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Haha, fake choke!?

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Conundrum

Sat Oct 10 2009, 10:26PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Hmm. There was a case a while back of bad "dies-soldered-together" BJT power amp transistors, which worked at 1/2 their rated power and voltage, then failed catastrophically.

I can see the EU being very interested in this, as its a serious safety risk (bet the PSUs have not been CE tested)

-A

"Bother" said Pooh, as his secret moonbase was pwned by LCROSS...

Dr. Dark Current

Sat Oct 10 2009, 10:39PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Well thats pretty bad

brtaman wrote ...

Well I managed to destroy my ATX psu. A thermistor blew up while my sstc was in operation, blowing up my GDT!? and all IC's as well as the psu.

You used the PSU to power your gate driver? Did you happen to have the GDT wound with an enameled wire? I don't like making GDTs with enameled wire because you can have a small kink in the insulation and interwinding breakdown can occur. Also "standard" enameled wire is rated only at 50 volts.
If this happened, your full DC buss voltage may have gone through your gate drivers into the PSU, blowing up everything on its way...

Steve Conner

Sat Oct 10 2009, 10:49PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

well spotted brtaman!

I can think of a few possible reasons why they faked it:

1: to save money as others suggested
2: to make the PSU more efficient and cooler running (those passive PFC chokes get pretty hot)
3: they couldn't get the required inductance and current rating to actually make the choke do its job (see below) in a package that would fit inside the PSU, so they just said f*** it

Conundrum wrote ...

I can see the EU being very interested in this, as its a serious safety risk (bet the PSUs have not been CE tested)

I don't see a safety issue (if anything it's safer than a properly wound choke, because it runs cooler!) but it would probably fail testing for the CE mark. There are limits on harmonic currents for appliances over 75 watts, and that's what the choke is for, to keep the harmonic currents within CE limits! :P

PS: Is it me, or are all of the EMI filter components missing from the board too?!

Bird-Dawg

Sun Oct 11 2009, 01:19AM

Registered Member #2360 Joined: Sun Sept 13 2009, 05:43PM
Location: Kennesaw, Ga USA
Posts: 14

Hmm. that is lame. Mabey the old warning to not buy cars made on friday goes the same for chokes. The guy in charge of winding the wire was to busy chatting it up with his budy on the line about his weekend plans and let acouple of chokes slip buy. Or mabey they are cheap-skates. Most likely the later.!mistrust

Sulaiman

Sun Oct 11 2009, 08:33AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

The purpose of the choke is to add weight to the product so that it 'feels' worth the money, and due to copper prices it's sufficient to just add steel.
Similarly the 'feel-to-cost' ratio of line filters has now made them redundant.
And don't get me started on those little smd electrolytics!

Just a note to anyone who thinks that the CE mark is proof of quality;
Manufacturers self-certify their products, anyone can stick a CE mark on a product! Even then there is the CE mark which means 'China Export'!

However, if you are killed by a CE marked device, you can sue the manufacturer.
Caveat emptor

applies !

As for EU rules on emc/emi/rfi/line noise, etc. ..... they're ridiculous - only a range of consumer items are covered, for the sake of expediency the worst offending items are exempt! e.g. plasma tv.

I guess I woke up in a cynical mindframe this morning !

mikeselectricstuff

Sun Oct 11 2009, 11:58AM

Registered Member #311 Joined: Sun Mar 12 2006, 08:28PM
Location:
Posts: 253

On the subject of dodgy PSU fakery .... Fake Laptop PSU complete with lumps of metal to make it weigh the right amount

wrote ...
As for EU rules on emc/emi/rfi/line noise, etc. ..... they're ridiculous - only a range of consumer items are covered, for the sake of expediency the worst offending items are exempt! e.g. plasma tv.

Not true - EMC applies to anything put on the market, although some product groups have different standards, these are often more onerous than the generic standards ( e.g. lighting).

I'm reminded of something a customer of mine told me a while ago - they needed some transformers with a particular country's safety approval mark. Their Chinese supplier replied "sure - no problem - just send us the artwork"!

doctor electrons

Sun Oct 11 2009, 02:50PM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

Here is something to think about! At my job we sometimes have to "UL" control panels per customer request. Once a year a "UL" inspector will come to the shop and do a complete inspection of a panel that will be "UL" labeled. Interestingly enough, when they do their inspection they look for these things!
1) All components are "UL" marked or uR (recognized)
2) Certain component combinations are "UL" tested.
3) All correct labeling ie : arc flash, cautions, warnings, torques, etc. are applied to the panel.

It seems odd that the inspectors don't really care about things like say, a direct phase to phase short of a 480v line.
If this is the way "CE" operates, this is the reason for your fake choke! Simply there to make an appearance! I would agree the reason is based on money. Thats what all the big firms like "UL" "CE" "DVC" really care about. At 400 to 500 dollars for a "UL" sticker, what do they care if a product fails and takes out a whole family? I personally do not trust any components that are marked anymore than ones that are not.

ragnar

Sun Oct 11 2009, 04:08PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Avalanche wrote ...

this is amazing, I think this one beats the 'small capacitor inside a large capacitor' that was posted a few months ago.

totally nuts! but quite amusing

For those who missed it:

Steve Conner

Sun Oct 11 2009, 07:05PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

mikeselectricstuff wrote ...

Not true - EMC applies to anything put on the market, although some product groups have different standards, these are often more onerous than the generic standards ( e.g. lighting).

This is absolutely true. My work just recently sent me on a course run by the CE Marking Association, and it all is (or should be!) taken seriously. It is self-certification, in so far as the EU don't have inspectors that go round testing all new products. But the whole point of it is that if you place the CE mark on your product, and it's then found not to meet the CE standards, you are breaking the law and can be sued. And if you don't place the CE mark on it, you can't legally sell it in Europe.

CE is not a corporation like UL, the Underwriters' Laboratories. It's a European Union thing.

The product we developed just passed EMC testing to CE standards. I was in charge of digital, power supplies and PCB layout, and I even chose the wall wart, so if anyone could have screwed up the EMC it would have been me. I think we're throwing a test pass party this week

Proud Mary

Sun Oct 11 2009, 07:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

The other massive racket that springs to mind, is the putting of size "C" NiMH cells in "D" cases , which is almost universal in Britain unless you go to a specialist supplier. Feel how light they are compared with a real "D" cell brimming with chemical goodness.*

This swindle has given folk the impression that NiMH batteriies don't last long, because most look to the enclosure size only, and not to the AH capacity. The rotters!

*I remember this phrase from a detergent advertisement some years ago. Times change.

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