What I don't get is why the counterfeiters doesn't at least put something that is remotely suitable in their wares. I mean if you are going to sell fake 2SA1302/2SC3281 transistors, put something like 2N3055/2N2955 dies inside. It will at least work for a while or give a degraded performance. Some buyers would not notice the performance downgrade and look for other culprits when the transistor fails.
This way, you can sting your marks more than once. The way they are doing it is so blatant, it is beyond stupid. I suppose that is what happens when greed is your only reason for doing things. A very sad reflection of the world we live in.
This way, you can sting your marks more than once. The way they are doing it is so blatant, it is beyond stupid. I suppose that is what happens when greed is your only reason for doing things. A very sad reflection of the world we live in.
There is an other way, to find out at least in respect for a too large internal thermal transition resistance.
1) Mount the BjT device on two large independend heatsinks without mica for an electrical isolating mounting (test amp with Vbe multiplier is necessary).
2) Adjust idle current between 100mA and 150mA for each transistor
3) If you observe a quickly enhancing of the quiscent current (termal runaway) despite correct flat mounting and correct designed VBE multiplier, BjT device is faulty manufactured. In this case you have the same situation than by mounting without heatsink - thus you must switch off very quickly, otherwise you will receive a shorting between C and E connection leads (sometimes also to the B connection lead).
I must send back 300 pairs of Toshiba's 2SC5200/2SA1943 cause exact this unwanted behaviour.
To this topic there are a lot of other threads like this examples:
http://www.diyaudio.com/forums/solid-state/111749-fake-real-2sa1943.html
http://www.diyaudio.com/forums/solid-state/46155-genuine-2sc5200.html
http://www.diyaudio.com/forums/solid-state/154216-possible-fake-toshiba-sanken-transistors-3.html
A good overview you will get by this URL:
http://sound.westhost.com/counterfeit.htm
Unfortunately I am not able to say, whether this manufacturing fault comes through a fake (counterfeit) exemplars or not (even genuine parts may have such internal errors.
BTW - can I assume, that there are the risks to get counterfeits is lower by chosing the brand Fairchild than by Toshiba?
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From NEDIS.From where did you get them?
an earlier delivery (10 pairs approx. 6 months ago) also from NEDIS works perfect.
The supplier from NEDIS was Toshiba.
Inferior smaller dies usually have different junction capacitance than original components. Sometimes you can measure/compare with a known original and pick out non-obvious fakes without having to destroy or abuse them.
The more knowledge out there about how to spot fakes, the less money can be made from them, so the shysters have less motivation to create them...
The more knowledge out there about how to spot fakes, the less money can be made from them, so the shysters have less motivation to create them...
In my case this wasn't the reason.
Have a look to the pic about
http://sound.westhost.com/fake/fake3-2sa.jpg
After opening two destroyed devices of the faulty charge I note, that the sizes of the die was like that one of follow pic:
2SC3281 | 2sc3281, offtopic | hifi-forum.de Bildergalerie
Thus not the size itself was the reason for thermal runaway, but the lossy coupling to the mounting flange was the cause (thermal resistance too large).
This means additional, that also genuine devices can cause a lot of trouble.
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There are only a few official distributors of the genuine 2SC5200 according to toshiba.com webpage. There are no official distributors in EU listed as having them in stock on toshiba.de
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Its unfortunate that these asian companies actually go through the hassle of MAKING these fake devices.😱
This is one of those threads that keeps repeating.
If you want none fake parts then buy from top quality vendors like RS components or Farnell.
If you are buying cheap parts then someone has cut corners somewhere to make them cheap.
If you want none fake parts then buy from top quality vendors like RS components or Farnell.
If you are buying cheap parts then someone has cut corners somewhere to make them cheap.
To RS component I must send back a certainly medium power transistor type, after I have heard, that Magnatec is only a lable, but not the manufacturer itself - have a look to this link:
BD135-16
STMicroelectronics | Transistor, NPN, 45V 1.5A, SOT-32 | 714-0492 | Welcome to RS Online
Here you will se the ST-logo and on the transistor surface itself the Magnatec logo.
The actually reason for sending back was a too low value for hfe by my version with magnatec logo.
Do you know the suppliers resp. the real manufacturers for RS and Farnell ?
Please note - the price class haven't definitely to do with the actually quality standart, particulary by NOS devices. OTOH - offers from China with extrem low prices and as a condition forecast "pay in advance" should be voting for suspicious.
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I would never suggest anyone was 100% but I would expect the likes of RS and Farnell to check suppliers better.
read in this case post #117, #121 and #124 about
http://www.diyaudio.com/forums/soli...dels-quasi-complementary-power-output-13.html
http://www.diyaudio.com/forums/soli...dels-quasi-complementary-power-output-13.html
I don't think there is any problem with the RS supplied part. It will almost certainly be the correct ST part. RS (and many similar suppliers) tend to show a photo of a generic component that looks at least similar to the part supplied but they do say that the goods supplied may not be of identical appearance to the goods in the photo...
Sometimes you can choose your designs carefully and use middle tier parts instead.
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