Hi

[Mike The]

Hi to all, very new to electronics find myself learning a little more each day and enjoying it!
After stumbling into EEV on youtube and watching Dave demonstrating basics of soldering I gritted my teeth and retried (25+ years after failing miserably) my hand at soldering once more. This time successfully
Have now upgraded my el cheapo soldering iron to an Antex XS 25watt and........................................................

Plugged in, tinned tip then used briefly, the blackening occurred after tinning and before soldering (a few minutes between)
/Users/mikesenior/Desktop/IMGP0468.jpg

[ebastler]

Hi Mike,
Welcome to the forum, and welcome (back?) to electronics!

The blackening of the iron's heated metal parts is quite normal. It does not affect the functionality of the iron, as long as the actual tip remains nicely tinned. You did well tinning it right after heating up the iron. During use, regularly wipe off oxidized solder on a damp sponge or metal wool pad, and add a bit of fresh solder. (Do this every few solder joints, or after the iron has been sitting on its stand for a couple of minutes between joints).

You may find that, sooner or later, you want to upgrade your soldering iron once more. A temperature-controlled iron is really another big step forward. It avoids overheating the iron while it is sitting idle (reducing oxidization of the tip), and automatically applies more power to keep the temperature stable when you solder larger metal parts. You can find plenty of recommendations and personal preferences on this forum.

But for the time being, just go ahead and build something! There is really no magic to soldering, and your Antex iron should serve you well for now. As long as you remember to first heat both parts you want to connect, then add a bit of solder (which should flow nicely over the parts), then remove your iron, you should be alright!

[Ian.M]

One old trick for non-temperature regulated irons with direct from mains elements is to wire a switch with a 1N4007 diode across it in series with the supply.   That gives you a half-power setting which can be used to keep the iron warm but not up to full soldering temperature.  Switch it to half-power if its going to be more than a minute till you need it for the next joint and you'll vastly extend the bit life.  It takes a few seconds to come up to full temperature again when you close the switch but as the bit is less oxidised you typically save time cleaning and retinning it.

[Mike The]

Hi
Thanks ebastler, wasn't sure if I'd fried it or something. Have tidied it up using siasoft ultra fine paper and it looks a lot better.
Replaces a Victsing 60watt variable iron that has an all or nothing control, have burnt out a couple of practice circuit boards with it.

Previous electronics experience, fitting AM CB's, ariels equipment etc to my (and others) trucks when am rigs first appeared here in the UK in the good old 70's,
Have completed a couple of Ebay LED clock kits, and charles platt make electronics book.

[Mike The]

Interesting, thanks Ian.M

[IanB]

I'm surprised how black yours looks. This is what mine looks like. Perhaps there was some oil or grease on the surface that has burned? Maybe give it a good clean with something like methylated spirits before the next use?

[Brumby]

The appearance of IanB's iron is what I would have expected.  Yours does seem rather overdone - especially if after a first use.

Try the clean-up exercise and see how it looks before and after the next soldering session.

If it's just as black again, I'd be checking to see if you're using a 110-120V iron on 240V.

[tablatronix]

Almost looks overheated or oxidized like the plating is burnt.

[Ian.M]

An Antex XS iron purchased new should have the handle labelled with the supply voltage.  They are available in 12V, 24V,  115V and 230V models.  I suppose its remotely possible you bought a 115V model by mistake so *PLEASE* check the label on the handle.   If it came with a fitted UK plux its *extremely* unlikely to be anything other than a 230V element.

A 115V element on 240V would be running at around 100W which would mean it would run extremely hot, burn off flux nearly instantly, badly oxidise the solder tinning the bit almost too fast to use,  and would soon overheat and damage the black insulating bush that attaches it to the handle, if it didn't go open circuit first.   *NOT* good, so if it is 115V you need to replace it (or at least the element).   You  could put it on a small autotransformer to buck the voltage to 120V or use a light dimmer to turn the power down enough (around 25%) , but either option is likely to be more expensive than simply replacing the element

Used Antex irons may have had the element replaced or may be missing the label. If you are unsure what's fitted, you need to measure the element resistance and calculate the dissipation at the various possible voltages.  The element resistance increases when hot so after ruling out impossible voltages, you then need to try it at the lowest possible voltage, measure the current and see if the wattage is correct for the iron type.   If its way under-powered, suspect it of being a higher voltage iron and *briefly* try it on the next higher voltage.

I suspect there was simply a light coating of preservative wax or oil to stop the bit plating corroding in storage and that's all that's burnt.   I wouldn't recommend using even a fine abrasive to clean the shaft or bit regularly as that will wear away the iron plating on the bit and reduce is life, and also risks weakening the shaft.    If you feel the need to clean it often^#, I would recommend bronze wool (available from fine woodworking suppliers and good marine chandlers) as that's softer than the iron plating so wont wear it excessively.  You can also use a brass turnings panscourer (NOT a stainless silver one).

Keep the bit lightly wetted with solder while its in the rest and only wipe it off immediately before use.  Running a fully wiped clean bit at temperature for too long can oxidise its surface and make it very hard to re-tin it enough to be usable.  Apply a small dab of solder to the tip (for thermal contact) after wiping it, then as ebastler pointed out, its apply tip to the joint, then feed into the joint from the opposite side to the bit, enough solder for the required fillet (conical, slightly concave) as soon as its hot enough to take it.

For through-hole work, and SMD discretes^*, its generally frowned upon to carry the solder to the work on the bit as the flux burns off typically in under a second so worst case you get a so-called 'dry' joint: a claggy blob of oxidised solder on the joint that hasn't fused properly with the surfaces of the component lead or pad.   However you do need a *little* bit of fresh solder on the tip to form a thermal bridge so the pad and lead are heated up rapidly.   If you have an absolutely clean tip (or worse an oxidised tip), you wont get enough thermal transfer, it will be hard to get the joint up to temperature and if you dwell on it long enough to do so, you'll cook the pad off the board and will damage any heat sensitive components.


# Preventative maintenance: Its advisable to remove the bit at least weekly in  production/rework/repair use and monthly in a hobbyist use and clean the shaft to prevent a buildup of corrosion, oxides and carbonised flux fumes etc. jamming the bit on the shaft.  Antex bits can almost always be freed by levering the split open, but there's no point in risking damage when its so easy to prevent.

* There are a few SMD soldering techniques like 'drag' soldering that can legitimately carry the solder on the bit, but they all rely on extra flux pre-applied to the board.  Even so, minimise the time from loading the bit to making the joint to minimise the oxidisation of the solder