Installing a Cap in circuit,help

[ivtec]

hi guys; i have here a Graffics card that when i pulled it from the mother board i also snatched this Cap leaving the legs in the board, i tried to disorder and remove the solder but since this is led free i had a hard time to remove it ,but i think i damaged the solder in the holes, I could open holes to put in new Cap,but now i see coper all over no cut in the board to separate positive from negative,the negative i can solder but the positive do you know to what component i can solder it to ? how I could i go about putting the new cap in the circuit? Here some pics, thanks

[ivtec]

Re: Installing a Cap in circuit,help

Here 2 better pic, the board is all scraped because i was looking for separation lids between ground and positive from the cap on the board.

[R_J]

Re: Installing a Cap in circuit,help

The white half of the cap is the positive, the negative has a space between the leads feed-through (which looks destroyed) and the positive copper trace. Same on the other side, where the positive lead has a space between it's feed-through and the negative copper trace. That is if this is a 2 layer board in this area

[ivtec]

Re: Installing a Cap in circuit,help

The white half of the cap is the positive, the negative has a space between the leads feed-through (which looks destroyed) and the positive copper trace. Same on the other side, where the positive lead has a space between it's feed-through and the negative copper trace. That is if this is a 2 layer board in this area

Thanks R_J, strange i have another same module# graphics card on another PC but it doesn't have this type of cap in the same place, you think i can scrape some more to find the Positive Trace pad?, i test all around the holes and it tests ground all over.

[petehall347]

Re: Installing a Cap in circuit,help

one hole is plated through by the looks of it
easy fix with cut of lead if pass through is gone .. just had to that with some relays .

[momaka]

Re: Installing a Cap in circuit,help

The vias / holes for that cap look completely destroyed. Don't bother scraping off any more solder mask or going deeper into other layers - you could short something out.

Most likely, the easiest thing to do at this point would be to solder the leads of your new cap across the tan ceramic cap that's right above the MOSFET in this picture:
https://www.badcaps.net/forum/attach...2&d=1618073043
Before you do that, though, check that the other (upper) side of the ceramic cap shows close to 0 Ohms / short-circuit to ground. I imagine it should, but it could also be a boot-strap cap or something similar for the VRM controller... and if it is, then that's not going to work out too well.

[ivtec]

Re: Installing a Cap in circuit,help

Thanks good people; i tested across that sm cap with resistance o2 ohms and with diode it's short either across cap or to ground.i sent a pic of the cap, should i try to put the cap across the cap or one leg on the positive side of the sm cap and other to ground? see pic ; thanks for all your help,

[R_J]

Re: Installing a Cap in circuit,help

I suspect you have caused a short between the positive copper trace and the negative feedthrough. But I can't tell because your pictures are not clear, they are too out of focus (shakey) to make out the detail.

[momaka]

Re: Installing a Cap in circuit,help

Thanks good people; i tested across that sm cap with resistance o2 ohms and with diode it's short either across cap or to ground.i sent a pic of the cap, should i try to put the cap across the cap or one leg on the positive side of the sm cap and other to ground?

Hmmm... 2 Ohms resistance to ground across that cap is suspicious. You may have shorted that rail to ground when the holes were damaged. I suggest to test the video card in a motherboard that isn't of much value (if you have any like that), as the card may end up puffing up a nice smoke show if any traces got shorted from those damaged holes. Be ready to kill power to the PC when testing the card after the repair.

Speaking of which, I still suggest to connect your cap across the SMD ceramic cap. This being an ASUS video card, the shaded semi-circle for the through-hole spot is the positive side... so that means on the SMD ceramic cap, the lower pad (that connects to the MOSFET) is where the positive (+) of your cap should go, and the upper pad is where the negative (-) of your cap should go. That is, when using this picture as a reference to which pad is upper and lower:
https://www.badcaps.net/forum/attach...2&d=1618073043

Again, after you solder your cap and are ready to test your video card, be ready to cut off power from the PC (via switch on back of PSU or through pulling cord), as that 2-Ohm resistance seems really suspicious there. Let us know how it goes. Hopefully no fireworks, though.

*EDIT*
Looks like R_J beat me to it while I was slow-typing my post.

[ivtec]

Re: Installing a Cap in circuit,help

Thanks guys , i don't have other computer that accepts this card besides the 3 lenovo desktops Thinkcenter Intel 5 M series that i can use this card, i only use one of the lenovo with this Hd ASUS video card with HDMI connection for streaming TV ,the other 2 are for other stuff and i use the integrated HD 2000 which is fine,no reason to risk anything, thanks guys for all trying to help,i've been here for so long and love this forum and you all that have helped me for so many years and made me a better an acknowledged person,thanks.