Need advice on how to id/replace cap

[bisk]

Aloha all,

I messed up and accidentally popped a cap off of my video card while removing it from the PC. It sits right behind the blade and blocks the PCIe slot release tab. I'm always fumbling around it while testing so it was just a matter of time, I guess.

One of the legs broke off so now need to replace it. It's one of those caps that does not go through the board but instead, just sits on of top of pads. It has a plastic saddle that sits between it and the PCB but I doubt that I'll be able to keep that 'cuz how the heck do I resolder with that thing in the way ?

Anyhow, I'm hoping somebody can steer me to the right replacement item so I don't screw that up too. The video card is an NVidia GeForce 8600GTS and the cap has these markings (from top to bottom) ...

781
100
25z

There is a photo included.

Thanks in advance

[mariushm]

Re: Need advice on how to id/replace cap

It's a 100uF , 25v smd capacitor. Unlikely to be polymer, as those are usually up to 16v, but not impossible.

The most important is to get one that matches the size of that plastic bottom, there's capacitors with various footprints

examples

6.3mm diameter : http://www.digikey.com/product-detai...6TR-ND/3088058

8mm diameter : http://www.digikey.com/product-detai...8-6-ND/2300443

Look in the datasheets where it says the size of that plastic square that holds the capacitor.

mouser may be cheaper, heres some example from there:

http://www2.mouser.com/ProductDetail...pmHkBF6NhFQ%3d
http://www2.mouser.com/ProductDetail...yqYZbyuPvSA%3d

[bisk]

Re: Need advice on how to id/replace cap

Wow !

Thanks for the swift reply

OK, so I should try to match the plastic saddle diameter, fair enough. But, in this, are you assuming that I will be able to resolder the cap on WITH this plastic part between the cap and the solder points ?

If so, how do I accomplish this ?

Wouldn't I need an oven for that ?

I was just figuring that I'd resolder w/o the plastic saddle.

Please advise. I'd certainly prefer to do it the correct way.

[mariushm]

Re: Need advice on how to id/replace cap

Normally, you put some solder on the tip of your solder iron, then put some solder on the flat leads under the plastic cap, and some solder on the pads.
You then put the capacitor on top and reheat the solder so that both sides merge.
But for this, it's important to have flux in the solder (most solder wires do) and it wouldn't hurt to add extra flux.

If you plan to remove the plastic cap, then you're better off with any electrolytic capacitor with leads, just get some quality capacitor (panasonic fc, fm , fr, nichicon pw, he, hd etc) and solder the leads to the pads.. see this video from 10:39 where he replaces surface mount capacitors with normal electrolytics:

http://www.youtube.com/watch?feature...fYHUIIY#t=636s

[bisk]

Re: Need advice on how to id/replace cap

Well, thanks !

I guess that if I am really careful that I could just catch the outer edge of those legs on the surface mounts where they stick out from under the plastic saddle, huh ?

[LDSisHere]

Re: Need advice on how to id/replace cap

Yes, you can get the tip of your iron on both at the same time. You should really practice on a junk board to get the hang of it before you attempt it on what you want to save.