Here's a picture of a TO-3 I took apart when I was an R&D tech and was curious about what things look like when I was learning CAD:

Teardowns I've seen for newer devices all used bond wires to connect to the die. This device was from the 1970's.

The solder blob on the upper connection was a misguided attempt by me to reattach the lead that came loose.

 

Thank you guys for the replies and sorry for late respond . I had an original mj15024 trans
taken from an old amplier but it spoiled. So i used this for comparison. So opened both mj15024
and 2sc1619 to compare the inside construction . What I found is the MJ trans has a big blue isulator at pins while the 2sc trans smaller insulator. The MJ has another thick layer of heatsink and 2sc just has small circle bump up as heatsink . MJ trans has big rengtular chip but 2sc has smaller rectungar chip . But then again the
MJ trans has high power, higher voltage and higher current rting, so maybe ... Then I got an idea to test , but I really dont know whether this is correct way to test. I use the 2sc trans to bypass a 12 v regulaor to power up osram bulp (12v /20w). I dont know how describe it but
If yiu look at the circuit diagram attached, you will undrstnd the exprmnt.

 

I dont know why but half of what I had written above post is missing , so i write again. This is contunuition of above post. I use 2sc1619 to bypass the regulator. At certan point , say at 100ma the 2sc trans will stert conduct . Higher current will passthrough 2sc ,it ll measured by ammeter #1. When i test with one bulp it show 1.4A , after add one more bulp in shows 3.2A.
The voltmeter 1 show 30mv. The output voltage remai 12v. The 2sc1619 is 50watt it handle 40w load , so can it be an original? Should I measure the Vce and multipy it wuth Ic to calculate power handling of the trans? Is it rightway tto test a transistor? I highly appreacite your replies.
Thank you.

 

Is it rightway tto test a transistor?

You were already given a couple of tests. See if it will conduct the maximum continuous current specified in the datasheet (not mentioned earlier - also measure the saturation voltage). Operate the transistor in active mode and see if beta is in the specified range.

Be sure to provide adequate heat sinking.

I couldn't see much from the 2SC pictures - too blurry. Were all of the pictures with the white spot a covering on the suspected fake?

 

You were already given a couple of tests. See if it will conduct the maximum continuous current specified in the datasheet (not mentioned earlier - also measure the saturation voltage). Operate the transistor in active mode and see if beta is in the specified range.

Be sure to provide adequate heat sinking.

I couldn't see much from the 2SC pictures - too blurry. Were all of the pictures with the white spot a covering on the suspected fake?

Yes, the blue insulator one is MJ15024 (the first pic) , others are 2sc . When I opened the
2sc there was a dustlike substance on the top of the chip(2nd pic). I cleaned the grey dustlike
substance then therewas a white colour glue covered the chip( 4rth . pic). The 5th and 6th pic are after the white glue removed. The MJ tans doesnt have any glue on its chip.

 

Pictures in daylight are the best. Experiment a little to get reasonable settings. Avoid sun shining directly on them.

That white glue could be something similar to the grease coming inside the mechanical mouse to lubricate the wheel.

I found same inside of a 2N3055 (and others) I opened by carefuly filing the top cover.

Are you sure that the "dust" is not the result of sawing the cover?