Harman Kardon HS 300 ME SMPS Dead or Power Supply Fault fixed in Tamil. - YouTube
Basically, all Harman Kardon amplifiers (including subwoofers) show power supply issues after a few years | The Wiert Corner - irregular stream of stuff
Harman Kardon BDS 270 - eBay Junk, Repair for DOA (Ep. 15) - YouTube
User manual Harman Kardon HKTS 200 (English - 6 pages)
Basically, all Harman Kardon amplifiers (including subwoofers) show power supply issues after a few years | The Wiert Corner - irregular stream of stuff