On the left of the image are original 22 year-old Toshibas . On the right are the transistors I bought today. The case, the metal parts and the laser engraving on the case all seem to be professionally made, looking real good (not like many fakes). I think they are probably original Toshibas made more recently. But they look different from the 22 year old ones on the left (maybe no surprise). Any of you seen original Toshiba power transistors made more recently? Are those on the right original Toshibas?
Doubtful...the new Toshiba use their 'T' logo.
Better post the back photos, also tell tab thickness.
Sometimes the tab is plated, sometimes it is punched from plated sheet, the copper shows at the tab edge.
And the tab punching pattern is also characteristic.
Telling more could make fakers improve their act...
Better post the back photos, also tell tab thickness.
Sometimes the tab is plated, sometimes it is punched from plated sheet, the copper shows at the tab edge.
And the tab punching pattern is also characteristic.
Telling more could make fakers improve their act...
Tab thickness is like the original. hFE @10uA base current is 99 for the NPN and 137 for the PNP. B-E and B-C opening voltages are appropriate for a 100W power BJT, these are surely not small signal transistors.
The vendor I bought them from almost always sold me original OnSemi amnd STM transistors, but a very few times I got fakes. Never bought Toshiba transistors so far, so I don't know how they should look like.
This costed about 2 USD / piece. I just bought 1 NPN and 1 PNP to try. I would need more, but I'm afraid to buy before I'm sure they genuine.
See 2 more photos.
The vendor I bought them from almost always sold me original OnSemi amnd STM transistors, but a very few times I got fakes. Never bought Toshiba transistors so far, so I don't know how they should look like.
This costed about 2 USD / piece. I just bought 1 NPN and 1 PNP to try. I would need more, but I'm afraid to buy before I'm sure they genuine.
See 2 more photos.
Another 3 images. The back is perfectly even where the plastic-metal joins. There is this pale, "hazy" substance layer on the metal surfaces which can be easily scraped off, I have seen this on many original OnSemi power transistors as well.
The writing, "Toshiba" and "C5198" on the NPN transistor is in bigger letters than "Toshiba" and "A1941" on the PNP transistor. This is suspicious,
Please note that the writing is different also on the original ones: that being two different production lines is plausible and a good sign instead. IMHO 😉
Probably a counterfeiter would make the writings perfectly the same.
If I were an expert I would tell you to carry out related measurements too, but I'm not an expert...
Probably a counterfeiter would make the writings perfectly the same.
If I were an expert I would tell you to carry out related measurements too, but I'm not an expert...
I have exactly same C5198 A1941 (which you bought today). These are quite cheap in india & of good quality, made in china. I have few same type c5200/a1943 too but their authenticity is still a mystery (licensed made i guess).
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Running your parts through a curve tracer would answer the question if they are fakes or the real thing. Let me know if you want me to test your parts.
Nano Farad, the Toshiba marking on the right side photo was made by repeated passes with a laser, so definitely made in a small workshop...
The problem now is that these lasers have become so cheap, and can be driven with a CAD program...
I had to put an IS logo on a mold, the client sent his logo with other details, I took it to a graphic designer.
He scanned it, cleaned up the stray pixels, saved the Corel file, then made a copy in AutoCad (.dxf format).
Corel Draw has that function in the 'save as' menu, you can choose the format you need.
And there are other programs, maybe from Adobe, Dassault Systems, Siemens and others too, which allow these functions.
That file was given to a CNC shop, and the result was good.
Making fake markings is that simple now...
IS means Indian Standard, it is a series, the administrative body is the Bureau of Indian Standards.
The problem now is that these lasers have become so cheap, and can be driven with a CAD program...
I had to put an IS logo on a mold, the client sent his logo with other details, I took it to a graphic designer.
He scanned it, cleaned up the stray pixels, saved the Corel file, then made a copy in AutoCad (.dxf format).
Corel Draw has that function in the 'save as' menu, you can choose the format you need.
And there are other programs, maybe from Adobe, Dassault Systems, Siemens and others too, which allow these functions.
That file was given to a CNC shop, and the result was good.
Making fake markings is that simple now...
IS means Indian Standard, it is a series, the administrative body is the Bureau of Indian Standards.
I have found this Indonesian advertiser who sells the same looking transistors. The writing on the packaging box says "Diffused in Japan, Assembled in China".
https://www.bukalapak.com/p/elektro...shiba-2sa1941-2sc5198?from=list-product&pos=0
So now I think they are not original (but maybe of acceptable quality).
https://www.bukalapak.com/p/elektro...shiba-2sa1941-2sc5198?from=list-product&pos=0
So now I think they are not original (but maybe of acceptable quality).
Try finding equivalent original parts in UK (BD) or US (2N, MJ) series, you might luck out.
And if your amp is running at or below 80% volts, take a chance, they should work.
And see the sites of Chinese makers, they may be making the parts, using similar numbers (like D2030 for TDA2030 copy).
Put '5198 transistor' as search term and see what results you get.
And if your amp is running at or below 80% volts, take a chance, they should work.
