This part is a kind of semiconductor called 2SD1555.
Function of this product has Silicon NPN Power Transistors.
Manufacturers : SaventIC
Image and pinout :
Some of the text within the PDF file :
SavantIC Semiconductor Product Specification Silicon NPN Power Transistors 2SD1555 DESCRIPTION ·With TO-3P(H)IS package ·Built-in damper diode ·High voltage ,high speed ·Low collector saturation voltage APPLICATIONS ·For color TV horizontal output applications PINNING PIN 1 2 3 DESCRIPTION Base Collector Emitter Fig.1 simplified outline (TO-3P(H)IS) 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 CONDITIONS Open emitter Open base Open collector VALUE 1500 600 5 5 2.5 50 150 -55~150 UNIT V V V A A W SavantIC Semiconductor Product Specificati [ ... ]