My Transistors, original or copy? - Page 39 - 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 3rd October 2011, 10:36 PM   #381
diyAudio Member
 
Join Date: Sep 2011
Location: Athens
Default MJL4281A MJL4302A - Dont think so...

Sourced those from ebay. The one that I opened burned at the first 2 minutes on the pcb.
I am sure those are not the real think. Lesson learned the hard way. Thankfully only a resistor was burned together with the fake transistor.

Click the image to open in full size.
  Reply With Quote
Old 8th October 2011, 09:14 AM   #382
jitter is offline jitter  Netherlands
diyAudio Member
 
jitter's Avatar
 
Join Date: Aug 2004
Location: Eindhoven, The Netherlands
Quote:
Originally Posted by nkalogridis View Post
Sourced those from ebay. The one that I opened burned at the first 2 minutes on the pcb.
I am sure those are not the real think. Lesson learned the hard way. Thankfully only a resistor was burned together with the fake transistor.

Click the image to open in full size.
At work I have seen thousands of the ON MJL1302/MJL3281 over the years. Without fail they have always looked like the top and bottom left transistors in your photograph right down to the font, size and position of the printing.

Normally I am careful not to judge by looks alone, but in this case I'd be fairly certain that the bottom right one is indeed a fake.

Last edited by jitter; 8th October 2011 at 09:23 AM.
  Reply With Quote
Old 8th October 2011, 02:55 PM   #383
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
Default "SC5200+2SA1943" from Toshiba with Runaway of the adjusted Idle Current Value

By the repair of the damaged pure class-A integrated amplifier Luxmann (Luxmann) L550 (L 550) I note, that the shortly ordered output devices from Toshiba (about Nedis) don't work how they actually must.
The behaviour is exact in that kind, as if I had not screwed the transistors on the heatsink (respectively as if I had used thermal isolated insulating slices - but I use mica washers).
This means, the internal chip haven't contact to the die.
I guess, I have fakes resp counterfeits, although from the typeface (kind of font) nothing is striking to see.
How I can open this kind of outline (seems to be more difficult than TO-3) ?

Are there such observations were already made?

Thank you for your comments.

Last edited by tiefbassuebertr; 8th October 2011 at 03:04 PM.
  Reply With Quote
Old 8th October 2011, 03:02 PM   #384
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
here the attachement of the transistors mentioned in my previous post. Please note: this isn't my own foto, but the kind of font is the same.
Attached Images
File Type: jpg 2SC5200_2SA1943.jpg (111.8 KB, 433 views)
  Reply With Quote
Old 8th October 2011, 08:21 PM   #385
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
What do you make out of those JFakes, eh sorry, JFets?

They measure ~6mA in majority. Got just a few to check out. Legs longer than other Tosh, x mark inside the back circle unlike other Tosh having none. Unless they packaged any outside Japan, they are highly suspicious... Is anybody having any J74s looking like those, knowing more?
Attached Images
File Type: jpg JFakes.jpg (759.9 KB, 441 views)
  Reply With Quote
Old 9th October 2011, 03:52 AM   #386
diyAudio Member
 
unclejed613's Avatar
 
Join Date: Dec 2006
Quote:
Originally Posted by tiefbassuebertr View Post
here the attachement of the transistors mentioned in my previous post. Please note: this isn't my own foto, but the kind of font is the same.
by the horizontal scratching across the face as if the case was shaved, i would say they are fakes. the font and everything else looks corerect, but the surface finish is not original.... upon further inspection the dot in the date code is too far to the left of the date code digits. it looks like * 7A when it should look like *7A
__________________
Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net
spammer trap: spammers must die

Last edited by unclejed613; 9th October 2011 at 04:09 AM.
  Reply With Quote
Old 23rd October 2011, 02:55 PM   #387
loek is offline loek  Netherlands
diyAudio Member
 
Join Date: Feb 2005
Location: The Hague
Quote:
Originally Posted by tiefbassuebertr View Post
How I can open this kind of outline (seems to be more difficult than TO-3) ?
Clamp the transistor with the wires in a bench vice and with a knife and hammer split the 2 halves. With a little luck it opens nice..
Good luck, Loek
  Reply With Quote
Old 23rd October 2011, 04:11 PM   #388
diyAudio Member
 
triode_al's Avatar
 
Join Date: May 2004
Location: Westland
Blog Entries: 1
Quote:
Originally Posted by Salas View Post
What do you make out of those JFakes, eh sorry, JFets?

They measure ~6mA in majority. Got just a few to check out. Legs longer than other Tosh, x mark inside the back circle unlike other Tosh having none. Unless they packaged any outside Japan, they are highly suspicious... Is anybody having any J74s looking like those, knowing more?
I had similar typeface on the 2SJ74 JFakes made by laser burning (or some other artifice) of the letters in the plastic, with rough edges in the letters. I would not trust them
I got same leg model. And I did not buy cheapo.

albert
__________________
DAC TDA1541 S1; Kondo post-I/V filter; MC30-Super --> two stage RIAA; Pre: Kaneda ; F5 ; 300B PP ; ESL 57
  Reply With Quote
Old 23rd October 2011, 04:19 PM   #389
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Has no Toshiba hallmarks at all. I chucked them out.
  Reply With Quote
Old 24th October 2011, 12:34 PM   #390
diyAudio Member
 
tiefbassuebertr's Avatar
 
Join Date: Jul 2005
Location: D-55629 Schwarzerden
Quote:
Originally Posted by loek View Post
Clamp the transistor with the wires in a bench vice and with a knife and hammer split the 2 halves. With a little luck it opens nice..
Good luck, Loek
Thanks - yes this is so. Size of die looks correct.
How I can check the internal thermal resistance between the die and the metal heatsink face by a device, that is yet not damaged ??

Last edited by tiefbassuebertr; 24th October 2011 at 12:38 PM.
  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 02:39 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