The Workbench

Re: Counterfeit transistors

ipaul — Tue, 29 May 2007 16:22:32 GMT

Yeah, i know about the housings etc, the fully isolated ones have an F added, less heat transfer but also no need for insulation foil so that's more or less the same thing.

Anyway, the BU in the MX2000 was the same housing etc (and doesn't use isolation foil, simply puts the over 145V pulsating current on the heatsink...not so 'neat' but yeah, these were already thomson chassis....).

Even the new 'original' B&O ordered part behaved quite diferent in heat dissipation compared to an 'old' original (which i took from another MX).

Even if not counterfeit ones, it shows apparently that specs seem to change (for the same type/model/housing etc.) over the years....and in this case not always improve :)

Re: Counterfeit transistors

Dillen — Tue, 29 May 2007 15:57:54 GMT

I don't do TV's so I can't comment specifically on the MX but for some BUxxx's there are different power ratings depending on the transistor housing (and sometimes also the brand).
Some transistors have a metal backside with the rest of the house being a ceramic material, allowing much heat to dissipate to a heatsink. Others are completely covered in plastic, also the backside so won't be able to transfer much heat = lower power rating.
Often, the ones in plastic housings bear an extra letter after the type, like f.e. an "S" or "K".
Unfortunately, some suppliers mix up the types and, agreed, it's quite a jungle and the presence of counterfeit semiconductors doesn't help.

I can't say if you were sold counterfeit transistors or not and I am not sure for how long they've been around.

Martin

Re: Counterfeit transistors

ipaul — Tue, 29 May 2007 14:32:34 GMT

A couple of years ago, when it was still worth while fixing MX2000 tv's i had a strange experience with the switching transistor BU806 (i might have the number wrong, it's the one to boost the 110V into 145V) used in this tv, i don't know if it fits into the 'fake transistor' story though....

Anyway, i changed the broken BU for a new one from the 'parts shop' (also BU806) and after a few minutes it burned out.

So after a lot of measuring etc and changing another 2 or 3 times i got suspicious.

Ordered the 'original' ones from B&O and...that kind of worked, that is they get much more warm than the old original version (which hardly gets warm) but at least doesn't get blasting hot and dies :).

So all BU806 and all 3 different behaviour (and all are low hfe types so it can't be that i guess...).

Re: Counterfeit transistors

Dillen — Sat, 26 May 2007 01:43:57 GMT

Yes, even the large well-known suppliers sometimes haven't got a clue what they're selling.

Luckily, the 2N3055 is not the hardest part to find but prices are very different from one supplier to another, which also suggests something "fishy".

In case a supplier has sold fake components, the best thing he can do is cooperate with the buyer, unfortunately not all suppliers do. I am perfectly aware that my supplier didn't sell me fake components on purpose and he very soon offered to take the fake ones back and send me replacements of a different brand so I wouldn't hesitate buying from him again.

But thanks anyways Johan, I like to buy in larger amounts, rarely just one or two so it's always nice to have good component sources.

Martin

Re: Counterfeit transistors

johancte — Fri, 25 May 2007 09:12:12 GMT

Hello Martin,

I work as a "component broker", hunting down hard-to-find items for customers all around the world. We've ran into many counterfeit components in our way, luckely we've always managed to discover it in time. We are very carefull these days, especially when we're using our contacts outside Europe. Most of our parts comes from our own stock, and local OEM's.

Anyhow, If you're looking for any transistors or other components as we speak, I would be greatful to help you out.

Best regards,

Johan Molin

Re: Counterfeit transistors

nobby — Fri, 25 May 2007 07:54:09 GMT

No. But I bought them from www.cpc.co.uk

Re: Counterfeit transistors

Dillen — Fri, 25 May 2007 07:10:30 GMT

nobby, BM5500 transistors.... do you remember what "brand" they were ?

Martin

Re: Counterfeit transistors

nobby — Fri, 25 May 2007 05:48:09 GMT

I recently had this experience with output transistors for a BM5500 ... no npn junction inside at all! It made a horrible mess.

