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BMW E65/E66 LOGIC 7 AMPLIFIER REPAIR

 

Models Affected:

BMW 7 Series E65 / E66 (manufactured between 2002 and 2008)

 

Introduction:

The unreliability of the Harman Becker LOGIC7 amplifier is well known and very well documented across the internet. To give it credit, the amplifier design is ingenious, nobody can disagree the performance and spatial surround experience is fantastic, but it could also be considered a marvel of high volume cost cutting design. Most aspects of the design were simply to make it as cheap as reasonably possible to mass produce.

 

With this in mind, and the pleasant thought that Harman Becker haven’t diversified into the medical equipment and life support market, this all comes at a price, that of course is reliability.

 

The amplifier utilises 'chip on board' technology, cost saving and simple assembly were the major factors for this, but this is also the major weakness in the design. Repeated thermal cycling simply breaks the wire bonds between the amplifier IC die and the PCB substrate resulting in loss of speaker channels.

 

The simple solution is to replace these faulty IC's, many vendors offer LOGIC7 repairs, and this is exactly what they do. However, the TDA1562 amplifier used is rather unique, it’s a Class H amplifier that utilises a 'charge pump' method to effectively increase the supply rails to achieve a maximum output power of 70W.

 

And this is the problem, the TDA1562 has been obsolete for roughly ten years, they are expensive and difficult to source, and many are counterfeit or don’t even work at all. Therefore, literally every other vendor, or repair kit you will find on eBay, use a Class A/B amplifier instead, cheap and very easy to source.

 

The real issue now is that the Class A/B amplifiers can only produce 20-25W of RMS power from a 12 - 14.4 V supply. This results in underpowered subwoofers and heavy distortion when the volume approaches around 50%. It's not really a repair, arguably you will have bass, just not very much of it!

 

The BAVtronik Solution

This where the BAVtronik repair is different, the subwoofer channels are now powered by a custom designed Class D amplifier module. To realise this, an entirely new power amplifier card has been designed. This new card improves many aspects of the original design:

 

  • Class D amplifier module producing 20% more bass
  • Class A/B midrange amplifiers in standard packaging (no ‘chip on board’)
  • Dual speed fan control for improved cooling
  • Improved ground routing to remove fan ‘noise’ allowing it to run continuously
  • Automotive grade over voltage and over current protection for the subwoofer amplifiers

 

The replacement board is designed to occupy the footprint of the original board and all electrical interfaces are identical, the 20 way main connector, four power inductors and the TVS protection diode are recovered from your original board and fitted to the replacement.

 

The midrange Class A/B amplifiers are mounted to a custom heatsink which is screwed to the side of the case, with the fan now running continuously at low speed the heatsink allows lateral airflow across its surface and ensures the A/B amplifiers remain cool. The fan circuit is dual speed, if the internal amplifier temperature exceeds the threshold governed by the processor card, then it switches to full speed.

 

All repairs are covered by a 12 month warranty, this is limited to replacement board and work/repair undertaken, I cannot offer a warranty on the entire unit, i.e. the processor card. However, the later style 4 clip amplifier processor cards have proved to be very reliable.

Please get in touch using the ‘Contact’ form if you have any questions.

BMW E65 LOGIC7 Amplifier Repair

SKU: BAV_L7_AMP
£184.99Price
  • Step 1:

    Verify that the amplifier is the unit at fault by reading the LOGIC7 page.

     

    Step 2:

    Contact us using the form on this page or make the purchase using our online shop, ensure you add your contact details so we can send the shipping instructions. International Customers Beware: You will be liable for all import/duty charges for shipping, please contact us first before ordering.

     

    Step 3:

    Remove the unit and post it to us using the address details provided, please also include your contact/order details to ensure units dont get mixed up.

     

    Step:4

    Upon reciept of your unit we will bench test your unit to ensure it can be repaired, we will contact you for payment if you havent purchased through our shop.

     

    Step 5:

    We will contact you to confirm your unit is repaired and will provide the return shipping details/tracking number.

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