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Thread: non standard electrolytic capacitor values

  1. #1
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    Default non standard electrolytic capacitor values

    So I am attempting a recap of a macintosh LC psu. The problem with these tiny things is they have strange value capacitors. Some of the values I need to replace are 270uF, 56uf, and 8.2uf. All the voltages are 50V and below, these are small caps, sans the largest which is rated 180uf 385wv (What does the WV designation mean?),

    Any ideas where I can find these or how to proceed?


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    Actually, most of those capacitance values are pretty standard. You may have to go up a bit on the voltage rating (WV = working volts); e.g. 180 F at 450V aren't uncommon at all. Just verify physical size match. The 1000F at 10V may have to be replaced by 16V caps, but that's no big deal.

    Just use a reputable brand.

  3. #3

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    You might also look at the tolerances of electrolytic capacitors. It might surprise you.
    Also, why are you replacing all the capacitors? Is there a problem with the supply and what is the cause that would require replacing all the capacitors?
    Dwight

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    Generally, NIchicons are regarded as being top-notch, particularly when compared with some of the Chinese/Taiwanese brands.

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    Quote Originally Posted by Dwight Elvey View Post
    You might also look at the tolerances of electrolytic capacitors. It might surprise you.
    Also, why are you replacing all the capacitors? Is there a problem with the supply and what is the cause that would require replacing all the capacitors?
    Dwight
    The LC "brick" PSUs are notorious for having leaky secondary caps. The rubber plugs in the bottom dry rot and shrink, letting electrolyte seep out the bottom. I've recapped a few so far.

    Unfortunately, the 180uF 385WV "pancake" line cap is basically unobtanium. A potential substitute is this:

    https://www.mouser.com/ProductDetail...sKS%2Ftiekk%3D

    It has the same farad rating and a slightly higher working voltage. The issue is size, the internals of the PSU are basically moulded to the size of the existing capacitor. I don't remember the exact dimensions, but there is basically zero room both height and circumference wise. Fortunately, the line cap never seems to be bad in the units I've recapped.

    The only other oddball is the 8.2 uF 50v cap, which can be a bit difficult to find, but it is available. I use this one:

    https://www.mouser.com/ProductDetail/710-860160672008

  6. #6

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    Yes, they all leak. Had to do the same with my 475 PSU just a few months ago and the leakage already caused severe damage on the bottom side of the pcb. I had no issues finding replacement caps - in Germany at least. For some, I didn't even bother and used ones close to the original ones, e.g. 10uF for the 8.2 uF one, since I had these already. With tolerances >20% it's not much of an issue.

  7. #7
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    Quote Originally Posted by Dwight Elvey View Post
    You might also look at the tolerances of electrolytic capacitors. It might surprise you.
    Also, why are you replacing all the capacitors? Is there a problem with the supply and what is the cause that would require replacing all the capacitors?
    Dwight
    They all have what looks like crusty black coffee under them and the smell of rancid coolant. Just about all of them except for the large 180uf cap are leaking and I want to repair the board before its too corroded to do so.

    Quote Originally Posted by GiGaBiTe View Post
    Unfortunately, the 180uF 385WV "pancake" line cap is basically unobtanium.
    So the size of the old cap is the limiting factor? Apple,,, man they made some bad choices.

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    Check the EPCOS/TDK catalog. There's a 25mm high 220F/400V version. Amazon even has a lot-deal on them.

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    Thanks guys, Ill buy enough of the main caps to rebuild four of the 6 psus I need to fix. Chuck ill take a look at those 220uf caps. Is tha variance from 180uf still ok?

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    Aluminum electrolytics are nominally +/-20%. Given that the cap serves as a smoothing cap, 220 F should be fine.

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