C1 capacitor specs for Onyx 550MHz logic board?

Discussion in 'MacBook Pro' started by jdhupp, Dec 29, 2009.

  1. jdhupp macrumors newbie

    Joined:
    Dec 29, 2009
    #1
    I have an Onyx 550 showing no signs of life (light ring on power plug doesn't even light). Swapping in a known-good logic board confirms that something on the board is the problem. The C1 capacitor rattles when I shake the board, so I'm thinking it has dried out and simply replacing that might fix the problem. Anyone know the full specs of the C1 capacitor?

    Some specs I can read/see on the cap:

    * surface mount design
    * Rubycon (manufacturer)
    * 220 uF
    * 35 V
    * 105 degrees C (apparently the top end of the rated operating temperature range)
    * NO144 (not sure if that's exactly what it says or what it means)
    * 10 mm diameter and 10 mm high
    * presumably this is an aluminum electrolytic type

    If I have all that right, then it narrows down the selection of caps at Mouser pretty well. See http://www.mouser.com/Passive-Compo...D/_/N-75hqx?P=1z0wrjqZ1z0sq5yZ1z0scm8Z1z0rxa7.

    But there is at the least a question of the low-end temperature rating, and beyond that I would be happy to have someone confirm my overall assessment above.
     
  2. miles01110 macrumors Core

    miles01110

    Joined:
    Jul 24, 2006
    Location:
    The Ivory Tower (I'm not coming down)
    #2
    The low-end temperature essentially doesn't matter. Capacitors are about as simple as you can get; if the footprint is correct it probably wouldn't even matter which one you bought from the list.
     
  3. m85476585 macrumors 65816

    Joined:
    Feb 26, 2008
    #3
    This one has a bit longer life, and lower impedance which is almost always better for capacitors.
    http://se.mouser.com/ProductDetail/...=sGAEpiMZZMtZ1n0r9vR22eG4mPLoVMJwWBX82Kg9YNc=

    In the future, if you need to narrow down a search, check the box for Stocked since electronics distributors tend to list a lot of out of stock products.

    I was able to find an even better capacitor from Digikey (another distributor), but I don't know how their shipping is if you are not in the US. This one is rated for 3000 hours at 125C, and the ESR is low.
    http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PCE4935CT-ND

    Honestly it probably doesn't matter what you use for a replacement. Aluminum electrolytic capacitors degrade over time, so there is usually extra capacity built-in, and circuits using them won't usually depend on the exact capacitance. By the end of its life, an electrolytic capacitor might have 50% of its original capacity. Any capacitor with at least the same voltage and capacitance rating will probably work if you can physically fit it, even if that means soldering the leads of a capacitor from your local electronics store to the SMD pads, though if you don't mind SMD soldering and you can get a similar part to the original, you might as well do it right.
     

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