BUL128D-B Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 400 V
• Collector-Base Voltage, max: 700 V
• Emitter-Base Voltage, max: 9 V
• Collector Current − Continuous, max: 4 A
• Collector Dissipation: 70 W
• DC Current Gain (h_fe): 12 to 32
• Operating and Storage Junction Temperature Range: -65 to +150 °C
• Package: TO-220

Here is an image showing the pin diagram of this transistor.You can replace the BUL128D-B with the 2N6740, 2SC3056, 2SC3056A, 2SC3057, 2SC3310, 2SC3795, 2SC3795A, 2SC4242, 2SC5241, FJP13007, FJP13009, KSE13005, KSE13007, KSE13007F, KSE13009, MJE13005, MJE13005G, MJE13007, MJE13007A, MJE13007G, MJE13009, MJE13009G, MJE13070, MJE13071, MJE16002, MJE16004, MJE8502, MJE8503, STD13007, STD13007F, STD13007FC or STD13007P.