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

[ I have another Audio head unit and 2 x Bose speaker AMP waiting to be
serviced so I hope the owners won't get confused with this thread below.
It is not related to their services and will start working on them from
tomorrow. ]




While I was carrying out the Eng Refresh, I received one audio head unit that
the owner was having problem with imbalance between R & L channels
and also cracking noise when rotating the volume dial.

So before removing anything, started testing the unit on the bench and
found no noticeable pre-amp signal level difference between the R & L channels
so informed the owner that it is very likely to be AMP issue.

Tried to re-create the cracking noise issue by rotating the volume dial but
only managed to recreate it once.

Later, I found that it was actually a logic circuit issue than a volume element related.








Even before removing any parts, I saw bent chassis and after start removing
the parts, it became obvious that this head unit experienced quite big impact shock
in the past.

The internal frame was bent in several places and some of them were
so severe that once the screw was removed, the thread hole and the screw
didn’t line up.






There was trace of someone tried to do something on the board in the past.

The soldering at BTT and ACC terminals were not from when it left the Alpine factory
and almost as if a certain wire was removed in the past.




The normal issue of cap acid cutting through the circuit board track but not too bad.
Some of the acid was splashed around the area.




No majour leakage in this area.




Soldering bridge to strengthen the dissolved tracks.