Counterfeit Parts or Why Doesn't My ** Work?

Many of the Asian sourced parts are not even what they are marked.

 One recent YouTube video showed parts sourced from a certain Asian country at a very good price.

 He also ordered the same from a trusted supplier.

He showed that the Asian parts had laser engraved info. in the epoxy coating- identical to the Hi dollar parts from the supplier, but the OEM had the ID PRINTED on the xistor in WHITE INK!

Putting the transistors on a Peak Xistor tester ID'd the Asian ones as bipolar xistors, and way lower breakdown voltage.
 The expensive ones showed as they should- A Darlington Pair, and on the scope showed their characteristics to be correct.

If he had put them in the amp he was repairing, it would have blown up.

The moral to this is CHECK ANY PARTS BEFORE USING THEM. (Even OEM parts can be defective or counterfeit).
I have the Tee shirt and ball cap for those too. 

Checking parts before use is a must for resistors and capacitors, fuses, etc. also.

So save yourself from some heartburn. That transistor or 'lytic you got for $.05 cents, VS the high quality one for $.25  will often turn around and damage the equipment if it is not a good quality one. Not to mention the time troubleshooting.
As for NLA parts to build or repair many projects I have in mind, well, I have to take my chances. Even parts sold on "The big A" have proved to be counterfeit.