2SC2705 / 2SA1145 obsolete? - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th July 2004, 11:43 AM   #1
OliverD is offline OliverD  Germany
diyAudio Member
 
OliverD's Avatar
 
Join Date: Nov 2002
Location: Germany
Default 2SC2705 / 2SA1145 obsolete?

Hi,

does anybody have reliable information whether these parts are obsolete? I used them in many projects, but recently I'm always shipped "second source" transistors (which I'm not happy with).

Do you know a source where I can buy those genuine Toshiba devices for a reasonable price?
  Reply With Quote
Old 25th July 2004, 10:15 PM   #2
diyAudio Member
 
StevenOH's Avatar
 
Join Date: Jun 2004
Location: USA
Oliver,
Apparently, these transistors are alive and well, since they are still recommended on Toshiba site:

http://www.semicon.toshiba.co.jp/eng...poweramps.html

You may want to check several German sites for stock:

http://www.lobtron.de

http://www.ersatzteile-onlineshop.de...ansistoren.asp

http://www.gmkelektronik.de/index.ht...ren_2sc....htm

I don't have any experience with these distributors, and it will be interesting to read any comments from those, who does.

Steven
  Reply With Quote
Old 26th July 2004, 05:17 PM   #3
OliverD is offline OliverD  Germany
diyAudio Member
 
OliverD's Avatar
 
Join Date: Nov 2002
Location: Germany
Thank you very much, Steven.

Indeed they are still recommended in many Toshiba PDFs, and also the datasheet is still downloadable. However, they silently dissappeared from the browsable product tree, which might be an end-of-life indication (The same happened to our beloved 2SK389).

The official distributor of Toshiba discrete semiconductors in Germany (as listed on the Toshiba site) is ebv, and they don't list this part (minimum order quantity would be 3000 pieces anyway).

The shops I usually order my parts from (thanks for you additional links) all stock a 2SA1145, but you never know whether you get genuine parts. Sometimes yes, sometimes no...

There are those "original spare parts" shops, but prices are from the moon...

Seems like a never ending story...
  Reply With Quote
Old 26th July 2004, 11:10 PM   #4
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
A lot of the parts that we like, Toshiba has made "special order", with a 3000 piece minimum. They are still available, but getting a distributor to work with you may be a problem. They are shrinking their distributor list.

Jocko
  Reply With Quote
Old 27th July 2004, 12:35 AM   #5
OliverD is offline OliverD  Germany
diyAudio Member
 
OliverD's Avatar
 
Join Date: Nov 2002
Location: Germany
Thanks Jocko.

So I'll just continue randomly ordering parts from different distributors, hoping I get the right ones. A good indication is when the distributor lets you select the hfe colour code.
  Reply With Quote
Old 27th July 2004, 03:41 AM   #6
Banned
 
Join Date: Feb 2002
Location: As far from the NOSsers as possible
Don't think that I have any to offer you. Believe that I am running out, and since I am not building amps these days, I do not plan to get any.

But if that changes, I'll let you know.

Jocko
  Reply With Quote
Old 27th July 2004, 09:27 AM   #7
moamps is offline moamps  Croatia
diyAudio Member
 
Join Date: Oct 2002
Location: Croatia
A1370/C3467 pair is good replacement IMO.

Regards
Milan
  Reply With Quote
Old 28th July 2004, 04:28 PM   #8
diyAudio Member
 
StevenOH's Avatar
 
Join Date: Jun 2004
Location: USA
Oliver,

Can you explain what do you call genuine parts and "not genuine".
What "indicators" do you use to tell the difference?

Steven
  Reply With Quote
Old 28th July 2004, 10:50 PM   #9
OliverD is offline OliverD  Germany
diyAudio Member
 
OliverD's Avatar
 
Join Date: Nov 2002
Location: Germany
I categorize transistors in these groups:

1. Parts actually made in a plant of the original manufacturer, conforming to the official datasheet (where "original manufacturer" is the company which first used a particular part number like 2SA1302). These I call genuine.

