# MMI Bose Audio Not Working (No Sound)



## 5BetShove (Jan 17, 2017)

Dear fellow TT enthusiasts, I am hoping you can help me!

Firstly I'm driving a 2010 Audi TT S Line SP Edition TFSI with the Bose sound system.

Not too long ago I returned to my car having visited a friend, and turned the engine on to realise that there was no sound coming through my speakers, either from the Audi MMI (radio, aux, SD Card, etc...) or from my SatNav, although everything seemed to work as expected, I could change radio station, skip tracks, etc... there was just no audio. My rear sensors and seat belt warning notification still sounded however (though I don't think these come through my speakers).

About two days later, after turning on my engine one morning, the sound returned. Everything was ok for a few days, then a week or so later, it went again when I turned the engine on. I turned off my engine at the end of my journey and back on again, and my sound was now working.

Then a few days ago, it stopped working again. And this time, it has not returned. I have done some research, and have narrowed the possible cause down to three things:

• The Bose amp needs fixing or replacing.
• Main board within the MMI computer needs replacing (not sure if this would apply to a 2010 MMI, or just the newer cars though).
• The car's battery is somehow to blame for this, and replacing the battery may solve the issue.

There are a few things I should mention:

• No matter how much I turn up the volume, I cannot hear any sound.
• I never noticed any speaker failure.
• Sound only ever seems to come and go when I turn the engine/ignition on and off, it never cuts in or out when the engine is on or mid-journey.
• I am convinced I can a hear a very faint static like humming noise from my speakers whenever the car is on (although I can't be sure about this).
• I have tried resetting the MMI to no avail whatsoever.

I am hoping, with your expertise, you may be able to help me understand further what might be causing the issue, and suggest a possible solution that isn't going to cost an excessive amount of money! I was planning on removing my amp this weekend and carefully cleaning it up in case dirt may have somehow caused interference leading to this problem, do you think this could be the case, or am I kidding myself by doing this?

Thank you in advance for your help with this, if you have questions please let me know.


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## leon263 (Feb 12, 2007)

These are typical symptoms of Bose amp failure which is a very common fault with the Mk2 TT. The amp is situated behind the panel on the left hand side of the boot as you look in. Moisture finds it's way into the amp, either as condensation or as water ingress from behind the rear wheel. The moisture causes corrosion on the circuit boards in the amp which leads to partial of complete failure. The accepted cure is to remove the amp and post it off for repair. Many Forum members, my-self included, have used SVT Services in Edinburgh who specialise in Bose amp repair and they have an excellent reputation for repairs and a quick turn round time. Basically the circuit boards are cleaned, repaired where necessary and sealed to prevent any future re-occurrence of the problem. Expect to pay around £180 for repairs.
If you are happy enough to remove the amp, by all means do so. Remove the cover and have a look at the circuit board. If there is obvious corrosion on the board, you have found your problem. if not, perhaps the problem lies elsewhere.
The link below is for SVT Services, have a look at their site where you will find information re. your problem.

http://boserepairexperts.eu/audi-tt-bos ... er-repair/


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## tttony (Dec 21, 2014)

Bose amps usually give signs of impending failure with crackles or pops from one or more speakers. It would be unusual for all the power amplifier chips in the amp to totally fail at the same time. By all means open the amp up and look for corrosion of the terminal legs of the power amp chips. In severe cases the legs are eaten away by corrosion and the chips must be replaced.


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## marteemoose (Mar 4, 2018)

[*]


tttony said:


> Bose amps usually give signs of impending failure with crackles or pops from one or more speakers. It would be unusual for all the power amplifier chips in the amp to totally fail at the same time. By all means open the amp up and look for corrosion of the terminal legs of the power amp chips. In severe cases the legs are eaten away by corrosion and the chips must be replaced.


My amp worked perfect one day then nothing the next. There was corrosion on some of the chip pins so i sent it away and it was repaired, it's easy to remove and check


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## AAJ (Mar 24, 2018)

Mine is with SVT services now. How did you prevent it from reoccurring? I was thinking a cover but does the unit still need to "breathe" as I imagine it gets very hot?


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## pcbbc (Sep 4, 2009)

AAJ said:


> Mine is with SVT services now. How did you prevent it from reoccurring? I was thinking a cover but does the unit still need to "breathe" as I imagine it gets very hot?


Read the repairers website linked to above.
Once repaired (assuming it is possible) they conformally coat the PCB to protect against water damage.


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