Audi A4 A5 Bang and Olufsen Lear Amplifier Repairs – CanBus Units
International postal repair service for Bang and Olufsen car amplifiers
This 10 channel DSP Multimedia CanBus ( non- fibre optic) is found in certain variants of A5 and A4 – all S5 from 2009 to present day. It’s easily identifiable as being fitted as the speaker grilles have the ‘Bang and Olufsen™’ emblem on them. Capable of 7.1 true surround it has an impressive 505 Watt output due to its onboard voltage inverter and 4 output modules.
These units come in 3G systems only.
Note – there is no cooling fan on these units – or fibre data socket
Coding
These units are ‘paired’ or component protected to the original vehicle – so simply swapping one over will result in only one operation channel .The reason for this is down to Audi protecting the modules of each car – the VIN number of the car is stored in the amplifier module – when the unit is being recoded the VIN number is compared online against a database of blacklisted VIN numbers , coding can not proceed if there is a match, rendering the unit useless.
Recoding can only be achieved using ODIS or VAS online … checking status only can be achieved with VCDS
What Fails and Why
This unit is situated in the rear right hand side of the boot – on the top of a metal bracket – or at an angle mounted lengthways .
These units rarely fail due to water damage , problems are mostly down to overheating issues ( there is no fan on this unit unlike the fibre models )
Due to the unit having a 30+/- voltage inverter the voltage lines are monitored by the processor – any abnormalities and the unit is disabled causing no sound . We can re-enable the unit and also protect the VIN data to ensure it’s just plug and play after repair.
THE AUDI A4 A5 B and O Lear AMP
2009-2017 AUDI A series Amplifier
Models We Repair
- 8t0 035 223 AJ or 8t0035223AJ
- 8t0 035 223 AP or 8t0035223AP
- 8t0 035 223 S or 8t0035223S
- 8t0 035 223 B or 8t0035223B
Other Reasons For Failure
Often we see units that have ‘shorted out’ causing them in extreme cases to catch fire. Reports of a burning smell is quite common – we can replace the burnt out board and reprogram the unit with your original data (cost for this is extra) – In most cases we can rebuild the output section to full functionality.
All units are tested on a MOST Fibre test bench to ensure full operation and function.
Diagnosis
When the amplifier is faulty diagnostic equipment will report back a problem with ‘DSP module error’ – or may not see the unit in the system at all. There will be no visible sign of failure , just no sound .
Is It Definitely The Amplifier?
9 times out of 10 it is only the amplifier – occasionally the tuner unit or navigation drive may have failed – proper diagnosis is important as you don’t want to send us the wrong unit.
Prevention
As they don’t suffer from water ingress , there is little to prevent failure – we do however fit an extra heatsink to the circuit board to ensure the main components have a more efficient cooling system.
Our Repair process
First of all the unit is disassembled and inspected and also electrically tested on our jig. The board is then cleaned of all corrosion and any factory applied protective coating is removed. The board is inspected in closer detail.
We use factory sourced production line components to ensure the sound quality is as precise as the unit should be. With regards to the Bang and Olufsen unit – we upgrade certain parts that are prone to failure.
Finally, once assembled – the unit is reprogrammed and bench tested.
What We Can’t Repair
Occasionally we see units that are beyond repair , this happens when either the water damage is too severe or there short across the supply rail . As there are no fuses in the unit , the circuit tracks superheat causing the board to burn out – sometimes even catch fire.
It is not possible to repair or safe to attempt a repair when this happens – the fibreglass circuit board becomes conductive potentially causing a fire.
We can often supply a replacement board and reprogram it to function in your vehicle.
Removal Instructions
Location of amplifier
In the boot on the left hand side – pull the compartment flap open , the amplifier is the top unit.
Tools for removal are;
- T30 torx
- Right angled ‘bit’ holder
- Trim removal tool
It’s easier to access the unit by removing the grey trim panel – its held in place by the boot seal and plastic clips.
Find Your Model Number
Model numbers are usually located on the underside of the amplifier.
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