2. Sometimes after a manufacturer announces the end of life of a semiconductor, they transfer the manufacturing data to a third party which continues to make the product to the original specs, mainly to support the low-volume aftermarket and customers whose designs depend on that particular part. This doesn't often happen to transistors, mostly to integrated circuits.

3. "Second source" components
Sometimes competing manufacturers name their equivalents similar to (good) or exactly like (evil) the originals (you can buy MJL1302 as a replacement for Toshiba 2SA1302 from On Semi, but I also had a 2SA1216 from Mospec when I expected to buy a Sanken part). Nothing wrong with this, as datasheets are available and you know what you get. The problem is mainly that retailers don't tell you what you get before you buy. Often they just don't realize the problem. They buy a 2SA1216 from whereever they get it cheap and the customer ends up with a bunch of parts from different manufacturers, sometimes even in different packages.

4. Counterfeits / fakes
Counterfeit transistors are cheap generic parts which are intentionally relabeled by criminals to profit from the good reputation of other manufacturers. Some even repackage a cheap die or complete TO-220 part into a bigger case. For example, counterfeits of the famous (and expensive!) Toshiba 2SA1302 or Sanken 2SA1216 have been floating around for some time. Probably even the distributor doesn't know he sells bogus parts.

Here are some pictures.

How to tell the difference?

You will only know when it's already too late.

Second source parts are easy to recognize because you'll see a Mospec logo instead of the SK marking on Sanken parts.

For the other cases, when you look at them and know what genuine parts look like, you will most likely recognize fakes. It's hard to describe in words, but each manufacturer has its own distinctive way of labeling, the size, position, colour, font and quality of the markings, look of the package, look of the legs, etc. etc. Fakes are getting "better" and better, though.

If the parts break when they shouldn't, or when they perform significantly worse or not at all, you likely have fakes. When they perform worse in a subtle way, you might have a lower quality "equivalent".

The best advice to avoid this problem alltogether is only buying parts from official distributors, even when you have to break a 500$ order minimum.
  Reply With Quote
Old 29th July 2004, 04:56 PM   #10
diyAudio Member
 
StevenOH's Avatar
 
Join Date: Jun 2004
Location: USA
Oliver,

Thank you for your thoughtful response. I think, this subject is always worthy to be brought up, since it relates to everybody's needs. Your experience agrees with the previous discussion on this forum and the mentioned link, and with my accumulated "wisdom".

I strive to obtain the genuine parts too, although I did not encounter the kind of problems you have mentioned. The explanation, I guess, is that I do not necessary look for mainstream parts (with a big market/demand). I do look for the best parts available (in their class) from different manufacturers from every continent, but only fitting my design philosophy. So, this approach allows me to stay unaffected (so far) by that type of "luck".

Of course, buying 10-30 transistors at a time (it is a hobby for me) force me to deal with small distributors, who serve the repair industry (in case of japanese transistors). Dealing with them I learn not to ask for "2SK170BL", for example, but rather ask them, what letter codes do they have for 2SK170 in stock. And if they "can't help me", I can't help them.

Sometimes they will list ransistor from one japanese manufacturer under the name of another japanese manufacturer, but I always see that just as a mistake.

Asking for non-mainstream parts can create new kind of problem: You ask for, let's say 2SK110, but receive instead 3SK110, simply because japanese manufacturers omit first digit in marking, and these distributors typically do not have a clue about what they are buying (and selling). In this case I simply return the wrong parts back for refund (or ask to describe the case in advance).

Steven
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SPICE models for 2SC2705 & 2SA1145 Gunders Solid State 3 20th January 2010 04:02 PM
2SC2705, 2SA1145 alive again? OliverD Parts 2 10th March 2009 03:16 PM
Installed the 2sc2705 in differential.. vynuhl.addict Solid State 0 10th December 2006 09:06 AM
2sc2705 for differential?? vynuhl.addict Solid State 2 30th November 2006 12:13 AM
2SA1145 Ic classd4sure Solid State 4 5th October 2004 08:10 PM


New To Site? Need Help?

All times are GMT. The time now is 01:47 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2