Freebie Nvidia XFX 9800GT - Lines on screen

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Turns out FP's ESR is much too high, 0.08 ohms vs. 0.025 ohms. But I can't find anything to replace the FJ with. It is well any truly ruined. Last I tested it, measures 11 ohms with the lead inserted back in, I guess permanent damage has been done. Maybe a polymer would be good. Never poly-modded before, there's a chance to learn something in the process. So I would use an ~820uF poly (halve capacitance?)

[ratdude747]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Turns out FP's ESR is much too high, 0.08 ohms vs. 0.025 ohms. But I can't find anything to replace the FJ with. It is well any truly ruined. Last I tested it, measures 11 ohms with the lead inserted back in, I guess permanent damage has been done. Maybe a polymer would be good. Never poly-modded before, there's a chance to learn something in the process. So I would use an ~820uF poly (halve capacitance?)

half capacitance doesn't work with such low ESRs. I'd try to find a poly with enough voltage and a similar ESR... In a VRM, ESR counts much more than capacitance.

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Well, I probably should have checked my caps box first. Found my pack of Nichicon HM, 1500uF 6.3V has 25 mohm ESR, which is the same as the FJ. It's through hole, but there's nothing stopping an ugly bodge job now... I am not going to pull the caps off this board, it is too much work and too much can go wrong.

[momaka]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

So, I tried pulling the caps off the board, no dice. I ruined one FJ cap in the process - pulled the lead out of the cap, although I did get it off eventually. I am using a temperature regulated soldering iron and the same method I've always used for though hole caps, but that only works on single layer and *maybe* two layer boards, not 8-10 multilayer beasts...

Perhaps you didn't use enough heat. We have nice regulated soldering irons at work, and normally I keep it 270-300C for soldering. If the board is thick, I use 350C. For removing caps, I max it out - 400C to 450C. This actually does the least amount of damage vs. having the iron at lower temperature and holding in on the board for a longer period of time.
I supposed this is why my cheap RS iron works so well - it's unregulated and probably tops out at ~400C when I let it heat up for 5 to 10 minutes.

half capacitance doesn't work with such low ESRs. I'd try to find a poly with enough voltage and a similar ESR... In a VRM, ESR counts much more than capacitance.

???

Judging by the capacitance of tom66's cap, it's most likely on a VRM (probably RAM). Pretty much all modern, high-power cards have at least 2 VRMs (1 for RAM and 1 for GPU VCC). If you see MOSFETs connected to toroidal coils, it's a VRM.

It's through hole, but there's nothing stopping an ugly bodge job now...

Hey, as long as it works . That's my motto.

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

I've got an Aoyue 968 temp controlled hot air and solder station. At 400°C I started melting the rubber of one capacitor so I quickly stopped. If I had a nozzle just the right size it might work better.

[ratdude747]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

I've got an Aoyue 968 temp controlled hot air and solder station. At 400°C I started melting the rubber of one capacitor so I quickly stopped. If I had a nozzle just the right size it might work better.

You have hot air?

(didn't know that)

You can use that to reflow the board w/o removign that cap... not sure ont he temps and times, but flux every BGA chip and reflow it with it.

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

You have hot air?

(didn't know that)

You can use that to reflow the board w/o removign that cap... not sure ont he temps and times, but flux every BGA chip and reflow it with it.

Yeah... waste of £130 in my opinion, it works okay but it has soo many problems, last time I buy a cheap all in one unit! It keeps locking up and the display goes funky, it burnt out the hot air element in about 15 months and the soldering iron is on the way out, needs a new element too.


Anyway, I'm happy to report the operation was a success, at least, I think. No more lines. Yet to run anything powerful on it. I think the Nvidia drivers don't like the new card so I may have to reinstall them as it's stuck in 640x480, but absolutely no lines appeared through the boot process unlike how they did on my dad's PC.

Now how did I fix the cap...? I'm sort of ashamed to post the picture... but it works, just about. I need to glue it down.

Unfortunately I got my motherboards confused, my media PC (some Asus board, forget which) has dual PCI-E x16 but this Abit KN9 Ultra motherboard only has one 16x slot. The only reason the media PC is dual PCI-E is because I was given the motherboard with the single core AMD FX64 processor on it already, and didn't feel like swapping the CPUs and keeping the dual PCI-E dual core FX64 to myself. (I don't even know if the processors are cross compatible. It's chance that I've got two similar processors, I'd take a free Intel or AMD any day.) Anyhow, graphics performance is very good with one card, and I hope to get the 24" monitor working soon for some epic-ness. The 24" has essentially the same vertical height as my current 19", but it is much wider.

