This part is a kind of semiconductor called MPSA42.

Function of this product has NPN Silicon Epitaxial Planar Transistor.

Manufacturers : SEMTECH

Image and pinout :

Some of the text within the PDF file :

MPSA 42 / 43 NPN Silicon Epitaxial Planar Transistor for high voltage switching and amplifier applications. The transistor is subdivided into one group according to its DC current gain. As complementary type the PNP transistor MPSA 92 and MPSA 93 is recommended. On special request, these transistors can be manufactured in different pin configurations. TO-92 Plastic Package Weight approx. 0.19g Absolute Maximum Ratings (Ta = 25 oC) Collector Base Voltage Collector Emitter Voltage Emitter Base Voltage Collector Current Total Device Dissipation @ Ta=25℃ Derate above 25℃ Total Device Dissipation @ Tc=25℃ Derate above 25℃ Junction Temperature Storage Temperature Range Symbol VCBO VCEO VEBO IC Ptot Ptot Tj TS Value MPSA 42 MPSA 43 300 200 300 200 6 500 625 5.0 1.5 12 150 -55 to +150 [ ... ]

MPSA42 PDF Datasheet Download