What are old Phillips caps from begining of 90's like? I also found Roederstein caps, as I read here they are part of Vishay now, but are these old ones better than now or total craps too?
15-20 + year old caps and very likely dried out by now.
Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
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Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr Seuss - You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
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The Panny without logos might be straight Matsushita instead of Panasonic.
Matsushita is the parent company.
They have made caps from time to time but they don't do retail [only sell direct to manufacturers] so they might feel they don't need a series mark as they are essentially made-to-order and bypass the normal distribution network.
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Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr Seuss - You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
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Thanks for the info, I think I've encountered the Chemi-con logo with dot once, labeled United Chemi-con. I hope the Sam Young caps have some quality if they make caps for Chemi-non from time to time (hope they do not make the known problematic series ).
As for the Panny/Matsushita, these are from old CD-ROM drive, I'll be attentive to re-use them only out of PSU's :
Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts
The danger [one of them] of using old caps is that electrolytic caps reform in service.
Reform means the thickness of the aluminum oxide layer [which is the dielectric] changes.
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The thickness of that layer determines how much voltage the cap can handle without [what I will call] microscopic arcing between the plates. Once that arcing starts it gets worse quickly because the arcing burns off even more oxide layer leading to more arcing. The cap is 'done' at that point. It's on its way to becoming a short.
A used cap might say 16v on the label but if it has been in a 2v circuit then -now- it is only a 2v cap. [The oxide layer got thin in use.]
I hope that makes sense.
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Old but unused electrolytic caps have a similar problem because the oxide layer in unused electrolytic caps gets thinner over time.
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The oxide layer in lytics can be restored through a process called [what else?] reforming.
- There are as many different methods as people that do it...
Here is the Basic idea, look up more info on it if you plan to try it.
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Use a DC power supply with an adjustable voltage and a resister [to limit current] and apply a small voltage [1 or 2 vdc] to the cap[s].
[This can be done in batches of caps vs one cap at a time.]
Then every 10 minutes or so raise the voltage 1 volt until you get to the voltage marked on the caps.
Let it sit at rated voltage for 20-30 minutes.
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This will bebuild the thickness of the oxide layer without any internal arcing.
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[At the factory when caps are first built [depending on what the caps design can handle] they go to 120% to 150% of the rated voltage but that is to increase shelf life and isn't needed for caps you will use in a year or so.]
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Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr Seuss - You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
-
I've read something about reforming, but than elsewhere somebody wrote that high-quality caps keep their specs over long time of use and actually do not need to be reformed.
Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts
I've read something about reforming, but than elsewhere somebody wrote that high-quality caps keep their specs over long time of use and actually do not need to be reformed.
I think this would be in relation to storage in that case (I.e. when the caps have never been used)
"The one who says it cannot be done should never interrupt the one who is doing it."
... high-quality caps keep their specs over long time ...
Right, just like they last longer in a circuit.
Originally posted by Behemot
... actually do not need to be reformed.
Wrong. It's called Shelf Life. They all have one.
Mann-Made Global Warming. - We should be more concerned about the Intellectual Climate.
-
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr Seuss - You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
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Alluminum caps rarely short out in service. Usually they just dry out or bloat.
Never had one explode or bulge even if it was old, but that is 5years top.
However, tantalums are a completely different story. Those suckers will burn a hole in your board for no reason at all.
Quick question here! I got some presumably Panasonic FR capacitors off some dead motherboard, but i am not sure if they are real. They have the usual T shaped vent and they look like Panasonics, but there is no [M] logo on them. They are rated for 16V 100uF and the printing quality is somewhat questionable (big print). 16V 1000uF 105c FR 23IDA.
Panasonic FR series doesn't have the M logo on them, and it's plain white ink on black plastic.
I actually have some 100uF 16v panasonic FR capacitors, here's how they look:
btw, the 100uF shouldn't have a T vent at all, the size is too small for the capacitors to do any real damage or have enough gas to explode, so usually such small capacitors don't have any vent.
As for SMD ceramics, the best is X7R electrolyte, I think it does not really depend from which manufacturer but maybe somebody will correct me.
As for radial ceramics, not really sure, I usually buy whatever they sell me in shop if I need something and don't have it "on stock" digged from already dead and dismounted HW.
Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts
There are loads of types of ceramic capacitors... and there's several temperature ratings for such resistors, X5R, X7R and C0G/NPO being some of the best. NPO is actually above x5r and x7r as it's not as sensitive to vibrations (piezoelectric effect).
But these ratings are loosely defined... a x5r build with some specific components by a manufacturer could have the same performance as a capacitor rated as X7R by another company.. you can't be 100% sure.
Or, for example, a 2.2uF X5R in 0805 package may have the same performance as a 2.2uF X7R in 0402 or 0603 package (or footprint, whatever).
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