[jdkJake]

Hello all, 
 
Having no reference for what a "real" set of Toshiba 2SC2238/2SA968 parts look like, I am hoping one of our more experienced members who may have actually worked with the part can lend an opinion.
 
I have two sets I recently obtained, the first, from RF Parts with no source identification are seen below:
 
 

 
 
The second set, from MCM electronics (source identified as Bag and Tag Japan) are seen below:
 

 
 
Any ideas if these might be the real deal or just another set of counterfeit parts?
 
Thanks in advance!

 

[KWS]

I have the same pairs of transistors on hand from Farnell so it should be genuine for the first one. 

 

[tomb]

Bag and tag from Japan doesn't mean much - I've had Korean and Indian in those bags.  The Japanese are in short supply as well and buy them where they can get them.

 
I was going to say that I haven't seen green in these particular transistor sets, so I'd vote for the bottom grouping as being genuine.  That said, Toshiba definitely used green, but it was usually in conjunction with lower ouput versions of the same transistors ("O" vs. "Y" type, for instance).
 
It helps to see the backs, too.  Toshiba was much more quality-conscious with the plastic/metal interface.  Many of the Chinese, Korean, and Indian transistors have some pretty messy backs where the plastic is smudged over, etc. - another reason the bottom group look more genuine to me.
 
I've also never seen the 2SC2238 with the straight "T", but they are known to be genuine that way with the 2SA968's.  Also, the round indentation with letters and numbers are known to be used on the genuine 2SA968's.
 
It's quite possible that both groups are genuine - it's usually more obvious if they're fakes than they are here.  Anyway, that's about the extent of my experience with them.  MCM is easily your best chance of getting the real thing, too.  

 

[jdkJake]

Quote:

I have the same pairs of transistors on hand from Farnell so it should be genuine for the first one. 

That is a good point of reference. Thanks!

 

[jdkJake]

Quote:

Bag and tag from Japan doesn't mean much - I've had Korean and Indian in those bags.  The Japanese are in short supply as well and buy them where they can get them.

 
I was going to say that I haven't seen green in these particular transistor sets, so I'd vote for the bottom grouping as being genuine.  That said, Toshiba definitely used green, but it was usually in conjunction with lower ouput versions of the same transistors ("O" vs. "Y" type, for instance).
 
It helps to see the backs, too.  Toshiba was much more quality-conscious with the plastic/metal interface.  Many of the Chinese, Korean, and Indian transistors have some pretty messy backs where the plastic is smudged over, etc. - another reason the bottom group look more genuine to me.
 
I've also never seen the 2SC2238 with the straight "T", but they are known to be genuine that way with the 2SA968's.  Also, the round indentation with letters and numbers are known to be used on the genuine 2SA968's.
 
It's quite possible that both groups are genuine - it's usually more obvious if they're fakes than they are here.  Anyway, that's about the extent of my experience with them.  MCM is easily your best chance of getting the real thing, too.  

Thanks Tom, I really appreciate your opinion.
 
Here is a shot of the backs for the first set, as you can see, they look pretty good as well, if not even better than the second set.
 

 
I guess this comes with the territory of obsolete parts. It is a shame there is so many counterfeit parts out there.
 
I suppose I will have to bite the bullet and either build a test rig or an amp and try them both out. One thing for sure, I have learned a heck of a lot about BJT's over the past few months, so, at least something very positive has been gained from the exercise. 

 

[tomb]

No, seeing those backs in your new photo leads me to belive that you have genuine Toshiba's.  To be honest, the fakes are more obvious than that.  I still think the green ones are probably a reduced HFE output version, though. 

 

[jdkJake]

Quote:

No, seeing those backs in your new photo leads me to belive that you have genuine Toshiba's.  To be honest, the fakes are more obvious than that.  I still think the green ones are probably a reduced HFE output version, though. 

Okay, thanks again Tom, I really appreciate your feedback.
 
I will measure the HFE this weekend (abet, with my multimeter and not in circuit) and let you know.
 

 

[qusp]

look legit to me, I agree with Tomb, as good as counterfeiters are getting, its often more obvious than what you have hear and I would think that the green is a good sign, because why would you specifically designate something as the lower HFE part if you were making copies for profit and didnt want to stick out from the crowd. most likely just different production. I wonder how long it will be before we start seeing fake Lovoltech LU1014D 

 

[cobaltmute]

Quote:

No, seeing those backs in your new photo leads me to belive that you have genuine Toshiba's.  To be honest, the fakes are more obvious than that.  I still think the green ones are probably a reduced HFE output version, though. 

I'd guess the green one is the Y grade (as it is marked) and that is high hFE of 120-240 as the datasheet says.

 

[wink]

The Toshibas from Japan have a block type of T. The ones from other parts of asia have the straight T as in your examples.
 
When I was building my Jaycar headphone amp, I got both types from WES Components here in Sydney Australia.
I checked them and the gain of the straight T version were abyssmal.
I ended up getting the Japanese ones and each one was up to spec.
 
The moral here is that genuine Toshibas or not - where they are manufactured makes a difference.

 

[wink]

 
Examples of Toshiba Japan logos on transistors. These are up to spec. The others with the straight T are asian junk...
 
 
 

 

 

 

[tomb]

Sorry, no.  The straight "T" is known to have been used on some Japanese Toshiba transistors, especially the pair in question in this thread.  The counterfeits often try to use the more elaborate slant "T."  I've seen counterfeits where the slant "T" was actually molded into the plastic, but they were still fake.  Some pairs, like the 2SC3422/2SA1359 and 2SC3421/2SA1358 (and perhaps other completely plastic ones such as those in your pics) never use anything but the slant "T," but their TO-220's are different.

 

[jdkJake]

This thread is starting to get very interesting.

Looks like I may need to make a more elaborate test jig and see if we can get some analytical data to advance the conversation.

 

[tomb]

Quote:

This thread is starting to get very interesting.

Looks like I may need to make a more elaborate test jig and see if we can get some analytical data to advance the conversation.

Actually, it's why I quit selling them.  All it takes is one person's opinion to spread doubt.  Take your case - you buy from a reputable dealer who supplies source packaging from Japan and yet now - the situation is "very interesting."  I think you'll find that testing for HFE may be inconclusive.  Counterfeits often have sufficient specs in HFE - perhaps better.  In any event, the 2SC2238/2SA968 is not worth this kind of trouble, IMHO.

 

 

[jdkJake]

I hear you Tom. It does seem fairly silly for what should be a simple set of transistors. 
 
I think doubt is always going to be a problem with obsolete parts, regardless of the number of counterfeits out there. My over-whelming instinct is to just use a current production part and be done with it.
 
BTW, this being Head-Fi and all, I fully expected a full range of contradictory opinions.