Fake onsemi 2N3773

Tekko

Banned
2005-01-01 3:33 pm
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

Member
2004-06-19 11:30 am
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.
 
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".
 
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.
 

Tekko

Banned
2005-01-01 3:33 pm
I got them at my regular parts outlet, never had a prollem before.

Seller said they were motorola substitutes and that he forgot to tell me and wanned me to return them for a refund, but im not gonna pay return shipping!!!

Im guessing the return part is so he can resell them to other buyers.
 

MJL21193

Disabled Account
2007-03-10 1:20 am
Im guessing the return part is so he can resell them to other buyers.

I got scammed the same way about 7 years ago - guy selling dud P4 processors. Charging $20 for shipping, sending them out in a $1 bubble mailer. You return it for a refund on the purchase price, he keeps the shipping cost. 2 days later the same item is up for auction again.

It's the best policy to buy from a reliable source whenever possible. These are available from major vendors. Save some money and aggravation.
 
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