Desoldering question (Miller XMT welder repair)

A solder sucker ain't the same as a desolder station. Of course solder wick is useful but the desolder station works for pretty well everything here. But probably too large an investment for occasional use.

A good compromise are those suction bulb desoldering irons, I've used one for probably 15 years now. I never had any luck at all with the separate solder suckers, it's too hard to apply heat and suction at the same time. I keep wick around too, neither is a one size fits all solution.

Snag with both of those is two hands needed - which usually means rigidly mounting the work piece.

Not with the suction bulb desoldering iron, I'm not sure how you'd use it two handed if you wanted to..

I've not used one but I'd have thought trying to hold it steady on the joint while operating the bulb with one hand might be a tad tricky?

Not at all, you hold it in your hand with your thumb on the bulb, it's really easy to use. I'd rather have a vacuum operated desoldering station but this fits in my toolbox. Only real trick is to keep a fresh tip on it, when they wear out they don't get a good seal.

Oh Boy ! Now he's REALLY in trouble ... Does he not realise that the magic smoke is kept in by this thick layer of magic dust ????

Arfa

None of those little solder suckers compare to a real properly functioning desoldering station. When I spent a summer working at a fiends stereo repair shop we had the Hako deoldering stations and I could desolder blown output modules faster than you could even uncoil your solder wick.

I've also noticed that I often need to add solder to make a second try at unsoldering a component lead if the solder sucker didn't get everything on the first try. I theorize (but can't prove) that the extra solder is sometimes necessary to carry heat all the way down into the plated-through hole, to melt the solder all the way through the hole.

If the component that's being removed has nice fat copper leads, those can carry heat pretty well (assuming you can make good enough contact between the iron tip and the lead). But IC leads don't seem to be terribly good heat conductors. A nice bit of liquid solder does a better job of conducting heat from the iron tip down into the PCB hole.

Dave

I don't think anyone who's used one can argue against it being the superior choice, but wick and other methods have their place, they fit comfortably in a small portable toolbox.

Just a little update. I found a certain adjustment that I adjusted and the vacuum increased very substantially. I think that this station is perfectly usable now as it is.

That's probably true, but there's also a lot of amalgamation going on. That's why copper soldering iron tips get pitted from solder; it amalgamates with the copper. Notice that the pasty glop on a soldering iron that isn't continuously re-tinned (or that has an iron-plated tip) has a higher melting temp. When you wipe the glop off and re-tin, it runs a lot easier. The same is true in a soldered joint.

-- Ed Huntress

You say "built in", that has the diaphragm pump in the power supply box, or a Ped-a-Vac venturi vacuum generator that runs off compressed air? Either way, there are likely disc-type filters in the line that become clogged with flux residue. The old ones had filters that you could pop open and replace the elements in, the new ones are "non-repairable". But, I found you can drip rubbing alcohol through the hole, let it sit a while and repeat a couple times, allowing the alcohol to drip out onto a paper towel. When the drips come out clean without staining the towel, the filter is magically rejuvenated. (Note the box may have ANOTHER disc filter hidden inside, it may also be dirty.)

Second, there is a wad of felt in the glass tube inside the handpiece that also becomes saturated with fine solder dust and flux. I have not found those to be recoverable due to the non-soluble dust. I got a bag of them with the machine, so I'm probably set for life.

Third, the hole in the desolder tip fills with oxidized solder. I have to rod the hole out every half hour or so when using one a lot. I just use some handy solid wire and jam it in, twist it around and pull it out, suddenly the "Suck" is audibly stronger.

I'll bet your filters are clogged. I have a motorized one at work and a compressed air one at home. Whenever I hav a problem, it is the filters or the tip.

Jon

I've never quite understood this adjustment. Never use mine on anything other than max.

What a shame lead-free doesn't do the same ... d;~}

Seriously though, most soldering iron tips have been made from nickel plated iron rather than copper, for many years now, and they get just as pitted as the copper ones did, but at least you could file the copper ones down. I never used to put a new bit in my old Adcola, until it was a 'stump'. I am more of the opinion that tip erosion, both back then and now, is caused mainly by the mildly corrosive action of the flux in the solder core, and that the nasty gob of metal that you find on the tip when the iron hasn't been used for a while, is oxidised components of the original solder almalgam. Smitty, what thinks you ?

Arfa

If they are anything like the felt wads fitted in the same place in my Weller vacuum desoldering station, you can recover them once, sometimes twice, by just running a curved, blunt scalpel blade over the surface as a scraper. The surface layer thats stuffed with solder dust, just falls away re-exposing clean, uncontaminated felt. I would guess that you perhaps lose a half a mm from the pad's thickness.

Arfa

Dracula? Rotwang?

Are all desoldering tips (such as 1/8" tips) compatible? I need to buy a few and am a little confused about brand compatibility.

Dunno. Are you having trouble sourcing OEM replacements?