Dead BOSE PS28 III subwoofer (no sound) repair

Описание: This Bose subwoofer doesn't turn on, Media center and display work. The problem is a a fault on the power supply board inside the subwoofer.

Please be reminded that every repair is unique. However , if one of the MOSFETs shown in this video is defective chances are you will be able to repair it with these instructions.

I get my parts mainly from digikey.com
The power Mosfets are in a TO220FP package, if not available you can choose similar types, important parameters would be VDSmax, Idmax, total gate charge.
The diodes are in a SOT23 package, any fast small signal diode will probably do.
Resistors come in a 1206 package.

The two big capacitors 470uF/250V (LGU2E471MELA from Nichicon) should be replaced too, they had their ESR increased by 35% and 15% loss of capacitance compared to new ones of the same model.

If you don't have power on the controller chip (pin 12) there might also be the two SOT23 components damaged, one of which is a zener diode 13V, the other an MMBT3904.

This subwoofer may be used for
Bose Lifestyle 48 series IV (AV48)
Bose Lifestyle 48 Series III (AV48)
Bose lifestyle V30 (MC 1 media center
Bose Lifestyle V35 (AV35 Media Center)
Bose Lifestyle 35 series III (AV18)
Bose Lifestyle 35 series IV (AV18)
Bose Lifestyle 28 series 3 and 4 (AV18)
Bose Lifestyle 38 all series (AV38)
Bose Lifestyle T20
Bose Lifestyle V20
Bose Lifestyle V25

Good luck!