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Leuren Moret
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How do I read alum. electrolytic capacitors?

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I need to order new capacitors for my logic board but I don't know how to read the numbers on the ones I want to replace. For instance on the 5mm X 5mm alum "can" capacitor the numbers are in three rows:

2 9

220

1 6F (F is very small and up to the right of the 6)

What do these numbers mean?

Edited by: rab777hp ( )

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Edward James
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I'm a bit late but for anyone who finds this now you can ignore the post above suggesting the capacitor runs on 220 volts. That's mains voltage and these tiny capacitors would fry instantly. Still the information provided in the question post here is a bit of a puzzle. Typically motherboard, video card etc circuits have three values: Microfarads, Volts and the temperature. An example of a typical motherboard/video card would be 6.3 Volts, 1500 microfarads mf (the m of the mf will look a bit weird because they use the Greek m probably because some other value used in other components is shown by the normal m) and 105 Centigrade. Some capacitors don't show the temperature but as they're cheap don't worry too much as they'll only pop if they get too hot and then you'd have to think again. The temperature is unlikely to cause problems but if they are rated then 105C works fine in motherboards/video cards. The details from the original post are 29, 220 and 16F and have probably been misread. From the size of the can I doubt they'd be as low as 29 or 16 mf - very unlikely. The "29" is probably 2.9 volts but 16F is a puzzle and probably misread. So, 220 is definitely not voltage and highly unlikely to be the temperature. Looks like it's 220mf using 2.9 volts. As the information is sketchy I could be wrong but here's a "rule of thumb" for capacitors around these sizes, 5 millimetre diameter to 10 millimetre diameter. Mf will be in the range of about 200 to 2000. Volts in the range of 2.5 to 8. The commonest voltages on boards seem to be 6.3 and 3.0. Capacitors also have a polarity (+ and -). The cans that have two legs both coming from the circular base will have one lead longer than the other. This is the positive lead. The "in line" type capacitors have a lead coming from each of the circular ends: one per end. Again the positive will be the longer one. If the leads are the same size the lead from the "crimped" end will be positive. The circuit board will be marked for polarity but before you take the old one out look for details of polarity on the board or, more unusually, on the old capacitor. Obviously mark up where the pos and neg go if necessary. If a device fails you might get a clue that a capacitor has blown. If you're around you might here a sharp electrical crack. The top of the capacitor "can" will probably be blown, sticking up a bit. Don't forget to double check that there is no supply to any electrical equipment before working on it. To avoid damage to components avoid touching circuitry as far as possible and "ground" yourself to get rid of static before you start.

Edited by: Edward James ( )

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Chris Green
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it's been a while, but i believe there are 220 volts, 16 farads (it's must likely a uF, not an F meaning millifarads) i'm not sure about the 2 9

It has been a long time since I did any of this but as I recall that would be a 220 microfarad cap. And as I recall the small letter was tolerance--f=1%. Ralph

rj713,

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Troy
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220 will be the uF, what color is the half circle? Different manufactuars use different labels.

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