Mercedes Harman Logic 7 amplifier repair

Cause of the problems

In practice we actually see 3 reasons why the amplifier breaks down. The most common cause for Harman amplifier repair is dust blown into the amplifier by the fan

Harman Kardon amplifier w221 fabric
Harman kardon amplifier w221

Dust and moisture create problems internally in the amplifier

Harman Kardon amplifier w221 water damage
Water damage harman kardon amplifier

Result of water damage at the connection plugs

Harman Kardon amplifier w221 bad repair
Badly done repair harman kardon

Poorly performed previous repair (s) (attempts) lead to a lot of follow-up problems

Our solution

We can repair the amplifier in almost all cases because we have built up a good knowledge base and network due to the many problems. In addition, we have (original) readout material so that we can also properly check the internal operation.


As soon as you indicate that you want to have the amplifier repaired by us, we will initiate the process. This means that we replace all components of the 3V3 and logic part with new (Farnell supplied) components. With us, these are always components with a very low tolerance (0.1%-1%) and very low ESR value (with elco's / capacitors).

As soon as the amplifier plays again, we will update the internal firmware (software) to the latest state. While this is obviously not the reason for the failure, it does mean that all known bugs have been removed and the perfect litmus test. If something is not right yet, it will certainly be revealed in a software update.

Repair: When is an amplifier repair no longer useful

In which cases can the amplifier no longer be repaired?

  • Serious water damage (e.g. suitcase / car has been under water)
  • Wrong or poorly performed previous repair or attempted repair
  • Customer tried to clean the amplifier himself and then reconnected it (12V -> 3.3V circuit)

Based on knowledge, experience and method, we dare to say that we can repair 98/100 amplifiers effortlessly. Also units with DSP, Oasis / Sahara or Flash problems. Connoisseurs know how and what.

Rules of the game

In order to keep it as fun as possible for everyone and still affordable in relation to a new amplifier, we work with a few simple rules in this case. Experience has shown that unfortunately, attempts were made to repair the amplifier before it was offered to us.

  • You inform us in advance or when registering the repair if the amplifier has been (attempted) to repair earlier, on your behalf.
  • If you decide to buy an exchange amplifier, it is our risk. You do not pay a deposit or other forms of guarantees. Our risk.


Also take a look at amplifier repair hall-of-fame with amplifiers with the most enduring problems

A practical example of an amplifier repair

IMG 3983
Mercedes Harman Logic 7 amplifier repair 18

Harman kardon is brought to us with the customer that he is no longer working. Reason is clear. Particularly filthy

You can see that the mess is mainly under the blowing area of the fan. The fan blows on the board, as it were, and dirt / grime accumulates.

This is not a problem in itself, but it is mainly the moisture that causes problems and that collects under the dust

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Harman kardon amplifier very dirty

Important in our working method. There is also a lot of dust under the components themselves (boards). That is why it is important to take everything off and clean it thoroughly

This means that the CPU board and the transformer are removed so that everything can be cleaned under these components.

If not, the problem will return quickly.

PHOTO 2021 04 22 10 12 56
Harman logic new mask

Board has been cleaned and we have applied a new mask on the weak spots. The reason is that oxide (rust) under the mask causes damage. To prevent this from spreading further, this must be repaired.

This mask heats up and cures so that it can do its job properly.

IMG 4060
Harman kardon amplifier 221 after repair

Everything repaired and fitted with automotive grade components. The track itself has also been restored (blue color).

The reason is oxide formation and if this would not have been restored, this would certainly have caused problems in the coming years.

In addition, we provided the MOST controller with a new one because the old one could no longer be saved. The MOST controller conceptually works in the same way as a TV remote control

IMG 3559
Harman Logic 7

Important. The logic circuit mainly operates on 3V3 (or lower). It is extremely important to keep this tension as stable as possible.

It is precisely this circuit that is damaged by moisture and dust.

That is why we thoroughly test every amplifier so that we can determine that the control circuit outputs exactly 3V3 to the logic circuit. If this deviates too much (in terms of percentages) you will have problems and thus (incidental) malfunctions. This listens very carefully

Harman logic close up

The result of a successful overhaul. The power circuit has been completely rebuilt.

(The optical controller and vertical board are still missing in this photo)

How we don't think an amplifier should be repaired

Over the years we have come across many cases as a result of, in our opinion, poorly executed repairs. With the examples below, we indicate how our working method differs from the often cheap (er) solutions that you find online. It really applies here, cheap is expensive. This is because a lot of specialized work is required to solve these problems.

Wall of fame

IMG 3495
Badly done repair harman kardon
IMG 3494
Mercedes Harman Logic 7 amplifier repair 19
IMG 3551
hk logic 7 flux

Too thick wire used to repair a broken connection. Wire was of course shattered

Sloppy repair that left flux (solder flux) and corroded through electrical conductivity

Used way too much flux and not cleaned properly. Flux will eventually conduct, so you get power in places where you absolutely do not want it

after repair
HK logic 7 w221 repair

Board not cleaned properly leaving dirt under the components. You can already see the voltage bridge between the anode and cathode of the capacitor

most receivers
Mercedes Harman Logic 7 amplifier repair 20

Allow optical light receivers (must) to become too hot during (de) soldering

bad repair 1
Mercedes Harman Logic 7 amplifier repair 21

Track half recovers and wire not properly secured. This is really not possible.

The result of a successful amplifier repair

Radio stations are available again, CDs can be played again and the telephony is working again

Mbnaviworld youtube channel
Video of the repair
Mercedes Comand NTG3
Mercedes Comand NTG3

Price and availability

Overhaul of your own amplifier costs 600 euros incl. VAT and 1 year warranty. If you want an exchange amplifier, the costs are 750 euros incl. VAT and you will receive it within 1 day (if in stock)

If your amplifier has previously been (attempted) to be repaired on your behalf. We get a lot of questions about amplifiers that are offered elsewhere and cannot be repaired. Because the supplier does not currently supply amplifiers, we are willing to repair them. If these can be repaired, the costs are 850 euros incl. VAT. This is because we often lose twice as much time because we first have to investigate what exactly has been done and why it does not work before we can proceed for revision.

The harman amplifier repair is available for this

Model numbers

  • BE7021 / 7021
  • BEM005 / M005
  • BE9061 / 9061
Part numbers
  • A 2218707789 / A2218707789
  • A 2218205789 / A2218205789
  • A 2218206889 / A2218206889
  • A 2218701589 / A2218701589
  • A 2218701789 / A2218701789
  • A 2218208789 / A2218208789
  • A 2218705089 / A2218705089
  •  A 221 900 53 02 / A2219005302