how to identify fake transistors - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 6th May 2004, 12:31 PM   #1
Wagener is offline Wagener  South Africa
diyAudio Member
 
Join Date: Mar 2004
Location: Paarl
Default how to identify fake transistors

I received a few quotes on the MJ15003 and MJ15004. One company (which supplies most of the components for our technikon) quoted about a third of the price of that of most companies.

I am concerned about buying fake transistors because the technikon aparently bought some fake products from them some time ago.

How do I chech a component to see if its fake (other that using a multimeter)
  Reply With Quote
Old 6th May 2004, 12:49 PM   #2
karma is offline karma  Canada
diyAudio Member
 
karma's Avatar
 
Join Date: Feb 2003
Location: hamilton,ontario
there are a few threads on it do a search on fake chips


counterfiet sa1943's ??

  Reply With Quote
Old 6th May 2004, 01:11 PM   #3
sam9 is offline sam9  United States
diyAudio Member
 
sam9's Avatar
 
Join Date: Jun 2002
Location: Left Coast
As a victim of fake transistors here are a couple of things to watch for:

If the price is "too good to be true" that's because it is.

If you have the means to easily measure Hfe, an unreasonably high figure (like 100++ ) from a power transistor is a sign something is not right. Mine had a tiny chip that was probably intended for a low voltage, small signal transistor.

If you have a known good copy of the transistor, beware of version where the printed label looks different. Sometimes the fakes actually have better quality printing on them than the original.
  Reply With Quote
Old 6th May 2004, 01:45 PM   #4
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
It would be a good idea to request a sample of each and measure Hfe and B-E, B-C zero-bias capacitances

Hfe should not be too far from the figures quoted on the datasheet, but if the dies are fakes taken from other smaller power transistors then their Hfe value will be in the correct range and won't be useful for fake detection

Zero-bias junction capacitance values are very useful in determining die sizes. Each model of transistor shows typical capacitance values. Fake transistors tend to have 1/2 to 1/10 of expected capacitances due to smaller die sizes. Capacitance is roughly proportional to die area

You may post measured capacitance values on the forum, asking for other people to compare them to the ones measured on devices known to be genuine. Fakes will allways show smaller capacitances
  Reply With Quote
Old 6th May 2004, 01:46 PM   #5
jaycee is offline jaycee  United Kingdom
diyAudio Member
 
Join Date: Apr 2004
Location: Norwich, UK
Mr Elliot has a pretty good article on this:

http://sound.westhost.com/counterfeit.htm
  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
More fake transistors taj Solid State 25 30th October 2007 04:46 AM
fake transistors tinkerbell Solid State 17 19th January 2006 11:51 AM
Fake Transistors MGR Solid State 10 28th October 2002 10:46 AM


New To Site? Need Help?

All times are GMT. The time now is 03:16 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