Fake AC Adapters or Just Cheep ? - Page 1
Forum section: electronics / general

author: Sionyn
author_rank: Frequent Contributor
timestamp: June 07, 2012, 11:38:56 am
content: bbc this morning aired this program fake Britain, were they shorted a few plugs and were surprised when they caught fire.now these devices were cheep and nastyi can see there is danger but what is the likely is riskhttp://www.bbc.co.uk/iplayer/episode/b01jv9pk/Fake_Britain_Series_3_Episode_14/

author: Dataforensics
author_rank: Unknown
timestamp: June 07, 2012, 12:37:45 pm
content: I have seen moulded three pin British cables where under x-ray you could see the bare wires just under the surface of the plug. They were obviously non conforming, however just a small problem with the manufacture and you end up grabbing line and neutral with your fingers, oh and there was no fuse.Tony

author: PeterG
author_rank: Frequent Contributor
timestamp: June 07, 2012, 12:40:22 pm
content: The video is not available outside uk it seems.Regards

author: tom66
author_rank: Super Contributor
timestamp: June 07, 2012, 12:41:24 pm
content: I found an extension lead really cheap, 1.5m 4 way for about £1.50. However, I quickly worked out why it was so cheap: The plastic was so thin on the plug and the unit, it would literally crumble if you applied even slight pressure, exposing the live internals. The first failure occurred when the plug was pulled from the wall; half of the plastic fell off! The wiring inside was otherwise okay...

author: Sionyn
author_rank: Frequent Contributor
timestamp: June 07, 2012, 09:55:00 pm
content: their test seemed a bit phtonicinduction like to me chop the divce from the end of the plugtwist wires together, put too many volts through it....... BOOMseemed pointless and proved nothing.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 07, 2012, 11:32:05 pm
content: Fake Shure SM58's - WTF is this doing on a consumer programme? Surely airtime would be better spent on showing people how to identify dangerous plugs etc.Typical piss-poor journalism. None of the plug faults would have caused more than a minor flash burn, but I suppose stuff going bang is more televisual than showing faulty insulation etc....

author: Unknown
author_rank: Unknown
timestamp: June 08, 2012, 02:35:38 am
content: Quote from: iamwhoiam on June 08, 2012, 02:20:24 amWhy because Mike demonstrated he has a clue? Why is it idiots like you will take as gospel some rubbish spewed out by a bunch of trash tv journalists and yet completely dismiss the comments of a well respected engineer? Enjoy your Clue Free Zone!

author: vk6zgo
author_rank: Super Contributor
timestamp: June 08, 2012, 03:21:40 am
content: It's not only the Beeb that does this sort of thing.The 7 Network here in Oz comes up with some bloody nonsense at times.They will get some "Expert" in ,who's more expert at self-promotion than anything else,& he will pontificate on,while giving stupid examples which a moment's thought would shoot down.I remember a particular one,where they were trying to prove TV service companies rip people off,& this bloke set up a few artificial "faults".One "fault" was to reprogram the TV to do something strange.As it was a fairly illogical fault,the TV service guys took a while to find out what it was.They were then in the situation of finding outwhythe programming had changed.Obviously,after a while,as they weren't in on the joke,they had to just reprogram it & give up.Of course,this "expert's" argument was that they should have found the programming fault & just reset it..He put some other "silly" faults on TVs,removing parts & the like.At no time did he try to simulate a real fault,he was too busy preening in front of the camera!What made it worse was that the network had access to internal experts who could have set up a more realistic test!I hate their "Motoring Expert" too!!

author: grumpydoc
author_rank: Super Contributor
timestamp: June 08, 2012, 07:36:21 am
content: Stuff going bang makes for "better" TV.But Mike's right - in fact I don't think that even a flash burn would result in most cases. For any house with even vaguely modern wiring the breaker or RCD/GFI should trip for any of the "faults" displayed.Back to the piss poor journalism: AFAIU a fuse is not there to "protect you from electric shock" but to stop the cable being a fire hazard in a fault+overload scenario so these thingsaredangerous in that they're a fire hazard but that doesn't make for whizz bang viewing. Of course any manufacturer prepared to produce something with such piss-poor plugs presumably has a high failure rate so there's an increased risk of cables overheating.But plugs with fake fuses is new to me - given the effort to make itlookright how much more would it cost to simplydoit right?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 08, 2012, 09:43:11 am
content: QuoteI've seen that numerous times on "cowboy repair/plumbing/heating/whatever" programmes - they introduce simple faults, but ones that would be highly unlikely to occur naturally.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 08, 2012, 10:02:10 am
content: OK but you'd expect a competent plumber/builder/electrician to spot that the "fault" was set up and, if honest, say "what's going on?". Possibly if dishonest realise what's going on and just do the job properly.Which suggests that they are "catching" the incompetantanddishonest crowd.But what irritates me about these programs is a) there's no evidence of follow-up, or that their actions deter the cowboys in the slightest fashion. b) They are always based "somewhere else" so no real use in knowing who to avoid - even if they do give enough information to properly identify them (which they don't always - fear of litigation perhaps?)It's sensationalist rather than useful most of the time - but that's TV for you isn't it?

