On 4/3/2016 7:25 PM, Cursitor Doom wrote:
Hi all,

Is there any reliable method for testing parts for authenticity? I just
bought a bunch of LM317T variable voltage regs off Ebay (from a dealer
with a solid rep, admittedly - but they could themselves have been
fooled) and would like to know if they're genuine or not, as a quick
search on the net showed there *are* fake LM317s around.

Would one be safe to assume that any fake part would not be capable of
performing at the maximum levels claimed by genuine manufacturers in
their datasheets? For example, the 317 is claimed to be good for 1.5A,
but if mine burn up at say 1.3A, is that a clear indication that they're
fake?

Your thoughts, gentlemen....


Wherever possible I try to source parts from a reliable vendor. In the
USA, that means (alphabetically) vendors like Allied, Digikey, Mouser or
Newark. Companies that buy their parts from the original manufacturer.
I don't mind spending a bit more for parts that I believe will be
reliable, as I like avoiding reworks, and wondering if the problem was
my diagnosis or the new part.

Another theory I have is how subcontractors handle duds. Let's say a
major optical laser maker subcontracts with "Dumb-Luck" electronics to
make 10,000 CD player lasers (optical blocks) for them. Dumb-Luck knows
they have to make 13,000 to come up with 10,000 that meet spec. They
know they are SUPPOSED to destroy any others, but instead sell them as
new "A" stock lasers. They look like real ones, because they are, they
just don't meet spec or work at all, and we have no way of knowing.
They think they are being good businessmen by getting money for their scrap.

Regards,
Tim
Bristol Electronics