Jump to content
kevin gilmore

and now for something completely different part 3

Recommended Posts

2SK170 and 2SJ74 are the singles for those. And there are the Linear Systems versions (LSK389 and LSJ109 or variants).

Of course the majority of the original Toshiba parts on ebay, aliexpress and even some suppliers (dalbani and their ilk) are fakes.

  • Like 1

Share this post


Link to post
Share on other sites

The 2sk389/2sj109 have unusual packages so the chances of fakes are probably quite low. For TO-220 its a different story. In the uk  on ebay I have had fake 2sa1486 from littlediode, fake 2sa1968 from nikko, fake 2SJ79  from littlediode_components (same seller as littlediode). I strongly recommend if you are going to spend money on original Japanese transistors you buy both a dca75 transistor identifier and a DUOYI DY294 transistor breakdown voltage tester.  If you put a fake into a circuit the consequences can be catastrophic and cause considerable damage not to mention a danger to your life. For example the fake 2SA1486 had around 200 volts LESS breakdown voltage then they should have had and the 2sj79 did not even have the correct pin out and would fail as a dead short at almost any voltage if wired up as 2sj79.... The other problem is that ebay only give you a few months to return purchases. I did not get the DUOYI DY294  tester until about 9 months after I purchased the transistors (I simply did not realise fakes where a thing. I purchased the dca first and it identified the 2sj79 pintout as not consistent with the spec sheet... I thought the dca75 was miss identifying. Later I got the DY294  after reading about fakes on the T2 build pages and found the dca75 was correct) . Although I contacted ebay explaining that the seller was selling fraudulent components AND presenting a clear safety risk ebay said they could do nothing....  I contacted paypal.. again they refused to do anything and the sellers are still selling the same fake parts. So now I test everything. Luckily I did not lose a lot of money but I don't want to think about what would have happened if I had built an original blue hawaii with those components....  The dca75 is also useful for troubleshooting if you have a component failure. I had a 10m90s die on a golden reference HV board which caused a chain of destruction in my blue hawaii. The dcs75 was very useful for quickly identifying bad transistors. The hawaii was back up and running the next day.  Although the dca75 is not designed for in circuit testing, if you have one channel fail or you are super paranoid after completing a new build you can always compare test results with the other channel. (its not totally foolproof compared to desoldering the components and testing out of circuit) but it can save a lot of time. Obviously you don't want to use the DY294  in circuit because injecting high voltages into a circuit is not a good idea.

One word of caution, the dca75 cant be used to breakdown test depletion mostfets since by their nature they are conducting by default and so register as having a very low breakdown voltage. The DY294 can also be used to match and test high voltage zeners which can be useful. The sockets on the DY294 are not that great, but its trivial to replace them with colour coded leads with test clips on the ends, this also allows you to test smd parts using sot23 adaptors etc. 

Edited by jamesmking

Share this post


Link to post
Share on other sites

The transistors I got performed up to spec and looked similar to known genuine parts. Even the legs had slight discoloration characteristic to old electronics. 

Share this post


Link to post
Share on other sites

^Is that the guy who is selling some on diya as well? I think it is, and I would bet that those are genuine.

Share this post


Link to post
Share on other sites

I bought some 2SJ109BL from a guy named Gary at DIYAudio. Something expensive. Once at home checked and everything was perfect according to the readings he had made and Toshiba's specifications.

Luck? Maybe .... but if you don't want to play Russian roulette, better the Linear Sis 2SC174 / 2SJ74.

 

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...