author: tom66
author_rank: Super Contributor
timestamp: June 08, 2012, 10:03:03 am
content: There was one where they unplugged the speakers on a CRT TV...! I'm not sure how that is supposed to occur on its own.

author: metalphreak
author_rank: Frequent Contributor
timestamp: June 08, 2012, 11:37:48 am
content: Does anyone remember that story where some guy kept getting a buzzing feeling every time he grabbed a certain plug. He couldn't work out for ages what it was until he looked *very* closely. Turns out a frayed wire had been poking out during the injection moulding process leaving AC voltages on the surface of the plug! Pretty sure I read it on here too.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 08, 2012, 11:39:28 am
content: Quote from: tom66 on June 08, 2012, 10:03:03 amBad solder connection or some plug not correctly plugged in, and rattling loose while transported or someone just giving the TV a "repair" whack. Or plug corrodes.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 08, 2012, 12:42:38 pm
content: Quote from: grumpydoc on June 08, 2012, 10:02:10 amNo,the point is,that weird faults,whether false or not,need more manhours to check out.Certainly this is the case with Electronics repair.A serviceman's "bread & butter" are the standard faults,which are easy to fix & give him the reputation of being competent.If the faults had been put on by a working Tech,rather than a "show pony" they would be standard faults,& if the TV service companypretended they were a big deal ,& charged appropriately,we would know they were either scammers or incompetent.As it was,the obvious inference a good Tech would draw is that the TV had been messed around with by someone,with the owner as obvious suspect.This raises the question of what else had been stuffed around with?As customers will blame anything that goes wrong on the last person to work on it,checking the thing thoroughly,after finding evidence of "tampering" is only self preservation.

author: grumpydoc
author_rank: Super Contributor
timestamp: June 08, 2012, 01:08:20 pm
content: QuoteSorry, I was replying to Mike's comment really.Yes, if they introduce a fault which is unusual and unexpected rather than something simple but not the way things commonly fail a decent technician should want to get to the bottom of the problem.But your other example - removing components should be fairly obvious.ISTR that one of the UK TV shows did it with computers by wiggling a hard drive cable so that it didn't make contact reliably but still looked as though it was connected. For an IDE cable in a header socket that's almost, but not quite falling out. Some of the dodgier computer "techs" then charged them for a replacement hard disk when all that was needed was to push the IDE connector home properly - that's the sort of induced fault I was thinking of - cables are a weak point and should always be checked but one completely loose is less usual (not impossible though).

author: vk6zgo
author_rank: Super Contributor
timestamp: June 08, 2012, 02:26:26 pm
content: "But your other example - removing components should be fairly obvious."This is why I mentioned "tampering".Very few Techs would run across such a "setup" in their working life,but most will have encountered equipment which has been butchered by would-be "fix-it men",who get in a mess & pretend they never touched it.By the same token ,Ihaveseen butchery done by TV service organisations,so it does happen!At one point,the TV Station I worked for decided it would be a good idea to "outsource" some work.We used a fair few big old Sony 27" TVs with AV inputs,as floor monitors,so they were chosen to be outsourced.We sent them to a major TV repairer.Well,it was a nightmare!Once,we sent a TV,along with a rebuilt tube so they could do the tube change,with strict instructions not to de-evacuate the old tube,as we wanted to rebuild it,too.They knocked the base off the old tube !In addition,we had to set the colour balance, convergence & picture geometry again,as they made a mess of it.Later,we found a smaller shop who did good work,& sent them some smaller TVs,but took the big stuff,& all the Broadcast Standard monitors back in-house.

author: siliconmix
author_rank: Frequent Contributor
timestamp: June 09, 2012, 04:45:28 am
content: the general public still need to feel that the items on our shelves are ligit and meet all the saftey criteria.not only cheap fly by night marketeers but from the big retailers .myself car phone chargers worry me most.a lame program though i must admit.hands up who leaves things plugged in over night ? me

author: G7PSK
author_rank: Super Contributor
timestamp: June 09, 2012, 11:59:10 am
content: They interviewed a woman whose son was supposedly killed by using a fake Nintendo or gameboy charger. Not sure how that worked as I did not see the whole program and instead of working one story right through they keep chopping about from one story to another to keep the 30 second attention span viewers happy.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 09, 2012, 01:23:14 pm
content: QuoteThe problem is that if they sex up the TV content, it potentially discredits the whole safety message, not just the bit they exaggerated.

