# Replacing 8J0 035 223 A amplifier with 8J0 035 223 F



## MK2ollyTT (Mar 3, 2019)

Could someone tell me if I was to replace my amplifier P/N 8J0 035 223 A with 8J0 035 223 F, would this work or would this not? Also if this was to work, would this mount differently to how it is currently mounted? My amplifier is from a 2006 MK2 TT 2.0 FSI with a Bose system and the other is from a 2014 MK2 1.8 TFSI again with the Bose system. Any advice is appreciated


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## SwissJetPilot (Apr 27, 2014)

Worth a read -

https://www.ttforum.co.uk/forum/viewtop ... 2&start=15

If you're still concerned, you could send these guys an email and ask. If they write back, please share it with the forum.

https://boserepairexperts.eu/product/au ... 223-c-a-d/


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## MK2ollyTT (Mar 3, 2019)

UPDATE:

I have had a reply from Bose repair experts and they have said this would not work.


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## happychappy (Feb 9, 2015)

Did they say why?


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## Wolvez (Jun 22, 2018)

MK2ollyTT said:


> UPDATE:
> 
> I have had a reply from Bose repair experts and they have said this would not work.


That's how expert say he don't know. It will not work

They assumed that your car is still mk1 because of 2006. 
2007 = MK2 2 wire bus high & low. It's possible the car was bought in 2006 but it's a 2007 model.


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## SwissJetPilot (Apr 27, 2014)

+1 for MT-V6

https://www.ttforum.co.uk/forum/viewtop ... &t=1846805

_A was superseded by C on 01/04/2007
C was superseded by D on 01/02/2008
D was superseded by D 001 on 01/04/2015

Going by that I'd say there is a very strong chance that the A you are looking at will have some damage being over 10 years old, so be careful. Every Bose amp will definitely fail at some point unless protected_


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## Wolvez (Jun 22, 2018)

The Bose on my coupe don't shows any sign of corrosion. I just put small amount of silicon to prevent water draining inside when the tailgate is opened.


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## SwissJetPilot (Apr 27, 2014)

@ Wolvez - The image you show is the cover which is zinc plated steel, so it's not likely to show any corrosion.

The issue for corrosion is inside the Bose Amp and affects the circuit board and components. Water ingress is a legendary issue with the Bose Amplifier especially in areas where salt is used in winter. Over time, salty water it gets into the trunk through the various vents and grommets (or every time the Coupe rear hatch is opened) which just happens to be near the Amp and ends up getting onto the circuit board.

The two pictures below are from two different circuit boards. The white is thermal paste and should be there. The rest of the discoloration is corrosion. In some cases, it's so severe it completely eats away the IC chip legs or gets into the layers of the PC board and can't be repaired.

While replacement Bose Amps are available on-line from eBay and other re-sellers, the older versions (A, C, and D) could already have various stages of corrosion, especially if they're used units from wrecked TTs.

Unless someone has the skills and know-how to repair the circuit board and affected components, the best bet is to send a defective unit to these guys as they have been recommended by a lot of Forum members with Bose Amp problems and they seem to have a good reputation.

https://boserepairexperts.eu/contact-us/


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## MK2ollyTT (Mar 3, 2019)

Wolvez said:


> MK2ollyTT said:
> 
> 
> > UPDATE:
> ...


Sorry, I should have included what they said. They are aware that I have a MK2 2006 TT with the Bose system. See picture.


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## Wolvez (Jun 22, 2018)

SwissJetPilot said:


> @ Wolvez - The image you show is the cover which is zinc plated steel, so it's not likely to show any corrosion.


I can't find the picture so I decided to check it again. Good as new? It's easy to prevent corrosion in a coupe. Just don't let the lake of water in the rear glass drain inside. The seal on the glass is very deep. This is what causing corrosion on coupe.


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## SwissJetPilot (Apr 27, 2014)

*-----------------------My email to Bose Customer Service - *

_Dear Sir, 
I own a 2007 Audi TT Mk2 Roadster with the factory Bose sound system. Can you provide me with the service manual or any technical information for the Bose Amp, 8J0035223. Also, can you tell me the differences between the Revision a, c, d and e? 
K/R -
_
*-----------------------Their reply to me - *

_ Thank you for your message. Different letters behind part numbers often advises change of hardware and/or software. Sometimes they are compatible backwards. Looking at the model year 2008 of your TT-Roadster, amplifier version 8J0035223 C and or D should be compatible. Could you please check if you find further numbers at the labels of the unit you have on hand?
_

*-----------------------I provided some specific data on my Bose Unit from the Address 47 Scan - *

Address 47: Sound System Labels: 8J0-035-223.lbl 
Part No SW: 8J0 035 223 C 
HW: 8J0 035 223 C 
Component: J525 Amp High H04 0110 
Revision: PROD_01 
Serial number: 00000000003111 
Coding: 0246126

*-----------------------Here's their follow up email - *

_ As far as we can see amplifier version 8J0035223 C is installed but also version D should work. Changes sometimes are necessary if components are changed (like radio/head unit) or improvement of performance. We remember there was an issue with navigation voicing with a certain type of radio which might have been the reason for the D version.

If your amplifier unit was damaged by corrosion you should make sure that location of water entrance will be found and corrected. Otherwise you might have an issue again with an exchanged amplifier some years later.

