# DIY Bose Amp Repair



## auditt (May 10, 2012)

*PROJECT: Repair my Bose Amp*

Finally it's the end of April and my Android Tablet informed me it's spring. So, I finally went out after spending the winter indoors. My TT was still there in the garage, nice and cosy, ready to enjoy the sunshine. It started nicely, but then, as I switched on the radio, I remembered the Bose Amp was knackered. How really annoying.

To remind my teenage lads, that I'm the kinda guy that gets things done, I thought I would have a go at repairing it myself. I mean, it's a hifi, how hard can it. Worst case scenario, if it looks a bit complicated, I can always send it off to helpful guys at http://www.boserepairexperts.eu to get it fixed. Their website suggests it will cost £180 with a warranty.

*1) WATCH THE VIDEO*
First thing I did was watch the video on YouTube that explains how to remove the Amp without breaking the interior.





*2) REMOVE THE AMP*
Then I stepped outside. I was amazed at how cold it was. My Google Calendar had said it was spring already. Anyway, after whizzing back indoors for a couple of minutes, I donned a jacket and tried again.

I followed the video and in just 10 minutes I had removed the Amp, and put all the interior back in place. Really easy.

*3) MY INSPECTION*
The next thing I did was carefully remove the Amp pcb from the aluminium 'heat sink' housing. On inspection, there was no visible sign of water ingress from anywhere at all. However, the aluminium heat sink was definately corroded. I will upload some photos later. A closer inspection of the PCB shows some corrosion around the chips. Whilst the 'experts' all suggest that water is seeping in from the wheel wheel, I could not see any indication of this at all. Not even a minor stain. My car was completely mint and clean. So I would think it is condensation from a hot heat sink in winter climates creating condensation as the air temperature is low. Certainly the 'grit' identified by the chaps at *boserepairexperts.eu* does not appear to be present in mine. Though some of the heat sink paste appears to have solidified and become part of the problem when it has become wet with moisture. This is just my opinion purely on observation.

You will need to be really confident to clean and remove the chips on the printed circuit board, as they are very small. You will need a special soldering iron with a ceramic shaft designed to limit the amount of electrical energy transferred into the chip, a really big magnifying glass and a the steady hand of a surgeon. Each chip has 36 pins, and there are 4 chips to replace, so considerable patience is needed.

*4) ORDER 4 REPLACEMENT CHIPS*
The chips that get damaged are located at the top edge of the PCB. These are underneath the board when in-situ in the car. So reinforcing my opinion that it is condensation that causes the problem. The chips that appear to get damaged are *7575B BC*. These can be found on ebay for between £15 and £20 each. However, *I ordered some from China, on aliexpress.com for just £1.19 each*. _The total price including postage was just £6.54._ You MUST keep the total price including postage under £15 to avoid import tax and an extra £8 admin charge by the Post Office. Given the low cost, I thought I would give it a go, and if all else fails, I can always ask the BoseRepairExperts to come to my rescue for £180. However, given that I could save £175 if I do it myself, then I thought I would give it a go.

I will upload some photos and update my progress when our friends in China have despatched my chips and they have been safely delivered. I suspect this will take several weeks. By which time, it might be warmer outside.

PS. I have heard the chips from China are not very good. However, I am not sure where else you would get them, and the ones on ebay are probably from China anyway. My iPhone says made in China, and that has been fine for a couple of years now! So we shall see


----------



## MT-V6 (Jan 11, 2015)

Will be interesting to follow your progress on this one


----------



## Ady. (Oct 25, 2009)

Watching...


----------



## auditt (May 10, 2012)

*CORRODED BOSE AMP HOUSING*



*CORRODED CHIPS ON PCB*



*CLOSE UP*



The white powdery stuff on the top of the chips is the heatsink compound. It does make it look slightly worse than it is. You can see where I wiped one of the chips clean. The compound helps the chips dissipate heat into the aluminium casing. However, it looks like the heat sink compound might be responsible for some of the corrosion. It appears the compound gets wet, then remains wet causing the chips to start to corrode. There is no corrosion elsewhere on the board. Suggesting that any moisture is able to evaporate before causing any damage.


----------



## auditt (May 10, 2012)

*HAVE YOU HAD PROBLEMS WITH YOUR BOSE AMP?*

I wonder how many people have had similar issues with their Bose Amps. It would be useful to know how many people have experienced similar problems.


