Repairing video cards

[Calchaqui]

Well, I used to buy broken mobos (no more than u$8) to fix and use myself. I wonder wot about VGA cards. For example there are lotta Gf4 Ti with bad caps, but I'm seeing a lotta of modern "middle-high end" agp cards broken. Most of them overclocked but I saw like 20 Radeon 9800pro giving artifacts all the time at stock speed, even underclocked. It is just an example.
As u know, caps are of polymer on those boards, and they are not the problem. But , can they be fixed anyway ?

Example : http://www.ixbt.com/video2/images/r9...scan-front.jpg

The 2 mean mosfets are no-standart (above left corner), if they are shorted can be desoldering and solder 2 standart mosfets? like in this r9800p http://www.ixbt.com/video2/images/r9...scan-front.jpg

I hear any kinda oppinion.

[Rainbow]

Re: Repairing video cards

Get datasheets for the original mosfets and look for suitable replacements on dead boards.
A very common failure on VGA cards are bad solder joints, especially under BGA memory chips.

[Calchaqui]

Re: Repairing video cards

Rainbow, can you tell me more stuff about repairing vga's ? .
I've hard people changing BGA memory chips , but I dont see Soldering at all! , how are this chips fixed to PCB?
What other bad solder joints did u see?

thanksss

[stretch0069]

Re: Repairing video cards

BGA is Ball Grid Array and it defines how the component is soldered to the board. In this case, all the solder connections are "under" the chip. The soldering is done by a special solder flow machine. I've seen BGA rework stations, but since I have little interest, I know little about their operation. I'm sure someone here will chime in with a lot more info.

[Calchaqui]

Re: Repairing video cards

Perfect, but sounds like impossible to do with my Pencial 15W soldering Iron

[RJARRRPCGP]

Re: Repairing video cards

Forbidden
You don't have permission to access /video2/images/r9800xt-3/connect3d-9800xt-scan-front.jpg on this server.

[Calchaqui]

Re: Repairing video cards

I think the link/url is right , i can open it . Anyway , here u got those strange mosfets or "power things"

[Calchaqui]

Re: Repairing video cards

I mean, they are u$150 - u$230 cards , they're worth a try

[Rainbow]

Re: Repairing video cards

BGA = chip has solder balls on the bottom side. When put on the PCB and heated up, the balls melt and solder it to the PCB. The problem is that it sometimes does not solder properly - it works but when the PCB is bent, some solder joints under the chip break. If you get artifacts/completely broken image and pressing on the memory chips helps, then you know that this is the problem. I've seen this problem on mainboards too - it does not work at all but when I push the chipset hard enough, it works fine. But I don't have any tools to repair this. The BGA rework stations are very expensive. Heat gun might work (heat up the chip but be very careful not to move it) - but I haven't tried it as I don't have any.

[Calchaqui]

Re: Repairing video cards

VERY VERY VERY INTERESTING . But how are Chipset soldered to mobo pcb? in standart (440bx, Nforce2, etc) mobos? I've never thought chipset could had bad solder joints .

http://www.technoa.co.kr/content/lec...40BX%20big.jpg

[stretch0069]

Re: Repairing video cards

Depends on what you consider expensive. Its been a while, but I've seen decent reflow stations for around $500 used. If you do enough reworking, it'll pay for itself easy.

I've gotten away from the whole soldering scene lately. Not by choice. It goes with my "throw-away world" thread.