Blown cap on video card, help me location a replament?

[seanc]

Re: Blown cap on video card, help me location a replament?

What card is it?
Did you put the cap in the correct way?

[spatimouth]

Re: Blown cap on video card, help me location a replament?

It's a XFX 7900GS AGP card. The I'm pretty sure the cap is installed the correct way. It's a surface mount cap and there are white lines on the pcb board that indicate how it should be aligned. When I first got the board it wouldn't show video until I took off the bad cap. Without the cap it would not do any 3d acceleration.

I'm thinking what ever blew the first cap is causing this replacement to go bad as well. I'll probably remove the cap and see if it displays video. Wish I knew how to diagnose it. Guess I'll just sell it on eBay to recoup what I paid for it.

[seanc]

Re: Blown cap on video card, help me location a replament?

Some more pictures might help.
Perhaps the mosfet OK1? is shorted. Looks like the pads have gotten hot.

[spatimouth]

Re: Blown cap on video card, help me location a replament?

I'll have to post some pictures when I get home. I'm kinda afraid to show off my butchered first attempt to solder a surface mount cap. Wasn't as easy for me as some would say. But I guess that's the learning process, screw-up a bunch of stuff so I can perfect my skills.

When I got the board the top part near the shorted cap had this sticky brown film around the board. Almost as if some cola was dumped on it. I've since then cleaned it off with alcohol. I suppose I'll need to learn how to test mosfet switches now.

During the desolding process I nicked a through hole cap close to popped cap and I thought I might have damaged it. I've replaced it with another but that didn't help.

[yyonline]

Re: Blown cap on video card, help me location a replament?

I think it's safe to say we all destroyed a few things learning how to do this. There's no shame if it's messy.

The brown residue you mentioned is likely flux residue left over from the manufacturing process, or from resoldering the new cap.

The cap that you damaged during soldering - what was the old cap, and what did you replace it with? Perhaps your replacement selection was not optimal, and that is causing problems. If it was an inadequate replacement, it may be causing your other cap to run hot.

[spatimouth]

Re: Blown cap on video card, help me location a replament?

Here are some pics of the area. I removed the replacement cap to see what the card would do.

Before I put in the replacement cap, I removed the old cap and the card at least would show 2d. Now with or without the replacement cap it gives garbage at the post screen. I think I might have ruined the gpu core. This was happening with the nicked cap and the one I replaced it with. The capacity rating and voltage rating were the same.

[yyonline]

Re: Blown cap on video card, help me location a replament?

Your replacement cap looks to be a counterfeit Rubycon. Where did you get these caps? I wouldn't order anything else from that supplier, as they are not genuine.

Real Rubycon caps have a "K" vent, not a "T" vent. Given that the quality of the counterfeit cap is unknown, it should be replaced with something reliable. I see two of these "T" vent fake Rubycon capacitors in your photos.

One of these fake Rubycons is in a location where there was no capacitor in your first photo - did you add a capacitor where there wasn't one previously?

Voltage and capacity are NOT the only important attributes you need to consider when selecting a replacement capacitor. ESR and ripple are just as important, if not more important for computer applications.

The capacitors look like 6.3V 1500uF capacitors. I would order some 1500uF genuine Rubycon MCZ from badcaps.net, and replace all the fake Rubycons (as they're unknown quality), and replace all the GSC caps on the board (as GSC are very unreliable).

Rubycon MCZ from badcaps.net: https://www.badcaps.net/store/produc...products_id=40

I'd say it's unlikely you damaged the GPU core during soldering. One possibility is that you created a short from stray pieces of solder. This would result in shorting something out when you applied power to the card. Check for any stray bits of solder on the board. Once you remove the short, it may start working again, or the damage may be permanent.

Given that we don't know the quality of the fake caps, they could be insufficient and not providing enough power, or clean enough power to the GPU. Replace them with good caps and see what happens.

[spatimouth]

Re: Blown cap on video card, help me location a replament?

Those caps were left overs from a G5 Imac kit I ordered from some web vendor called iFix Mac Computers.

I double checked the whole board and don't see any spots where there would be any solder shorts. On my first attempted I only replaced the original blown cap and tried the card out. It appeared to work correctly, but when I had to restart the computer the card started to freak out. I then noticed the replacement cap becoming extremely hot.

After this I started monkeying around by replacing caps and adding in new caps (the more the better right :P). I figured that the replacement surface mount cap probably fried something and since the card is probably toast I should just experiment. For me I'm more concerned with learning about what works and does work as apposed to fixing it. Don't get me wrong fixing it is cewl and all, but if it's toast I'll just find another broken one and attempt fix/trash it.

What could have also caused the card's screen corruption is that I had zip tied a fan to the heatsink and one of the chips underneath may not have been making contact with the heatsink. It's not the gpu but I guess a agp conversion chip near the agp connector. Maybe the chip got hot and caused damage. If so I guess I've learned my lesson.

Can those cheap caps going bad cause other caps to go hot or pop? All the original caps on the board look physically okay. I guess I'll order all new caps for this and find out what happens. It will give me more practice.