----------



## MT-V6 (Jan 11, 2015)

What symptoms did you get to make you investigate?

The corrosion is clear, maybe it would be worth waterproofing somehow after repair?

Sent from my Nexus 5 using Tapatalk


----------



## auditt (May 10, 2012)

*SYMPTOMS OF A FAILED BOSE AMP*

_It was the lack of volume control and no bass that made me suspect my Bose Amp was faulty. _
The sound system worked, but it was near impossible to turn the volume up or down. You would have to turn the volume knob very very carefully adjust the volume. I have the Audi SatNav head unit.
There is absolutely no bass on the system at all, and very little control over the volume.

*WATERPROOFING*

I have read just about every post on the forum regarding the Bose Amp failure issue. Lots of discussion, but I could not find anyone who had actually repaired their own amp. I did come across one post which suggested Audi were fitting a plastic shield over the Amp to prevent drips. Another post suggested using a 'fizzy drinks bottle' fashioned to create a protective 'umbrella' to cover the amp. I will be putting a cover over my amp when it is repaired, but I am still not entirely convinced there is water seeping in. If there is, then I was completely unable to identify where it was coming from. My boot is absolutely like brand new. Not a single tell tale stain etc.


----------



## TT-driver (Sep 14, 2010)

There was a post from someone who successfully managed to repair his Bose amp using replacement amp chips.

With regards to where the moisture is coming from: wrote it before... I still think it's condensation from damp air that flows past the amp towards the air exits behind the rear bumper.


----------



## MT-V6 (Jan 11, 2015)

I believe that post might have been Aoon. I am certainly lacking base on mine as well as VCDS fault code, I need to take mine out and have a look at the state of the chips

Sent from my Nexus 5 using Tapatalk


----------



## trickyd (Apr 14, 2016)

auditt said:


> *SYMPTOMS OF A FAILED BOSE AMP*
> 
> _It was the lack of volume control and no bass that made me suspect my Bose Amp was faulty. _
> The sound system worked, but it was near impossible to turn the volume up or down. You would have to turn the volume knob very very carefully adjust the volume. I have the Audi SatNav head unit.
> There is absolutely no bass on the system at all, and very little control over the volume.


I have these symptoms, the system works but the bass and volume is shite.
It only sounds reasonable if I turn the whole thing to the rear to engage the "sub" I guess...

My plan is to replace with new aftermarket amps, as my general car audio experience is that OE budget is a few pennies for most pars. This is an interesting cheaper option though. My worry is the "fix" wouldn't be good enough - hmm


----------



## mcdhibs (Jan 13, 2015)

I'm on Amp number two. There are loads of people on here with the same issue.

Mike


----------



## poder (Mar 18, 2015)

auditt said:


> I have read just about every post on the forum regarding the Bose Amp failure issue. Lots of discussion, but I could not find anyone who had actually repaired their own amp.


A number of us did:
viewtopic.php?f=19&t=555809&p=5928378#p5928378


----------



## MT-V6 (Jan 11, 2015)

Took my amp out today to see the same problem as you.

The two side chips are fine:









The two bottom ones are corroded, one much worse than the other:


----------



## auditt (May 10, 2012)

poder said:


> auditt said:
> 
> 
> > I have read just about every post on the forum regarding the Bose Amp failure issue. Lots of discussion, but I could not find anyone who had actually repaired their own amp.
> ...


Thanks. This is a really useful post. You can seee I don't get out much 8)

It's going to be a few weeks before my £1.19 chips from China arrive. They are significantly cheaper than the chips on ebay.
Because suppliers on AliExpress change regularly, the best thing to do is visit http://aliexpress.com search for '7575B BC' Order the results by price.


----------



## auditt (May 10, 2012)

MT-V6 said:


> Took my amp out today to see the same problem as you.


Yours is not nearly as bad as mine. It looks like the corrosion might be due to the heatsink compound getting damp and then causing a localised spot of corrosion. Just seems odd that only the part of the board where the heatsink compound is located is getting damaged. I suspect the only chip damaged on your board is U26. On my board U24 and U26 are both seriously corroded. 
I would recommend you clean the corrosion off using Servisol PCB Cleaner from Maplin before replacing the chip. _£3.99 for 200ml aerosol._

My car has spent virtually all it's life in a garage with full Audi service history. So I suspect no TT with the Bose system is exempt from damage.


