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Old 22nd Dec 2015, 8:49 pm   #21
Jonster
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Default Re: Warning fake components

I have had problems with fake RF power devices too, I needed a Mitsubishi M57735 power module to repair a VHF link transmitter a while back, the only place I could find one was a Chinese supplier on eBay. It duly arrived a couple of weeks later, I thought it was strange that it only weighed about half of the original genuine device, it didn't work either, I didn't dissect it due to the Beryllium Oxide risk....
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Old 23rd Dec 2015, 12:16 am   #22
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Default Re: Warning fake components

I've just thought of another instance, involving some TO220 audio driver transistors. The originals were NEC and for a 5000W pro amplifier. A batch of 10 new ones arrived from a mail order company known in the TV trade. They looked genuine and had the NEC stylized logo. I fitted the 2 required and consigned the rest to the drawers. The amp didn't work, and after at least another day of wasted time, I found that one of the new transistors was of the opposite polarity; ie NPN instead of PNP! When I checked the others I found another the same. The lot went in the bin and I cross-referenced the NEC part to a more modern OnSemi part from Farnell which did the job just fine.

The whole thing is really keeping us on our toes!
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Old 23rd Dec 2015, 12:23 am   #23
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Default Re: Warning fake components

Quote:
Originally Posted by Jonster View Post
I thought it was strange that it only weighed about half of the original genuine device, it didn't work either
They've been known to be empty, just the encapsulation.
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Old 23rd Dec 2015, 2:08 am   #24
Lucien Nunes
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It's worth calling attention to counterfeit plug fuses. Amongst our vintage kit there is probably a greater reliance on the plug fuse than with modern stuff, so it pays to make sure that the 1" x 0.25" cylindrical thing in your plug is, in fact, a fuse. There are two separate issues here - whether the branding and approvals shown on the body are legitimate and, even more critically, is it capable of doing its job? Tests have shown that some counterfeit and substandard fuses can explode in the event of a short-circuit, or fail to break the circuit in a timely manner. Some do not contain the necessary silica fill, or have poor connections to the endcaps that can cause overheating.

Substandard fuses have been around for a long time and I always used to associate them with cheap goods that were imported without any UK or EU approvals before the CE-era, but last week I made a rather alarming discovery. After an installation project where all the equipment is wired to rackmount power distribution units, there is usually a pile of surplus 13A - IEC cordsets that came bundled by the OEM. In this case there were about 100, along with a similar number of US and EU types for equipment that comes with both. I flipped a dozen fuses out and three of them, each from a different brand of cordset, were substandard. One did not bear any approvals, was too short, unfilled and had the wire tucked under the endcap. The other two were counterfeits bearing the 'Bussmann' name, moderately convincing in appearance but definitely not made by Bussmann and also internally defective. Had they been from a pile of no-name domestic goods sold in the high street, I wouldn't have been so surprised, but all of these cordsets came with top-brand professional equipment bought traceably from the official distributors. It seems you can pay £5,000 for a piece of kit and still get a firecracker in the plug.

I'd recommend studying the spotters' guide to fakes in the link below, maybe go on a hunt round the house or workshop (it could be a good excuse to escape from festive monotony!), and when you buy plugs or cordsets check a sample from every pack. Faulty plugs and cordsets are also a menace but I expect most people on the forum would tend to spot these more easily than the somewhat inscrutable fuses.

Counterfeit fuse guide at BS1363.org
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Old 23rd Dec 2015, 2:53 am   #25
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Default Re: Warning fake components

Why limit ourselves to fuses and semiconductors??
A few years ago, after Red Lion branded GEC,s had attained godlike prices,
I was sold an "exact match".
I must admit that the price was less than 1/8th the price of the audiophool GEC,s. A matched pair with some eastern european numbers written on the end of the boxes, ( which were just wrap around THIN cardboard painted in bright red and blue colours, and NO glue, so when you "untucked" the end flap, the box continued by itself to form a flat bit of tat) One immediately red plated and died, as I watched the screen grid melt into several short pieces of wire.

I ended up buying 20 of these Katy adey ates to get two to work !!!!

Now you know why all the pics of my projects have British, Australian or American valves in them. Even though one of my Brimar 6BW6's "exploded" on first switchon. BUT as the valves are origional 1950's stock, I think its a good record.

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p.s. Sorry mods, Im ( as usual) a bit off topic.
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Old 23rd Dec 2015, 12:21 pm   #26
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Default Re: Warning fake components

Counterfeit parts are a serious issue for the mainstream electronics industry with some sources suggesting that 6% parts are actually fake. There are companies making a good living checking that parts are genuine. When I was working we were asked to verify a stock of old parts before use on Concorde (that dates me) by decapping a few samples and comparing the die to the original manufacturers. A very costly operation as these parts cost £100 each for what was actually a cheap part originally.

