OK, well, there's this bi-amped Advent powered loudspeaker. The tweeter amp is blown. The outputs are 2N6284 and 2N6287 Darlington TO-3 package transistors. Pretty obscure these days. The schematic info also included NTE subs but those were nearly 20.00 each, with no guarantee in my mind as to quality, etc.
So I ordered the 2N numbers from MCM. More like 5.00 each and I've had pretty good luck with MCM lately. When I received them, they were mismatched vendor markings, and one looked like cheap crap so I tested them right away. Actually, the one that looked like crap was OK, but the "2N6287" with Thomson ST markings was SHORTED emitter-base right out of the chute. I
called MCM - "Oh, gee we're sorry" and they sent me another, no need to return the bad one.
So I cut it open. It wasn't even a Darlington, just a single emitter base junction and the die was only 2mm instead of 5mm. There was a visible gash across the die, so obviously the thing was never tested in manufacture.
So I receive the replacement. I test it, and this one is OPEN emitter base. Once again I call MCM, got credit and no need to return them, so I cut this one open as well. Here's the fun part:
The transistor case was EMPTY. No die, no leads, just an empty case. I've emailed pics to MCM.
With a little more research I was able to get the Onsemi MJ versions from
Allied Electronics, so all is well, and the repair worked out OK.
Mark Z.