Fake onsemi 2N3773

Tekko · 26th December 2010, 12:20 AM

So i have finally gotten bitten by this counterfeit thing.

I got some 2N3773's that sez 2N3773 Mexico 0813 and has ON in a ring at the top.

According to rod elliott's site about fakes, everything suggest that my devices are genuine but a onsemi datasheet suggest the markings shouldent have the ON logo at all.

Anyways i ripped the can off one of them and the die is about 2x2mm square and covered in white rubbery stuff, trying to build an amp around them failed, with a load, the amp would stick to the positive rail but go though the startup as soon as the load was removed, but it wouldent draw any bias current, and when i turned it off, the small spike of noise from the switch contacts picked up by the amp was enough to blow both output devices, exploding VAS and a resistor in the LTP as well as the B to E resistor on low side output. During all tests there was a 40 watt light bulb in series with the mains.

Conclusion, i guess transistors with a ON in a circle on them are likely fakes

bigpanda · 26th December 2010, 12:49 AM

Are you talking about the 2N3773 or all ON products (about the "ON" in a circle on the top)? I got some MJ15003/4 MJ21193/4 directly from ON and their authorized distributor which have the same printing as you describe. Your guessing is, I must say, reckless.
Try to post some pictures and let us see what you have.

Tekko · 01:41 AM

The seller claimed they were motorola and even had a picture of a genuine motorola device!! I have contacted seller and see if hes willing to resolve, return is not an option though since 4 out of 12 blew up with ZERO bias current!!

Pics:
http://i.imgur.com/VaVye.jpg
http://i.imgur.com/OGdfL.jpg

The lettering on these rubs off pretty easily as well.

wrenchone · 26th December 2010, 04:16 AM

Lettering that rubs off easily - sounds like some shoddy counterfeit money. Other giveaways - the glass to metal seals on the TO-3 case are larger than what is usually seen in a U.S. - style TO-3 package (that's not a 100% sure indicator, though). Another dead giveaway (not seen in this case, though) is an "hourglass" insert in the TO-3 base, used by many Far East manufacturers, but never for the major U.S. manufacturers. I saw some purported IRF240s pictured here at Diyaudio with that sort of package, which immediately screamed "fake" to me. Somebody was probably re-marking some some surplus Chinese/Japanese SMPS-duty FETs to sell as the much more marketable IRF240.
Of course, a puny die globbed with white silicone also screams "fake".

jaycee · 26th December 2010, 05:20 AM

On Semiconductor is the new name for the semiconductor branch of Motorola, which was spun off as a separate company in 1999. The ON in a circle is their logo.

They have all the hallmarks of fakes - 2mm square die (2N3055 or TIP41 really), covered in silicone (no legit manufacturer does this), no copper heat spreader, printing that rubs off, even the fact that you got the case open easily.

The seller probably knows he's selling fakes - the best you can really do here is never deal with him again. If you bought them from eBay, then never do that again - eBay is one of the prime outlets for fake transistors.

astouffer · 26th December 2010, 05:20 AM

Contact the manufacturer. They will give you information about the date or plant codes. Companies are interested in knowing if someone is making fake parts.

ravslanka · 26th December 2010, 02:00 PM

its a fake if there is silcone on the die no reputed manufacturer use this way.
i myself used these kind of transistors.

ravs

be a vegeterian

megajocke · 26th December 2010, 03:09 PM

Quote:

Originally Posted by Tekko

Conclusion, i guess transistors with a ON in a circle on them are likely fakes

The originals do have that logo. The printing on them is much sharper than your fakes though.

Tekko · 26th December 2010, 03:23 PM

I destroyed the remaining 8 and binned them to prevent garbage pickers from getting ahold of them and selling them further.

Lee Knatta · 26th December 2010, 08:25 PM

Tekko, could you please be so kind to tell us where exactly you bought the counterfeit parts?

