[Coco] Powering up our retro systems

Dave Philipsen dave at davebiz.com
Mon Jan 27 07:05:39 EST 2020

The links you provided for “reforming” electrolytic capacitors imply that the cap should be removed from its original circuit in order to carry out the process properly. That being said, I have three CoCo 3s that we’re purchased around 1990 (so about 30 yrs old). They had been stored in a garage where temperatures likely varied from around 32F to at least 90F and they all powered up without problem after all those years. 


> On Jan 26, 2020, at 9:11 AM, wrcooke at wrcooke.net wrote:
>    On January 26, 2020 at 8:31 AM rietveld rietveld <
>   [1]rietveldh at hotmail.com> wrote:
>   A lot of us have a backup coco; and maybe a backup to that backup
>   How often do you power up the spare equipment?
>   How often should we turn it on?
>   The electrolytic capacitors used as power supply filters and for other
>   purposes will deteriorate over time, especially without use.  It's a
>   good idea to power up the equipment (ANY device with such capacitors)
>   about once a year or so.  When in use, the caps "reform" themselves.
>   If the device hasn't been turned on in a while, using lower voltage to
>   power it up is recommended.  If the caps have deteriorated, they can
>   short out, causing a large amount of damage.
>   There are lots of articles on the web about "reforming electrolytic
>   capacitors."  Here are links to some:
>   [2]https://www.6v6.co.uk/vcomp/tech_tips/reform_caps.htm
>   [3]https://www.qsl.net/g3oou/reform.html
>   [4]https://www.diyaudio.com/forums/parts/51492-reforming-electrolytic-c
>   apacitors.html
>   I only briefly looked at those to see if they looked reasonable.  There
>   are some bad ones.  YMMV.  Generally, I use a variac (variable voltage
>   transformer) and slowly raise the voltage to the device over a few
>   hours.  Then let it run for a few hours more.
>   How long should we leave it on?
>   Estimates vary.  Overnight or 24 hours seems to be good.  See above.
>   --
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>   [5]Coco at maltedmedia.com
>   [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    // "
>   -- https://isocpp.org
> References
>   1. mailto:rietveldh at hotmail.com
>   2. https://www.6v6.co.uk/vcomp/tech_tips/reform_caps.htm
>   3. https://www.qsl.net/g3oou/reform.html
>   4. https://www.diyaudio.com/forums/parts/51492-reforming-electrolytic-capacitors.html
>   5. mailto:Coco at maltedmedia.com
>   6. https://pairlist5.pair.net/mailman/listinfo/coco
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