Desoldering question (Miller XMT welder repair)

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.

Thanks. I bought AS196LS and some tips thereof.

Might sell the rework station if this one works OK.

Also got some conformal coating.

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

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

No, these things (at least with the right handpiece, like the SX70) can remove an INCREDIBLE amount of solder in one slurp. Remember, companies won't pay $2500 for something like this if it didn't actually work. One nice thing about this sort of unit is it has a temperature-controlled heater with temperature readout of the tip, and the heating tip is also the sucker, so you don't have to switch quickly from soldering iron to sucker before the joint cools. Another nice thing about the high-end Pace and Weller gear is that individual replacement parts are available, so you can replace any single piece that wears out or breaks.

Iggy wasn't replacing a high-power switch, but an electronic switch on the control circuit board.

Those Soldapullt things are a JOKE compared to a Pace dsoldering system.

I routinely salvage some expensive 68 pin through-hole connectors on 6-layer boards. I can just barely tell which pins are connected to the ground plane and which aren't when using the Pace. With a soldering iron and a soldapullt I would never be able to desolder one of those ground pins, the solder would freeze before I could get the soldapullt on it.

Jon

Bet you didn't pay for the desoldering station, though.

Wick is my go-to for surfacemount, the Soldapullt for thru-hole and terminals. If production were an issue, revenue would buy best-available tools. These get 'er done for me.

It was a larger-than-microscopic thru-hole component on a fairly low-tech board, was it not? I've not seen anything in a Miller welder that looks much like the innards of a cellphone...

I certainly won't refute your good experience with the $2500 tool ... but if you didn't have the $2500 tool available to you then you might benefit from a Soldapullt lesson by a technician who is proficient with one.

I also doubt that repair of circuit boards in Miller Welders is strongly comparable to the rather more sophisticated and challenging work you do with 68-pin connectors on 6-layer boards.

I believe that it is that part indeed.

The leads of the switch were rather fat.

No argument here.

In fact, this is what I like about these boards, they are 1) very low tech and 2) easy to repair due to good part placement 3) easy to identify components, which look mostly off the shelf.

My repair was, obviously, the most trivial kind, but I appreciated repairability of these boards.

I paid for mine, I believe it was $470 for two PACE stations.

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