This part is a kind of semiconductor called 1N4751A.

Function of this product has 1.0W ZENER DIODE.

Manufacturers : Diodes

Image and pinout :

Some of the text within the PDF file :

OBSOLETE – PART DISCONTINUED PART OBSOLETE – NO ALTERNATE PART 1N4728A - 1N4761A 1.0W ZENER DIODE Features  1.0 Watt Power Dissipation  3.3V - 75V Nominal Zener Voltage  Standard VZ Tolerance is 5%  Lead Free Finish, RoHS Compliant (Note 2) Mechanical Data  Case: DO-41  Case Material: Glass. UL Flammability Classification Rating 94V-0  Terminals: Finish  Sn96.5Ag3.5. Solderable per MIL-STD-202, Method 208  Polarity: Cathode Band  Marking: Type Number  Weight: 0.35 grams (approximate) DO-41 Glass Dim Min Max A 26.0  B  4.10 C  0.86 D  2.60 All Dimensions in mm Maximum Ratings @TA = 25°C unless otherwise specified Characteristic Zener Current (see Table page 2) Power Dissipation Derate Above 50°C (Note 1) Thermal Resistance [ ... ]

1N4751A PDF Datasheet Download