Video Capacitor Question

[manic_man]

Hi all,

I have a Leadtek GF4 Ti4600 and its never been stable, ever. I have always presumed it was iverheating but cant find a reason why it would! Anyway, i recently did a quick swap with a mate for an hour or so and for him it not only froze every 5 minutes whilst playing games it actually completely corrupted, his ti4200was rock solid in my system.

anyway, with the graphics card the definate culprit, I have replaced the thermal gunk, lapped he HS, improved the air flow over it etc etc all to no end.

Anyway, on closer inspction a cap towards the abck of the board is bulging at the top!

Could this cause the perhaps some components to be over volted and as such heat up to much? Or just generally cause its instability?

anyway, im trying to fix it, SO I have just ordered some replacemment caps.

problem is, ive been looking round the site and u say they must be low ESR. Now, I dont have a clue if what i bought is! None of the sites mentioned it!

The cap on the card is a GSC 1000uF 6.3v, so I have bought some Rubycon 6.3v 1000uF, i thought this would be fine, but am i going to blow the card up completely by replacing it with these new caps, as i dont know if they r low ESR!

im a bit of a n00b to all this

cheers guys

[Topcat]

Yeah, I'd say that the bad cap is definitely the root of the troubles... If there's more than 1 electrolytic on your card, I recommend replacing all onboard that are 470uF and up. I have pulled quite a few caps labeled 'GSC' out of Chaintech, PNY, and Leadtech graphics cards that were flaky, and once those caps were replaced, the cards were good as new and reliable!

Honestly, some devices are picky about low-ESR, some arent. Motherboard VRM circuits seem to be the most finicky about this... However, I think your Geforce4 will be OK without. I would install the 1000uF cap you ordered, I'd bet that it'll be OK. It certainly won't be worse than it was, that's for sure. In the past, I have used standard-grade caps in place of low-ESR and had no troubles, and some of these motherboards are still in operation today with no probs...

[manic_man]

hey thnx topcat, nice informative reply

the board is covered in caps
however only 3 are the same type, so ill swap out those three, luckily its quite an uncluttered board as they made the PCB so darn huge, cos my soldering can get a bit messy at times

hehe, well, heres hoping they do the trick :|

nice site btw, very informative and useful

[Topcat]

Don't be too messy soldering, if ya blob solder and short something, it could be fatal for your card. There may be a lot of cpas on the card, but the electrolytic are the only ones you need to worry about. Most video cards are usually covered in tantalum caps, but only have a few electolytics...most anyway... I look at my ATi 8500AIW 128, and it's covered in caps also... heh...

Good Luck and let us know the outcome!! Feel free to post a pic also...

TC

[manic_man]

hehe, im not TOO bad, although my iron is a tad on the large side it must be said, still ill be fine with the actual soldering.

Out of interest, how do you tell an electrolytic cap to other ones?

are the electrolytic ones the ones with the cross scored in the top? As I count 7 of em! then a further 5 non scored ones

only 1 of em is bulged thouhg, theres no sign of leakage.

[EDIT] Lol i hope this stabilises the card as im currently running a GF4 MX 420, and it aint pretty :S [/EDIT]

[Topcat]

The tantalum caps are the very small surface mounted caps. The electrolytics are the ones that will resemble a battery. If you've got one bulding, it's definitely toast! It only takes one bad one to reek havoc on your card/system stability! Here's a couple crude photo's... My camera sucks at closeups, but you should be able to get the idea.

*NOTE, NEVER attempt to remove or replace the tantalums!! They almost NEVER fail!! If one fails, it will usually incinerate itself, and destroy the card. From the symptoms you describe, your problem is the electrolytics. If a tantalum fails, there's usually a more deep rooted problem that caused it to fail in the first place, and your card would be completely dead.

Replacing tantalum and any other surface mounted components requires extremely precise soldering equipment. Don't worry about the tantalums, I'm sure they're fine!!





Hope that helps.

[manic_man]

ah yes that does cheers

it would seem my GC has 11 electrolytic caps in total :S

lol, its a beast of a card.

newho, cant do nething for a few days whilst i wait for the caps to arrive!

cheers again