Greetings Arfa & others..
Regarding: "It's an interesting observation. Can you elaborate as to what equipment you see a lot of them in and in which bits of circuitry ? Also, what is your experiences of them failing ? Has anyone else in any other parts of the world got any observations on this ?"
As previously mentioned, I've got several of them in an elaborate AT&T telephone that I've got here beside me. How do I know this? Sure enough, after about 10 years the phone started revealing a "BUZZZZ" on digitally recorded messages and, conversely playing those messages back. In fact, it was so bad that parts of the playback would be overcome in buzz or interrupted & blank. As expected the aluminized electrolytics were suspect. High ESR readings on many of them revealed that they were just getting hot in addition to their age in an area of more than warm DC voltage regulators. Both polarized and non-polarized are used in the circuitry. In fact, I've also seen this with various two-way equipment in addition to various audio equipment. Obviously, the audio applications can be in any type of electronics that passes or processes audio. Electrolytics, by their nature whether polarized or non-polarized tend to age and eventually dry up resulting in high ESR readings or poorly filtered signal/DC paths. It's for this reason that when I DO go back in to replace them, I absolutely insist on 105C parts. I don't even bother looking at the 85C parts anymore. I find it a bit disheartening to find (as I'm sure you've seen all TOO many times) at 6WVDC electrolytic on a 5V DC line. Talk about design-wise penny-pinching to an absolute extreme! I cringe when I see this in a [rather] expensive piece of electronics and replace them (when needed) with a capacitor with at least a 16WVDC rating at 105C.
I will grant you that we are rather spoiled over here in the states when it comes to component suppliers. After growing up in San Jose, CA. and calling Silicon Valley my home for more years that I care to divulge, we also tend to create a great number of designs & components. As you've mentioned, unfortunately in many ways, those designs are now days being forwarded along with manufacturing etc. to Taiwan & mainland China. In addition, there are MANY other countries that are now receiving such manufacturing plants and major operations. It seems that the domestic corporate decision makers for high technology want to do it ANYWHERE but here in the states these days.. Don't get me started on this as I'll end up writing a dissertation on the subject!
Since Mouser isn't all that far away and their catalog is sporting no less than 1490 pages with no minimum order, I tend to gravitate to them first. In addition, I've had the unfortunate experience here of late of ordering some electrolytics (polarized types) for the motherboard that I'm using right now. A quick background on that.. The previous owner noticed that it was resetting all the time and a quick glance revealed the infamous GSC capacitors out of Taiwan where the electrolyte formula was [supposedly] stolen for local manufacturing efforts. Apparently, they thought they could reproduce what the Japanese take pride in doing for substantially less money. Unfortunately, as later revealed by a multitude of failing motherboards from various manufacturers, the formula wasn't quite right... Result, most of the Taiwanese motherboard manufacturers are now incorporating excellent quality Japanese components (electrolytic capacitors) as they *should* have done from the beginning! Trying to save a few pennies resulted in a major black eye to the Taiwanese motherboard industry there for a while! I ordered some of those needed electrolytics from Mouser but, unfortunately, at 5mm L.S. In fact, what I *really* needed was 3mm L.S. I called Mouser and fully admitted that this wasn't their fault but mine! They said, no problem, we'll send the 3mm components to you immediately. I asked, what address to I send these 5mm parts back to, they replied, don't worry about it - just keep them. I've been rather satisfied with them ever since. Further, the ladies at the order desk are absolutely delightful to chat with on the phone - they just want to make you happy and get you the components you need. What I [typically] find is they've got
*exactly* the components you need and in the off chance they don't, they'll point you to who does have them. Of course, crossing a foreign component over to the "American" equivalent often has to be done - which can be a challenge in and of itself! But once done, I have found Mouser typically has the component.
Cheers, Mr. Mentor
"Arfa Daily" wrote in message news:TBSWj.10740$ snipped-for-privacy@newsfe10.ams... | | | > | I don't dispute that they exist in suppliers' catalogues, nor that | > they are | > | used occasionally in a variety of kit, but I think that anyone in | > the repair | > | business would agree with me that they are "fairly rare" in day to | > day | > | encounters with most consumer equipment of average quality and | > design. I | > | thought that was what I was conveying by using that phrase. Perhaps | > I should | > | have said "comparitively rare". To qualify that, I have in stock | > perhaps 500 | > | polarised electrolytic caps of maybe 30 different values. I use them | > on a | > | daily basis. Compare this to 5 each of two different values of | > bipolar | > | electrolytic. The last time I used one was probably 3 months ago in | > a | > | Musical Fidelity preamp (very expensive, and in my opinion not very | > well | > | designed). | > | | > | If you took 20 'average' service engineers, and asked them what a | > bipolar | > | electrolytic was, I'm willing to bet that probably seven or eight of | > them | > | would never even have heard of them, and fifteen or more would never | > have | > | replaced one, or had any in stock. | > | | > | As for them being in a telephone, that is a bit of a special case, | > with lots | > | of high level AC voice signals, floating on high DC levels. With | > signals | > | like this flying around inside, any coupling cap that needs to be | > big enough | > | to have to be an electrolytic, will of course need to be bipolar ... | > | | > | Arfa | > | | > | | >
| >
| "dBc" wrote in message | news:grPWj.111$ snipped-for-privacy@petpeeve.ziplink.net... | > Arfa.. | >
| > With the spelling as "polarised type" you may also be in the U.K or | > Australia... | >
| > Perhaps they're not all that common over there, here in the U.S. they | > show up in a variety of consumer and non-consumer products. Further, | > as illustrated by Mouser, they're not that specialized. No doubt that | > they aren't used as much as aluminum polarized electrolytic | > capacitors, but they show up in a variety of various electronics these | > days. If they didn't, the good folks at Mouser would have absolutely | > no reason to carry the variety of assortments they currently stock. | > Which further implies that there is a demand for them. | >
| > Cheers, | > Mr. Mentor | | You are correct that I am in the UK. I am frankly amazed at the quantity of | these devices that Mouser apparantly stock - although it has to be said that | they appear to be endlessly duplicating effectively the same product from a | lot of different manufacturers, but in slight variations of case style etc. | Digikey seem to also keep a good range, but nothing like as many as Mouser. | | Looking at Farnell's website (they are probably the joint biggest supplier | of electronic components in the UK) turns up just 22 items spread across a | limited range of 12 values. A similar search of RS Components (the other | joint biggest supplier) turned up just 35 items spread across 14 values. | Contrast this with 9154 entries at Farnell, and 3898 entries at RS for | normal polarised types. Applying the same logic as yours for Mouser, if | there was a big demand for them here, the two biggest suppliers of | components to both the domestic and industrial repair industries, would have | every reason to stock them in much bigger quantities / varieties? | | Compared to polarised types, I definitely see these devices only used in | very limited applications here such as coupling caps in some high end audio, | caps in speaker cross-overs, and sometimes as the coupling caps in voltage | multipliers for VFDs or as coupling caps for the filament supply on VFDs. I | can't actually think of many other applications where I would expect to see | them. | | I would think that most of the consumer equipment that we see here in the | UK, comes from the same Japanese / Korean / Chinese stables as that which | appears in the US, so I am a little puzzled as to why you seem to see, | apparently, so many more of these devices in use in equipment over there. | | It's an interesting observation. Can you elaborate as to what equipment you | see a lot of them in and in which bits of circuitry ? Also, what is your | experiences of them failing ? Has anyone else in any other parts of the | world got any observations on this ? | | Arfa | |