Power supplies with solid polymer caps
in [Repair]
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From: Jeff Liebermann on 22 Nov 2009 19:29 On Sun, 22 Nov 2009 17:26:02 -0000, "Arfa Daily" <arfa.daily(a)ntlworld.com> wrote: >As far as your contention that most of the caps that fail are running at >under 60 deg and are not in hotspots, that may be true if you are talking >just mobos, Generally true. This is old (2005) but the best I could find: <http://www.bigbruin.com/reviews05/nf4thermals/index.php?file=1> 6 pages. The hottest they found was 70C and that was in an odd corner of the MB for no obvious reason. More of the same: <http://www.bigbruin.com/reviews/thermalimages/> However, these show some chips getting up to 99C. Ouch. >fake electrolyte, the caps that fail are all decouplers on constant DC >rails, and are rated voltage wise pretty close to the continuous voltages >that are applied to them. Worse. The caps are not on constant DC. There are huge ripple currents going through these caps at they heroically try to filter the DC voltage. You wouldn't need low-ESR caps were it not for the heating caused by the internal resistance and this ripple current. It's even worse in power supplies. >However, if we take junk out of the equation, anyone >directly involved at the sharp end of electronic service will tell you, as I >do now, that over the last five years or so, the incidence of electrolytic >failure has increased a lot with the increased use of switchmode power >supplies in all sorts of consumer equipment, and the unstoppable rise of >Chinese designed and manufactured equipment, where many good design >practices, such as ensuring adequate ventilation, are not observed on cost >grounds. Yeah, but along with the general decrease in quality, there has been proportional decrease in price. It's price that driving the decline in quality. Running the operating temperature and voltages near the point of failure is one way to save on costs. >As to whether the increased process temperatures of lead free >soldering has had any effect on long term reliability of electros, I really >don't know for sure. I could be wrong, but it seems to me that over the last >couple of years, the incidence of electrolytic failure has increased even >more than the trend of the last 5 or 7 years, so it was just a thought in >that this was something else that had changed in that timeframe, and may >have been a contributory factor Good point. I have no idea if there is a correlation but it seems worthy of investigation. >> The real fault lies with the makers of junk, period. >Some of the fault lies with the makers of junk, agreed. But not all, by any >means. They wouldn't make junk if consumers didn't demand low prices. There are usually "premium" versions of almost any consumer product, but few can afford the price. (If you want quality, be prepared to pay for it). Personally, I prefer to blame the government for literally everything, but maybe not this time. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Daniel Prince on 24 Nov 2009 03:51 Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Thu, 19 Nov 2009 21:44:36 -0800, Daniel Prince ><neutrino1(a)ca.rr.com> wrote: > >>I have also read that there are >>motherboards with solid polymer capacitors. > >Sure. However, they're very difficult to identify without back >tracking the part number or chopping one in half and looking for the >black goo inside. The clue is that they tend to be short and not very >tall, while conventional electrolytics are much taller: Both Asus and Gigabyte make motherboards that they claim use all solid polymer capacitors. I doubt that they would lie about something like that. -- I don't understand why they make gourmet cat foods. I have known many cats in my life and none of them were gourmets. They were all gourmands!
From: Jeff Liebermann on 24 Nov 2009 13:09 On Tue, 24 Nov 2009 00:51:02 -0800, Daniel Prince <neutrino1(a)ca.rr.com> wrote: >Jeff Liebermann <jeffl(a)cruzio.com> wrote: > >>Yeah, but along with the general decrease in quality, there has been >>proportional decrease in price. It's price that driving the decline >>in quality. Running the operating temperature and voltages near the >>point of failure is one way to save on costs. >> >> >>They wouldn't make junk if consumers didn't demand low prices. There >>are usually "premium" versions of almost any consumer product, but few >>can afford the price. (If you want quality, be prepared to pay for >>it). >How much would the retail cost of a computer power supply or >motherboard etc. increase if they were made to last twice as long? >Five times as long? Ten times as long? The usual markup from cost to sales to retail prices is about 4.5 times. It's somewhat lower for commodity electronics, perhaps 3.5 times. It's somewhat higher for newly introduced products, where the R&D costs need to be recovered quickly. I'll call it about 4 times so I can do the math without a calculator. That means that for every $1 increase in parts cost, Joe Consumer gets to pay out $4 at the cash register. The problems start when there are competing products. I call it the Walmart effect. Walmart, Kmart, and many online vendors specialize in selling solely on the basis of price. If there are two competing products, differing only a few pennies in selling price, *ALL* their orders will go to the lower priced product, with nothing to the higher priced equivalent. Walmart aggravates the effect by setting the price at some artificial low level, and challenging their vendors to meet their price goal. If they fail, then they either take a loss selling to Walmart, or all the business goes to the competition. Much as I don't like it, such cut throat pricing practices are becoming the norm in computer sales. If I were to design and produce a premium and long life computer product, I can forget about the mass market, volume dealers, and most direct sales channels. I would have to rely on distribution and probably heavy advertising, which dramatically raise my costs. Do you think a $50 Monster Cable power strip is really any better than a $5 hardware store equivalent? It is a little better built, but the rest of the price tag is distribution and advertising. Incidentally, if you want to see premium electronics, the audiophile market is a good place. Need a $1,000 premium power cord? <http://www.audioadvisor.com/prodinfo.asp?number=KKPK14PAL> That's what it takes to sell a premium product. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Dave Platt on 24 Nov 2009 18:35 In article <1h7ng51khb8co7dq8pio9j4o94hpvjp3g9(a)4ax.com>, Daniel Prince <neutrino1(a)ca.rr.com> wrote: >How much would the retail cost of a computer power supply or >motherboard etc. increase if they were made to last twice as long? >Five times as long? Ten times as long? I don't know the specific numbers for those multipliers. However, I've seen some motherboards for sale recently which proudly stated that they use all solid-polymer caps in their CPU power supply circuit. They come at some price-premium but it didn't appear to be outrageous. -- Dave Platt <dplatt(a)radagast.org> AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads!
From: Daniel Prince on 30 Nov 2009 11:21
Jeff Liebermann <jeffl(a)cruzio.com> wrote: >The problems start when there are competing products. I call it the >Walmart effect. Walmart, Kmart, and many online vendors specialize in >selling solely on the basis of price. If there are two competing >products, differing only a few pennies in selling price, *ALL* their >orders will go to the lower priced product, with nothing to the higher >priced equivalent. Walmart aggravates the effect by setting the price >at some artificial low level, and challenging their vendors to meet >their price goal. It seems to me that there is a good opportunity here for other retailers. If a retailer sold only electronic goods that were well made and well designed, they could sell them for ten to thirty percent more than the junk sold at Walmart and Kmart. I think many consumers would be willing to pay a little extra for devices that would probably last four to ten times as long. This would be especially true if they had two (or more) cheap-junk brand devices fail. The retailer could require vendors to only use non-junk capacitors with voltage ratings at least three times the voltage the capacitors would be exposed to. They could also require that no part of the device ever get more than 30 degrees warmer than the temperature of the room it is used in. The devices could have much longer warranties and the store could advertise itself as "The quality store". I do not think this would require excessive advertising, especially after the first few years. -- I don't understand why they make gourmet cat foods. I have known many cats in my life and none of them were gourmets. They were all gourmands! |