author: G7PSK
author_rank: Super Contributor
timestamp: June 09, 2012, 03:21:28 pm
content: Quote from: iamwhoiam on June 09, 2012, 02:24:53 pmI don't mean the boy was not killed and i don't mean he was not killed by the adapter What I meant is they do not state what he was doing to the adapter. And on the other hand I do not take what I see on the TV as gospel either, but perhaps the word allegedly might have been a better choice, it would not be the first time that TV programs have used creative licence to emphasize a point or to deliberately mislead.

author: _Sin
author_rank: Regular Contributor
timestamp: June 09, 2012, 03:40:02 pm
content: The child in question, Connor O'Keeffe was killed in Thailand, plugging in a charger bought for him in Thailand.The local authorities claimed he had wet hands, as he'd just been in the swimming pool. His family deny it.A possibly preventable tragedy. Nothing, however, to do with "Fake Britain" IMHO - not entirely sure why this was relevant to the programme, other than to spice up the segment...

author: Fraser
author_rank: Super Contributor
timestamp: June 09, 2012, 04:43:46 pm
content: I have several of the white USB chargers that were condemned on the program. I have to admit I bought them for 99p each, delivered from China for Free ! I can see why retailers would be tempted at the potential profit margin.I have opened one of the chargers for your perusal. It was better inside than I had expected and I have seen far worse designs in some 'official' mobile phone chargeres. I believe the problem related to the L & N pin insulated shrouding, or lack of finger guards, and possibly not the electronics....that really wasn't made that clear in the BBC's program. I was going to bin the chargers but see what you think..... the PCB has decent HV/LV separation but who knows how good the transformer isolation is.Its interesting to note that there are a lot of components not fitted on the PCB, most notably, the full wave input rectifier has become a single diode half-wave reactifier. Possible cost cutting or maybe this charger can be made to produce different outputs and currents for non-USB applications. The unit in the BBC video appeared to be a hard-wired cable output. There is also an 'IC2' not fitted in teh ouput circuit... possible a linear regulator ? IC1 for those who are wondering, is the Opto-Isolator SFH617A. There is no fuse on the inputs and no spike protection.Aurora

author: G7PSK
author_rank: Super Contributor
timestamp: June 09, 2012, 04:49:07 pm
content: If you have a megger you could find out how much isolation there is that transformer. Mind you that does not tell you how well they stand up to getting warm but you could put it in an oven before the megger test.

author: Fraser
author_rank: Super Contributor
timestamp: June 09, 2012, 05:18:12 pm
content: Nice idea :-)I can do better than a Megger, I own a lovely piece of kit designed for just such tests. Its a HIPOT non destructive tester that can produce up to around 30kV, if I recall correctly, and measures the leakage current unitil insulation breakdown occurs. Its interesting that they call it non-destructive as I thought that once the insulation failed, the item was unsafe ? It may be that the test is a go/no-go on the insulation at a specific maximum voltage.I've had the unit years and have only used it to detect HV leakage in car ignition secondary circuits where it was great for finding cracked or porous insulators. Sadly the unit is a tad heavy so it still resides at my other house, so this test will have to wait until I have the time to get it.I attach a picture of a Danbridge JP30A unit that looks to be the same type and manufacturer as my unit (bought from Radio Spares) is RS branded.Aurora

author: tom66
author_rank: Super Contributor
timestamp: June 09, 2012, 09:13:33 pm
content: Most of these AC adapters are built around a fairly simple self-resonant oscillating ringing choke converter.It's a simple circuit but it has a few issues. EMI (especially if there's no filter) isn't great and efficiency is about 75-80%. Short circuits up to 1 ohm or so are tolerated (output drops to limit current to ~1.2A), below this the auxillary winding gets starved, and the MOSFET goes into self destruct mode.Most common failure will be C9 probably. If C9 ESR goes high (>0.1 ohms), output voltage drops. Most cheap chargers omit the extra LC filter but then you get a lot of noise on the output.The -really- cheap ones omit the feedback loop, and tweak the duty cycle, but it doesn't work for more than 100mA of load.But it does work from 100 - 265V AC and will give a stable 5V, 1A. And it would probably cost under £1 to produce it.

author: Unknown
author_rank: Unknown
timestamp: June 10, 2012, 12:20:15 am
content: Quote from: G7PSK on June 09, 2012, 03:21:28 pmNo allegedly about it, you were right the first time! particularly when it appears the great danger of it all is some ab sense of save thyself finger insulation. Still Earl has his quota of conversions to get in so he's out to save you from the sin of cheap plug-paks. Go figure.