This part is a kind of semiconductor called 2SB686.
Function of this product has SILICON POWER TRANSISTOR.
Manufacturers : SavantIC
Image and pinout :

Some of the text within the PDF file :
SavantIC Semiconductor Product Specification Silicon PNP Power Transistors 2SB686 DESCRIPTION ·With TO-3P(I) package ·Complement to type 2SD716 APPLICATIONS ·Power amplifier applications ·Recommend for 30~35W high-fidelity audio frequency amplifier output stage PINNING PIN 1 2 3 Emitter Collector;connected to mounting base Base Fig.1 simplified outline (TO-3P(I)) and symbol DESCRIPTION Absolute maximum ratings(Ta=25 ) SYMBOL VCBO VCEO VEBO IC IE PT Tj Tstg PARAMETER Collector-base voltage Collector-emitter voltage Emitter-base voltage Collector current Emitter current Total power dissipation Junction temperature Storage temperature TC=25 Open emitter Open base Open collector CONDITIONS VALUE -100 -100 -5 -6 6 60 150 -55~150 UNIT V V V A A W SavantIC Semiconduc [ ... ]
2SB686 PDF Datasheet Download