----------



## efunc (Oct 12, 2008)

I wonder if these components could be sealed with epoxy to keep the moisture out, or if that would reek too much havoc with heat dissipation? I have tons of vintage analogue synthesisers in my studio and some of my Moogs and Rolands are suffering from component failure where they are sealed in epoxy. But that's 30 - 40 years after production. I doubt my TT will outlive one of my synths!

I need to address the corrosion on my Bose amp board too, but don't have the skill/patience to sit there desoldering and resoldering for a whole weekend.


----------



## auditt (May 10, 2012)

poder said:


> A number of us did:
> viewtopic.php?f=19&t=555809&p=5928378#p5928378


Hi Poder,
What did you use to clean the board?
What type of soldering iron did you use?


----------



## auditt (May 10, 2012)

efunc said:


> I wonder if these components could be sealed with epoxy to keep the moisture out,


The guys are *BoseRepairExperts.eu* seem to put some kind of expoxy over their replacement chips. So I guess it must be ok. I have no idea what they use though. Looks like a top job though.

I cannot imagine this would present a heat problem as the heat is dissipated through the aluminium heatsink and the seal between the chips and the aluminium using a heatsink compound.

I agree with you on the de-soldering and then soldering task. I plan to see if I can repair mine easily and cheaply, otherwise I will be sending mine off to the hard working helpful chaps at BoseRepairExperts and let them de-solder, re-solder and spread their magic black stuff.


----------



## MT-V6 (Jan 11, 2015)

auditt said:


> I would recommend you clean the corrosion off using Servisol PCB Cleaner from Maplin before replacing the chip. _£3.99 for 200ml aerosol._


I might try cleaning it in that case. Is this the cleaner you are referring to http://www.maplin.co.uk/p/servisol-isop ... 00ml-re87u ?


----------



## auditt (May 10, 2012)

Hi, I have just finished reading post http://www.ttforum.co.uk/forum/viewtopic.php?f=19&t=555809. It is an exceptional post. It has a complete list of products and a detailed step by step guide to repairing your Amp. I am going to follow the guide and see if I can repair mine. The recommendation was to make sure it is 100% Isopropyl alcohol. Anything less contains water.

Definately read the topic carefully. It recommends using a USB microscope to check if the corrosion has damaged the PCB. It looks relatively easy to repair.

_Rather than copy and paste links to products here, the original topic is very complete and contains some excellent reference material._

After reading the post, I still think it is worth attempting to repair the Amp myself. However, there is a trade off on how much you need to invest in equipment to do the repair. USB microscope etc. The BoseRepairExperts price of £180 looks quite reasonable when you consider the cost of the chips and the potential time needed to repair damage to the board, the shipping cost and the warranty they give.

The biggest challenge looks like removing the damaged chips without further damaging the PCB. Particularly the pads the chip sits on.


----------



## poder (Mar 18, 2015)

auditt said:


> Hi Poder,
> What did you use to clean the board?
> What type of soldering iron did you use?


I cleaned the affected area using an old toothbrush first. I then used flux to clean the connections points.
My soldering iron for small electronics is a Weller WHS 40 (http://www.harald-nyborg.dk/p5882/welle ... tion-whs40).
This allows for setting the temperature, as to not be too high...

For removing the old chip, I prefer to bend up one or two pins at a time. I do this by heating them up and using a needle to lift them.


----------



## auditt (May 10, 2012)

Thanks, that was really helpful. The total investment in equipment to complete a DIY repair is slowly creeping up!


----------



## auditt (May 10, 2012)

Brief update on progress.
As a complete novice, I cleaned up the board today with Servisol from Maplins. It all cleaned up okay, but one chip is definitely missing at least one pin. I imagine this is not like a centipede missing one leg. I expect that one leg is mission critical as far as the chip is concerned. A close inspection suggests there is some smaal amount of corrosion to the PCB too.

So the next job is to carefully remove the chip.
I plan to do this when my new chips arrive from China.


----------



## deeve (Apr 5, 2004)

The problem gets more difficult when the legs of the chip have corroded through and replacement is the only answer.
I gave in and ordered a new Audi amp at nearly £600 this was before the diy'ers and pro repairers were on the scene


----------



## deeve (Apr 5, 2004)

and why couldnt Bose have put that expoxy stuff on the chips in the first place [smiley=bigcry.gif]


----------



## MT-V6 (Jan 11, 2015)

I cleaned mine using PCB cleaner and a similar problem (missing legs), but not so bad at the above photo. Replacement of the chip will be the only solution


----------

