A typical problem in several-year-old Mercedes ML, GL and R series cars is the lack of sound. The silence is caused by a fault in the factory 7020 amplifier made by Harman Becker. Finding a working used replacement is next to impossible – what is offered on internet auctions costs a fortune. And if you do find a “bargain”, unfortunately you get one that is damp, burnt out or electrically damaged. Today we’ll explain how we repair amplifiers from this series and why it is worth refurbishing your faulty one.
3 amplifier identification methods
If you want to make sure the amplifier discussed here is the same as yours, check whether:
- On the sticker with the serial / part number, in position M/N, you can see 7020
- Your car is an ML W164, GL X164 or R W251
- Your Comand (radio/navigation unit) is NTG2 or NTG2.5
Part numbers on the housing
You can also compare the “part number”; below are only some of the possible ones:
A2518201289 A2518209589 A2518703190 A2518706689 A2518207689
Symptoms of a sound system fault
A faulty amplifier causes the following problems:
- no sound from the speakers on any source (silence on the radio, from a disc, during a phone call)
- crackling, whistling, sound anomalies, no balance
- the radio lights up, there is no sound, and you can only hear a slight click in the speakers when the radio is switched on.
- flat battery (the amplifier draws extra current and drains the battery)
- no SOUND icon in the Comand radio menu
2 Main causes of amplifier failure
The BE7020 amplifier can be damaged by:
- water ingress (it becomes damp due to leaks in the car, causing the circuits to short; in the end you may even smell an unpleasant burning odour)
- power surge in the electrical system (the car has a weak battery and you jump-start it with leads or from another booster; the result is burning and electrical damage to the circuits from the fibre-optic bus)
What does Harman Becker 7020 amplifier refurbishment involve?
In the case of water ingress – we replace burnt components, rebuild damaged connections and, if necessary, update the amplifier software. We finish by protecting the main board with an anti-corrosion coating, and finally test it using a test environment.
After a power surge – as in the case of water ingress, we remove short circuits and burnt components. Additionally, and importantly, in 99% of cases we repair the OASIS XS8805 processor (responsible for the fibre-optic connection). If the circuit is electrically damaged – we replace it and programme it with the appropriate content.
We restore the comfort of travelling by car
Many companies offer car amplifier repairs, but only at OEMatic do we have our own proprietary procedures for measurements, testing and fault removal.
We use new components designed for use in vehicles. We give you peace of mind, meaning a warranty on the service performed.
Every time:
- We carry out a functionality test before and after repair
- We rule out an incorrect current draw (which could drain the battery)
- We verify communication via the MOST / CAN bus
- We preserve the unit with a special anti-corrosion treatment
- We only start the repair after diagnosis and approval of the costs
This is how we understand professional refurbishment of a damaged Harman Becker 7020 amplifier.
Does your Mercedes have a sound problem? Contact us.
