[Coco] Powering up our retro systems

Dave Philipsen dave at davebiz.com
Mon Jan 27 11:30:13 EST 2020 

I just checked the rated leakage current of a typical TDK electrolytic.  
It's .01 microamps.  Mutiply that by 100 and you get one microamp.  
Let's, just for snicks, multiply it by 10,000 (one hundred times as much 
as the TDK document said would occur after prolonged storage). Do you 
think the CoCo power supply will tolerate 100 microamps per electrolytic 
capacitor for maybe an hour? Let's say there are 100 electrolytics on 
the CoCo motherboard (which there are not). Do you think the CoCo power 
supply could handle 10 milliamps of extra current for an hour or two in 
order to reform the caps?

Dave


On 1/27/2020 10:16 AM, wrcooke at wrcooke.net wrote:
>     Oh, well.
>
>     On January 27, 2020 at 10:14 AM Dave Philipsen < [1]dave at davebiz.com>
>     wrote:
>
>     I read the document (or at least the pertinent parts) and it said, "The
>
>     result is that a higher than normal leakage current will flow when a
>
>     voltage is applied after prolonged storage. As the oxide layer is
>
>     regenerated in use, however, the leakage current will gradually decline
>
>     to its normal level. When designing application circuits, attention
>     must
>
>     be paid to the fact that after storage the leakage current may be up to
>
>     100 times higher than normal during the first few minutes following the
>
>     application of power."
>
>     Then under the storage section it said, "If the capacitors have been
>
>     stored at temperatures above +35°C or for longer than above-mentioned
>
>     periods, it is necessary to consider whether the application circuit is
>
>     able to tolerate high initial leakage currents. If this is not the
>     case,
>
>     one should perform the special reforming procedure."
>
>     So here's what I glean from the document.  Make sure your power supply
>
>     is designed in such a way that it will tolerate/sustain an initial
>
>     leakage of at least 100x the normal leakage current after the circuit
>
>     has remained idle for some time. If your circuit can't sustain that,
>
>     then you may need to manually reform the capacitor(s). As long as your
>
>     circuit is tolerant of that, the capacitor(s) will reform by virtue of
>
>     their being used after a relatively short amount of time.
>
>     And the document reiterates what I said, that high temperatures are the
>
>     biggest culprits. So you can either allow the CoCo power supply to
>
>     reform the capacitors (which it likely has the capacity to do in most
>
>     cases) after a prolonged storage period or you can gradually apply
>
>     voltage starting at a lower potential in the case of the power supply
>
>     not having the ability to sustain the higher leakage currents at its
>
>     rated voltage.
>
>     So from what I understand, the only reason to be concerned about the
>
>     CoCo's ability to reform the caps on its own by merely turning the CoCo
>
>     on, is if the power supply doesn't have enough "oomph" to handle the
>
>     higher leakage currents.  And from your statement that the transformer
>
>     is capable of delivering ten amps of power (albeit for a limited time)
>
>     then I would have a hard time thinking that the power supply couldn't
>     to
>
>     that.
>
>     Dave
>
>     On 1/27/2020 8:05 AM, [2]wrcooke at wrcooke.net wrote:
>
>     This document:
>
>     [3]
>     [3]https://www.tdk-electronics.tdk.com/download/530704/6ad5ed9e1ff4f727
>
>     c328cb92da2adf2b/pdf-generaltechnicalinformation.pdf
>
>     From TDK, a reputable manufacturer of electrolytic caps, has a great
>
>     deal to say about the life and storage of them. It specifically says
>
>     they are expected to be reformed after storage. See sections 3.7.7 and
>
>     7.3
>
>     Best,
>
>     Will
>
>     But that's just me.
>
>     Good luck.
>
>     Will
>
>     References
>
>     1. mailto: [2] [4] [4]dave at davebiz.com
>
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>
>     [3] [5] [5]Coco at maltedmedia.com