I have bought a few batches of transistors from China and the distributors mentioned in this thread. I usually do a sample test on my curve tracer and have been lucky so far, except for a dual transistor sent to me (free) which did not work as expected. BUT it was 40+ years old. Tested out bad on the curve tracer. Never actually thought I would ever use it in anger but it has proved to be surprisingly useful.

Happy Christmas.

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Old 23rd Dec 2015, 6:31 pm   #27
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Default Re: Warning fake components

With regard to the fuses mentioned in post 24, I have read the linked document and it appears the 'tests' are either not that clear (e.g. 'the body looks whiter than it should' or 'the 3A red is too orange') or destructive to the fuse (take it apart, measure wall thickness, look at the fuse element, etc). I guess I could weigh each and every fuse I have here, but it's going to take a lot of fiddling with the chemical balance...

Now fake transistors in general just waste time (often a lot of time), whereas fake fuses could be a lot more serious.

Is there any known way of being sure you have a genuine BS1362 cartridge fuse? Given that even reputable suppliers sometimes end up (unknowling) supplying fakes, I don't think just avoiding 'dubious' sources is enough.
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Old 23rd Dec 2015, 8:31 pm   #28
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Default Re: Warning fake components

Without wanting to sound as if I'm defending substandard safety critical components, I wonder how genuinely dangerous these non-compliant fuses are. There is a real danger of the fuse shattering ('exploding' is overly melodramatic in my view) but the fragments should be fully contained within a BS1363 plug.

I don't deny that there may be rare occasions when the plug top is shattered or blown away, or the plug is blown out of the socket, but even these circumstances won't be lethal unless somebody is very unlucky.
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Old 23rd Dec 2015, 9:09 pm   #29
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Default Re: Warning fake components

This type of fuse might not be lethal by electrocution, but would certainly capable of causing death by fire.

In the early 1970's when I was still living at home, I heard a bang from the next room, accompanied by a momentary dimming of the lights. It turned out that the insulation of the flex of my mother's iron had developed a short between L and N. The fuse was a non-BS one bought from a street market in the mid-1960's. The ceramic body of the fuse was undamaged, but the short circuit current had blown holes in the thin end caps, evidently filling the interior of the plug with metal vapour that allowed an arc to establish itself between the L and E terminals inside the plug. There was another arc in the flex at the point of failure, and the resistance of the arcs was sufficiently high that the 30A ring main fuse did not trip. By the time I got there, I could hear the sizzling of the arcs and my mother had the presence of mind to pull out the plug before it got too hot (the socket was unswitched). The socket was next to the window and right under the curtains, which extended a couple of feet wider than the window opening to allow them to be drawn back fully. Had she not been there, the arcs in the plug and flex could have set fire to them.

These fuses only bore the current and voltage rating, and so were readily identifiable for what they were. I checked all our appliances and replaced about half a dozen with proper fuses from Woolworths. I haven't seen any of this type on sale in the UK for years, but this type of fuse was on sale in a rural supermarket in ROI when we visited there in the early 1990's.

At least it was obvious that my 1960's fuses were not to BS standard. Identifying fakes that resemble genuine ones is indeed more problematical. Possibly weighing them might work, if you have sufficiently sensitive scales. Using my wife's kitchen scales, whose digital readout only reads to the nearest 2g, the five old non-BS fuses that I kept weigh ~8 grams, whereas samples of 5 "proper" BS fuses weigh ~12 grams. The heavier weight is no doubt accounted for by their sand filling and heavier end caps. The non-BS fuses simply consist of a hollow ceramic tube and a length of fuse wire secured by flimsy brass end caps.

In view of #24, perhaps I had better check the fuses in my more recent appliances against my stock of (presumably) genuine ones acquired from RS and Farnell more than 10 years ago.

Last edited by emeritus; 23rd Dec 2015 at 9:28 pm.
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Old 23rd Dec 2015, 11:39 pm   #30
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Default Re: Warning fake components

Thanks for that story. It answers my point very well.
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Old 24th Dec 2015, 12:17 am   #31
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Default Re: Warning fake components

Not quite fakes but do I remember clive sinclair using transistors that were bound for landfill for some of his early radios, I think he hand tested every one to weed out the duds and far below spec devices.
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Old 24th Dec 2015, 11:37 am   #32
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Default Re: Warning fake components

I have actually seen a plug ejected from the socket in my IT hardware repair days. They are a bit harsh on your hand if you are plugging them in when they go off.
It was on an EPOS terminal from a hamberger bar and the fat had entered the female end of the mains cable and gone conductive. Sometimes this used to destroy the 30 amp MCB.
That fat had special electrical properties for sure.
Modern plugs have the fuse holder between the pins so if the fuse blows up it is more likely that the plug will be ejected from the socket. On older plugs the top cover could fly off.
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Old 24th Dec 2015, 10:58 pm   #33
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When we moved into a new council flat in 1967 we were provided with some 13A plugs that had an opening in the pin face that allowed the fuse barrel to be seen when the plug was removed: I don't remember the make. I had thought this was to allow you to see what rating fuse was fitted without dismantling the plug, but I suppose it would provide a vent for escape of hot gas that could cause the plug to be ejected under fault conditions.
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Old 24th Dec 2015, 11:11 pm   #34
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Default Re: Warning fake components

