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Old 3rd July 2007, 12:06 AM   #1
pooge is offline pooge  United States
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Default Authentic Toshibas?

Does anyone know of any available pictures of authentic Toshiba transistors to get an idea if purchased transistors are legit?

Just purchased a batch of 2SA970BLs, among others, and the hfe of some of them were under spec (~230s, when they should have been over 350.

Some were to spec, though, and they appeared different. The ones to spec had a grey ink labeling, whereas the ones not to spec appeared to be laser marked. The good ones had a different sized package, too. From the top, they completed more of a circle before the flat than the bad ones. The bad ones also had a letter of various letters of the alphabet in a small round flat on the opposite side of the main flat, where the good ones had a plain round flat with no letter.

The different packages made me wonder if they are authentic. It's possible Toshiba changed the packaging when they went no lead, but I can't get anyone from Toshiba to give me an answer on that. It's also possible that they mislabled a batch. However, a changed package and not to spec makes me wonder.
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Old 3rd July 2007, 01:23 AM   #2
AKSA is offline AKSA  Australia
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Don't be fooled by high beta. Sometimes they are the inferior devices; recently I bought a whole batch of 5401s made in Korea, and they are less robust and yet higher beta.

Hugh
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Old 3rd July 2007, 02:22 AM   #3
sam9 is offline sam9  United States
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The fake power BJTs I bought a couple of years ago had glossier pins and case than the real thing. Also the makings on the real Toshibas were hard to read except in really bright light while the fakes had much more legible markings. Overall the fakes "looked" more "genuine" than the real thing -- went up insmoke when power applied. Strange but true.
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Old 3rd July 2007, 02:42 AM   #4
sandyK is offline sandyK  Australia
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Default Authentic Toshibas

Considering that you can buy 2SA970s from as low as U.S. 10C
each from suppliers such as Futurlec, it may not be worthwhile for forgers to make them. There is much more money to be made selling counterfeit Toshiba power transistors etc.
How accurate is the transistor tester, and is it being used with the same base current etc. as Toshiba tests their devices?
HFE readings will vary dramatically with different makes of DVM, where Transistor Test is added more as a marketing ploy.
Best results are obtained with a dedicated transistor tester fitted with a digital panel meter. An ordinary moving coil meter, for example, has trouble giving a close reading , and sometimes may be useless with devices like MPSA18 , where the HFE often goes as high as 1,200

SandyK
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Old 3rd July 2007, 07:15 AM   #5
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The genuine toshiba devices like you say "complete more of a circle" before the flat front, they are also larger width wise (around 5mm) than the american TO-92's which seem to conisistently use a smaller case size with more of a half circle rear profile, I have been sold in the past numerous questionable to-92s, I recall reading somewhere that the counterfeitting of these small devices are more rampant than power devices, most unfortunately unfortunate in all cases.


Colin
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Old 3rd July 2007, 08:55 AM   #6
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Here you go, the one on the right is the Indian Bentley "Continental" so to speak
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Old 3rd July 2007, 09:08 AM   #7
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If you are serious in audio best is to buy a great many and stick 'm on a piece of paper, write the hFE numbers next to them.
You can then just pick the matching/desired items.
Only issue is that every time you buy a new batch you add another piece of paper with Q's untill you end up with an encyclopedia, unless you fancy transistor puzzles.
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Old 3rd July 2007, 09:13 AM   #8
sandyK is offline sandyK  Australia
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Default Authentic Toshibas

Jeez, that looks familiar !

SandyK
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Old 3rd July 2007, 12:09 PM   #9
pooge is offline pooge  United States
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Quote:
Originally posted by jacco vermeulen
Here you go, the one on the right is the Indian Bentley "Continental" so to speak

Thanks for the pic. My good spec ones do look like that. The printing and fonts are the same. I didn't manage to get a response from a nameless person in Toshiba support that actually had some value. The explanation of the code "7C" means made in March of 2007. STILL couldn't get any answer about whether or not they changed their packaging and printing recently. I was informed after a half dozen email exchanges that if I didn't buy them from Toshiba or an authorized Toshiba distributor, that they couldn't guarantee that they were authentic. I'm starting to wonder if tech support people are actually skilled and trained to dodge questions rather than being just plain stupid. I just can't get them to state whether or not they have made this other package or not, or refer me to someone who actually knows.
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Old 3rd July 2007, 12:13 PM   #10
pooge is offline pooge  United States
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Quote:
Originally posted by AKSA
Don't be fooled by high beta. Sometimes they are the inferior devices; recently I bought a whole batch of 5401s made in Korea, and they are less robust and yet higher beta.

Hugh

I know high beta does not mean that they are authentic. But a low beta means they do not meet spec. Granted, I only prescreened them with a DMM hfe tester. I don't argue that they are really accurate, but all of the devices measured in the proper spec range except for the odd looking packages.
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