This post explains for the transistor.
The Part Number is D2581, 2SD2581.
The function of this semiconductor is 1500V, 10A, NPN Transistor.
The package is TO-3PML Type
Manufacturer: Sanyo Semicon Device
Preview images :
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Description
The D2581 is NPN Triple Diffused Planar Silicon Transistor.
Features
1. High speed.
2. High breakdown voltage (VCBO=1500V).
3. High reliability (Adoption of HVP process).
4. Adoption of MBIT process
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Absolute maximum ratings ( Ta=25°C )
1. Collector to Base Voltage: Vcbo = 1500 V
2. Collector to Emitter Voltage: Vceo = 800 V
3. Emitter to Base Voltage: Vebo = 6 V
4. Collector Current: Ic = 10 A
5. Collector Dissipation : Pc = 3 W
6. Junction Temperature: Tj = 150°C
7. Storage Temperature: Tsg = -55 ~ +150°C
Application:
1. Color TV Horizontal Deflection Output