X1900 XT displaying artifacts

[mitchmaster]

Re: X1900 XT displaying artifacts

uh oh... it looks like u tried to wrap the video card like a baked potato. the foil isnt supposed to be touching the card. the flux too isnt supposed to come into contact with the foil. most likely a chemical reaction occured between the aluminium and the flux causing the charring of the flux that u see. u are also supposed to remove all stickers too as they can combust and turn into carbon in the oven heat.

Well tinfoil doesn't normally get hot in the oven, I can always take it with my bare hands right after taking it out of the oven when I make a cake.

sorry about the card. i hate to see good ol' stuff go like that too. should have kept it for display as a museum piece.

I would have kept the card but the PCB was really foul and sticky, isopropyl alcohol would only spread the burnt flux even more. I should have tried with alien acid blood (I have recently seen the movies again ).

[momaka]

Re: X1900 XT displaying artifacts

*Sigh* There goes another one from the "mighty" oven

This is what I mean people - oven reflows are generally not a good idea and rarely work. I really don't want to be the person here, who just points fingers and tells people of all of the mistakes they made... but I guess there is just no way around it this time.

Mr. mitchmaster, please don't take it personally if I point out some of the "Don't DO's" from your attempted repair above. My only hope here is that you, or anyone else who reads this thread can learn from it so that the same mistakes are hopefully averted in the future.

I shielded the board with tinfoil

That's Don't DO #1 on the list - NEVER shield the whole board/PCB. Only shield plastic parts.

applied flux on the sides of the chip (maybe too much)

Yes, that is way too much flux indeed.

Not only that, but you have it all over the PCI-E connector. Soldering flux *is* a fairly good insulator (especially burned flux). Even if you did a successful GPU reflow, with all of that flux everywhere, that card probably would still appear not to work, because the flux on the PCI-E connector will prevent the pins to make good contact.

I did cautioned you against using too much flux, but I guess I wasn't specific enough how much is "too much". So here is the easier rule in case you (or anyone else) attempts a reflow: if in doubt whether you have applied enough flux or not, just remember that it is better to have less flux than more flux.

I followed some guide I found here with temperatures up to about 230°C but something obviously went very wrong, as you can see in the pics.

YES, that card is quite burned.

Looks like your oven was running way too hot. Did you pre-heat the oven and then insert the card? Because if you didn't, that would be the most likely reason why the card got so burned.

When first turned ON, the oven can take several minutes before it reaches full temperature. During those several minutes, a typical electric oven runs its heating element to-the-MAX. The radiating heat from that element could easily make thin objects (such as a video card PCB) heat up to well over 300C. It really depends on the size of the oven, though. Bigger ovens tend to run the element for a very long time when the oven is first turned on.

Because there is too much that can vary between different ovens, this is yet another reason why I tell people to stay away from the oven reflow method. You are better off using even the burner on the stove than the oven.

After I let the card cool I took off the tinfoil and saw that the flux was burnt and spread all around the PCB, which had turned to a darker hue of red.

Wow, that flux looks nasty. I wonder if this is because it is regular rosin type (meant for leaded solder) or if the tinfoil really did create some kind of a reaction, as ChaosLegionnaire suggested.

I've only seen similarly burned flux once on a board that was given to our repair shop to fix. Whoever worked it before us used some cheap nasty flux that turned all black and could barely be removed even with Acetone.

So here is another general suggestion: if in doubt whether your flux is the right type for reflow or not, just remember that in this case it is better NOT to use flux AT ALL than to use a flux that is not suitable.

I've done the latter mistake mentioned above myself, and the flux actually sealed some of the solder joints in such a way that nothing could be soldered to them afterwards.

The stickers on the back were burnt as well, even if they were under the tinfoil. I though that maybe the temperature was too high but I had been checking it with an oven thermometer.

Yes, temperature was too high indeed.

The problem with the oven thermometers is they measure the heat by conduction - i.e. usually temperature of the air in the oven (or whatever food you got it stuck in). But like I said above, when that heating element is glowing, the radiating heat from it can make objects easily reach temperatures of 300-400C with the air around them still being 100-200C lower.

This is what actually allows me to make the crust on my home-made bread nice and crunchy.
But for PCB reflow, this is not good.

I kept it lying around a few more days, then I binned it.

If you do electronic repair, you should have kept it. Those ceramic capacitors on the board are very useful. I've had many computer items come my way with broken off or shorted ceramic caps. So having a good source of those is always good. The MOSFETs on that card are useful too.

I guess I'm done with reflows for a while.

That's how I feel too when I don't get a successful reflow. But don't be discouraged! It's all just part of learning . Everything that you did wrong with this card can help you learn so that your next reflow can be successful.
As Thomas Edison himself said about his unsuccessful attempts to make a light bulb:
"I have not failed. I've just found 10,000 ways that won't work"

[momaka]

Re: X1900 XT displaying artifacts

u are also supposed to remove all stickers too as they can combust and turn into carbon in the oven heat.

