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Desoldering Techniques / Tools

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Desoldering Techniques / Tools

by honestbob » Wed Feb 27, 2013 2:10 pm

Hi All. I thought I'd move this out of the SC-3000 video daughterboard thread as I'm curious about your favourite desoldering techniques in general for maintaining old hardware.

To recap from the bits sprinkled through the previous thread, those little handheld $10 desoldering pumps you buy at Dick Smith or Jaycar seem largely useless.

Most of the stuff I do involves through hole rather than surface mount. My preferred technique at the moment is to use desoldering braid. If I don't care about the component, the quickest / safest way to remove it is to cut the pins, remove the chip body, then quickly remove the pins from the board and clean up the pads with desoldering braid. That gets the component out fast, and minimizes the risk of damaging the PCB. Of course, it means the component is toast. I can usually get through hole components out in one piece with desoldering braid too, but it takes a long time, and you put a lot of heat into both the component and the PCB.

I would love a decent and inexpensive desoldering gun. Carcenomy said he has a good clone of a Hakko 474 which he bought for about $250.

natshaw is about to try some $50USD tool off eBay which SpidersWeb didn't think was great.

I have seen some people rave about cheap little tools like this Radioshack one before which is about as brute force as you can get for $13USD :)

http://www.radioshack.com/product/index ... esoldering
Image

What about something like this? (Approx $80-$90USD on eBay)

http://www.ebay.com/itm/251191119518
Image

How about you guys? What are your preferred tools, tips, and techniques for quickly removing components without damaging them or the PCB?
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Re: Desoldering Techniques / Tools

by manuka » Wed Feb 27, 2013 2:22 pm

I use pretty much the same techniques as you describe, My iron until I can afford something better is a 60w Dick Smith special that came into work, I replaced the thick tip with a much finer tip, this seems to work on most boards - apart from some of the flat screen Macs which you need quite a lot of heat to desolder. Not all solder wick is equal though I have used some rubbish stuff in the past and pretty much only use Goot these days, I have ordered some off Deal Extreme which claims to be goot but we'll see what it's like when it gets here....

I haven't used on of those desoldering pumps before but have one coming in with the solder wick so am interested to see how that goes.
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Re: Desoldering Techniques / Tools

by tezza » Wed Feb 27, 2013 2:48 pm

honestbob wrote:My preferred technique at the moment is to use desoldering braid. If I don't care about the component, the quickest / safest way to remove it is to cut the pins, remove the chip body, then quickly remove the pins from the board and clean up the pads with desoldering braid. That gets the component out fast, and minimizes the risk of damaging the PCB. Of course, it means the component is toast. I can usually get through hole components out in one piece with desoldering braid too, but it takes a long time, and you put a lot of heat into both the component and the PCB.

This is my preferred technique and for the same reasons.
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Re: Desoldering Techniques / Tools

by SpidersWeb » Wed Feb 27, 2013 3:05 pm

On computers now I'd be using my temp controlled iron + either a desolder pump and/or desolder wick. (I tend to do the "snap component then braid" method a bit as well). I don't recommend desoldering tools with mechanical pumps built in and no temperature control - for anything other than big power supply components the desoldering always ended badly for me.

The cheapest tool for the job that will work well in my opinion is this: http://www.ebay.com/itm/AOYUE-474A-Deso ... 4601b94866

I'll be ordering mine as soon as I have the cash spare (I just bought a house, a ring, and I have a sick car). I beleive Carc has one and he's been raving about it (so have others I've seen who own them also). Firstly you get temp control, secondly instead of a poofy mechanical pump you get an actual electrical air pump, and each join should only take a couple of seconds - reducing the chance of any damage from heat.

Edit: that white one looks more precise than my blue one, but I'd still recommend spending a bit more if you're going to invest money in to it
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Re: Desoldering Techniques / Tools

by manuka » Wed Feb 27, 2013 3:19 pm

SpidersWeb wrote:The cheapest tool for the job that will work well in my opinion is this: http://www.ebay.com/itm/AOYUE-474A-Deso ... 4601b94866


Wow, shippings a bit of a killer. My latest acquisitions off EBay is being shipped here free from china, although the camera items I bought are much lighter and smaller I suppose. I did try a very cheap desoldering pump a wee while back, that particular one was nigh on useless, the tip would melt the solder but as soon as you turned the pump on it cooled the solder down too much and it hardened.
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Re: Desoldering Techniques / Tools

by SpidersWeb » Wed Feb 27, 2013 3:35 pm

In that example I wonder if they've moved some of the unit cost in to postage so it looks cheaper - because shipping from China is cheap usually.
I also love it when I find things I need in countries like Bulgaria - it arrives quickly and costs dollars to send!
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Re: Desoldering Techniques / Tools

by Carcenomy » Wed Feb 27, 2013 5:42 pm

The unit I run is an Aoyue 474A+ - looks like the basic 474 (as it is, a Hakko clone) but a little more specced. It's not quite so great on modern equipment - especially leadfree - but works beautifully on older gear. The trick with the Commodore 64s at least, is to refresh the solder joints with some fresh solder first THEN hit it with the desolder gun. Just take it nice and quietly and you won't overheat anything either. Leaves a beautiful clean board with perfectly clean vias as long as you take your time.

