Pissed!! Fake 2SC5200 today!

diy didi · 30th December 2011, 05:08 PM

Bought some fakes today! They even say Toshiba on them!
Measured?compared to some known good ones. Yikes!!!! Vceo should be 230V and up.
These bastards measured a mere 130V!!!
How do I tell the shop that sold them to me they're no good?
I don't usually buy them locally, but took a chance cos they had 'Toshiba' on them.
Are there ant tell-tale signs of knowing when Transistors such as these are fake???

madtecchy · 30th December 2011, 05:25 PM

Hi. "How do i tell the shop that sold them to me they are no good"

I guess much the same as when you asked the shop for them. Just change sentence to .. These transistors are no good and are fakes and if you dont give me my money back im going to tell the diyaudio forum the name of your shop..

mr_push_pull · 30th December 2011, 05:27 PM

Quote:

Originally Posted by diy didi

Are there ant tell-tale signs of knowing when llTransistors such as these are fake???

NOS double crown TDA1541 from China? sounds like tell tale enough to me.
I'd love to know the answer to that but there can't be any reliable signs as the fakers can always "improve" the faking process.
fakes will spread more and more and the only solution will be to buy from safe sources. I can only hope Farnell, RS and the like will not be touched by the disease.

madtecchy · 30th December 2011, 05:30 PM

I wouldnt be so sure about RS components i was supplied six fake lm3886 from there nuneaton trade counter. They where the uninsulated version..

godfrey · 1st January 2012, 09:46 AM

Quote:

Originally Posted by diy didi

Yikes!!!! Vceo should be 230V and up.
These bastards measured a mere 130V!!!

How did you measure? The datasheet does allow for 50mA at 230V.

cliffforrest · 1st January 2012, 10:21 AM

Quote:

Originally Posted by godfrey

How did you measure? The datasheet does allow for 50mA at 230V.

It doesn't "allow" for 50mA!

50mA has to be forced, with an inductive load (usually) and the VCE0 measured. Has to be done with a short pulse or one dead transistor - see SOA curve.

AndrewT · 1st January 2012, 11:26 AM

Vce0 is the CE voltage with 0 (zero) current.

Surely all we need is a very high voltage supply and a high value resistor in series.

But, who likes playing around with ~300Vdc to 400Vdc for a test jig?
Would a pair of 39k 600mW resistors do the job @ 400Vdc?
When the current rises to or above ~2mA, then you have passed the Vce0

cliffforrest · 1st January 2012, 12:23 PM

No, the "0" refers to what the base is doing, in this case open.

This breakdown test at a high current ("normal" reverse breakdown is usually at 10uA forced) is a special case for power transistors more accurately known as VCE(sus), the sustaining voltage.

This happens with an inductive load when the device is turned off (base open or reversed biased). The collector will fly up and break down the CE and the inductance will sustain whatever current was in the collector at switch off.

A bit off topic this, but VCE0 at realistic currents is not easy (or safe!) to do without special testers. It requires short pulses with low duty cycle to limit the power dissipation

look at the first test parameter and note the warning!

cliffforrest · 1st January 2012, 12:24 PM

sample datasheet

godfrey · 1st January 2012, 12:35 PM

Thanks for the explanations Cliff. The reason I asked is that maybe the transistors are good, but the OP's testing was wrong.

30th December 2011, 05:08 PM	#1
diy didi diyAudio Member Join Date: Sep 2009 Location: Pretoria	Pissed!! Fake 2SC5200 today! Bought some fakes today! They even say Toshiba on them! Measured?compared to some known good ones. Yikes!!!! Vceo should be 230V and up. These bastards measured a mere 130V!!! How do I tell the shop that sold them to me they're no good? I don't usually buy them locally, but took a chance cos they had 'Toshiba' on them. Are there ant tell-tale signs of knowing when Transistors such as these are fake???

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30th December 2011, 05:25 PM	#2
madtecchy diyAudio Member Join Date: Dec 2010 Location: wigan	Hi. "How do i tell the shop that sold them to me they are no good" I guess much the same as when you asked the shop for them. Just change sentence to .. These transistors are no good and are fakes and if you dont give me my money back im going to tell the diyaudio forum the name of your shop..

30th December 2011, 05:30 PM	#4
madtecchy diyAudio Member Join Date: Dec 2010 Location: wigan	I wouldnt be so sure about RS components i was supplied six fake lm3886 from there nuneaton trade counter. They where the uninsulated version..

1st January 2012, 11:26 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Vce0 is the CE voltage with 0 (zero) current. Surely all we need is a very high voltage supply and a high value resistor in series. But, who likes playing around with ~300Vdc to 400Vdc for a test jig? Would a pair of 39k 600mW resistors do the job @ 400Vdc? When the current rises to or above ~2mA, then you have passed the Vce0

1st January 2012, 12:23 PM	#8
cliffforrest diyAudio Member Join Date: Sep 2004 Location: UK	No, the "0" refers to what the base is doing, in this case open. This breakdown test at a high current ("normal" reverse breakdown is usually at 10uA forced) is a special case for power transistors more accurately known as VCE(sus), the sustaining voltage. This happens with an inductive load when the device is turned off (base open or reversed biased). The collector will fly up and break down the CE and the inductance will sustain whatever current was in the collector at switch off. A bit off topic this, but VCE0 at realistic currents is not easy (or safe!) to do without special testers. It requires short pulses with low duty cycle to limit the power dissipation look at the first test parameter and note the warning!

1st January 2012, 12:24 PM	#9
cliffforrest diyAudio Member Join Date: Sep 2004 Location: UK	sample datasheet

1st January 2012, 12:35 PM	#10
godfrey diyAudio Member Join Date: Nov 2009 Location: Cape Town	Thanks for the explanations Cliff. The reason I asked is that maybe the transistors are good, but the OP's testing was wrong.