What's with wall warts?

Shouldn't be hard to find a replacement.

--
Les Cargill

Already ordered from Amazon. But bench supply makes for instantaneous getting system back-up ;-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Do you leave them plugged in and energized?

I have an old blank CD 100 pack lid that I use as a bucket for them and place it near the outlet. when I want to charge something, I dig the correct device out of the bucket and plug it into my 6 way outlet adapter, which allows such typically oversized devices to reside next to each other.

Wow... those are actually pretty beefy in my experience. well, the ones which Linksys made were. After Cisco bought them and what Cisco uses on their stuff I cannot say.

Those last a while. Just be sure to current limit it so that if something fails on the device end, it will not get baked by the power feed end.

Electrolytic caps on switcher supplies have a lifetime of about 3 to 5 years if used continuously. This is due to poor grade capacitors. We've fixed many routers and monitors by replacing capacitors. Heck, I've even seen capacitors go on non-switching supplies (caused a large electrolyte vapor cloud!), but I think that was a counterfeit part.

Caps, and switching supplies can have the startup resistor or the semis die. Also the RoHS solder joints and Chinese assembly may not be so great.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

This one probably pre-dates RoHS. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     | 
| Analog Innovations, Inc.                         |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| Phoenix, Arizona  85048    Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.

Yes. The conspiracy theory is that components are selected to survive no longer than the warranty period.

Check your AC voltage. It may be on the high side.

Yes. Also sometimes a thermal fuse. Linksys makes two types of wall warts. Your antique is almost surely just a transformer, diode bridge, and electrolytic capacitor. To provide minimal voltage regulation, the transformer is run just below saturation, which causes some heating. The newer types use a switching power supply. They draw no power without a load, are more efficient, but are more sensitive to power line transients. They also tend to spew EMI/RFI. As usual, they kill electrolytics:

Ummm... yeah, that's ancient. There are 4 different hardware versions. From the release notes, the earliest version was Aug 2000 and the latest was last updated in Sept 2009. Yours is somewhere in between.

Need some spare wall warts? That's about a 3 week collection at the local recycling center.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

I think it's more a design spec than a conspiracy.

Looking at a typical specs of the internal parts of a linear wall wart- at full rated current, the winding temperature rise is 70°C. At a 30°C average ambient, if we assume the temperature in the wall wart interior rises only 15°C (say half rated current), and 10°C internal cap heating from the ripple current, we'll have the cap at 55°C. With a 105°C/2000 hour rating, we should get

Life = 2000 hours * 2^((105-55)/K) where K is 10-15

Assuming K is 15, we get a life of 20,000 hours. Plugged in all the time (24/7) that's about 2-1/3 years.

Run it at full rated current in a high ambient and you'll be at a small fraction of that.

There are caps that will last longer, but they're too expensive to use in an AC adapter.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

My first clue of a conspiracy was about 15 years ago, when I was fixing a Sony CRT monitor (in the days when Sony made complete monitors). It suffered from the usual electrolytic capacitor failures. On any other brand, I could replace one or two caps, and it would work. However, on this Sony, I discovered that a rather large number of caps failed an ESR test, making repair uneconomical. Inspecting the components, I noticed that there was a wide range of rather strange voltage ratings on the electrolytics. In the past, I would see dozens of electrolytics in a small number of standard values. In this Sony, I saw a rather wide assortment of values and voltages. I didn't do any lifetime calculations, but my impression was that the voltage ratings were calculated for some target lifetime, and no more. The result was near simultenous failure of all the caps.

That sounds a bit on the low side. Let's see how it compares with one of the online capacitor lifetime calculators: For the wall wart, I used: L1 = 2000 hrs Load Life Rating Vr - 16VDC Maximum voltage rating of capacitor Vo - 12VDC Operating voltage of application Tm - 105C Maximum temp rating of capacitor TA - 30C Ambient Temp. which results in 483,000 hrs or 55.1 years.