And see the sites of Chinese makers, they may be making the parts, using similar numbers (like D2030 for TDA2030 copy).
Put '5198 transistor' as search term and see what results you get.
As i said before these are of good quality. I purchased those from local authorised dealer (US$1/pair). I also have genuine toshiba but their price is very high compared to these.
I guess they are the A1941 and C5198 made by CDIL in India, and someone put a Toshiba label on them to make them more "valuable".
You have a point but their price is quite similar here (CDIL made vs Toshiba marked TRs in question). Genuine CDIL c5200/a1943 costs around US$2/pair (less if you buy in quantity) which is next to nothing for such 150w transistors.
"Are these original Toshiba power transistors?"
The following thread is very informative and I actually agree with those who say that the only (destructive) way to answer your question is to open them (at least I would do this for me).
https://www.diyaudio.com/community/threads/how-to-identify-fake-transistors.297370/
However it's not clear to me if you are willing to accept a different quality from the original, or if you want the original anyway (assumed it was possible).
Please note that on an external forum a poster recommended these ones (no interest with that distributor), but I don't even have any idea whether they are really original or not
https://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2sa1941 $2.88
https://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2sc5198 $3.56
Also I agree that if a transistor is discontinued then you most probably have fake ones and in any case you should only buy from authorized dealers and/or look for equivalents, but about this argument everything seems very nuanced, as a matter of fact a reputed dealer as Mouser (no interest with it) has the immediate availability of the 2SA1941 (2,27 €), but not of the 2SC5198. 🙄
https://eu.mouser.com/ProductDetail/Toshiba/2SA1941-OQ?qs=s6nfgz3miVwN9gIQs%2By%2BCw==
The following thread is very informative and I actually agree with those who say that the only (destructive) way to answer your question is to open them (at least I would do this for me).
https://www.diyaudio.com/community/threads/how-to-identify-fake-transistors.297370/
However it's not clear to me if you are willing to accept a different quality from the original, or if you want the original anyway (assumed it was possible).
Please note that on an external forum a poster recommended these ones (no interest with that distributor), but I don't even have any idea whether they are really original or not
https://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2sa1941 $2.88
https://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2sc5198 $3.56
Also I agree that if a transistor is discontinued then you most probably have fake ones and in any case you should only buy from authorized dealers and/or look for equivalents, but about this argument everything seems very nuanced, as a matter of fact a reputed dealer as Mouser (no interest with it) has the immediate availability of the 2SA1941 (2,27 €), but not of the 2SC5198. 🙄
https://eu.mouser.com/ProductDetail/Toshiba/2SA1941-OQ?qs=s6nfgz3miVwN9gIQs%2By%2BCw==
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Bigger die tells nothing about authenticity, curve tracer is the best option. Anyway i can assure that those transistors will work reliably for a 50wRMS amplifier with good performance.
No doubt at all about your word, but please note that I further meant to compare the 2 ones seeing inside them side by side, original vs. suspected fake (only then I personally would be satisfied).
The fact remains that the OP asked if they are original, so I take on that he want just original. 🙂
We still don't know if it will be satisfied with a different thing.
Just out of curiosity, how much a curve tracer?
The fact remains that the OP asked if they are original, so I take on that he want just original. 🙂
We still don't know if it will be satisfied with a different thing.
Just out of curiosity, how much a curve tracer?
Even in used condition, a curve tracer for real power semis costs an awful lot - you would need to be a pro. repairer or researcher to justify even a used instrument that was fully capable of testing power transistors. 'Nothing much under $10k there. e.g. https://www.ebay.com.au/sch/i.html?...1313&_nkw=semiconductor+curve+tracer&_sacat=0
Otherwise, I would not assume that all Toshiba semiconductor product comes from Japan or from the same fab and assembly line as all others of a similar type. Toshiba has operated extensive manufacturing facilities in China too and the semis produced there may have distinctly different style and techniques for their markings which have evolved from inks and foil marks to lasers of several types, over the lifetime of their popular audio power transistors - going back decades now. For some years, their production has been distinguished with marks like JPN and CHN or a different suffix like "N" added to the part number but I'm unsure what practices are obsolete now. We see semis labelled "JAPAN" too but that should not be interpreted as meaning it's last manufacturing operation was in Japan.
As a footnote , the Dalian (China) plant was scheduled to close after 30 years operation and is by now, probably be resited elsewhere in SE Asia.
Otherwise, I would not assume that all Toshiba semiconductor product comes from Japan or from the same fab and assembly line as all others of a similar type. Toshiba has operated extensive manufacturing facilities in China too and the semis produced there may have distinctly different style and techniques for their markings which have evolved from inks and foil marks to lasers of several types, over the lifetime of their popular audio power transistors - going back decades now. For some years, their production has been distinguished with marks like JPN and CHN or a different suffix like "N" added to the part number but I'm unsure what practices are obsolete now. We see semis labelled "JAPAN" too but that should not be interpreted as meaning it's last manufacturing operation was in Japan.
As a footnote , the Dalian (China) plant was scheduled to close after 30 years operation and is by now, probably be resited elsewhere in SE Asia.
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