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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Changing the electrolytic capacitors in vintage tube gear is a must
these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). |
#2
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#3
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On Monday, 11 February 2019 06:32:57 UTC, wrote:
Changing the electrolytic capacitors in vintage tube gear is a must these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). The main cause of failure for modern caps is that they're run at high ripple current, something that does not happen in valve equipment. If you want best reliability, get 120C rated caps rather than 85 and look at their mfr rated lifetime expectancy. If you plan to send it to the moon, for extreme reliability for small values on HT, put plastic film caps inside the old cases, choosing higher v ratings & putting 2 in series. Then vacuum pot them. This is of course not necessary ![]() NT |
#4
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On Monday, February 11, 2019 at 5:32:57 PM UTC+11, wrote:
Changing the electrolytic capacitors in vintage tube gear is a must these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). ** You are so full of ****. Any of these "snap-in" types will replace the high voltage electros in tube amps with advantage. If more then 450V is needed, connect two in series. https://www.google.com.au/search?ei=...450v+snap+ in Out last you for bloody sure. ..... Phil |
#6
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On Monday, February 11, 2019 at 1:32:57 AM UTC-5, wrote:
Changing the electrolytic capacitors in vintage tube gear is a must these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). Mouser.com DigiKey.com And any of a dozen other suppliers will be glad to take your money and send you pretty much _exactly_ what you need. Need multi-section caps? There is AES, Parts Express and half-a-dozen others. There is a company in Germany making Cornell-type cans on OEM equipment, but using modern materials. And CE Does it right here in the US: https://www.cedist.com/products/capa...0Manufacturing Remember, it is ONLY money. Peter Wieck Melrose Park, PA |
#7
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#8
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On 2/11/19 9:43 AM, Ralph Mowery wrote:
Remember the computer boards that had capacitors on them that only lasted about a year ? A friend and I had to send back several boards to one of the big computer board and part suppliers , but that was about 20 yars ago. That wasn't because of modern capacitors. That was because the bean counters at Dell went with cheap counterfeit caps that were ****. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
#9
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#10
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#11
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#12
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On Monday, 11 February 2019 15:43:50 UTC, Ralph Mowery wrote:
In article , says... All of the new "small modern" caps will out live you. I would not sasy ALL. Remember the computer boards that had capacitors on them that only lasted about a year ? A friend and I had to send back several boards to one of the big computer board and part suppliers , but that was about 20 yars ago. You may say the quality capacitors will outlive most of us. Even the big name companies have problems. I have some test get that I bought surplus when the cell phones went from the 800 Meg to higher frequencies. The $ 50,000 piece of gear had capacitors go bad in the switching supplies. That was made around 1995 so they only lasted about 20 years. I don't know how long they will last, but I just bought a lot of capacitors from China off ebay. About a dozen of them are in use in my equipment and have worked for the last 3 months. They may or may not go out today. I would not put them in equipment that I was repairing for anyone for money, but this isfor my hobby work. I don't think you're understanding why they died. NT |
#13
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On Monday, February 11, 2019 at 12:04:17 PM UTC-5, Chuck wrote:
On Mon, 11 Feb 2019 00:32:54 -0600, wrote: Changing the electrolytic capacitors in vintage tube gear is a must these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). Panasonic and Nichicon. When I build (or rebuild) something for myself, I always go with Panasonic capacitors. |
#14
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#15
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On Mon, 11 Feb 2019 10:05:09 -0800, wrote:
On Mon, 11 Feb 2019 00:32:54 -0600, wrote: Changing the electrolytic capacitors in vintage tube gear is a must these days, but no one makes the old style (large size) caps anymore. I personally do not trust these small modern caps to last very long. Many computer motherboards have proven how short the life span is on modern caps, and most of them are low voltage types. Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern caps will last even 10 years. I tend to wonder if that is because of their small size. Or is it just the construction or materials used? There are some NOS (new old stock) caps available, but they fail regardless if they were used or not, since the electrolyte drys out and moisture may enter them as well. I dont mind changing caps on vintage gear once, but if I have to change them every 5 or 10 years, I will not be happy. But since new caps are no longer made, which are made the same as the old ones they are replacing, I have little choice but to use these small modern ones. That leads to finding brands which are reliable. And I assume price tells all. Cheap imports are likely the worst, while high priced US made ones will last longer. I doubt any modern caps will last even close to the life span of the old ones, but which brands are the best? (Particularly the ones used for high voltages in tube gear). Yeah, I totally agree with you. The new smaller modern caps just can't last. A perfect example. My Pioneer SX-434 is only 46 years old and the ****ty small caps in it must be getting ready to fail. Even though I listen to it every day and though there is no degradation in the tuning or the sound I just know the caps must be getting ready to fail. They are just so small. Eric When you finally have a failure, I would replace all Sanyo brand capacitors. |
#16
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On Mon, 11 Feb 2019 13:32:07 -0500, Ralph Mowery
