Toshiba trannies from ebay

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That's a well thought out method, thanks.

So I started at 3.3A from 36V and both versions took this for 5secs or so, long enough to get a stable reading on the emitter resistor voltage. I just so had a Motorola TIP2955 on the same sink so I tried that as well and it withstood 5secs. That works out to 3.3A and 26V across c-e which is on the hairy edge of the DC SOAR. Chalk one up to Motorola.

Then I switched to 72V rails: 3.3A and 62V is a hair over the DC SOAR for the 1302. When I touched the base on the 1302, the voltage on the emitter resistor shot up to 40V (12A) so I pulled the plug.

Didn't try the Motorola on 72V.

Interestingly, both transistors pass a diode check but the emitters are short to collector. Guess the emitter bond wire came off and fell to the tab.

Is there a way to open these ceramic packages up? Grind it with a dremmel? I'd like to be able to see what happened and possibly some die markings.
 
Iain McNeill said:
Interestingly, both transistors pass a diode check but the emitters are short to collector. Guess the emitter bond wire came off and fell to the tab.

Is there a way to open these ceramic packages up? Grind it with a dremmel? I'd like to be able to see what happened and possibly some die markings.

Short from C to E with the base still working indicates second breakdown - the expected failure mode at high VCE.

Hold the transistor on edge, and give it a good whack with a hammer. The epoxy case will separate from the heat spreader. For a good device, the die will be destroyed becuse the epoxy adheres well to the die. But you can still get a good look at the size. Fakes will usually be covered in white silicone goo inside - and it will remain intact upon opening the case.

Run your suspects down at 40 or 50 VCE at that current - they might actually be good there and as such may be useful in something like a DX. I would expect original Toshibas to take the 62V for a fraction of a second. It's a bit outside of ratings, but a lot of amps out there that are quite reliable run them there.
 
die measures 3.45mm x 3.45mm

Opinions?
 

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I just noticed. While the die size is the same, the interdigitations on the BK tranny are thinner than the fake and there's more of them.

What does that do? lower C or increase gain?

BTW, I guess this tiny die size confirms my frail DMM capacitance reading. Got some On Semi TT's coming soon, can't wait to to see what a real transistor can do!
 
Iain McNeill said:

Here's my "genuine" Toshiba that I purchased from Digikey back in 2000. Guess you can't even trust the distributors any more either.

Kind of surprising - I thought Digikey's incoming QC was always pretty good. They're now considered one of the few places left in the world that you can always get good C5200's (they only carry current production parts).
 

taj

diyAudio Member
Joined 2005
wg_ski said:


Kind of surprising - I thought Digikey's incoming QC was always pretty good. They're now considered one of the few places left in the world that you can always get good C5200's (they only carry current production parts).

I emailed Digi-Key about that last year, and they were so sensitive about it that their "Toshiba Product Manager" called me and assured me that they ONLY buy Toshiba parts directly from Toshiba. He sounded pretty convincing (and exasperated).

..Todd
 
Just to wrap this up...

I tested another BK 1302 at 2.2A and 62V and it survived 5 seconds to confirm emitter resistor voltage.

I got my NJL1302's this morning and, glory halleluia, I believe they are genuine. (at least that's what the packing slip from On Semi said:) )

They passed 62V at 3.3A for 5secs

Nice!

...and I can read 2.2nF on my cheesy meter!!

Thanks guys!
 
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