My Transistors, original or copy? - Page 11 - 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 28th May 2007, 04:47 PM   #101
diyAudio Member
 
Gold_xyz's Avatar
 
Join Date: Dec 2005
Location: Italy
Quote:
Originally posted by sbrook
Look at the *difference* in those heatsinks!

The ones to the right, with the stamp can't be flat on the back! and look at the irregular top of the heatsink. They SCREAM FAKE!
I agree at 100%
but I don't understand from where all these false bjts come
__________________
My English originates from here
  Reply With Quote
Old 28th May 2007, 04:57 PM   #102
sbrook is offline sbrook  Canada
diyAudio Member
 
Join Date: Feb 2007
Location: Ottawa Canada
Like where did this melamine tainted gluten that found its way into pet food come from?

From small to medium size companies in countries with little to no care for who they rip off and are desperate for western currencies.

Goodness knows it's easy enough to do ... get some metal to fabricate a heatsink, buy cheap transistors to put inside the case so the leads show something like correct characteristics then pot them in epoxy and paint the numbers on.

Then you sell them through middle men who will take the fall. Or sell them through things like ebay (sadly, while ebay is brilliant, it's also a terrific way to market knock off products). If a large electronics distributor has need of particular components and he sees a supply available, he'll buy to meet that need, not always checking quality or source. Of course, if he asks for samples, they'll send a few of the "real thing".
  Reply With Quote
Old 30th May 2007, 12:43 PM   #103
PB2 is offline PB2  United States
diyAudio Member
 
PB2's Avatar
 
Join Date: Sep 2004
Location: North East
Blog Entries: 1
Quote:
Originally posted by anatech
Hi Pete,
I am currently (very slowly) playing with a couple SymAsym boards. They sound really good, and are overkill for what I wanted and expected. So overkill it is!

We must thank Mike and Pavel who developed this amp, and Carlos who started the first thread. If you get a chance you should zap a couple together.

-Chris

Hi Chris,

Just wondering for the SymAsym, which hfe range do you think is best, I think they'd all probably work fine (matched P to N of course), but do you have a preference:
Sanken hfe codes: O(50 to 100) P(70 to 140) Y(90 to 180)

Pete B.
  Reply With Quote
Old 30th May 2007, 02:17 PM   #104
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Pete,
I used MJW0281A and MJW0302A. All of the transistors measured hFE close to 100. That's for NPN and PNP! Other transistors I checked had hFE ranges further spread apart and measured higher in THD. I was also able to run these at lower bias currents than normal. All the other transistors were as the BOM, but matched and thermally coupled.

You can match your outputs close I know, but getting PNP and NPN's to come close is much more difficult. I did try some other types but kept coming back to the On Semi devices.

I wouldn't mind trying this with some other Japanese numbers, but my selection these days is both suspect and very limited. I haven't had a chance to go through your list very well due to a number of things. It's not due to a lack of interest on my part.

I am also in the process of completely revamping my work space and will have higher capabilities when I'm done. That is soaking up a fair amount of time.

-Chris
__________________
"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote
Old 31st May 2007, 12:38 AM   #105
PB2 is offline PB2  United States
diyAudio Member
 
PB2's Avatar
 
Join Date: Sep 2004
Location: North East
Blog Entries: 1
Quote:
Originally posted by anatech
Hi Pete,
I used MJW0281A and MJW0302A. All of the transistors measured hFE close to 100. That's for NPN and PNP! Other transistors I checked had hFE ranges further spread apart and measured higher in THD. I was also able to run these at lower bias currents than normal. All the other transistors were as the BOM, but matched and thermally coupled.

You can match your outputs close I know, but getting PNP and NPN's to come close is much more difficult. I did try some other types but kept coming back to the On Semi devices.

I wouldn't mind trying this with some other Japanese numbers, but my selection these days is both suspect and very limited. I haven't had a chance to go through your list very well due to a number of things. It's not due to a lack of interest on my part.

I am also in the process of completely revamping my work space and will have higher capabilities when I'm done. That is soaking up a fair amount of time.

-Chris
Those are rated for 75 to 150 so it seems they'd be similar to the mid grade Sankens. Thanks, was just curious.

Pete B.
  Reply With Quote
Old 31st May 2007, 03:52 AM   #106
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Pete,
Quote:
Those are rated for 75 to 150
Forget the rating. Every single one was very close. I think I had a flyer or two sitting at 105. No kidding.

With tolerances this close I immediately fell in love with these parts ... well not quite true. After some testing and listening they became a clear choice for me.

-Chris
__________________
"Just because you can, doesn't mean you should" © my Wife
  Reply With Quote
Old 31st May 2007, 07:34 AM   #107
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Anyone ever seen these, or heard of the brand ?

The number is supposed to be an NEC(ETC), became obsolete in 2002.
I also got a bunch of the 2SA partner from a different source, but those do read NEC.
These devices are supposed to have a 100 watt rating and an Ft of 80/90 MHz.
The capacitances measure ok but it has an insulated casing, similar to TO-126 and some TO-220 Sanyo devices.
Haven't put one through Eva's full force test yet.

Speaking of which, i hope "La Mejor" de la alta energia conmutation occasionally reads this thread.
Fred says : Evaaaaaaaa !!
Attached Images
File Type: jpg 2sc2681.jpg (55.4 KB, 1302 views)
__________________
The buck stops Here
  Reply With Quote
Old 31st May 2007, 08:49 AM   #108
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Jacco,
can you tell from the damaged one what size the chip is?
I see a pale grey square and a dark triangular patch, which?
Can you tell what material (and it's thickness) that stretches across most of the width of the backplate?
__________________
regards Andrew T.
  Reply With Quote
Old 31st May 2007, 09:41 AM   #109
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
I'm a bit of a brute, i opened the case with a nutcracker.
Touching a wine glas has been a no-no for like 25 years, i can torque the thread off the most incredible size hexagonal nuts though. First time i'm opening up a transistor.

One half of the die is left on the epoxy that cracked off, the triangular patch is part of the intermediate layer of the die.
The die measures a wee over 4mm x4mm, measured the metal bonding plate by hand and the die from an enlarged digital pic.
Also the first time i see a fully insulated device of this size.
__________________
The buck stops Here
  Reply With Quote
Old 25th July 2007, 08:51 PM   #110
Nordic is offline Nordic  South Africa
diyAudio Member
 
Nordic's Avatar
 
Join Date: Sep 2005
Click the image to open in full size.
"2sc5200"
  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 07:25 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