ECN Forum Forums Photo Discussion Forums Photos for General Discussion Improper protection of "wall wart" supply (U.K.)

Yes, it was screwed together, but with screws having a peculiar head for which I had no tools. Why can't they just use [/quote] regularly slotted or Philips on something like this?
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What? You dont have TORX scewdrivers?:)

Simple--they don't want people to be able to repair it.

TORX isn't much of a deterrent anymore, even the ones with the center pin can be found at the orange and blue box stores.

The tamper-resistant screws nowadays have triangular or 5-sided socket heads, or a 2-hole "spanner" type of drive arrangement. Then there are the ones that are ramped so they drive in with a standard slotted driver, but cannot be backed out without heroic measures like vise-grips.

Paul:

For quite some time here in the US, the common door chime/door bell transformers were made to deliberately burn open the primary winding as a fail-safe. They were not supposed to get so hot as to ignie anything, but the end result would still be very hot to the touch.

I think now more of these transformers have the themal one-time fuse imbedded in them, IIRC some areas require them as a local admendment to NEC.

And my days spent servicing CCTV gear, the early plug-in transformers had no fuses and would literally go up in flames if shorted. (I metered one once, normal output at 24vac was one amp max, shorted it was pushing over 8 amps as it burned up!!)

It could be one of those xfmrs designed so that primary burning out is the protection I suppose. I'm not sure that this would meet the BS1363 standard though, since that specifies that each point of connection must be protected by a fuse of 13A max.



Sure I do, but the heads of the screws on this appear to need some sort of odd tool with two small rectangular prongs to fit.

As NJ said, they don't want anything to be repairable anymore. If this had used normal screws and had a fuse fitted, I'd have reterminated the damaged cord, dropped in a new fuse, reassembled and all would be right with the world. As it is, there's nothing can be done but to throw it in the trash.

We live in a throw away society fixing anything is not worthwhile,meanwhile people are crying "save the earth" while creating a mountian of garbage mostly from the PRC.
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Someone here said,"Buy well, buy once".

I don't know what the standard for these types of power supplies in the UK but the N Am standard requires a throw away design. It looks like a class 2 supply and any short on the secondary should render the supply as garbage. it might be done with a fuse embedded in the primary winding or fuseable wire and an over temperature bead. Once they open you throw the supply away. The cases should not be openable. IE plastic welded but no screws.

There are an amazing variety of oddball screwhead designs out there. A good overview here:

http://www.lara.com/reviews/screwtypes.htm

Note specifically the "tamper-resistant torx-plus", which is licensed/copyrighted, and only sold direct from the manufacturer, AFTER you provide specific info on what you need them for!

What's next, having to register our toolboxes as "copyright circumvention devices" under the DMCA or Patriot Act?

Back in the days before the Australian ones had thermal fuses, I watched the casing of one just melt in front of me. The ones with internal rectifiers are the worst with cheap under rated diodes fitted, which of course become a short circuit when they fail.
The cheap lossy transformers with welded together laminations certainly don't help with the heat situation either.
It is interesting to note that in recent years the better quality plugpack transformers are fitted with screws to hold the case together. I suspect this may have been done because of when people have cracked open the case to repair it and then not being able to secure the case together properly resulting in an unsafe situation(ie. lots of insulation tape wound around it or the wrong kind of glue).
Actually, the secret to getting a welded case apart (also for battery packs), is to place the item in a vice along the weld and gently apply pressure. Once it starts to crack you can gently lever along with a screwdriver.

Interesting stuff,
I used to get this thing all the time as an Appliance repair-man.
With the never ending formats that companies provide to prevent people from opening the cases on perfectly good appliances, that only need a fusible link replaced, because the said appliance was used either longer than it's miniscule duty cycle, or someone let the thing overheat.
Now there are here in NZ, a couple of new security screw formats, the Tri-wing and the (as Paul was referring to above) the Modified Snake Eyes bit.
I ground a screwdriver down to accomodate the MSE and hardened the tip.
The Tri-wing is a bit harder to get, but a search on Radio Spares components found me a whole set of the things.
This disdain of mine comes from trying to convince customers that a $300 Toasted Sandwich Maker is not merely junk, because the label on the cord says Do not attempt repair, this appliance if it stops working, please discard responsibly
How can you win?.

How about we put it all on a boat and send it back to Red China?

It's all geared toward simply getting people to buy a new whatever-it-is.

They were out of luck with this modem supply though. A quick search through my "junk" stockpile revealed a spare "wall wart" which was a suitable replacement. It was a D.C. unit, but with a tapped xfmr and normal fasteners holding the case together. Five minutes with screwdriver and soldering iron and we were in business again!