Sheesh, no input box for ripple current. Plugging the same numbers into the above equation: x = (Tm - Ta + Tr) / 10 = (105 - 30 + 10) / 10 = 8.5 L2 = L1 (Vr/Vo)*2^x L2 = 2000hrs*(16/12)*2^8.5 = 2,666*362 L2 = 965,000 hrs = 110 years

Here's yet another formula: L2 = L1 * 2^(T1-T2/10) = 2000 * 2^((105-30/10)) = L2 = 362,000 hrs = 41.3 years

Assuming that I'm not making any of my usual math errors, there seems to be a discrepancy between the various methods of estimating capacitor life.

There are extended life capacitors, with up to 10,000 hrs rated life for commodity components. I don't have a clue on pricing. Example:

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Or 9.7 years using 55 C for the ambient.

I assumed 55 C temperature, so you'd get 7 years with that formula. The transformer core and copper loses and capacitor ripple current both heat the cap (plus a bit from the diodes and thermal fuse), and the adapter will heat the air around it to some extent. If the ambient is 30°C (ambient for the adapter), the cap will be warmer when the adapter is plugged in and much warmer when it is doing something.

Some of the crappier ones even use 85°C caps. Some of them use crappy lams so they run quite warm to the touch even without load. I'll bet some Chinese caps are 85C marked as 105C.

The ones I spec'd I had reasonable confidence they will last 5 years under normal use (so far, so good), but I don't think it would be harder to consistently kill them faster than that.

Sure, they are just estimates.

From the prices I've seen, it would cost ~10x as much to use the cheapest such 10K-hour caps (maybe doubling the cost of the adapter). They're also physically larger, pushing up the size of the case, pushing up the size of the packaging, and allowing fewer units to fit in a TEU, so increasing sea shipping costs.

If you can get, say, 7+ years typical life, and 99% will last more than 5, meet all technical specs and safety requirements, as well as meet the price point marketing wants, what would you choose?

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Oops. I assumed that ambient meant room temperature or ambient for the entire thermal system, not the maximum capacitor operating temperature. It would have been helpful if the various web pages had specified operating temperature, not ambient temperature. Using 55C results in more realistic lifetimes. Thanks.

I've seen the cheap phenol PCB's under the diodes appear somewhat scorched from overheating. I haven't seen that under the capacitor.

Using my IR gun type thermometer, the warmest wall wart I could find in the house was 35C, with an (ambient) room temperature of 18C. Obviously, the insides will be warmer, especially if the wall wart is running into transformer core saturation. All of my switchers are the same as ambient.

Yep. The electrolyte in 85C caps boils at about 125C, while the 105C caps boil at about 190C. Other than that, there's not much difference between the two types. If you can keep the temperature low, 85C works just as well as 105C. Above 100C(?), the 85C cap develop increased leakage current, while the 105C doesn't leak.

On a previous cost cutting expedition for a former employer, I recommended switching to 85C caps. Total parts cost savings would have been about $0.40/radio or maybe $5,000 over the life of the product. The reaction was predictable as I was immediately accused of being a heretic, enemy of the state, and in league with the devil. Walmart quality was thrown in several times. Although it was decided that the possible gain was not worth the risk, I took the time to replace all the 105C caps with 85C caps in the radio, attach thermistors to all the major electrolytic capacitors, and run a 30C to

70C temp test in the env chamber. (The reason for the 30C is that we were low on CO2 for cooling and I didn't care about low temperatures). Since I had to do this anyway to run a preliminary test on some of the other cost cutting measures, it was an easy test. Since there were no ripple current, there was no self heating, so the capacitor temperatures matched that of the oven. I ran a few basic tests and found nothing that would suggest performance deterioration or failure. Upon presenting my results to the committee, I was again labeled a heretic, etc...

Of course. Why counterfeit a marginal product when the better quality product is more sellable. Extra credit for fake mil-spec markings.