I wonder what's happens with European and US plugs ?
Many are not fused at all !
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Old 24th Dec 2015, 11:47 pm   #35
Lucien Nunes
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EU and US plugs don't need to be fused because the fuses or circuit breakers at the distribution board are rated to protect the individual plugs and flexes. Typically these systems require a larger number of smaller circuits, just as we did with our round pin plugs. After WW2, in the UK we moved over to the innovative ring final circuit system, which reduced the number of circuits required and the amount of cable needed to wire a given floor area, by making each circuit larger in capacity. This however requires fused plugs, to protect the flex / appliance.

The problem with the counterfeit fuses is that you don't know what they are going to do. Yes, the plug can burst open or be ejected from the socket, there is a demo video of this here:
Fuse explosion

As proper fuses are cheap and take only seconds to fit, the investment is minimal and probably commensurate with the improvement in safety they offer over out-of-spec ones. I agree with Paul that in most cases a faulty fuse won't kill you or burn your house down in itself, if only because it is backed up by a 30A or 32A in the consumer unit, but it can be hard to predict the consequences because of the wide range of circumstances in which the fuse my be needed to act. You can certainly see how there could be greater risk, e.g. if you damage a flex with a tool, the longer the fault persists before the fuse interrupts the current, the greater the risk of shock or fire, even if the fuse itself doesn't deconstruct. The energy let-through of an unfilled fuse can be many times greater than a filled one.

As for the methods suggested for spotting the counterfeits, when you encounter a fuse meeting those descriptions you'll know it; the 'whiter body' is brilliant white compared to the usual off-white ceramic, the 'orangey' 3A fuse looks completely the wrong colour, the shiny chromed endcaps glare at you out of the plug!
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Old 25th Dec 2015, 11:12 am   #36
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Default Re: Warning fake components

About ten years ago I was building a Topband (160m) multimode transceiver of my own design. The prototype PA consisted of a BD135 driver and a pair of IRF640s from the junk box.
Once working nicely, it was treated to a nice new pair of 640's from a well-known supplier in East London.
I made a very neat job of the PA block and quickly hooked it up to the 35 volt supply and a suitable RF source. Very disappointed - only about half the expected RF emerged before compression set in and the current was significantly higher than previously.
After several trips around the houses with the PA assy getting more and more scruffy (don't you just hate that?), I eventually put the old junk-box devices back in and it worked a treat! So I ordered some new 640's from CPC at a higher price.
Straight away the problem was solved - plenty of output and nice linearity.
We live and learn.
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Old 25th Dec 2015, 12:16 pm   #37
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Default Re: Warning fake components

Last year when I was at home recovering from a road accident, I decided to make up some projects on Veroboard which I brought from a well known shop. One piece I had bought would hardly take solder at all even though I was using proper multicore solder and a Weller TCP iron with the correct bit, with many years experience of working with veroboard. It looked as if I had used a trowel and poker to make the joints!!.
There was no signs of damp or corrosion and I put this down to an unbranded or fake make of Chinese veroboard with very poor quality control of the copper (if it was actually copper in the first place!!).
When I then used a good brand of veroboard I was then able to make good joints again.

Christopher Capener
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Old 25th Dec 2015, 12:19 pm   #38
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Default Re: Warning fake components

In view of the discussion of BS1362 fuses here, I had a look at my fuse stash yesterday. One 13A fuse with minimal markings had a loose end cap, and on removing it I found the fuse body was a ceramic tube with a fuse wire running down the centre. The construction wasn't too bad but it certainly wasn't standards compliant. I've now chucked out all the dodgy looking ones. It's really not worth taking the (small) risk given that every piece of scrap mains equipment contains a plug fuse free for the taking.
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Old 25th Dec 2015, 1:12 pm   #39
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Default Re: Warning fake components

I recently purchased some small plastic transistors from eBay, which came in a pack of 10. On arrival I checked them on the transistor tester and compared to a working original. Only 2 gave readings that were actually near identical to the original. The others gave hFE and current readings well above or below. I selected the two that matched most closely to replace the faulty ones, but am now wondering whether even those are dodgy to use? I usually purchase from known retail outlets.
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Old 25th Dec 2015, 1:15 pm   #40
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It's normal for hfe to vary a lot, though transistors from the same production batch are usually similar.

I buy commodity transistors from cheap Chinese suppliers, but I wouldn't use them for anything critical. I always test them before use.
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