did I buy fake transistors?

[davidsrsb]

Some information here.

https://sound-au.com/counterfeit.htm

Double die MJ1503

https://sound-au.com/fake/counterfeit-p1.htm

Pete

The first article is inaccurate, there most definitely were dual die power switch npn transistors from Motorola in the 70s. I have used them long ago.
The nature of transistor current sharing means that you should not use dual die where SOA in the linear region matters, one die will always hog the power.

 

[JimmyB]

Parylene is going to be tricky

Har har..that's an understatement and a half!

It's a pig to rework after that stuff.

 

[jpk]

As one corner of the die of the opened BDY58 was a bit damaged I opened two more transistors.

BDY58:

BUV20:

BUV20 detail:

Just for fun I let the VBE break through lit up the die.

BDY58:

BUV20:

The BUV20 looked identical to the first one I opened apart from the slightly different looking white covering stuff. The second BDY58 had the same damage to the die corner, but the die itself looked different and also had a different wiring. So it seems these are rejects, I will probably return them. I have noticed that BUV21 and BUV22 are still available, would they suit the Naim clone?