I just finished a mini project. I fixed a "broken" Miller XMT 300 CC/CV welding machine, which had the switch for the display broken. That switch was switching the display between showing voltage or current on a mini LED screen.
The broken switch had to be desoldered and a new one had to be soldered in.
The issue that I ran into was desoldering. I have a "Pace SMD 2000 desoldering station" from my younger military surplus days. This station has a tool that is like a soldering iron, but has a axial hole in the tip and an adapter for a vacuum, and the built in vacuum. When I push on a pedal, the vacuum starts sucking through the tip. So I would melt the solder with the hot tip, push the pedal and...
My problem was that it barely sucked. Not enough to vacuum in the solder from the circuit board.
As a stopgap measure, I used my 1/3 HP vacuum pump by connecting it to the desoldering tool and turning on at the proper moment.
In the end, it all worked, the old switch was removed, a new one installed, and the welder has a working selector of V vs. A display.
All this leads me to the conclusion that something is wrong with the vacuum pump on this station. Would you say that it should provide very strong suction?
Obviously it should provide enough to remove molten solder from the joint.
Most desolder tools can get blocked. So check the pump with the tool disconnected you should feel the vacuum with your finger. Also check the output air stream from the pump. Many have an adjustable restrictor valve to set the vacuum level. If it's been used without the proper filters it's possible the pump is dirty, blocked or damaged. They usually strip down easily. The one Pace I've had apart had sort of carbon vanes which move in slots to make contact with the body by centrifugal force. If those were stuck it wouldn't work properly.
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*Why do overlook and oversee mean opposite things?
Dave Plowman dave@davenoise.co.uk London SW
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My Weller 900 desoldering station, is of exactly the same construction, and probably similar vintage. It has a vacuum gauge on the front, that reaches a reading of "-0.6" - so I guess that's 0.4 atmospheres - when it is working normally. But that's the trick to it. It works extremely well when it *is* working well. It develops enough suck to be able to hear it 'slurp' up the solder from a joint, and will readily remove solder from around IC pins in a thru' plated hole board - an action that's notoriously difficult to achieve.
But when it's not working well, then man, it's a dog. It requires regular maintenance of making sure that the hole in the nozzle is clear, using the proper ream-out tool, every few sucked joints. About once a week, I clear out the passage between the tip, and the solder collection chamber, again using the proper reamer. Once a month, it will need the chamber cleaning out, and the felt filter at the rear, just before the vacuum connection point, replacing or cleaning. Once every couple of months, it will need the front collection chamber gasket replacing, as the silicon rubber goes hard. Occasionally, a blob of solder will get past the filter, and lodge in the vacuum tube. It can get sucked quite a way in, so it's worth feeling all the way back to the vacuum pump unit, to make sure that there is nothing in there.
About once every 6 months, I clean out the main vacuum passageways. That's all of the solid pipe stubs that the various flexible pipes plug onto. It includes the ones at either end of the main flexi to the iron, and also the ones to the 'flywheel' chamber inside the base station. This also serves as the holder for the station's own protection filter - which should be replaced at this time, along with the exhaust filter - and the connection point for the vacuum gauge. The final one is on the vacuum pump itself. Despite all of the filters that are in line, all of these vacuum passageways get clogged with solidified flux residue, which is very sticky like tar, and needs poking out with a fine screwdriver blade, before finishing off with a flux solvent. This clogging up of these tubes has a *very* significant impact on the performance of the unit, and is the difference between the thing being a pleasure to use, and a royal pain in the arse.
About once a year, I strip out the vacuum pump itself, and clean all of the passageways, and the little rubber flap valves, which also get coated in flux residue. Hope this helps you get a handle on how well your Pace
*should* work, as I should think that it is pretty similar to my Weller.
:I just finished a mini project. I fixed a "broken" Miller XMT 300 :CC/CV welding machine, which had the switch for the display :broken. That switch was switching the display between showing voltage :or current on a mini LED screen. : :The broken switch had to be desoldered and a new one had to be :soldered in. : :The issue that I ran into was desoldering. I have a "Pace SMD 2000 :desoldering station" from my younger military surplus days. This :station has a tool that is like a soldering iron, but has a axial hole :in the tip and an adapter for a vacuum, and the built in vacuum. When :I push on a pedal, the vacuum starts sucking through the tip. So I :would melt the solder with the hot tip, push the pedal and... : :My problem was that it barely sucked. Not enough to vacuum in the solder :from the circuit board. : :As a stopgap measure, I used my 1/3 HP vacuum pump by connecting it to :the desoldering tool and turning on at the proper moment. : :In the end, it all worked, the old switch was removed, a new one :installed, and the welder has a working selector of V vs. A display. : :All this leads me to the conclusion that something is wrong with the :vacuum pump on this station. Would you say that it should provide very :strong suction? : :Any experience here? : :i
Your desoldering tool (like most) is probably fitted with a small diameter tip (approx 0.8mm - 1.00mm inside diameter) 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.
