE with the factory HK Hi-Line sound system. From time to time I'll experience either reduced volume or total drop out of a speaker channel. It's random in nature and no particular speaker is at fault and can last from seconds to minutes before coming good again. I've checked all the connectors to the amp under the drivers seat and they look ok so I'm wondering where the problem might be? My thoughts so far are 1) fault in the amp, 2) head unit to MOST bus, 3) other dirty/corroded connectors between the amp and speakers. Fault finding isn't easy as I can't diagnose the MOST side nor feed an analogue signal into the amp. I would ideally like to upgrade the whole infotainment system to a D3 upgrade/D4 touchscreen/gps and Logic 7 amp but parts seem to be scarce and expensive . I know there is a very good write up by Wiggs on Disco3.co.uk on his mammoth D3 upgrade but whilst I plan and dream of what may come, if anyone has any ideas on my drop out issue or thoughts on upgrades, your feedback would be appreciated.
Cheers
Matt

[Narangga]

I haven't had that Matt but have had the aftermarket Bluetooth adaptor cycle between left and right channels regularly. AM, FM & CD are all fine so it's obviously the lead into the Aux socket.

However from time to time the buttons on the steering wheel go haywire too. When on Aux, I press + to increase volume and it switches to FM...

Which makes me ask - do you have an aftermarket Bluetooth unit?

[Oztourer]

Hi Dale, everything I have is factory. I don't have Bluetooth, just the Aux input which is plugged into the centre console from the second row seats. I've got a feeling it's my amp however I don't listen to FM or the Aux much to test if it's the input or the output. As for your steering wheel controls, maybe you have dirty contacts on the buttons or dodgy connection to the clock spring. There are a couple of posts on here about this

steering wheel radio control button fault

cheers
Matt

[veebs]

Could it possibly be a dirty or covered heat sink on the amp? Did they ever have a fan in them? Something that would cause it to overheat and go into some kind of protection mode?

The variability in the symptoms could be due to listening to music with more bass in it sometimes (driving the sub), ambient temp, etc?

Not sure where the amp is on a D3 - it's under the drivers seat in my early D4, so relativity easy to access

Just a thought?

[Oztourer]

Thant veebs. I'm pretty sure the amps in the D3 and D4 are of similar heritage. D3 also under the driver's seat. No fan and the heat sinks are clean. I don't drive the sound too hard anyway (ABC local radio doesn't sound too good at 100dB!!
I might remove it and see if I can open it up. Maybe moisture has got in and caused corrosion somewhere. It's just frustrating that I can't test each component - unless someone has a head unit and amp lying around that they are not using .

[veebs]

Pulling apart and checking for moisture/corrosion sounds like a plan - there is also a Car Audio area on these forums that might be more help?