Over 12 years ago, I purch'd, brand new, what I think are genuine (made in Japan) Toshiba To-92 transistors including :
SC2240
A970
K170
Pretty sure these are from Newark, and some from Futurlec, both in the United States.
The Newark plastic baggie has a printed tag that notes: Japan and Toshiba. I'm pretty sure these are genuine. But any way be absolute sure that these are "genuine"?
I do have the ability to test them, as shown.
SC2240
A970
K170
Pretty sure these are from Newark, and some from Futurlec, both in the United States.
The Newark plastic baggie has a printed tag that notes: Japan and Toshiba. I'm pretty sure these are genuine. But any way be absolute sure that these are "genuine"?
I do have the ability to test them, as shown.
Check if the measured specs are according to the original datasheets if you can get those. 'Updated' datasheets can be changed, pinning as a starter. Make a simple testboard amp circuit on realistic settings/values and measure the dc/ac results (stability, beta, bode plot sweep). Just to be sure what in your bag&tag.
Those old Toshiba datasheets are still on line. And I saved them on my HDD decades ago, in any case.
Measurements aside, is these some special SUBJECTIVE sonic attributes to vintage Japanese solid-state parts -- like Nelson Pass and others have claimed in the past?
BTW: I also have plenty of new-old-stock Zetex solid-states in my bin. I think this manuf was also suggested by some as superior to typical Fairchild, National, Linear or TI.
Measurements aside, is these some special SUBJECTIVE sonic attributes to vintage Japanese solid-state parts -- like Nelson Pass and others have claimed in the past?
BTW: I also have plenty of new-old-stock Zetex solid-states in my bin. I think this manuf was also suggested by some as superior to typical Fairchild, National, Linear or TI.
The best evidence of being ”genuine” is the fact that you can track them back to regular distribution channels. If they had been just thrown in a bin and randomly mixed with who-knows-what, you would have to test them against a known good unit and compare.
Can anyone comment on the honesty/reliability of US-based Futurlec as parts source? They've been around for quite a while. Some of my parts were sourced thru them?
https://www.futurlec.com/
Their website uses old OEM Toshiba data-sheets for info. Not sure their parts are OEM. That said, the parts I ordered from them 15 years ago, such as Toshiba k117, are still listed, but out-of-stock. This might be a good sign as they are -- for the sake of inventory -- NOT stocking readily-avail Chinese version.
https://www.futurlec.com/
Their website uses old OEM Toshiba data-sheets for info. Not sure their parts are OEM. That said, the parts I ordered from them 15 years ago, such as Toshiba k117, are still listed, but out-of-stock. This might be a good sign as they are -- for the sake of inventory -- NOT stocking readily-avail Chinese version.
Are they? https://www.futurlec.com/AboutUs.shtml
"We are centrally located near our suppliers in the Asian region,"
Futurlec Offices
(For Mail Orders only, No Stock is Kept at These Offices)
US and North America: ... New York, NY 10010 USA
UK and Europe: ... London, EC1V 4PY UK
There is sure no stock at the NYC office: that's a very expensive address without good shipping facilities.
The main server may be in Australia? (Hard to know these days.) A tracert from Maine USA finally stalls at 203.208.168.250 which seems to be Singapore. Of course many web-operators park their box elsewhere for a better deal (mine was in France) or legal reasons.
For the 2sk170/2sj74, there are some features to check for genuine.
The appearance of the font of the designation can also be used for determination. This topic has been discussed many times in the forum.
The appearance of the font of the designation can also be used for determination. This topic has been discussed many times in the forum.
Your feedback is useful. Please see my USB microscope images of some of my inventory, and comment accordingly.
Not sure about 2240 and 970, but the K170 appears genuine.
About "This topic has been discussed many times in the forum." When making a remark such as this, be sure to provide supporting URLs and forum links to the posts/threads you may be referring to. Usually, when creating a new thread, the forum engine will suggest similar topical threads that my help in reducing duplicate topics. But that feature is often not very effective.
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For 2sk170 and 2sj74:
The vertical line from the seven "7" should be curved, not straight.
The one "1" consists only of a vertical line, without a small line at the top.
see here:
https://www.diyaudio.com/community/...e-pacific-gets-overloaded.394049/post-7228706
https://www.diyaudio.com/community/threads/replacement-for-toshiba-2sk170-2sj74.317563/post-6752273
The vertical line from the seven "7" should be curved, not straight.
The one "1" consists only of a vertical line, without a small line at the top.
see here:
https://www.diyaudio.com/community/...e-pacific-gets-overloaded.394049/post-7228706
https://www.diyaudio.com/community/threads/replacement-for-toshiba-2sk170-2sj74.317563/post-6752273
The characteristics described for the "1" and "7" only apply to 2sk170 and 2sj74, I am not aware of any features for the others.
I have some genuine 2SC2240's pulled from Adcom amps, and they look close to your pictures, but they don't have the "G" embossed on the back.
What is the typical difference in performance between the (original Toshiba) japanese and 'later' malaysian jfets?
FWIW, samples from my stock purchased over the years from various (trusted) suppliers, showing both the older / printed and the newer / etched markings. Note also that the genuine Toshiba packages have a very clean finish, while the fakes are usually rough with burrs along the seams, etc.
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Malaysia was only package and test, not the wafer fab, so no need for any functional change
If you refer to the picture named K170_Original.jpg, those are all genuine, "showing both the older / printed and the newer / etched markings."
Package and test is frequently outsourced to third parties. They will look different, but should test the same.
This means comparing photos can be pointless
This means comparing photos can be pointless