Desoldering question (Miller XMT welder repair)

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.

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    Dave Plowman        dave@davenoise.co.uk           London SW
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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?

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    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

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.

I cant help but ask why dont you take the solder sucker device apart and check out the problem ?

You were able to repair the welder .

:On 2008-01-30, Ross Herbert wrote: :>

:> Your desoldering tool (like most) is probably fitted with a small diameter tip :> (approx 0.8mm - 1.00mm inside diameter) : :Yes. : :> designed for sucking solder from around small gauge component leads :> and IC pins where the tip make full peripheral contact with the :> board. When the solder melts around a pin all the air passes solely :> around the lead and maximum effect is achieved inside the through :> hole. : :Well, it does this pretty well with a real vacuum pump attached :instead of the "desoldering station pump".

Yes, of course it will. But the desoldering station pump is NOT a specialised

1/3HP vacuum pump. It is designed as being adequate to suck solder from around component pins ONLY when the nozzle completely surrounds the lead AND make 100% peripheral contact with the pcb solder pad.

Well Ross, I gotta tell you that I use my Weller desoldering station just about every day, I keep the same sized tip on it with a 1mm hole at all times. It is used both for pin sizes where the hole will fit over the pin, as you describe, and also for any other joint that I need to get the solder off as well. I have never had a problem with it developing enough suck to remove solder from a joint that requires the tip to be applied in a way less than your stated 'ideal', unless it has reached the point where it needs servicing. I think that in common with most soldering / desoldering tools, it depends on how often you use it, and hence how much skill in its use, that you have developed.

Arfa

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.

i

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

This is the knob that throttles the OUTPUT pressure? Yeah, it chokes off the outlet of the pump, thereby killing its vacuum capability, too.

Jon

You can easily build your own inexpensive welder.

cuhulin

I believe that it is that part indeed.

i

:> :On 2008-01-30, Ross Herbert wrote: :> :>

:> :> Your desoldering tool (like most) is probably fitted with a small :> diameter :> tip :> :> (approx 0.8mm - 1.00mm inside diameter) :> : :> :Yes. :> : :> :> designed for sucking solder from around small gauge component leads :> :> and IC pins where the tip make full peripheral contact with the :> :> board. When the solder melts around a pin all the air passes solely :> :> around the lead and maximum effect is achieved inside the through :> :> hole. :> : :> :Well, it does this pretty well with a real vacuum pump attached :> :instead of the "desoldering station pump". :>

:> Yes, of course it will. But the desoldering station pump is NOT a :> specialised :> 1/3HP vacuum pump. It is designed as being adequate to suck solder from :> around :> component pins ONLY when the nozzle completely surrounds the lead AND make :> 100% :> peripheral contact with the pcb solder pad. :>

: :Well Ross, I gotta tell you that I use my Weller desoldering station just :about every day, I keep the same sized tip on it with a 1mm hole at all :times. It is used both for pin sizes where the hole will fit over the pin, :as you describe, and also for any other joint that I need to get the solder :off as well. I have never had a problem with it developing enough suck to :remove solder from a joint that requires the tip to be applied in a way less :than your stated 'ideal', unless it has reached the point where it needs :servicing. I think that in common with most soldering / desoldering tools, :it depends on how often you use it, and hence how much skill in its use, :that you have developed. : :Arfa :

Yes Arfa, I agree with what you say. I also can use my Hakko to remove solder from around larger pins quite quickly, but due to the large amount of solder which often must be removed from large terminals, several attempts may be required and sometimes the tip requires a clean out to complete the job on a single switch. I can't say if there is anything wrong with the OP's desoldering station, although this may be the case. I find that for small number of large terminals the old Soldapult takes less time and requires less cleaning.