Here's a few pictures of the insides of a couple of power transistors I purchased for use in a subwoofer amplifier. The amp is rated at 300 watts into 4 ohms and first blew rather quickly (20 seconds or so) into a 4 ohm load. I ordered replacement transistors from the same supplier and it then later blew into an 8 ohm load. Upon discovering via Rod Elliott's site at ESP that counterfeit transistors are available, I decided to pop them open and take a look. Sure enough, the die on the 2sa1302's is only half as big as it should be. It measures only 3.5mm square, whereas it should be over 5mm square.
UPDATE - I sent 2 of these transistors (both fine) to Rod Elliott, and he has verified that at least the 1302's are fake. The one I sent him had an even smaller die than the one shown here - it measured just 2.5mm square. There is NO WAY that a device with such a small amount of silicon could ever hope to withstand the rated power - thus my amp died rather quickly!!
What follows is some pictures of the transistors I popped open including what looks like a genuine (by the size of the die) 2sc3281. Click the images for a bigger picture.