We checked our inventory and it seems that we still have on stock an amplifier version 8J0035223 D / 309388-001. If you like we can send it to you and if it works we will invoicing you later on EUR 170, - plus 19% (German) VAT, additionally EUR 29.99* handling and shipping, *if you are living in Switzerland.

But we have to let you know that after installing the new amplifier your radio/head unit has to be Bose coded, which can only be done by an Audi dealership. Otherwise you might not experience the Bose sound. (We do not know, if it is the coding mentioned on the data you provided.)

If you are interested to get the part from us, please let us know. Then we would check if really available._

*-----------------------Here's another follow up email - *

_Thank you for your further messages. We verified our data and found following information:

Amplifier 8J0 035 223 A is a different generation of amplifier - not compatible with your car.
Amplifier 8J0 035 223 C and D, same hardware but different software versions.

Based on the recent scan of your Audi TT we assume that you have software version 110. For amplifier generation C exists also a newer software version 120. Amplifier generation D have been improved with first software versions 150 and latest 160. If you order officially replacement by your dealership, he should only be able to get amplifier generation D with software version 160, since amplifier generation C is not any longer available at Bose.

(With regards to water ingress) We have only heard that sometimes leakage was discovered near the antenna, the rear window washer system or rear light and that dealers could find information in the dealer intranet portal DISS. Might be that improvements have been made by changing/adding sealings. Honestly, we do not have any detail since modifications have to be executed at authorized dealerships.
_


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## SwissJetPilot (Apr 27, 2014)

@ Wolvez - A bit hard to tell from the photo, but the pins on IC U24 and a few on U26 are looking a bit dodgy. :? Might be worth a closer look as you're right, Coupes are prone to Amp PC board corrosion due to water ingress issues.

Did you remove and replace the white thermal paste when you put it back together? It needs to make good contact with the aluminum housing since it acts as a heat sink for these four ICs.

Is that a rebuilt unit? Odd that it has a double part label (one stuck on top of the other)...??


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## Wolvez (Jun 22, 2018)

SwissJetPilot said:


> @ Wolvez - A bit hard to tell from the photo, but the pins on IC U24 and a few on U26 are looking a bit dodgy. :? Might be worth a closer look as you're right, Coupes are prone to Amp PC board corrosion due to water ingress issues.
> 
> Did you remove and replace the white thermal paste when you put it back together? It needs to make good contact with the aluminum housing since it acts as a heat sink for these four ICs.
> 
> ...


No, stock from the factory. I can't find a thermal paste better than that. Most thermal paste sold today are not good. They harden like cement and have poor thermal conductivity. If I tried to correct the coding in VCDS I'm several DTC.


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## MT-V6 (Jan 11, 2015)

As mentioned above the F revision is not a Bose amp, it is a basic one

SJP, if that price direct from Bose is correct that is a bargain. My slightly outdated ETKA shows it as ~£770 from Audi


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## SwissJetPilot (Apr 27, 2014)

@ MT-V6 - I was surprised at the price too. You have me wondering if that's just for a replacement board. By the way if you haven't already put yours back together, this might be of interest to you -

https://www.ttforum.co.uk/forum/viewtop ... &t=1888669


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## SwissJetPilot (Apr 27, 2014)

And for anyone who wants to trouble shoot their unit, Bose Service was kind enough to provided this information -

*Defective Speaker*
*Measure speaker wires for correct resistance
*If speaker is presumed defectivve, try swapping with a known good speaker
*Check for creases in cone or surround, replace if creased

*Connector, Damaged or Loose*
For switching noises:
*Determine which speaker noises are coming from.
*Substitute known "quiet" device for the noisy device. If condition is corrected replace device.
*If noise is heard in all modes (AM,FM,CD) check wire harness to ensure proper connections. If only with AM or FM ensure antenna circuit is ok per antenna test page.
*In connectors (amp & radio) check connector terminals may be loose or bent over. Shake connector while powered for intermittent problems

*Antenna Circuit Issues*
*Check antenna measurements according to antenna diagram.
*If possible connect a known good antenna to test
*Note whether the problem occurs in all radio modes (AMFM-CD)
*If possible measure signal strength or look for "stereo" indicator in display

*Defective Amplifier*
*Ensure proper bus communication.
*For one distorted channel try swapping speakers to confirm defective part
*See also, "No Audio" chart
*Thermal intermittant problems may take several minutes to occur. To reproduce try playing audio system at loud volumes for several minutes

*Damaged Wire Harness*
*If single speaker defective check wires going to suspect speaker for damage to insulation. If possible disconnect both ends of harness and measure resistance;(e.g try flexing harness while measuring)
*If radio does not turn on check power (B+ & ground) connections at amp and radio, also checking switched B+. B+ should be 14-V with ignition on.


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## TTsdsgomg (Mar 19, 2013)

Swiss, reading through the info you have kindly provided there are references to 'bose centerpoint', 'surround stage' and 'audiopilot'. 
The 'audiopilot' I believe adjusts the overall volume to ambient noise levels via a mic in the interior light, but I can't seem to find much info on 'sound stage' and 'centerpoint' and how or if its applied to all inputs .... :roll:


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## SwissJetPilot (Apr 27, 2014)

Unfortunately this was all they were willing to share.


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## Wolvez (Jun 22, 2018)

There are 2 huge cables going the each sidewall. They used rubber grommet to protect the wire from rubbing on sharp edges on the body. The grommet are prone to failure.


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