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>     [4] [6] [6]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     "A designer knows he has achieved perfection not when there is nothing
>
>     left to add, but when there is nothing left to take away." -- Antoine
>
>     de Saint-Exupery
>
>     "The names of global variables should start with // "
>
>     -- [7] [7]https://isocpp.org
>
>     References
>
>     1. mailto: [8] [8]dave at davebiz.com
>
>     2. mailto: [9] [9]dave at davebiz.com
>
>     3. mailto: [10] [10]Coco at maltedmedia.com
>
>     4. [11] [11]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     --
>
>     Coco mailing list
>
>     [12] [12]Coco at maltedmedia.com
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>     [13] [13]https://pairlist5.pair.net/mailman/listinfo/coco
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>     Coco mailing list
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>     [14] [14]Coco at maltedmedia.com
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>     [15] [15]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     "A designer knows he has achieved perfection not when there is nothing
>
>     left to add, but when there is nothing left to take away." -- Antoine
>
>     de Saint-Exupery
>
>     "The names of global variables should start with // "
>
>     -- [16]https://isocpp.org
>
>     References
>
>     1. mailto: [17]dave at davebiz.com
>
>     2. mailto: [18]wrcooke at wrcooke.net
>
>     3.
>     [19]https://www.tdk-electronics.tdk.com/download/530704/6ad5ed9e1ff4f72
>     7c328cb92da2adf2b/pdf-generaltechnicalinformation.pdf
>
>     4. mailto: [20]dave at davebiz.com
>
>     5. mailto: [21]Coco at maltedmedia.com
>
>     6. [22]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     7. [23]https://isocpp.org/
>
>     8. mailto: [24]dave at davebiz.com
>
>     9. mailto: [25]dave at davebiz.com
>
>     10. mailto: [26]Coco at maltedmedia.com
>
>     11. [27]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     12. mailto: [28]Coco at maltedmedia.com
>
>     13. [29]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     14. mailto: [30]Coco at maltedmedia.com
>
>     15. [31]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     --
>
>     Coco mailing list
>
>     [32]Coco at maltedmedia.com
>
>     [33]https://pairlist5.pair.net/mailman/listinfo/coco
>
>     "A designer knows he has achieved perfection not when there is nothing
>     left to add, but when there is nothing left to take away." --  Antoine
>     de Saint-Exupery
>
>     "The names of global variables should start with    // "
>     -- https://isocpp.org
>
> References
>
>     1. mailto:dave at davebiz.com
>     2. mailto:wrcooke at wrcooke.net
>     3. https://www.tdk-electronics.tdk.com/download/530704/6ad5ed9e1ff4f727
>     4. mailto:dave at davebiz.com
>     5. mailto:Coco at maltedmedia.com
>     6. https://pairlist5.pair.net/mailman/listinfo/coco
>     7. https://isocpp.org/
>     8. mailto:dave at davebiz.com
>     9. mailto:dave at davebiz.com
>    10. mailto:Coco at maltedmedia.com
>    11. https://pairlist5.pair.net/mailman/listinfo/coco
>    12. mailto:Coco at maltedmedia.com
>    13. https://pairlist5.pair.net/mailman/listinfo/coco
>    14. mailto:Coco at maltedmedia.com
>    15. https://pairlist5.pair.net/mailman/listinfo/coco
>    16. https://isocpp.org/
>    17. mailto:dave at davebiz.com
>    18. mailto:wrcooke at wrcooke.net
>    19. https://www.tdk-electronics.tdk.com/download/530704/6ad5ed9e1ff4f727c328cb92da2adf2b/pdf-generaltechnicalinformation.pdf
>    20. mailto:dave at davebiz.com
>    21. mailto:Coco at maltedmedia.com
>    22. https://pairlist5.pair.net/mailman/listinfo/coco
>    23. https://isocpp.org/
>    24. mailto:dave at davebiz.com
>    25. mailto:dave at davebiz.com
>    26. mailto:Coco at maltedmedia.com
>    27. https://pairlist5.pair.net/mailman/listinfo/coco
>    28. mailto:Coco at maltedmedia.com
>    29. https://pairlist5.pair.net/mailman/listinfo/coco
>    30. mailto:Coco at maltedmedia.com
>    31. https://pairlist5.pair.net/mailman/listinfo/coco
>    32. mailto:Coco at maltedmedia.com
>    33. https://pairlist5.pair.net/mailman/listinfo/coco
>

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