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Old 07-22-2010, 01:16 AM
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Default Learning To Reflow

Hello all - I had a customer bring me in a Dell D620 Latitude laptop with no video. I did the normal diag stuff - external monitor-reseat the ram ect. I did get a checkerboard effect on the external monitor at one point, and that is what has lead me to believe a GPU failure.

Nonetheless, I did some research on this particular laptop, and it seems to suffer from the same problems as the infamous HP DV series, and apparently can be fixed with a reflow of the GPU chip.

I would like to take advantage of this system and try my hands at a reflow because the system is basically dead unless this reflow works or the customer gets a new MOBO, and I do not think the customer is viaing for getting a new mobo, therefore, I have a laptop to give this a go on.

I am going to ask the customer if I can try to reflow, and let her know that it may or may not work, and offer the reflow at a half off price of $50.00 if it works and no charge if it does not. If it works then I have a new skill, and I will charge $100.00 from here on out.

Ok back to the original topic "Learning To Reflow" I have been watching tutorials on Youtube and reading Howtos, and I notice people either use a Heat Gun or a Pin Torch, there in lies my question do I use a Heat gun or a Butane Pin Torch?

Second question. Some people cover the GPU with foil and some leave it un covered - Which is the best tactic?

Other than that re flowing looks like a simple process.

Thanks in advanced, and please if you guys have any other diagnostic tactics for me to try on this thing before I reflow it, please let me know.

- Shane
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Old 07-22-2010, 02:41 AM
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I'd highly recommend this blog by someone who does tons of reflows and component-level board repairs. He goes through a lot of the myths about reflow advice found on YouTube and debunks it, and spells out what he does in some detail. Personally, I'd want to use a hot air rework tool that provides precise temps. Absent that, a heat gun on low setting seems advised, as the temp you want is around 250C -- much lower than you'll get with a pin torch (which I assume is an open-flame butane torch) -- for 2 - 3 minutes. The key, according to the bloggist, is the use of proper (rosin-based) flux, as it oxidizes and begins to smoke at the temp you want to achieve, just when the solder begins to reflow. That's what he uses to tell that he's got the temp right. Let us know how you make out!
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Old 07-22-2010, 03:11 AM
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Quote:
Originally Posted by Larry Sabo View Post
for 2 - 3 minutes. The key, according to the bloggist, is the use of proper (rosin-based) flux, as it oxidizes and begins to smoke at the temp you want to achieve, just when the solder begins to reflow. That's what he uses to tell that he's got the temp right. Let us know how you make out!
I did see a guy who put a quarter on top of the chip and then a cut of solder on top of the quarter. I guess he was using the solder to see the visible melting point?

Thanks
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Old 07-22-2010, 03:20 AM
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Keep in mind also that some reflows will last the life of the notebook and some will last a day and fail again.
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Old 07-22-2010, 03:27 AM
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Originally Posted by vdub12 View Post
Keep in mind also that some reflows will last the life of the notebook and some will last a day and fail again.
I will deffiently let the customer know this, and offer a refund if it does not work.. I find it hard to really warranty a re flow.
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Old 07-22-2010, 07:15 AM
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well, reflowing isn't simple because you can't see when all the solder is melted so it is a bit of a guessing game.

I would recommend a hot air rework station with a tip the size of the chip you are working on.

Foil helps protect the other components from the heat, the ones putting it on the chip to be removed makes no real sense to me.

I have not done a reflow yet, so take my advice to be no better than the youtube videos.
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Old 07-22-2010, 01:21 PM
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Even if you do everything perfectly it definitely isn't a guaranteed fix. If it does work and you add nice copper shim and good thermal paste, usually the fix will last very well. I'm not sure if that Dell has a bios update that makes the fan run more like the HP's, probably want to check into that also.

The blog that Larry linked is about the best around. The flux is very important as is a very stable and secure mounting of the system board. Any vibration or movement during the reflow process and you can forget about it.

Ideally you should also have a pre-heater beneath the board to keep the temperatures more even to prevent the board from warping.

Best of luck to you.
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Old 07-22-2010, 01:48 PM
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Knowing that this is not a solid fix, makes me less willing to try it especially when I do not have the correct tools. I do not want to invest in a hot air station, for I am not to big on fixing hardware on a component level. When it comes to bad mobo`s I generally recommend getting another mobo or just getting a new computer if its an oldie.
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Old 07-22-2010, 05:00 PM
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Do you guys find it worth doing reflows? Just from what I am reading on here and random places on the net it sounds like a iffy fix.
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Old 07-22-2010, 06:58 PM
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To be completely open and honest, I haven't done one myself, in spite of having all the equipment required. I've been turning away re-flow work because I'd rather have no customer than an unsatisfied customer, and by all accounts, it isn't going to last long enough to take a chance. While Kevin at that blog has had excellent success, he has had many years of top-level experience soldering. However, one only acquires experience and success through training and practice. Go for it!
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