Capacitor brands that work are a favorite topic in the numerous "Bad Caps" forums. What most people seem to ignore is that all the capacitor manufacturers offer different technologies and formulations. Some work, some don't. If someone designs a board which requires high quality low-ESR caps in order to keep the self heating down, and someone later substitutes a different grade from the same manufacturer, of course it's going to fail. It's like buying anything solely by brand name. Every brand has its winners and losers.

Ouch.

It's usually not my decision. However, the cycle seems to be to initially specify the best quality parts. Contrary to what common sense would suggest, Rev 1.0 usually works fairly well. However, just before the product hits volume production, the cost cutting committee arrives and substitutes the absolute cheapest parts that can be found. When the failures and returns start piling up, an over priced consultant discovers that none of the production units were actually built according to the original parts list. Someone mumbles something about depleting the current stock, so the failures and returns continue to pile up. Better quality parts are eventually introduced just before the product is labeled end of life.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Somehow , it sounds like you are talking about our current pool of political 'officials'. And that is truly sad.

They'll both work okay at, say 40°C, but according to the formulas, _all_ things being equal, 105°C caps should last about four times longer than 85°C caps.

That's why I spec them, not because I think it will ever get to 85°C. They don't cost that much more, are not that much bigger and have a plethora of sources. I also like to have a generous margin on the WV (which one of the forumulas indicates would have an effect on the life- it tends to make the cap a bit bigger and helps dissipate power from the ESR). In both cases, I'm not sure what the real effect on life is, but I have had not had to revisit the choices, which is good.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

In another country, I found an alarm wall-wart, 18V/500 mA or so. It was a 50 Hz country and the line voltage was 125VAC+.

It had sagged; no longer a rectangle, it had become a parallelgram, with the wall-edge now ~1" higher than the sagging outer face...

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A host is a host from coast to coast.................wb8foz@nrk.com 
& no one will talk to a host that's close........[v].(301) 56-LINUX 
Unless the host (that isn't close).........................pob 1433 
is busy, hung or dead....................................20915-1433

What you describe is 'design' and not 'conspiracy'.

Look, you do not have the choice of making an eternal device because everything fails sooner or later so you can either Que Sera Sera, whatever will be will be, or design for a target life.

Now, given this fact, why would you expect someone to design 'section A' for life expectancy X and 'section B' for life expectancy Y when, if either fail, the damn thing is broke?

If X is too short you've missed the target and if Y is too long you're wasting money.

Unfortunately things are not that 'precise' and failures are 'rates' rather than a deterministic point in time. This makes things more difficult for designers and companies but puts the lie to 'conspiracy' theories because you simply can't design 'so it fails as soon as the warranty expires', which isn't the purpose of a warranty to begin with.

Component failures are 'higher' in the 'early hours' of operation, I.E. infant mortality, drop to a low, and then, as EOL approaches, increase again. Infant mortality is generally due to some form of manufacturing defect (which means process improvements can have a big impact) and is what a warranty is intended to cover so, in fact, after the warranty one should generally be able to expect more 'trouble free' life. You are 'over the hump'.

However, since these are all probability distributions over large sample sizes there will always be 'some example' one can point at to supposedly 'prove' any 'theory'. There will be 'one' that seems to last forever, the 'last one to die' (I love these things. Mine lasted 'forever'), and, if you made enough of them, 'one' that failed 2 seconds before, or past, the warranty period.

One persons idea of proper design is another persons conspiracy. It's all a matter of perspective. The gray area between the two is a very awkward place to work. I was asked to cost reduce a product I had designed about 3 years previously. I did my best but didn't hit the required "target" price. So, the problem was handed to someone else, who's idea of cost reduction consisted of removing components until the radio ceased to operate. I had designed it to work from 10v to

16.5VDC over a wide temperature range. It was better than what was required. When the cost cutting was done, it mostly worked at room temperature and would only work between 12.5 and 15.0VDC. I tried to keep my changes within FCC guidelines, but such radical changes should have required Part 15 recertification. I kept my mouth shut. Bottom line is they took a decent radio and turned it into a pile of junk. When the problems appeared both on the production line and in the field, I was recovering from surgery and missed the opportunity to tell them the obvious. Design or conspiracy? I would call it a conspiracy.

