Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

While carrying out the Engine Refresh,
spent some time on the Audio head unit for another owner.

Several years ago, he noticed intermittent cracking noise from
all speakers and at that time, someone disconnected one of
the Bose AMP and that seemed to fix the issue.

However, the issue came back later and the owner started to
think that the noise was actually coming from a specific speaker
although initially he felt it was coming from all of them.


Then, he completely lost the power to the audio head unit and
contacted me.

Probably, it is best for me to take a look at
his all three Bose AMP in the future.


The owner checked the fuse for the audio head unit and
it was fine so he took the audio head unit out of the car and
brought it to my place.

On the bench, the head unit was recognising the power but
not possible to power it up by pressing the on/off switch so
it confirmed that there were some damages to the circuit board.

Exactly the same issue that I saw on many head units in the past.


When I opened the head unit, immediately noticed that
one of the track at the upper board was partially burnt.


Normally, you will find burnt circuit at the bottom board and
not at the upper one but this typically happens when trying
to drive the iPod adaptor connected to the CD changer port.


Because of this, when I install the iPod adaptor for any owners,
I'm requesting the owners to include the audio head unit service
as I already experienced burnt circuit board issue immediately
after the installation.






As seen on several head unit, the ACC line was damaged due to excessive current.






And the main cause of the issue.
The leaked acid from the capacitors managed to cut through some of the narrow tracks.
Because of the zoom, it looks quite wide but each track is less than 1mm……







Inspected and then cleaned them thoroughly in preparation for the repair.






Planted nearly 10 hard wires at the narrow tracks to re-create and strengthen the missing connection.




Jumper wire used to strengthen the ACC line.







Another jumper for the burnt track at the upper board.


As the board was already burnt, not sure about the extent of
the damages to other areas and also the effect of using jumper wire from
the audio signal quality point of view.

Time to test the head unit.


Successfully powered up so now I need to find some time to go through the test scenarios.
I need to find old cassette tape to test the cassette player functionality......



More to follow later.


Kaz