wrote: In article , says... On 2/11/19 9:43 AM, Ralph Mowery wrote: Remember the computer boards that had capacitors on them that only lasted about a year ? A friend and I had to send back several boards to one of the big computer board and part suppliers , but that was about 20 yars ago. That wasn't because of modern capacitors. That was because the bean counters at Dell went with cheap counterfeit caps that were ****. The origional post was about which brands were the best. That is why I said not all modern capacitors would last. I am sure there are lots of crap China brands of capacitors. I probably bought some a few months back, but they go in my hobby electronics. The boards I sent back were not Dell. They were some boards from a company that sold computer boards and parts that I put together a computer. The boards were high rated before the capacitor problem. I think lots of companies had the cpacitor problem from that particular capacitor company. One of the main things is that the switching supplies or high temperature are the main killers of the capacitors. Any of the good brand capacitors should last longer than most of us will be around. Yes, the original question was which caps are BEST, but much of my concern is based on the failed motherboards, which only lasted a year or so. Knowing the name used on these really bad junk caps would be useful to know too. I'm pretty fussy when I buy caps and some other components, but I do sometimes buy "grab bags" (like on Craigslist) if the price is right, and I know some parts will be usable. But knowing the name used on those conterfeit caps, or any others known to fail is good to know. If the caps are known bad, I am not going to use them for anything other than a breadboard test design, (or not at all). I'm curious what brand of motherboards were the bad ones too.... It's just good to know things like this. Just like every brand of car seems to have certain common failure or breakdown problems, and knowing what to check and watch for, is helpful. |
#17
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#18
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#19
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Fox's Mercantile wrote:
wrote: Yes, the original question was which caps are BEST, but much of my concern is based on the failed motherboards, which only lasted a year or so. Which, as usual, you didn't make at the beginning. The Failed motherboards were, Dell. Their "Lets buy cheap ****" almost put them out of business. And that was almost 20 years ago. ** This old Wiki has the story: https://en.wikipedia.org/wiki/Capacitor_plague The brands of capacitor involved were previously unknown and unable to be linked to any of the well known makers. AFAIK the issue never involved electros that might be used in restoration of vintage tube gear. "tubeguy" is a ****wit - see " top definition " : https://www.urbandictionary.com/define.php?term=****wit ..... Phil |
#20
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On Sun, 17 Feb 2019, Phil Allison wrote:
Fox's Mercantile wrote: wrote: Yes, the original question was which caps are BEST, but much of my concern is based on the failed motherboards, which only lasted a year or so. Which, as usual, you didn't make at the beginning. The Failed motherboards were, Dell. Their "Lets buy cheap ****" almost put them out of business. And that was almost 20 years ago. ** This old Wiki has the story: https://en.wikipedia.org/wiki/Capacitor_plague The brands of capacitor involved were previously unknown and unable to be linked to any of the well known makers. AFAIK the issue never involved electros that might be used in restoration of vintage tube gear. "tubeguy" is a ****wit - see " top definition " : A little knowledge can be a dangerous thing. People hear the stories, but don't grasp the details. Modern use of electrolytics is different from the tube days. Not only have values gone up as size got smaller, but they are often expected to handle much higher frequencies than 60 or 120Hz in the days of tubes. Electrolytics are also a lot more common in the days of solid state. In tube days, a bad one would mean low voltage, or hum, or low audio gain, but there were a handful of electrolytics. Now they are everywhere, a shift to low impedance so larger values needed, and that means electrolytics. The circuitry is now more complicated and a bad capacitor may not be so obvious as in the old days. Michael |
#21
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On Sunday, February 17, 2019 at 2:13:03 PM UTC-8, Fox's Mercantile wrote:
The Failed motherboards were, Dell. Their "Lets buy cheap ****" almost put them out of business. Oh, no, it's not that simple. Dell was publiclly traded, and made formal notice in their stockholder report one quarter, and that was big news. But, Apple had similar problems (trust me, I own a couple or three), as did everyone else. The faulty technology was widely rebranded and even given counterfeit labeling, and wasn't purged from inventories for some years. The bad capacitors weren't significantly less expensive than any others on the market, and turned bad only after a year or so (so incoming tests couldn't catch the problem). |
#22
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#23
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On Sun, 17 Feb 2019 16:12:53 -0600, Fox's Mercantile
wrote: On 2/17/19 2:11 AM, wrote: Yes, the original question was which caps are BEST, but much of my concern is based on the failed motherboards, which only lasted a year or so. Which, as usual, you didn't make at the beginning. The Failed motherboards were, Dell. Their "Lets buy cheap ****" almost put them out of business. And that was almost 20 years ago. It dont surprise me it was Dell. A friend had a Dell that was from the early 2000s. It had XP on it. It was so frikkin slow I could literally outtype it, using notepad. She asked me if there was something wrong with it. I changed some settings and that did nothing. Since there was nothing on the computer except a few free games, I formatted the hard drive and reinstalled XP. Still slow..... Heck, I had a much older and lower powered computer at the time that was running Windows 98, which was 10X faster than that Dell. A few years later I got an almost identical Dell computer given to me. I installed XP on it and was shocked to find it was just as slow as the friend's computer. I didn't even bother with it any further. I removed the drives and sent the rest of it to the recycler.... Things may be different with Dell today, but I will never buy any Dell computers, new or used, after that experience. I strictly use all IBM/Lenovo computers. They last forever. I still have one that works fine and is 20 years old. My newer ones I own are great too. |
#24
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