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

It seems to work on Far Cry 2 Benchmark - I am letting it run for a while and seeing if anything goes wrong. So far so good. Excuse the blurry picture...

[tom66]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Okay, I got started playing a game, but it quickly bluescreened with "nv4_video.dll" being the cause. Tried again and it froze completely, no glitches on screen. I think I need to redo it again, I realise now I completely forgot the flux ... Anyhow at least it sort of works, so I'm fairly confident it can be fully fixed. I've still got my perfectly working PNY 9800GT to use, so no big deal if this one can't be fixed, but it would be nice to have a spare.

[ratdude747]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Lesson #349: When in doubt, use flux.

(We all learn a lesson or two this way, it happens).

[momaka]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

You have hot air?
(didn't know that)
You can use that to reflow the board w/o removign that cap... not sure ont he temps and times, but flux every BGA chip and reflow it with it.

Negative.

You CANNOT use a hot air station like that because it doesn't provide enough heat volume (if that makes sense). In other words, the temperature coming off of the nozzle of the hot air gun is hot enough, but the amount of air it provides is not enough to heat the whole board evenly. Turning up the heat is not an option because then you will (in most cases) burn out the chip. I've done this 2 times already just as an experiment on practice boards (dead Xboxes with good GPUs).

Basically, to do a proper and successful reflow, you need to have the board, the BGA chip, and the solder balls to reach the solder melting temperature point all at the same time (or very close). If you don't, you may warp the board, bridge the balls, or just have an unsuccessful reflow. This is why an oven reflow works the best (or second best... the best way is to have the right reflow/rework machines and equipment, but those are quite expensive) - the oven will slowly heat everything on the board, so everything will be more or less at the same temperature. Lead-free melts at 217C. Heating the board to 220-230C guarantees that everything will be hot enough. You just simply cannot do this with a hot air station because to get the board to that temperature, the chip would have to be pretty much on fire.

On the other hand, this is why people have reported success with those big "inaccurate' heat/paint-removal guns - it's because they are able to provide a big enough volume of heat, despite their loose heat control. They are basically the opposite of a hot air station - they provide a large volume of heat, but their heat control is often inaccurate.

So in conclusion:
- A hot air station is only good for putting or removing SMD chips (non-BGA).
- A heatgun can be used for a reflow, but you better know what you are doing (99.9 % of the people don't - they just heat the board and hope it works... and in seems like it does most of the time).
- An oven is the best method to reflow for the average person that doesn't have any experience with reflowing. The only exception is if the board has a lot of electrolytic caps and the user can't/doesn't know how to remove them (lol, not talking about you tom66, your board doesn't have that many electro. caps to qualify).

Yeah... waste of £130 in my opinion, it works okay but it has soo many problems, last time I buy a cheap all in one unit! It keeps locking up and the display goes funky, it burnt out the hot air element in about 15 months and the soldering iron is on the way out, needs a new element too.

We went through quite a few of these Chinese stations at work in the last 6 months (Aoyue, Kada, X-tronic... you name it - they are all the same anyways). When they work, they are okay. We only use them for the hot air, and they seem to do good with that. Personally, I've used the iron only once on one of them and I wasn't impressed at all - it was very slow. Ever since then, I never bothered with their iron anymore since we have better soldering stations. We do, however, have a separate Aoyue controlled soldering iron, and that one works very nicely. The model escapes me now, but it is digital one.

Lesson #349: When in doubt, use flux.

Yes .
Lesson #350: Always use flux.

[ratdude747]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Momaka, explain why hot air stations come with BGA shaped square nozzles? QFPs?

[momaka]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Momaka, explain why hot air stations come with BGA shaped square nozzles? QFPs?

Yes.

Frankly, I never use the nozzles, though. I find them to be more of a gimmick. There's been only a few very rare cases where I've needed them.

[ratdude747]

Re: Freebie Nvidia XFX 9800GT - Lines on screen

Yes.

Frankly, I never use the nozzles, though. I find them to be more of a gimmick. There's been only a few very rare cases where I've needed them.

During the day I got to use one, I found that the nozzles helped as the DIP ones had channels for the air that directed the air to the solder pads and away from the chip's body.