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Forum Index : Electronics : More fake transistor fun!

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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9257
Posted: 06:30am 15 Jul 2024
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I got given an old "High Energy Ignition" board from back in the April 1988 issue of Silicon Chip, cos the output transistor had failed.

The guy said he replaced the transistor himself, but the unit lasted half a block, then the engine would no longer start.

Transistor is a Motorola MJ10012 NPN Darlington power transistor, and he got some in from ebay.

I bet you know where this is going!    

"Replacement" transistor tested as open-circuit.  I asked what he paid for them - $10 for FIVE of them!    
Genuine ones are about $18....EACH.

I cut one open to see, and......there is no way the wires from the die can handle 10A!!!!
This transistor is capable of 10A continuous, and 15A peak.  
The BASE current can be up to 2A, and I doubt these wires can even handle that!
These are the linking wires inside the TO-3 can:





FAIL.  

At least we have one more person now aware of the fake parts thing.
Jaycar still stock the genuine transistor, so I will get a REAL one from them.  
Smoke makes things work. When the smoke gets out, it stops!
 
Godoh
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Joined: 26/09/2020
Location: Australia
Posts: 435
Posted: 10:10pm 15 Jul 2024
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Thanks for the post Grogster. I did not know that the dodgy components were that bad.
A friend who is a technician told me years ago that many of the capacitors he had replaced were half the weight of good quality components.
It seems that if there is a quick dollar to be made that unscrupulous manufacturers will make any rubbish
Pete
 
Grogster

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Location: New Zealand
Posts: 9257
Posted: 11:10pm 15 Jul 2024
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Unfortunately, fake parts ARE big-ish business in China, so I don't expect to see the end of this any time soon, if they can still make money by selling the fakes off as genuine.

I myself was bitten by fake parts several years ago, when I tried to buy several LM350T regulators in TO-3, and found they would cook themselves to death at about 2A or so.  The general consensus of the forums at the time, was that they were PROBABLY LM317 regulators, relabelled as 350T's, so only capable of 1.5A maximum.

So, it's easy to fall into the trap, if you buy any bits from ebay or AliExpress.
I did it once, but won't do it again!

A couple of easy ways to spot suspect fakes is that the markings on the top of the package rub off easily with your finger, the printing is fuzzy and not crisp as it would be with genuine bits, and.....THE PRICE!

The price is by far the biggest give-away: "If it sounds too good to be true, it probably is."  

The guy I did this job for had NO IDEA that fake parts even existed, and that is what the fakers/cloners bet on.  Fully assembled electronic modules tend to be OK from those sellers USUALLY, but discrete parts can often just be outright lies.  

For your discretes, ALWAYS buy from a trusted parts supply house.
That's the best general advise, but as with this guy I just helped out, if you don't even know or are not aware that a fake market even EXISTS - well then, it's easy to trick those that simply don't know.

But as I said, now he does, so he won't be tricked again, and I said please come to me and ask me if you have any doubts about the authenticity of parts, and I can see him right - pretty much!  
Smoke makes things work. When the smoke gets out, it stops!
 
Grogster

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Location: New Zealand
Posts: 9257
Posted: 04:42am 17 Jul 2024
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UPDATE:  Here is a photo of the fake on the left, compared to a genuine one on the right.  I sacrificed one genuine transistor, as I wanted to see the internal difference.





Check out the MASSIVE die-size difference!!!!!    

The connecting wires from the die, to the base and emitter pins are still thinner then I thought they would be, but my guess is that these wires(on the genuine part) are some special kind of linking wire with very low resistance, and can obviously therefore handle the rated current of the device.  Might even be pure silver or something.

But that die-size difference!      
Smoke makes things work. When the smoke gets out, it stops!
 
Godoh
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Joined: 26/09/2020
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Posts: 435
Posted: 06:26am 17 Jul 2024
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Wow Grogster, that is a massive difference in die sizes.
As you say the wires are not much different but the die certainly is.
I wonder just how much money the counterfitters are saving by making these copies. Surely they would have to sell thousands to be worth the trouble and to make much on them
Pete
 
Grogster

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Location: New Zealand
Posts: 9257
Posted: 06:49am 17 Jul 2024
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They're not "Making" the copies, they take either reject product, or a totally different product that LOOKS the same, and then they thwack a new label on it, saying that it is something it is not.  

There is basically ZERO cost to them to do this, as they get the factory rejects at a rock-bottom price per unit, or sometimes for nothing at all.  Then they slap the new part number on the top, and sell it as if it is the real thing.

EDIT: I also note, that in the genuine transistor I cut open, the die is bonded to the TO-3 case using some sort of silver-paste-glue-stuff.

It it hard to the touch, and you can't just scrape it off.
But it sits between the bottom of the die, and the TO-3 case.
This will be the AUTHENTIC thermal bonding of the die to the transistor case.
Something that you can't even see if it was done, on the fake.
Edited 2024-07-17 16:51 by Grogster
Smoke makes things work. When the smoke gets out, it stops!
 
Grogster

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Posts: 9257
Posted: 06:57am 17 Jul 2024
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Here is a closer look at the genuine part I cut open:


Smoke makes things work. When the smoke gets out, it stops!
 
Chopperp

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Joined: 03/01/2018
Location: Australia
Posts: 1041
Posted: 10:03am 17 Jul 2024
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I remember back in the early 70's that there were a quite a few fake 2N3055's around.
They were usually noticeably lighter than good ones.

Brian
ChopperP
 
poida

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Joined: 02/02/2017
Location: Australia
Posts: 1409
Posted: 10:38am 17 Jul 2024
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clearly a sponsored video but it's full of proper EE facts
https://www.youtube.com/watch?v=3BIpCOOiHKw
he tests fake v real FET using the best test setup there ever was in the world.
good stuff
wronger than a phone book full of wrong phone numbers
 
KeepIS

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Joined: 13/10/2014
Location: Australia
Posts: 1624
Posted: 08:44am 18 Jul 2024
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Great video, thanks for that link  
It's all too hard.
Mike.
 
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