Re: Counterfeit transistors

Die_Bogener — Fri, 25 May 2007 02:13:15 GMT

These counterfeit parts are produced in millions in china... of course it's illegal, but who cares? If it's cheaper a lot of people buy the cheap Rolex watch or the "original" Boss shirt. There is the real problem.

Why not produce electronic parts? :(

Or parts for airplanes... :(

or safety equipment...:((

I had already fake computer memory Rams, cpu's, lot's of electrolytic capacitors on computer boards.

Even the electrolyte itself was faked, using water in the aluminum capacitor... causing bombastic explosions on the mainboards and power supplys. ABIT and ASUS had a lot of fun with these faked parts...

B&O used a lot of these capacitors in the VX5000/5500 and VX7000 series, i think this is the real reason for a lot of defects on these expensive recorders.

Martin

Re: Counterfeit transistors

SWISS_2 — Thu, 24 May 2007 21:12:12 GMT

QUESTION: Where are the Inspectors in this scheme ?

ANSWER: Also in on the " payroll, " apparently.

Doing the math, this is profitable in a short span of high-volume manufacturing. It is illegal, unsafe ( electrocutions+ fires ) and unsound for any manufacturer in the long-run who values a good reputation in the Industry.

Any random inspection, performed by an independent inspector should have identified this problem, with the identified product batch being recalled..

Re: Counterfeit transistors

Puncher — Thu, 24 May 2007 17:47:50 GMT

My company actually had a problem that was traced to fake Triacs (approx £0.25 each) - made in the bowels of China but marked as a mainstream Manfacturer.

Why indeed - but there you are!

Re: Counterfeit transistors

Dillen — Thu, 24 May 2007 16:22:25 GMT

The cost of a transistor varies a lot depending on the brand, type, amount, dealer etc. but this particular type is normally a pound or two each.
For the producers of fake components, surely this type of business can't stay a success for very long.
Don't dare to think what would happen if f.e. B&O got some of these into their production ...
I am about to send a couple of these to Toshiba, clearly they can't be very happy having these lousy components around with their name on.

The real Toshiba semiconductor logo can be seen here : http://freespace.virgin.net/matt.waite/resource/logos/logo4.htm

Martin

A fake Toshiba 2N3055 transistor:

Re: Counterfeit transistors

Jandyt — Thu, 24 May 2007 16:15:34 GMT

I find that amazing, Martin. Can there be any money made out of counterfeit transistors?
I have never bought a transistor but imagine them to be a matter of pence.
If that was the case then they must be selling in vast numbers. Would the big Kikinoko companies know if they were getting a bum deal?
How much is a transistor, Martin?

Andy T.

Counterfeit transistors

Dillen — Thu, 24 May 2007 16:06:10 GMT

They have made counterfeit Rolex watches, counterfeit Gucci shoes and Lacoste shirts but counterfeit transistors ??

Yes indeed !

I recently had troubles with counterfeit transistors of the type 2N3055 made by Toshiba - or at least that's what it says on them.
For a start the Toshiba logo is all wrong, should have been the "handwritten" logo with the large T swung across the rest of the letters), like this (scroll down a bit):
http://www.datasheetarchive.com/search.php?q=2N3055

I opened up one of these fake types to compare to an original (RCA) transistor and this is what I found:

The house came off almost by itself on the fake one where I had to use
drastic methods to get into the RCA one.
The heat distributing backside on which the chip is fastened is much larger on the original than on the copy.
The chip itself is also larger and seems to be cast into the heat distributor on the original where it looks as if glued using silicone
in the fake one.
The internal junction leads are only very thin wires in the copy where the original has much larger bracket-like connections. Surely the fake
one will never handle 15A like this.

After Die_Bogener informed the link to their website I couldn't help visiting the Segor page. Seems like a good shop
but like many others, judging by the onsite photo, they too are selling the fake 2N3055's

More info on counterfeit semiconductors can be found here :
http://www.prodigy-pro.com/forum/viewtopic.php?p=219816&sid=d34dbec300687db036ff4a4059e826d5
and here:
http://sound.westhost.com/fake/counterfeit-p2.htm

Martin