This part is a kind of semiconductor called BY228.

Function of this product has Silicon Mesa Rectifier.

Manufacturers : Vishay Telefunken

Image and pinout :

Some of the text within the PDF file :

BY228 Vishay Telefunken Silicon Mesa Rectifier Features D Glass passivated junction D Hermetically sealed package Applications High voltage rectifier Efficiency diode in horizontal deflection circuits 94 9588 Absolute Maximum Ratings Tj = 25_C Parameter Reverse voltage =Repetitive peak reverse voltage Peak forward surge current Average forward current Junction temperature Storage temperature range Test Conditions Type Symbol VR=VRRM IFSM IFAV Tj Tstg Value 1500 50 3 140 –55...+150 Unit V A A °C °C tp=10ms, half sinewave Maximum Thermal Resistance Tj = 25_C Parameter Junction ambient Test Conditions on PC board with spacing 37.5mm Symbol RthJA Value 70 Unit K/W Electrical Characteristics Tj = 25_C Parameter Forward voltage Reverse current Total reverse recovery time Test Condition [ ... ]

BY228 PDF Datasheet Download