Question: If I double the useful life of an electronic product, have I also cut sales in half?

While various organizations pride themselves in recycling eWaste wherever possible, the same organizations are clueless as to why such products end up as eWaste in the first place. While various EU governments are pushing for cradle to grave "ownership" of electronics, where the manufacturer is responsible for disposal, the same governments seem to have little interest in extending the life of products. While various ecologically correct groups are extolling the virtues of keeping lead out of the environment, the same organizations are oblivious to the effects of unleaded solder has on the life of electronic products.

What fact? That failure is inevitable and that we should tolerate both the causes and the consequences? We all die eventually, but is that an excuse to live a worthless life?

In the not so distant past, I designed marine radios where the customers genuinely expected the radio to last the life of the vessel. The company offered a genuine "lifetime" warranty on it's products. Over the 10 years I spent at this company, I was seeing many older radios arriving for rebuilds and repair. Discussing the situation with management, they indicated that their customers would not buy their higher priced products without the lifetime warranty. They didn't want to do it, but it was a business necessity.

Enter Walmart, China manufacture, and cellular phones, all of which institutionalized the concept that products should be temporary, a warranty is a good substitute for quality, and that it's perfectly acceptable to trash 450,000 cell phone PER DAY. When I was doing radios, I was looking at a product sales life of about 5 years. Todays computers are sold for maybe 3-6 months before the new model arrives. I can see a product being recycled after normal wear and tear. I fail to appreciate the same from intentionally designed obsolescence and calculated component failure.

So, fix X so that it lasts longer.

True or false? Products with a longer life are better (for the buyer)?

The purpose of the warranty has changed over the years. It was previous a method of dealing with occasional workmanship errors and oversights. It's now the standard method of dealing with shoddy construction, design defects, misuse, and clueless customers. Many products have such a short lifetime, that there's no incentive to fix production line problems, especially when the next THREE generations of replacement products are already somewhere in the design cycle. By the time the complaints come back from the field, the product is already long obsolete.

Bathtub curve. The difference is that we never seem to get to the old age, wear and tear, type of failures. Instead, things literally break quite early in the curve. Eventually, the flat bottom of the bathtub curve starts looking like a "V", with the warranty period at the apex of the "V". If the goal is to sell more gizmos, then that's the ideal. If the goal is to keep the stuff out of the landfill, it's disaster.

Yeah, I guess, whatever all that means. Reading between your lines, I'll guess you're trying to rationalize the current trend in intentional decreases in product life, durability, and usability. I would be interested to hear how such things improve the quality of life, the environment, and the reputation of the vendor.

If we assume that intentionally targeting the product life at slightly over the warranty period is undesirable, that begs the question "What can we do about it"? I have some answers, but they all reek of government intervention and meddling. The best that I can offer is to give the manufacturers and vendors a counter incentive to NOT make throw away products. That will raise costs, but since the rate the consumer buys new gizmos will be correspondingly reduced, the overall cost to the consumers will be about the same. Creating a fashion where used products are considered desirable might also be useful. At this time, shinny new products are some kind of status symbol. If that could be replace with "used is beautiful" or something similar, there might be an incentive for manufacturers to extend the life of their products.

[Q] Is a civilization based on throw away everything sustainable?

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

It's still possible to learn from problems in the field and feed that into design or purchasing. For example, brand-X caps don't last as long as brand-Y, or all brands of caps die too early - maybe we are running them too hot.

It would be interesting to get lifetime data on consumer electronics.

Does anybody like Consumer Reports collect and publish it?

--
These are my opinions.  I hate spam.

This one only lasted a year (1951-52)

Bad management, not conspiracy.

"Never attribute to malice that which is adequately explained by stupidity."