Audi A4 A5 S5 Bang and Olufsen Lear Amplifier Repairs
International postal repair service for Bang and Olufsen car amplifiers
This 10 channel DSP Multimedia Fibre optic amplifier is found in certain variants of A5 and A4 – all S5 from 2007 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 either 2G or 3G versions – 2G up to 2009
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
Water damage
This unit is situated in the rear right hand side of the boot – on the top of a metal cradle – there can be a leak from the rubber boot stopper which perishes with age . Water can then drip onto the top of the amplifier and access through the cooling fan on the amplifier. Water damage can sometimes be so extensive it renders the unit beyond repair.
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 S5 B and O Lear AMP
2007-2015 AUDI A series Amplifier
Models We Repair
- 8t0 035 223 T or 8t0035223T
- 8t0 035 223 F or 8t0035223F
- 8t0 035 223 C or 8t0035223C
- 8t0 035 223 M or 8t0035223M
- 8t0 035 223 H (3G) or 8t0035223H
- 8t0 035 223 AN (3G) or 8t0035223AN
- 8t0 034 223 AK (3G) or 8t0034223AK
- 8F0 035 223 A
- 8F0 035 223 C
- 8F0 035 223 D
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 the MMI screen may come on and shut straight back off , Usually a sign of water damage . The screen may stay on but no audio , Usually a sign of an electrical issue within the amplifier.
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
Audi can no longer supply the protective cover 8T0 863 681 , cost of this part was around £25 – so we’ve made our own – it’s essential to stop water from entering the unit again . All repaired units come supplied with cover already fitted FREE of charge . We also coat the entire circuit board with a strong epoxy resin coating to further protect the unit as standard – this will not make it entirely waterproof but will protect it from the elements to a certain degree.
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
In the boot on the left hand side – pull the compartment flap open , the amplifier is the top unit.
Location of amplifier
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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