This part is a kind of semiconductor called STK4131V.

Function of this product has AF Power Amplifier.

Manufacturers : Sanyo Semicon Device

Image and pinout :

Some of the text within the PDF file :

Ordering number : EN4478A Thick Film Hybrid IC STK4131V AF Power Amplifier (Split Power Supply) (20 W + 20 W min, THD = 0.08%) Features • Built-in muting circuit cuts off various kinds of pop noises. • Current mirror circuit provides low distortion (THD = 0.08%). • Pin compatible with the STK4102II series, forming a series of products with output powers from 15 W/ch to 120 W/ch. Package Dimensions unit : mm 4040 [STK4131V] Specifications Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Thermal resistance Junction temperature Operating case temperature Storage temperature Available time for load shorted Symbol VCC max θj-c Tj max Tc Tstg ts VCC = ±24.5 V, RL = 8 Ω, f = 50 Hz, PO = 20 W Condition Rating ±37 2.6 150 125 –30 to +125 2 Unit V °C/W °C °C °C s [ ... ]

STK4131V PDF Datasheet Download