counterfiet sa1943's ??

[malloryn]

I've just received some Toshiba SA1943's from my regular supplier.
Previously these have been in a geen package with "Toshiba 2SA1943" and other text written on them.
This recent batch are all in black packages, some with the usual text but some just have "A1943" written on them.

Has anyone else received these devices like this?

Could these be counterfeit/clone devices or have toshiba changed their packaging and labeling?

I also had 2SC5200's in this order but they were the same as usual.

[richie00boy]

If they are not marked Toshiba they could be clones that are perfectly fine, or they could be sub-standard devices. However, if not marked Toshiba, I don't think you would have any real argument that they were fake as the supplier could say, "well, company X 2SA1943 is supposed to only be 34W dissipation" or somesuch other rubbish comment. If they are advertising them as Toshiba, that's a different story.

[dreamer]

I bought some counterfeit of 2sa1943/2sc5200. all marked
with toshiba logo and the outlook is nice too......however,
when I power up the amplifier and apply some test signal to it,
WoW......they brun !!! All die at once! So horrible!

after I replace those counterfeit with orginal, everything fine!

I may post the photos of them later

[Eva]

A simple way to distinguish fake devices from the originals is measuring zero-bias BE and BC capacitances

Original devices usually have higher capacitances due to higher die sizes. Each model tends to have typical capacitance values with little deviation from lot to lot

In the other hand, fake devices have lower capacitances due to smaller die sizes and each lot of fakes has different capacitance from the others due to different dies being used

Capacitance tends to be a good indicator of die size for bipolar transistors

Almost all fakes end blowing due excessive dissipation because of too small die size or too low Vce rating. Some may also oscillate when placed in an amplifier due to too low FT and excessively long switching times

[sam9]

I thought once I had some counterfeits because the went up in smoke when powered up. Turned out it was me putting them into 400kHz oscillation through a form of klutzyness I'm too embarrassed to mention.

[slowhands]

Toshiba's practice has been to package the PNP's in green epoxy, so those are probably fakes. Whether they are good parts is another issue. I don't know who else makes these, I've only seen the Toshiba catalog. Maybe Samsung??

If you can, return them for a credit. No sense risking other good parts if you are not comfortable with them.

[Eva]

I've seen clones labelled 'KSA1943' and 'KSC5200' used in some amplifiers. They are apparently made by Samsung, both NPN and PNP come in black case and appear to be reliable

[MGR]

From my experience the new Toshiba 2SA1943 is now black in Color.At first I was also curious on the change of color but I subjected the new transistors to a torture test.At +- 75 volts and a 4 ohm load with only 2 pcs. per side it passed with flying colors.The KSA14943 and KSA5200 is manufactured by Fairchild it also passed the torture test.Hope this helps.

MGR

[K-amps]

I got some 2sc 5359 (5200's elder bro) and the complement 2sa1987, both have Toshiba markings and are black.

However there are 2 kinds of 2sc5359 with slightly different fonts... I broke it up and checked the die sized were a little different.... probably fake, but is there a chance that a later batch may have slightly smaller die's?

Also the dies are slightly smaller than the 2sa1302....

Something smells right?

-K.

PS Malloryn got any pictures you can post?

[wrenchone]

Digi-Key is now offering Toshiba 1943s and 5200s, and the prices aren't too bad. If I weren't fixated on FETs, I'd try some...