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Operating caps well below rated voltage
I think this has been answered but I couldn't find the thread.
Someone asked me if it would harm a capacitor (10F [not a typo], 24v) if it was operated on nothing more than 12v.
So, I ask... Does it change any of the capacitor's characteristics/parameters/? in any way if it is never operated near rated voltage?
If operated for years at 1/2 rated voltage, does it accept full rated voltage like it would if it had always been operated at the higher voltage?
Or would it require reforming?
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The positive terminals are welded, internally. The negative terminal's internal connection varies. I've seen conductive epoxy, solder, silver adhesive... If this problem is new to those who frequent this forum, it's likely not an issue in real world use. I think what I read was for hand soldering....
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The back-back electrolytics are commonly used but they don't use the diode. The reverse voltage applied to one cap on each half-cycle doesn't seem to be a problem (doesn't cause failures). I don't know if it's common for other circuits that use caps in this way but they use two capacitors with 2x the rail voltage. For ±80v rails, they use two 200v caps in series....
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Tantalum Capacitors and Heat Sensitivity
I remember reading somewhere, years back, that tantalum capacitors are sensitive to heating on their negative terminals and using more than a minimal amount of heat could result in damage. Is this/was this ever true?
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That's what I've been using. They work perfectly but there isn't always space for them....
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The primary-side filter caps can take a beating and those are the only ones that fail in some amps. Other amps have caps of various makes and series that fail throughout the amp, even in linear voltage regulators for the ±15v op-amp supplies. I'm sure that this is one of the questions that could never be answered definitively with so few specifics. I always blamed heating during assembly and wanted to know if is was ridiculous or something that could cause problems....
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Capacitors of the same make/series that consistently fail in one amplifier while they rarely fail in a different make amp
This is for car audio amplifiers but I doubt that matters. There are amplifiers that use the same make/series capacitor as a different manufacturer and they consistently fail in one brand. In the other they are OK. The amplifiers are from the same era. Is it possible that the heating profile used when flow-soldering the boards could be the reason for the failure? If not, any ideas on what the difference could be?
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It's refreshing to hear the voice of sanity when it comes to capacitors. The 'it depends' is perfect. I constantly deal with people who are going to replace every capacitor because people on the internet told them it's the right thing to do. And of course, after replacing the perfectly good capacitors with new capacitors, the improvement is night and day. The one I like the best is that it 'opens up the soundstage'. Another thing they love to do is to resolder every solder joint which typically leads to a bridge that they can't find in an amp with no available schematic diagram....
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samwha capacitors 10uf 200v/250v
The attached capacitors are used in the output filters of class D amplifiers and hold up well but when they fail, replacements are difficult to find. I've tried the various options on eBay and crossover caps and none survived. Mouser, Digi-key... don't stock many bi-polar electrolytic caps. The only thing that I found survived (never a failure) was the Mouser E2106 (part number 667-ECQ-E2106JF) and the same from Digi-key. They look different but survive. Does anyone know a readily available drop-in replacement electrolytic? The dimensions are approximately 16mm x 25mm....
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I was hoping to hear that the manufacturers bought back all defective caps but it's more likely that they were sold.
Yes. Amazon and Ebay are bad for counterfeits, especially obsolete semiconductors, which they always have readily available.
I don't see much on Cornell Dubilier caps. I used quite a few and still recommend them. Is there a reason they aren't commonly mentioned? Quality? Price?
I deal with a lot of people (tech support) who blindly replaced capacitors (many plague caps) in their beloved collections (mainly amplifiers) and put them into storage....
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Unsold Plague Capacitors
What are the chances that plague capacitors are still in stock and being sold?
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