The usual problem:
Left or right channel not working.

A common fault showing up in BMW's and Range Rovers, is a failure of one or both channels of the Becker BM54 radio tuner amplifier.

The cause

Inside the BM54 amplifier is an electronic circuit which amplifies the radio, CD player etc.
The power transistors in the power amplifier part of the circuit are prone to failure, resulting in no sound in either the left or the right channel, and eventually the remaining good channel will fail too.
The design is such that the transistors cannot simply be replaced to effect a cure.

The solution

We have developed an upgrade/repair kit for replacing the complete power amplifier part of the circuit.
The old power amplifier circuit is disconnected, and the replacement is wired in its place.
It is fixed in place on top of the original circuit, inside the BM54 unit. BM54 repair kit

This delivers 4 x 55W of high quality reliable sound, instead of the original 20W.
We sell the kit for you to fit yourself.
It is suitable for all Becker / Harman BM54 units, with round or flat pins.

To check if this is the unit fitted to your vehicle, simply look at the label on the amplifier case.
It is usually located at the bottom of the boot.BM54 Location in BMW E39
Above: Location of BM54 amplifier in BMW E39
Above: If the label on the amplifier states "BM54", it is suitable for our kit.

What else to check for...

* If your amplifier was working normally on both channels, and then both channels went off, it is likely that the cause is elsewhere, and our solution will not help you.
* If only one channel was previously working, and now the other has stopped too, then our solution may work, depending on the cause, but to save unnecessary expense, please check first that your unit has not failed because of water damage, which is evidenced by white and green deposits.
This will affect all functions, and is not repairable.
* If your orange radio light is off, or there is no radio menu, this kit will not help.
* The hands-free phone function is not supported on this kit

What is included in the kit?

* High Quality 4x50W power amplifier.
* 3.5mm drill bit, nuts, screws, washers, heatsink paste, mounting pillars.
* Ultra Flexible interconnection cable.
* Printed and fully illustrated instructions in English.

Fitting the kit

Our DIY Amplifier Repair & Upgrade kit is designed for people with average DIY skills, although you will need good eyesight and good soldering skills, as some of the solder pads you have to solder to are very small.
We supply fully illustrated instructions, but in summary, you need to open up the unit, cut or grind through 8 circuit tracks, solder up 16 wires, and drill 2 holes in the case to accept the new amplifier.
All you need is a soldering iron with a fine tip, a drill, a craft knife or dremel type grinder and something to tighten two M3.5 nuts


Power Amp Specification

*High Output power capability:
4 x 50W/4Ω max
4 x 30W/4Ω @ 14.4v, 1KHz, 10%
4 x 80W/2Ω max
4 x 55W/2Ω @ 14.4v, 1KHz, 10%

* Mosfet output power stage
* Excellent 2Ω driving capability
* Hi-Fi class distortion
* Low output noise
* Automute at at min. supply voltage detection

Main filter - 10,000uf capacitor
Additional capacitor included - 22,000uF
LC filter 
Noise isolation with BA3121 (elimination of ground noise) 
No pops or bangs on changing channel or power up.

Our happy customers

"Thanks worked a treat....";
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"Well done guys! Received the item in under 24hrs, Part fitted and everything 100%."
(eBay ID b******11)

"Thanks item works perfectly as described."
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"Very good many thanks."
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Customer Satisfaction
Guarantee to our customers

All our products carry a full 1 year guarantee.
If a fault should develop at any time over the 12 month period, simply return for a free replacement or repair.

If, for any reason, you are unhappy with your purchase on receipt, simply return within 30 days for a full refund including P&P.