This part is a kind of semiconductor called LM120.

Function of this product has 1.5 AMP NEGATIVE VOLTAGE REGULATOR.

Manufacturers : Seme LAB

Image and pinout :

Some of the text within the PDF file :

IP120A IP120 IP7900A IP7900 LM120 SERIES SERIES SERIES SERIES SERIES 1 1 2 2 1.5 AMP NEGATIVE VOLTAGE REGULATOR 3 3 Pin 1 – Ground Pin 2 – VOUT Case – VIN Pin 1 – Ground Pin 2 – VOUT Case – VIN FEATURES • OUTPUT VOLTAGES OF -5, -12, -15V • 0.01% / V LINE REGULATION • 0.3% / A LOAD REGULATION • THERMAL OVERLOAD PROTECTION K Package – TO–3 R Package – TO–66  ! • SHORT CIRCUIT PROTECTION 1 2 3 • OUTPUT TRANSISTOR SOA PROTECTION • 1% VOLTAGE TOLERANCE OPTION (–A VERSIONS) Pin 1 – Ground Pin 2 – VIN Pin 3 – VOUT Case – VIN Pin 1 – Ground Pin 2 – VIN Pin 3 – VOUT DESCRIPTION The IP120A / LM120 / IP7900A / IP7900 series of 3 terminal regulators is available with several fixed output voltage making them useful in a wide range of a [ ... ]

LM120 PDF Datasheet Download