This part is a kind of semiconductor called S2055N.

Function of this product has Color TV Horizontal Output Applications.

Manufacturers : Toshiba

Image and pinout :

Some of the text within the PDF file :

S2055N TOSHIBA TRANSISTOR SILICON NPN TRIPLE DIFFUSED MESA TYPE S2055N COLOR TV HORIZONTAL OUTPUT APPLICATIONS High Voltage Low Saturation Voltage High Speed Built−in Damper Type Collector Metal (Fin) is Fully Covered with Mold Resin. : VCES = 1500 V : VCE (sat) = 5 V (Max.) : tf = 0.3µs (Typ.) Unit: mm MAXIMUM RATINGS (Tc = 25°C) CHARACTERISTICS Collector−Emitter Voltage Emitter−Base Voltage Collector Current Base Current Collector Power Dissipation Junction Temperature Storage Temperature Range Thermal Resistance DC Pulse SYMBOL VCES VEBO IC ICP IB PC Tj Tstg Rth (j−c) RATING 1500 5 8 15 4 50 150 −55~150 UNIT V V A A A W °C °C JEDEC JEITA TOSHIBA ― ― 2-16E3A DataShee 2.5 °C / W EQUIVALENT CIRCUIT Weight: 5.5 g (typ.) MARKIN [ ... ]

S2055N PDF Datasheet Download