Opamps under microscope

[restorer-john]

I have not, virtually everything I have seen has been rebranded wrong or lower grade parts sometimes even power FET's where the pins are not even in the same order.

I have some fake Toshiba MOSFETs here (2SJ-115/2SK405) that are so good, you cannot tell until you put them on the curve tracer or install them. I bought them from a supplier in China who guaranteed they were genuine. I knew they were not when I bought them, just wanted to see what was in them and whether they even worked. I also have plenty of original genuine ones and side by side, you'd never know, right down to the printing, the colour of epoxy, the plated copper etc. Even the legs are pretty much perfect replicas.

I only buy my obscure, NOS and so-called unobtainium semis from Japan from an OEM supplier I've used on and off for 30 years. Never once had an issue with them.

 

[scott wurcer]

that are so good, you cannot tell until you put them on the curve tracer or install them...

you'd never know, right down to the printing, the colour of epoxy, the plated copper etc. Even the legs are pretty much perfect replicas.
.

Sort of the point of my post above, run the curve tracer plots and they clearly are a different die. You run a cheap part through exactly the same manufacturing (packaging) process and of course they look alike. My point is in virtually all the "fake" parts for audiophiles cases the parts are not being made from scratch like say the fake vinyl Gucci bags.

A couple of examples, we had QA returns for AD620's which turned out to be a random op-amp in the same 8 pin DIP package no chance of it working in any application. I have also seen SK170's and SJ74's with fake laser brands, under microscopic examination the brands were obviously carved by hand, having a small collection of Chinese chops I know that these skills are readily available to counterfeiters.

I like to differentiate the problem to point out the possibility of potentially dangerous fakes, for instance, made on a poorly qualified process where they might pass an initial test but fail in a life/health threatening situation. I consider most of the fake device problems the DIY audio folks encounter a nuisance at worst.