This part is a kind of semiconductor called SB-WA870EB.

Function of this product has Active Subwoofer System Service Manual.

Manufacturers : Panasonic

Image and pinout :

Some of the text within the PDF file :

ORDER NO. MD0403127C2 Active Subwoofer System SB-WA870EB SB-WA870EG Colour (S)...Silver Type Specification n Active subwoofer Type Speaker unit Woofer Output sound pressure Frequency range 1 way, 1 speaker system (Bass reflex) Impedance 4 Ω 20 cm Cone type 84 dB/W (1.0 m) 34 Hz-220 Hz (-16 dB) 38 Hz-190 Hz (-10 dB) Dimensions (W x H x D) Mass 248 x 417 x 476.6 mm 16.4 kg n System : SC-HT870 (E) Music Center: SA-HT870 (E) Satellite Speakers: SB-HT870 (P) Active Subwoofer: SB-WA870 (EG) n General Power consumption Power supply Continental Europe and Russia The United Kingdom, Australia and N.Z. Power consumption in standby mode AC 230V, 50Hz AC 230V-240V, 50Hz n System : SC-HT870 (EG) 0.7 W Music Center: SA-HT870 (EG) Satellite Speakers: SB-HT870 (P) Active Subwoofer: SB-WA870 (EG) 390V [ ... ]

SB-WA870EB PDF Datasheet Download