26th December 2010, 12:20 AM	#1
Tekko diyAudio Member Join Date: Jan 2005	Fake onsemi 2N3773 So i have finally gotten bitten by this counterfeit thing. I got some 2N3773's that sez 2N3773 Mexico 0813 and has ON in a ring at the top. According to rod elliott's site about fakes, everything suggest that my devices are genuine but a onsemi datasheet suggest the markings shouldent have the ON logo at all. Anyways i ripped the can off one of them and the die is about 2x2mm square and covered in white rubbery stuff, trying to build an amp around them failed, with a load, the amp would stick to the positive rail but go though the startup as soon as the load was removed, but it wouldent draw any bias current, and when i turned it off, the small spike of noise from the switch contacts picked up by the amp was enough to blow both output devices, exploding VAS and a resistor in the LTP as well as the B to E resistor on low side output. During all tests there was a 40 watt light bulb in series with the mains. Conclusion, i guess transistors with a ON in a circle on them are likely fakes

26th December 2010, 01:21 AM	#3
Tekko diyAudio Member Join Date: Jan 2005	The seller claimed they were motorola and even had a picture of a genuine motorola device!! I have contacted seller and see if hes willing to resolve, return is not an option though since 4 out of 12 blew up with ZERO bias current!! Pics: http://i.imgur.com/VaVye.jpg http://i.imgur.com/OGdfL.jpg The lettering on these rubs off pretty easily as well. Last edited by Tekko; 26th December 2010 at 01:41 AM.

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26th December 2010, 12:49 AM	#2
bigpanda diyAudio Member Join Date: Jun 2004 Location: HKSAR	Are you talking about the 2N3773 or all ON products (about the "ON" in a circle on the top)? I got some MJ15003/4 MJ21193/4 directly from ON and their authorized distributor which have the same printing as you describe. Your guessing is, I must say, reckless. Try to post some pictures and let us see what you have.

26th December 2010, 04:16 AM	#4
wrenchone diyAudio Member Join Date: Feb 2004 Location: Silicon Valley	Lettering that rubs off easily - sounds like some shoddy counterfeit money. Other giveaways - the glass to metal seals on the TO-3 case are larger than what is usually seen in a U.S. - style TO-3 package (that's not a 100% sure indicator, though). Another dead giveaway (not seen in this case, though) is an "hourglass" insert in the TO-3 base, used by many Far East manufacturers, but never for the major U.S. manufacturers. I saw some purported IRF240s pictured here at Diyaudio with that sort of package, which immediately screamed "fake" to me. Somebody was probably re-marking some some surplus Chinese/Japanese SMPS-duty FETs to sell as the much more marketable IRF240. Of course, a puny die globbed with white silicone also screams "fake".

26th December 2010, 05:20 AM	#5
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	On Semiconductor is the new name for the semiconductor branch of Motorola, which was spun off as a separate company in 1999. The ON in a circle is their logo. They have all the hallmarks of fakes - 2mm square die (2N3055 or TIP41 really), covered in silicone (no legit manufacturer does this), no copper heat spreader, printing that rubs off, even the fact that you got the case open easily. The seller probably knows he's selling fakes - the best you can really do here is never deal with him again. If you bought them from eBay, then never do that again - eBay is one of the prime outlets for fake transistors.

26th December 2010, 05:20 AM	#6
astouffer diyAudio Member Join Date: Jun 2004 Location: Pittsburgh, crumbling wasteland	Contact the manufacturer. They will give you information about the date or plant codes. Companies are interested in knowing if someone is making fake parts.

26th December 2010, 02:00 PM	#7
ravslanka diyAudio Member Join Date: Oct 2006 Location: delhi	its a fake if there is silcone on the die no reputed manufacturer use this way. i myself used these kind of transistors. ravs be a vegeterian

26th December 2010, 03:23 PM	#9
Tekko diyAudio Member Join Date: Jan 2005	I destroyed the remaining 8 and binned them to prevent garbage pickers from getting ahold of them and selling them further.

26th December 2010, 08:25 PM	#10
Lee Knatta diyAudio Member Join Date: Apr 2010 Location: Germany	Tekko, could you please be so kind to tell us where exactly you bought the counterfeit parts?

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