This part is a kind of semiconductor called STK417-120.
Function of this product has (STK417-000 Series) 2-Channel High Effiency AF Power Amplifier 50W x 2 - 100W X 2.
Manufacturers : Sanyo Semicon Device
Image and pinout :
Some of the text within the PDF file :
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STK417-120 PDF Datasheet Download
