(Topic ID: 299610)

Question about increasing capacitance on PS

By Tomass

47 days ago


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  • 13 posts
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  • Latest reply 47 days ago by Tomass
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    #1 47 days ago

    I have several power supply boards and I want to recap them. A few are 18000 mfd and 1 is 20,000 and 1 is 25,000. Would it hurt to replace them all with the higher capacitance of 25,000? I would rather just buy a lot of 1 value if that is an option.

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    #2 47 days ago

    Electro caps usually have a tolerance of 10% - some even 20%.

    So a 10% cap that 'says' it's 18,000 could actually measure 19,800 and still be perfectly in tolerance.

    With filter caps usually bigger is better, not always but in most cases.

    I would replace them all with the 25K

    #3 47 days ago

    18000uF is pretty big for these power supplies ... let alone 20000 and 25000.
    There is a point of diminishing returns on cap sizes plus when you start getting too big then you run the risk of burning up diodes within rectification circuit due to ripple current.

    I would go with whatever the original design called for and stop there.

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    #4 47 days ago
    Quoted from G-P-E:

    18000uF is pretty big for these power supplies ... let alone 20000 and 25000.
    There is a point of diminishing returns on cap sizes plus when you start getting too big then you run the risk of burning up diodes within rectification circuit due to ripple current.
    I would go with whatever the original design called for and stop there.

    While you are essentially correct, you fail to take into account that the vast majority of electro caps available will actually be 10% (or more) LOWER than their stated capacity.

    That would make a 10% 25K cap possibly 22,500ufd or a 20% one possibly 20K.

    OP, I wouldn't sweat too much about it. It is SUPER common in the repair industry to replace caps with ones rated much higher and I have never yet heard of that causing any issues.

    #5 47 days ago

    pins4u ... I wouldn't question the guidance from Ed G-P-E .
    He knows what he is talking about.

    What PS has a cap that large.,
    The largest I've ever seen on a pinball PS is 18,000, or sometimes 4X 4700uf caps in parallel, the equivalent of 18,800uf. These were Data East power supplies.
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    -1
    #6 47 days ago
    Quoted from ChrisHibler:

    pins4u ... I wouldn't question the guidance from Ed G-P-E .
    He knows what he is talking about.
    What PS has a cap that large.,
    The largest I've ever seen on a pinball PS is 18,000, or sometimes 4X 4700uf caps in parallel, the equivalent of 18,800uf. These were Data East power supplies.
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    I agree he certainly knows his stuff but he isn't the ONLY electronic engineer on here!

    #7 47 days ago
    Quoted from ChrisHibler:

    //<![CDATA[
    window.__mirage2 = {petok:"071234edd537872eee08fc6e4cfb93e35bdcbaf3-1630464651-1800"};
    //]]>

    pins4u ... I wouldn't question the guidance from Ed G-P-E .
    He knows what he is talking about.
    What PS has a cap that large.,
    The largest I've ever seen on a pinball PS is 18,000, or sometimes 4X 4700uf caps in parallel, the equivalent of 18,800uf. These were Data East power supplies.
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    It is on a Data East Simpsons. Maybe I should check the schematics.

    20210831_185253 (resized).jpg
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    #8 47 days ago

    Same supply as an early Williams

    #9 47 days ago

    18000 axials for all and be done with it.
    Pay close attention to the little buggers near heat sink. Leaked electrolyte can cause lots of headaches.
    Data_East_Cap (resized).jpg

    Note that Data East calls out a 0.18F cap for the Simpsons board. OK...off by a factor of 10 on the actual drawing but they were sized at 18000uF.

    #10 47 days ago
    Quoted from Tomass:

    It is on a Data East Simpsons. Maybe I should check the schematics. [quoted image]

    That 25Kuf cap is not original.
    Like Ed (above) says, 18,000 is the right cap for that board.
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #11 47 days ago

    Image from the PinWiki...
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    pasted_image (resized).png
    #12 47 days ago
    Quoted from pins4u:

    I agree he certainly knows his stuff but he isn't the ONLY electronic engineer on here!

    Well then, glad to have you aboard!
    Greetings from America.
    --
    Chris Hibler - CARGPB #31
    http://ChrisHiblerPinball.com/Contact ... for board repairs
    http://www.PinWiki.com - The Place to go for Pinball Repair Info

    #13 47 days ago

    Thanks for all the input!

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