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

Addition to the A/C CCU Board, the owner brought all three Bose AMP and Alpine Head Unit.
The owner reported that there was no issues with the front (door) ones but the rear (passenger footwell) one was already making awful noise.

After checking the state of the four FETs on each board, tested each AMP on the bench and confirmed that both front ones were OK for the time being but I couldn't run the rear one even for 1sec because it was generating really loud high tone screaming noise.




The front ones were the early spec but with just 1 green audio spec capacitor.
Around this generation, Bose were using mixed spec with lots of audio spec green caps on the front AMP but also just one green cap like above.




The rear one was also the early spec with many green capacitors that were known to leak severy.





Even there was no nosie, one of the Front AMP was already splashing the acid from the leaky caps.





As expected, the Rear AMP was showing heavy corrosion with intermittent connection.
Scrape off the acid and strengthen the tracks and pads by using the hard wire and soldering bridge.
Used two hard wires in this photo.




Quick bench testing before applying the hot melt glue, thermal compound and the conformal coating.




Happy with the result so applied the above treatment.




Time for the final test session.

Each AMP was tested on the bench for more than 2Hrs,
As the owner didn't bring the silver metal top cover, used my spare one as it acts as a heat sink as well.

The owner is going to bring the metal covers when collecting all of the equipments from my place so that I can apply the thermal compound at the remaining area while waiting.


Signal gain, voltage output at each pins on the two ICs, etc checked.

Happy with the final testing results and done.


Kaz