Actually, that's not true.

Those stickers will shrink, darken, and typically end up looking charred to a crisp. But they will never combust.

I was actually playing with some boards on our gas stove the other day. Even when physically right above an open flame (but at a distance where the flame doesn't quite touch the sticker), those stickers will not catch on fire. Heck, they didn't even turn dark!

As for my little experiment.... believe it or not, a gas stove top is miles better than anything else I have tested so far when it comes to reflows. In fact, with a thermocouple or two, I'd say it's even better than some of the cheap reflow machines I've used back in the repair shop I worked at. I just reflowed a Radeon HD4850 the other day and it worked perfectly. No darkening of the PCB whatsoever from the heat - can't even tell that I've reflown this card.

[mitchmaster]

Re: X1900 XT displaying artifacts

Mr. mitchmaster, please don't take it personally if I point out some of the "Don't DO's" from your attempted repair above. My only hope here is that you, or anyone else who reads this thread can learn from it so that the same mistakes are hopefully averted in the future.

Don't worry, I find your information very useful.

Looks like your oven was running way too hot. Did you pre-heat the oven and then insert the card? Because if you didn't, that would be the most likely reason why the card got so burned.

When first turned ON, the oven can take several minutes before it reaches full temperature. During those several minutes, a typical electric oven runs its heating element to-the-MAX. The radiating heat from that element could easily make thin objects (such as a video card PCB) heat up to well over 300C. It really depends on the size of the oven, though. Bigger ovens tend to run the element for a very long time when the oven is first turned on.

Ehm... I read something about PCB thermal shock and said "hey I'll just put the card in when the oven is still off so that the temperature will rise nice and slow. Brilliant!"

Well, live and learn I guess.

If you do electronic repair, you should have kept it. Those ceramic capacitors on the board are very useful. I've had many computer items come my way with broken off or shorted ceramic caps. So having a good source of those is always good. The MOSFETs on that card are useful too.

If the temperature of the PCB really reached 300+ degrees don't you think that they may have been damaged or at least degraded?

Thank you.

[momaka]

Re: X1900 XT displaying artifacts

Ehm... I read something about PCB thermal shock

You're right, that's another thing to worry about. However, that' not something to worry about in a pre-heated oven, because there the temperature of the air will be around whatever you set the oven to. Thus, once the board is put in the oven, the board's temperature will rise slowly to the target reflow temperature.

Now, on a hot air rework machine, this is different, because the temperature of the hot air from the machine's nozzle will always be much higher than the target reflow temperature. Therefore, it is possible to heat the board too quickly and cause the board to warp if the reflow profile heats the board too quickly. Same goes for IR-based rework machine.

If the temperature of the PCB really reached 300+ degrees don't you think that they may have been damaged or at least degraded?

Well, the high temperature certainly isn't good for them. But in many cases, they will work just fine. At worst, you may get a latent failure from using those MOSFETs, perhaps some years down the road. But if you need to fix something and have no other replacement available, they can work for that.

I personally haven't seen MOSFETs damaged from heat - at least not with soldering iron or hot air.
Funny story: a friend of mine used a blowtorch on an Xbox 360 motherboard once, just for fun. He wanted to see how fast he can remove the GPU and CPU (the board was damaged beyond repair by someone else, so he didn't care for it). Along with the CPU and GPU came a dozen of MOSFETs, ceramic caps, and whatnot. My friend wasn't really interested in keeping those parts, but I was. Although the MOSFETs looked mighty charred (their cases were literally crumbling near the edges from too much heat), they all tested good on a multimeter. Thus, I decided to use a few of them on low power projects... and so far they are still working okay. I've had them for several years in storage now too. So overall, I think most components are pretty tough.

[ReeceyBurger123]

Re: X1900 XT displaying artifacts

Lol I like cake But listed to Mom and Chaos DONT use the shitty oven trick, just buy a hot air gun for crying out loud less chance of damaging it like this but ohh well whats done is done. Sorry for your loss

[momaka]

Re: X1900 XT displaying artifacts

Lol I like cake

Yup.
Cake, bread, turkey... you name it.
My family uses our oven A LOT as we eat mostly home-cooked food. NO WAY way am I going to risk it and put some crappy throw-away PC hardware in there that can stink up the oven and release who know what kind of bad chemicals that can then end up in my food. No sir! The oven is for cooking food only.

On the other hand, I tried the gas burner / stove top again the other day to reflow another HD4850. Setup worked flawlessly again. Got the whole reflow process done in less than 10 minutes.

Screw all of the cheap $1000 reflow machines. Gas burner FTW!

[jiroy]

Re: X1900 XT displaying artifacts

Waooo . That's what i call a true mess ..I think the best way to re-flow a board in an oven , is to put it on 4 Aluminium foil balls at its corners , keep it for seven minutes to 10 minutes at max. within a 300 c temp. leaving a normal dissipation of vapors .

In such conditions , reflowing will resemble to resoldering , and that's the real target .