If you are into vintage audio repair or building high-power DIY amplifiers, you have likely stumbled across the Sanyo series. The STK412-230 sits in the upper echelon of these thick-film hybrid ICs, promising serious wattage with a simple setup.
This component is considered an older or "obsolete" part but remains available through specialized distributors and marketplaces: Stk412-230 Datasheet Pdf
The STK412-230 comes in a 17-pin SIP (Single-In-Line Package) package. The pin configuration is as follows: If you are into vintage audio repair or