My Transistors, original or copy? - Page 7 - 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 1st March 2007, 09:06 PM   #61
sbrook is offline sbrook  Canada
diyAudio Member
 
Join Date: Feb 2007
Location: Ottawa Canada
One of the other problems in the "fake" market is the manufacture of "onspec" devices. A company goes to a manufacturer and asks them to do a run of say 100,000 unlabelled NPN and specify the simplest factors like VCE HFE and Dissipation.

Then they go and label them themselves with comparable type part numbers. Sometimes they're OK in the end user app. other times they're a disaster.

One of the clues with the "nonumber" parts is a different printing for the date code and the label. But you can't rely on that either, because a lot of transistors are similar and are manufactured from the same basic dies and are then selected and labelled according to the tests.

It's like buying in the "interchange" market. There are subtle differences between similar numbers, like BC182, BC183 and BC184 (BC107, 108 and 109) transisitors, but you'll often find them all under a single interchange number which for many applications, they are, but with different VCE and HFE and gain bandwidth products, you could come unglued.
  Reply With Quote
Old 7th March 2007, 12:01 PM   #62
diyAudio Member
 
halfgaar's Avatar
 
Join Date: Mar 2005
Location: Netherlands, Groningen
Is it possible that there also are fake TO92 devices? I recently got a couple of 2sa1123 transistors, to replace a couple of noisy input-stage 2sa942 ones. I got about 8 or so in total. A few were dead on arrival, a few died after installing, and the ones that do work, have widely differing Hfe values.

These are the original and the replacement:

Click the image to open in full size.
  Reply With Quote
Old 7th March 2007, 03:19 PM   #63
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi halfgaar,
The new transistor is okay for a sub, but I would have used 2SA872 instead.

With a wide gain spread and high failure rate, I would say those are either copies or factory rejects.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 7th March 2007, 03:43 PM   #64
sbrook is offline sbrook  Canada
diyAudio Member
 
Join Date: Feb 2007
Location: Ottawa Canada
2sa1123 is manufactured by Panasonic (Matsushita) and has the standoff blips on the leads and a factory lead offset like the 2SA942 you took out. Your 2SA1123 has neither. I'd say it is a fake since it appears that it doesn't even meet the specs.

Moreover, Panasonic has superceded the A1123 with the A1123S
  Reply With Quote
Old 7th March 2007, 04:10 PM   #65
diyAudio Member
 
halfgaar's Avatar
 
Join Date: Mar 2005
Location: Netherlands, Groningen
Quote:
2sa1123 is manufactured by Panasonic (Matsushita) and has the standoff blips on the leads
What exactly are standoff blips?

Quote:
and a factory lead offset like the 2SA942 you took out
Like so?:

Click the image to open in full size.

edit: I assume the 2SA872 also has an offset middle pin?

Quote:
Moreover, Panasonic has superceded the A1123 with the A1123S
Since when is this?
  Reply With Quote
Old 7th March 2007, 04:28 PM   #66
sbrook is offline sbrook  Canada
diyAudio Member
 
Join Date: Feb 2007
Location: Ottawa Canada
Not quite ...

Look at your A942 ...

The outer two legs bend outwards and then down. That's actually done in the transistor production and not during assembly into a board. This appears to be standard on Matsushita (Panasonic) TO92 case transistors.

Then also as you come out of the bottom of the A942, the legs get fatter and then thinner again (blips). This is so that the transistor cannot seat all the way down on the board when inserted into a PCB (It "stands off" the PCB)

See here ... http://www.ortodoxism.ro/datasheets/...JC00011BED.pdf
  Reply With Quote
Old 7th March 2007, 08:40 PM   #67
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi sbrook,
Lead forming occurs when components are supplied taped. Bulk transistors are typically straight with no bends. Component insertion machines need the bends done before they ram the part into the PCB. Just because the leads are not formed does not mean they are fakes.

I use offset pliers to form the leads into that shape.

The 2SA872 matches the specs of your 2SA942 more closely.

-Chris
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 7th March 2007, 08:55 PM   #68
diyAudio Member
 
halfgaar's Avatar
 
Join Date: Mar 2005
Location: Netherlands, Groningen
Quote:
Lead forming occurs when components are supplied taped. Bulk transistors are typically straight with no bends. Component insertion machines need the bends done before they ram the part into the PCB. Just because the leads are not formed does not mean they are fakes.
What about the standoff blips?
  Reply With Quote
Old 7th March 2007, 10:19 PM   #69
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi halfgaar,
Quote:
What about the standoff blips?
That's just a crimp. Special order I suspect. It's the same thing, parts supplied on tape for automatic insertion. Bulk parts are supplied with straight leads generally.
__________________
"Just because you can, doesn't mean you should" my Wife
  Reply With Quote
Old 7th March 2007, 10:55 PM   #70
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Quote:
Originally posted by halfgaar
Is it possible that there also are fake TO92 devices? I recently got a couple of 2sa1123 transistors, to replace a couple of noisy input-stage 2sa942 ones. I got about 8 or so in total. A few were dead on arrival, a few died after installing, and the ones that do work, have widely differing Hfe values.

These are the original and the replacement:

Click the image to open in full size.
I think that TO-92 devices have by far the largest fake market, although the quality sometimes is not as deceiving as with high power devices.

If some devices were faulty on arrival, you should return all them, get your money back and try another source. According to what you tell, all seem to be fakes (unless you managed to damage them in some unexpected way).
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  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
NTE transistors-->> Backwards from original case layout!! What the heck! 777funk Solid State 1 10th May 2009 03:49 AM
Need DVD copy software! Kyte_08 The Lounge 7 16th February 2008 02:48 PM
how to backup original cd as the same sound quality as original cd ctrn Music 3 16th May 2006 05:21 PM
Copy of Kore-Eda pre ? sinski Chip Amps 2 4th May 2006 01:03 PM


New To Site? Need Help?

All times are GMT. The time now is 04:43 AM.


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