Can anyone identify a part number for this capacitor? It was removed from a Wells-Gardner 19K6101 X-Y color monitor deflection board, c. 1981. Notice that there are 3 leads, with the middle lead marked NC. The opposite side has "CE 85º C 17 (U)(V) JAPAN". I can't find anything like it on the ELAN web site. The only 3-lead cap this size I can find at all is a Nichicon ULB1H472M at tedss.com, but there's no info on the lead layout, and Nichicon doesn't list this part number on their website.

Is this part still available? Or do you know of a suitable replacement with the same lead layout?

ELNA cap

update: [In response to Tom] looks like hot glue might be the way to go. There are some big holes next to the lead holes.

enter image description here


closed as off-topic by Nick Alexeev Nov 22 '15 at 20:35

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    \$\begingroup\$ Given that capacitors are two terminal devices, the third lead is probably for mechanical support. Do you have a multimeter? If you do, measure between each set of two pins with the diode tested. You should find one pair where the voltage shown by the diode tester starts increasing the longer you hold it there. These two are the capacitor terminals. The one near the --- stripe is the negative terminal. The third one will likely not be connected to anything. \$\endgroup\$ – Tom Carpenter Nov 22 '15 at 17:52
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    \$\begingroup\$ NC conventionally means Not Connected, as Tom suggests. \$\endgroup\$ – Brian Drummond Nov 22 '15 at 17:56
  • \$\begingroup\$ Sorry, I should have noted that the middle lead is in fact electrically inert. I'm just looking for a package with the same lead configuration. BTW, does the "(M)" after 4700uF have any significance? \$\endgroup\$ – user92359 Nov 22 '15 at 18:07
  • \$\begingroup\$ Double off-topic, I'm afraid. (1) Repair questions are off-topic on EE.SE. (2) Questions seeking recommendations for parts or places to purchase them are off-topic on EE.SE. \$\endgroup\$ – Nick Alexeev Nov 22 '15 at 20:36

In my comment I missed that you mentioned one of the pins is marked NC. That clears things up completely.

A capacitor is a two terminal device. On the one you have the third pin is marked N/C meaning, not connected (or no connect). On very large capacitors, adding a third terminal was done to give some mechanical support to reduce stress on the component leads caused by vibration. The third lead does nothing electrically speaking.

Basically what you need to do is find a standard two terminal \$4700\mathrm{uF}\$ capacitor rated for at least \$50\mathrm{V}\$ which has a similar spacing between the two important leads (the ones not marked N/C). Any will do, though ones with lower ESR ratings will perform better at smoothing out supply rails (in sensitive circuits the lower ESR could cause issues, but given it is an electrolytic capacitor, you probably won't find one that large with an ESR low enough to cause problems).

When you solder in the new component, be sure to use some potting compound to help provide the mechanical support that the third leg used to. Hot glue can be used, but unless you can get it to go through some holes somewhere nearby, or wrap over other components, it won't stay attached for long. You are better using something like silicone epoxy. If you use the search tool here, there are some questions about potting compounds.


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