When you try to suck solder from around pcb mount switch terminals you have to do it in stages because the tip doesn't have the closest contact with the pcb for most of its tip periphery. There is usually a fair gap between the switch terminal and the side of the mounting hole and when the solder melts and the suction starts it will pull solder from only a small section of the hole before the rest of the solder cools due to the air passing. There will be much more solder around a switch terminal as well so it may take several goes working your way around the pin.
My Hakko desoldering station has good suction but when it comes to desoldering switches and other large terminal items I usually prefer to use my old manual Soldapult. These only take one or two goes to remove all solder.
Ignoramus1782 fired this volley in news:EqOdnRGHEfpSgz3anZ2dnUVZ snipped-for-privacy@giganews.com:
Iggy, there are four things that go wrong with the Pace stations, and at least two of them are "intentional".
In the solder collection tube is a serpentine piece of aluminum strapping used to trap and cool the solder. That can collect so much flux and metal that nothing can get past it in the collector.
Upwind (vacuum side) of the strap is a cotton felt plug used to prevent droplets from passing into the vacuum line. It gets solid-filled with flux vapor, and will fail to pass air. Just massage it in a beaker of denatured alcohol to clean it, then thoroughly dry it before re-use. Replace if it's too gunked up with solder chips.
Further upwind, inside the base is a pancake filter. It, too will get rosin vapor deposited on the fabric. Once plugged, you must replace it.
Those are the three Intentional blockages -- all protection features of the system.
The fourth area of failure is the vane pump. It has graphite vanes and end-plates. They wear. They can be replaced easily, if you access to the parts.
I tried it last night, with the tool disconnected, as you say. I do feel a vacuum, but it is very slight.
OK. When I get time, I will take it apart and see what's wrong. The station is usable even without this pump, since I can use my other vacuum pump (1/3 HP Welsch DuoSeal), but, obviously, it is not as convenient. I would even say, "it sucks". :)
Well, it does this pretty well with a real vacuum pump attached instead of the "desoldering station pump".
your
Somehow, to my amazement, usually one "suck" was enough per pin. The pins were too thick to fit inside the tube, so I had to approach it from the side, and yet, it worked out.
I am confused as to how it works, do I need a separate source of heat for that one?
I cleaned the tube, but there was not that much to begin with, a few globs.
A great idea, I will check it.
Will check out, thanks.
Great, last time I checked, Pace was still around. Thanks Lloyd. I will try to approach it systematically, trying to isolate the problem. I believe that it is something inside the unit.
I have several solder suckers. In close quarters sometimes solder wick does the trick, and it always works. I've got one of those big blue nasty things, and a couple of smaller aluminum solder suckers. In close quarters I still find myself reach for the solder wick.
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I think that I would like to find Cirk-Grind device and also should buy more tips. This is actually a very nice station if I get it to its potential. I do have a manual for it also.
Ignoramus19508 fired this volley in news:NdOdnTFNr5aYPz3anZ2dnUVZ snipped-for-privacy@giganews.com:
Iggy, it's been a while since I had my Pace, but IIRC, those tips are plated with Indium/Nickle alloy to prevent them from being wetted by or amalgamated with the solder -- even in the bore. Thus, don't use a hard tool to clean the bore; use a plated copper lead from a resistor, etc. If you scratch the bore, it quickly begins to corrode and amalgamate with solder.
I think I still have some 0.025 tips for that. If I can find them, I'll drop 'em in an envelope.
The solder in a joint can wind up having a much higher melting point and much less wetting ability than it did when it was initially applied. That's because it amalgamates to the material being soldered to some degree. If the joint was the least bit overheated initially, or upon re-heating for removal, it can be a fairly high degree.
You notice it more trying to unsweat copper plumbing. Sometimes you have to wet the joint with some fresh solder to get it to come apart. But I've run into the same thing taking components off of an old board.
Another question. These circuit boards were originally sprayed with some coating. I surmise that the purpose of it is to prevent accidental shorts due to dust contamination or other debris being drawn into the unit.
This was, in fact, a great thing, as this particular welder had so much dust inside, that I was shocked. The amount of dust was nothing short of incredible, maybe 5 lbs of dust settled on absolutely everything. I took this welder out of its protective shell, vacuumed it, and then blew the dust out using compressed air (outdoors). The truly amazing thing, is that it was still functioning fine with all that dust inside.
Thanks to the Miller company.
Having said that, I would like to apply that coating to the areas that I re-soldered. What is that coating?
Ignoramus19508 wrote in news:TpSdnYx38KcYWj3anZ2dnUVZ snipped-for-privacy@giganews.com:
NOooooooooo, you blew away all of the magic dust!!!! Now it will surely self destruct when you need it the most. Never blow away the magic dust, it annoys the tool gods.. ;)
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