The unit:
Image

My very first removal, the PLA in my 64C project:
Image

I picked mine up via Shenzhen Scotle Technology in China directly via Alibaba for the princely sum of... $161US delivered :)
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Re: Desoldering Techniques / Tools

by TRS80 » Wed Feb 27, 2013 9:56 pm

One of the best techniques I have found for desoldering non surface mount parts, particularly those on boards with plated through holes is to add new solder to the joint first.

I just use the cheap Jaycar TH1850 and it works really well. If you are going to cut the part out anyway having the sucker separate from the iron works well by applying heat one side and sucking any surplus solder through the hole.

I am sure there are better tools but hard to beat the price.
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Re: Desoldering Techniques / Tools

by ZL2AOX » Thu Feb 28, 2013 8:07 am

I get by with just solder wick and one of those cheap spring-loaded, piston type suckers. Guns are undoubtably faster but not essential. I find it hard to justify the expense for the amount of desoldering I do. Still, I might splash out one day.

Soldering is a different matter though; I use a Hakko FX-888.
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Re: Desoldering Techniques / Tools

by arjoll » Thu Feb 28, 2013 1:40 pm

I just use a mechanical pump (one of the spring-loaded suckers) and my Antex 25W iron for most jobs. Saying that I have never had to do any component-level repairs of computers, the closest being recapping an Apple IIe power supply (unfortunately still squegging, but the board was soaked in electrolytic juice) - most of this kind of stuff that I do is with old audio gear with wider tracks and lower component density!
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Re: Desoldering Techniques / Tools

by Gibsaw » Thu Feb 28, 2013 4:09 pm

Well, all I can say is that I would have thought exactly the same up until recently. i.e. I've never needed more than my bog standard old dick smith soldering iron and a solder sucker... Old solder can be hard, but a bit of new solder to alloy with and lower the melt temp, and you're in business... Until the first time you come across factory-melted "lead free" solder that's had a few years to get nice and hard.

You'll find yourself screaming. Every other component on the board will be melting, and it STILL won't flow. I've been there with a laptop audio socket replacement. Wasn't fun. Utter failure. Bigger mess than the broken socket. I stopped there on the dead "donor" board, rather than destroy the working laptop.

From what I've been watching on youtube, It takes a really good desoldering iron (at least a 60w), preferably machine vacuum or at least good quality wick, LOT's of flux and a low temperature bismuth solder with good penetrative abilities like "chip quik" to alloy with, before you get anywhere. :)

So now, I have a little queue of jobs for my modern machines that I'm still trying to work out how I'm going to approach without buying hundreds of dollars worth of equipment. (for instance, I have a P4P800SE that needs a re-cap, and I'm scared to touch it.) :?
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Re: Desoldering Techniques / Tools

by Carcenomy » Thu Feb 28, 2013 5:47 pm

Leadfree sucks the big one. I've experimented with removing components from some dead boards kicking around the workshop using the desolder gun, if you throw a bit of new leadfree solder at them then take the gun to it, it will leave. That is, until you hit the bloody ground tracks. You can pour the heat at it and just not succeed.

I have recapped quite a few ECS MCP61PM-HM boards (aka the HP Nettle, found in AMD powered Compaq Presario SRs). Trick with them is to pull the cap first - even if its legs stay behind. THEN approach it with a hot iron pretinned with leadfree, and work the legs out. Reverse the process to get the new ones in and bingo. I've had about a 75% success rate with these boards. Similar technique should work for your ASUS board. Although I must ask - why are you wanting to repair an old 865PE board? Building some form of exotic Pentium 4? You must enlighten me in another thread about that one.
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Re: Desoldering Techniques / Tools

by Gibsaw » Thu Feb 28, 2013 9:15 pm

Nothing complicated about that one. It's just a nice machine that really cranked (and overclocked well.) The P4P800SE is a kickass P4 board and it's an old friend that I can't bring myself to throw out simply because it is one of THAT vintage which had "bad caps".

To put a little perspective on this, "gibsaw" is my QUAKE name, and I still have nearly all my major competitive quake machines.

My Asus TX97 based P200MMX w/voodoo
My Asus P2B based P-II-350 w/Riva TNT
My Asus P4P800SE based P4-2.8GHz "30-cap" w/GeForce4MX
My Asus P5K based Core2 Quad 2.4GHz w/GeForce8800GTX

... call me sentimental.
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Re: Desoldering Techniques / Tools

by Carcenomy » Thu Feb 28, 2013 9:25 pm

Dude you're preaching to the choir, we still run Quake III Arena tournaments at LAN parties to this day! Your competitive rigs awfully similar to my rigs of those sort of timeframes, great minds eh?
The P2B is a heck of a nice board too, was just playing with my own P2B-D tonight so I can test some soundcards for xjas. Oh that glorious feeling when it gives a POST beep and announces 'Pentium III 500MHz, 2 Processor(s) detected' :)
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Re: Desoldering Techniques / Tools

by Gibsaw » Thu Feb 28, 2013 9:35 pm

Funnily enough, I had major problems on my P2B... It would absolutely kick ass, until I put in an SBLive.

As with a lot of the later Creative Labs cards, their PCI compliance was slightly marginal, and when you matched that up with a Viper550 (TNT) it would produce a nasty hardware lockup.

fragged.net.nz... heh. Small world. I was the president of frag.gen.nz (The auckland uni games club. We ran monthly 50-80 person LAN's at the Tamaki campus for quite a while... )

However, I digress... this thread's about soldering. :)
Last edited by Gibsaw on Thu Feb 28, 2013 10:17 pm, edited 1 time in total.
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