This part is a kind of semiconductor called 2SD1941.

Function of this product has Silicon NPN Power Transistors.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

SavantIC Semiconductor Product Specification Silicon NPN Power Transistors 2SD1941 · DESCRIPTION With TO-3PFM package ·High voltage ,high speed ·Low collector saturation voltage APPLICATIONS ·Color TV horizontal output applications PINNING PIN 1 2 3 DESCRIPTION Base Collector Emitter Fig.1 simplified outline (TO-3PFM) and symbol Absolute maximum ratings (Ta=25 ) SYMBOL VCBO VCEO VEBO IC IB PC Tj Tstg PARAMETER Collector-base voltage Collector-emitter voltage Emitter-base voltage Collector current Base current Collector power dissipation Junction temperature Storage temperature TC=25 Open emitter Open base Open collector CONDITIONS VALUE 1500 600 5 6 3 50 150 -55~150 UNIT V V V A A W SavantIC Semiconductor Product Specification Silicon NPN [ ... ]

2SD1941 PDF Datasheet Download