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Old 6th March 2006, 03:21 PM   #1
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Default Genuine 2SD424?

Hi Gang,

I have just run into a lot of Toshiba 2SD424 transistors that I believe to be genuine. Some of the reasoning behind my initial thoughts:

1. The baseplate is within thickness specs on the datasheet. All of the fakes I have seen thus far have baseplates that are entirely too thick.

2. The heat spreader imprint, which you can usually see from the bottom, is an hourglass shape, identical to the known genuine originals I have seen. The counterfeits often have a (way too small) circular indent on the bottom.

3. The spacing between the leads and the case are pretty small, again consistent with the known originals I have. Another point of difference seen on most counterfeits is that their lead-case spacing is a bit larger.

4. The broker I got these from claims to only sell parts which have traceability to the manufacturer.


Admittedly, the reasons above are a bit 'thin'. It seems to me, that a lot of the counterfeits tend to blow out when the heat builds up. I was thinking of making a test to run these things at saturation for a while at a point within, but near the limit, of their SOA. Just to see what happens.

I am also in the process of running them though a Tektronix 371A curve tracer, but I was wondering if anyone could give me any other ideas or tests to try to further 'authenticate' them?

Thanks in advance.
-Funkenstein
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Old 6th March 2006, 04:46 PM   #2
ilimzn is offline ilimzn  Croatia
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You could 'sacrifice' one and open the top cap, and inspect the die itself. i believe there were pictures of genuine parts shown elsewhere on the net, so you can do a comparison. Fakes usually have a very small die or two smaller dies.
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Old 6th March 2006, 04:50 PM   #3
anatech is offline anatech  Canada
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Hi Funkenstein,
They sound like real ones from your description. I don't even have to look at one as I've seen enough real ones.

Do they have the old red Toshiba curved logo on top? Clear print?

-Chris
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Old 6th March 2006, 05:25 PM   #4
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Hi Guys,

Thanks for your replies.

Ilimzn, I think I will do that. I have a bunch and can get more. I have also noticed that, with fakes, the die is mounted about 45-degress off-center, so that should be interesting to see. Maybe I'll throw some pics up here, for kicks.

Chris, the logo is the red scripted 'Toshiba' word. I think that's what you're referring to. The date code appears to be 1984 (or 1994?).


Thanks again.
-F
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Old 6th March 2006, 05:31 PM   #5
anatech is offline anatech  Canada
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Hi Funkenstein,
All I can say is that things are looking good for them being real. I used to stock that pair for general use, along with a few others.

-Chris
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