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Old 02-27-2012, 10:22 PM   #1
ajcox1234
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Question Help! Small solder joints.

I have an ASUS motherboard with 2 bad capacitors, I have replacements but the joints are very small, my desoldering braid won't remove the solder. What else can I use to desolder the bad capacitors?
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Old 02-27-2012, 10:40 PM   #2
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Default Re: Help! Small solder joints.

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Originally Posted by ajcox1234 View Post
What else can I use to desolder the bad capacitors?
Add some 60/40 solder to the joint first.
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Old 02-27-2012, 10:44 PM   #3
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Default Re: Help! Small solder joints.

Can I use my 100w Weller or should I use my 45w Radioshack iron with a chisel tip?
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Old 02-27-2012, 11:30 PM   #4
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Default Re: Help! Small solder joints.

I try to wick the pads on these boards, so I know how you feel. 3/4 of the time, it won't completely wick, especially if the pad is near something that absorbs a lot of heat, like a copper coil or a grounding plane.

What you will have to end up doing is trying to coax the cap in while holding the iron to the pad. Be careful not to rip up the pad. If you do, you may as well toss out the board unless the lead has attached to the via (I think you can test this with a multimeter).

Quote:
Can I use my 100w Weller or should I use my 45w Radioshack iron with a chisel tip?
Of course use the 100w.. It's not wicking with the 100w!? I thought the reason it wouldn't wick for me was because I use a 25w.
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Old 02-27-2012, 11:36 PM   #5
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Default Re: Help! Small solder joints.

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Originally Posted by ajcox1234 View Post
Can I use my 100w Weller or should I use my 45w Radioshack iron with a chisel tip?
I would use the latter. Add some 60/40 solder to joints. Then heat up the same joints while pulling/rocking on the cap from the other side.

Once the cap is loose, heat up a stainless steel sewing needle from the backside and push until it clears the hole. I just switched to this method from a solder sucker and it is way easier.
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Old 02-28-2012, 12:22 AM   #6
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Default Re: Help! Small solder joints.

I'm not able to clear holes with a sewing needle. It just gets stuck in there.
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Old 02-28-2012, 11:59 AM   #7
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Default Re: Help! Small solder joints.

Thanks. I'll get some 60/40 to make the joints bigger, then use the wick to remove the rest of the solder and remove the bulging Ltec's.
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Old 02-28-2012, 06:12 PM   #8
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Default Re: Help! Small solder joints.

Looking on the Radioshack site, I found a nice desoldering iron. I've decided to buy one of those on Friday, with some 60/40 Rosin Core solder to desolder the old Ltec's and solder in the new Rubycon MBZ's.
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Old 02-29-2012, 03:52 PM   #9
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Default Re: Help! Small solder joints.

A good quality flux will help because it allows the heat to melt the solder.Manufacturers of electronic PCBs seem to make the PTH,s very small so components are a tight fit. If the capacitors are defintely going to be replaced you could always cut them off the board and take the pins out the board.
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Old 03-01-2012, 12:31 AM   #10
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Default Re: Help! Small solder joints.

Another thing you can do is pre-heat the board. I have a sub $20 heat gun for this that works great - I just blast the area of the board below the caps for 10-20 seconds or so and then use the soldering iron to heat the pads one by one on each cap and then wiggle the cap out. If you don't have a heat gun, a hair dryer will can also work okay - you'll just need to heat the board for a bit longer.

Flux and/or 60/40 lead solder is also very helpful.

In any case, don't be afraid that you'll burn the board with your soldering iron - you very likely won't. Keeping the iron on a joint for 10 seconds or more is usually not fatal.

Lastly, make sure the tip of your iron is clean and well tightened.
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Old 03-01-2012, 03:43 PM   #11
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Default Re: Help! Small solder joints.

I've struggled with some boards, with a 60 watt digital soldering station and even an 80 watt desoldering gun I borrowed, and after research and a bit of testing I have come to the conclusion that some boards (or some areas on the boards) are really only easy to work on with pre-heating.
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Old 03-01-2012, 04:42 PM   #12
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Default Re: Help! Small solder joints.

I haven't tried desoldering or soldering on it yet. I will tomorrow once I get the 45w desoldering iron. I got my Rubycon MBZ's today, I ordered 8, and I got 12! Score! Thanks eBay! And they're not Rulycon fakes either!
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Old 03-01-2012, 05:05 PM   #13
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Default Re: Help! Small solder joints.

Unfortunately just because they don't say Rulycon doesn't mean they're not fake.

eBay is a big haven for fake capacitors. The fact they gave you more than you ordered seems suspicious to me - why would a legit seller with a genuine product give you more than you paid for unless by accident?

Who did you buy them off?
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Old 03-01-2012, 05:22 PM   #14
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Default Re: Help! Small solder joints.

I bought them from here http://myworld.ebay.com/ny-electroni...id=p4340.l2559

They all have the same date code, 0524. The bung in all of them look the same, as well as the vent. They don't look fake to me, and I've seen a lot of MBZ's.
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Old 03-01-2012, 05:26 PM   #15
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Default Re: Help! Small solder joints.

Yea, I'm pretty sure their stuff is legit. Did you order only two? Why not re-cap the whole board?
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Old 03-01-2012, 05:33 PM   #16
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Default Re: Help! Small solder joints.

It was an 8 piece set. No reason to, none of the other capacitors are bloated. They're OST (I know they're a bad brand, but if you keep them cool, they'll be fine), and UCC KZG (They don't like heat either, but I keep at computer pretty cool, so I won't replace the rest of the capacitors unless they bulge.
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Old 03-01-2012, 05:34 PM   #17
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Default Re: Help! Small solder joints.

Quote:
They're OST (I know they're a bad brand, but if you keep them cool, they'll be fine), and UCC KZG (They don't like heat either, but I keep at computer pretty cool, so I won't replace the rest of the capacitors unless they bulge.
OST and KZG don't always bulge... You should have replaced them.
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Old 03-01-2012, 05:37 PM   #18
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Default Re: Help! Small solder joints.

I've ran small FFT's on it in Prime95 for about 2 hours and 30 minutes now, still going strong.
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Old 03-01-2012, 08:43 PM   #19
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Default Re: Help! Small solder joints.

Recapped the board tonight, was a pain in the a$$, thought I killed the board, but it's booted up and playing a YouTube video as I type this. I'm never soldering on an ASUS motherboard, ever again. lol.
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Old 03-02-2012, 12:47 AM   #20
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Default Re: Help! Small solder joints.

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Originally Posted by ajcox1234 View Post
I'm never soldering on an ASUS motherboard, ever again. lol.
It is not just ASUS. Pretty much all motherboards are multilayer and the copper planes suck up all the heat from the iron tip making it hard to desolder. Having a clean tip, flux, 60/40 solder, and the correct tip helps alot. A chisel tip is good for desoldering. The sharp conical tips don't have a lot of surface area for heat transfer.
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