There are fake power transistors too. Who would have thought? Just a functional item, not worth more than a few dollars apiece, goes inside an amp. But the good ones are 'branded' (ie labeled by the proper manufacturers, eg Toshiba, Hitachi) and are worth a little more because they are known to be excellent quality, and so some guys in China reckoned that if they got cheap generic power transistors that are sort-of close to the same spec, re-mold them in new epoxy casings that look the part and paint the right brand names on them, they can sell for a few times more than they should. You would hardly think it was worth it at the sort of profit margins you're talking about, but they did. The problem is that when you need to use the correct component to replace an old failed one in your 1970s or 80s hi-fi amp or solid-state guitar amp, eg Roland JC-120, the new ones that you get fail pretty much straight away, often causing other damage, and at the very least making the repair tech do the job over for free. The first time this happened to me I thought I'd messed up the repair, the second time I was certain I'd done it right and I thought it must have been because the NOS transistors could have degraded in storage, then after that I did some research and found I'd bought fake transistors.
