Weller WTCPT tip not hot enough

The temperature calibration is via the ferromagnetic slug at the back end of each individual tip. I suppose it's possible that the alloy in the slug can "drift" its transition temperature with time, although I haven't noticed this myself.

Try removing your current tip and replacing it with another of the appropriate tip shape and temperature range (they come in 600, 700, and 800 degree Farenheit ratings) and see if this resolves the problem. The tips themselves are not expensive... U.S. dealers seem to have them for around $5 in most shapes.

I suppose it's possible that the heater in the handle is giving out, or that oxidation on contacts somewhere is preventing adequate current flow to re-heat the iron.

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Nice mystery. I have about 8 Weller soldering stations with exactly the same configuration. I've never seen that problem. It's usually either stone cold, or seriously overheating.

I assume that the thermostat cannot be heard clicking when the iron is running luke warm.

Maybe a bit of logic might help. The voltage and resistance that you measured are normal. If there were any excessive resistance in the heater part of the system, such as bad thermostat contacts, bad cord, or bad twist lock connections in the handle, these would heat sufficiently to create noticable damage. Only the high resistance in the xformer area in the base could cause low output, yet still read the correct voltage. It might also be a high resistance thermal fuse or high resistance on/off switch.

Perhaps it would be useful to measure the resistances in the base. Ummm... unplug the soldering iron first. When stone cold, I measure

1.5 ohms across the 117VAC power plug and 1.5 ohms across the xformer output pins. My guess(tm) is that you'll find one or the other with a quite different resistance.

As for a replacement, I have enough parts to build and/or repair perhaps 10 more WTCPT soldering stations, so I've never needed to consider an alternative. If I need one, I just build one out of junk. Unfortunately, they'er not particularly reliable and require constant thermostat contact cleaning. I've also had heating elements die, thermostat movement jam from corrosion, cords fuse internally, and one xformer short and melt. If you buy something new, buy one that doesn't have any moving parts.

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Lead Free Solder in use?

"

Ummm.... He said: "When I put the heated tip against the sponge, I barely get much of a sizzle. Solder barely melts but does melt, just barely though." If it doesn't boil water, it's not going to melt solder.

I use a PTA7 (370C) tip with the evil lead-free solder. It's not the best, but it sorta works. A PTA8 (430C) tip works much better but I've been burning up a tip every 3 months or so.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

These are great stations, but many of them have one common flaw: One of the crimped female pins in the base, where you plug in the iron, is often crimped onto solid wire, and that connection will go bad within about a year of reasonable use. Once that connection goes bad, it will heat up and destroy the plastic connector body, so the best thing to do is to fix it before it gives problems. When we used to buy these new, I would fix this in new units before they were ever turned on.

If you have a large selection of pin remover tools you may have one that will work on these, but I've often had to make do with a bit of rolled up soda can alum sheet. It's tedious, but you really only HAVE to remove the one solid wire. The stranded crimps will be fine.

Once you get the pin out, just solder it and put it back.

My guess is that this is what's happened to your station. The power is being split between the heater and the connector. It's also possible that the switch in the iron handle is going bad. That certainly happens, but usually only after a lot of use.

The Magnestat control depends on the Curie temp of the alloy in the little slug at the end of the tip. That will never change.

It's a little confusing that you say you can hear the Magnestat control switching back and forth. This is normal, but it should only happen if the tip is reaching it's 700 F Curie temp. This one observaion makes me wonder if you're just not remembering how it used to work.

Even if it doesn't happen to be the problem right now, it's still a good idea to solder that pin, because it will save you headaches down the road.

-

----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

-----------------------------------------------

Ok, the thermostat is cycling. I've been assuming that it was NOT cycling.

If the temperature is as low as you measure, then the primary temperature determining element is the magnetic in the tip. If it's off for some reason, you will get different temperatures. I've had the base of the tip (the shiny part with the number "7" stamped into it) fall off. I can replace it, but the temperature regulation is rather erratic.

That will probably solve the problem. You might want to buy a larger blade tip for dealing with physically larger components.

I prefer 63/37 but 60/40 is good enough. It should work just fine with the 700F tip.

The outer plating disappears. The part that needs to be cleaned and tinned burns up (oxidizes) if left hot and sitting around for 10+ hours per day. Eventually, I can't tin it any more. The solder just doesn't stick. I've tried various potions for re-tinning the tips (Kester Ultrapure Tip Tinner), and Sal Ammonica (a flux), but have had no success in reviving the tips. Only the 800F tips seem to have the problem as the 700F tips last much longer. I would post a photo but I can't find a dead tip. A clue is that the tip slowly turns black instead of the usual shiny (tinned) silver color.

--
Jeff Liebermann     jeffl@cruzio.com
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Skype: JeffLiebermann     AE6KS    831-336-2558

You say you "can hear the tip cycling". If that's the case, it would seem that there can't be anything wrong with the electrical parts. The tip cycles based on reaching the curie temperature of the magnet.

Have you tried a new tip?

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I assume he means the plating gets destroyed so it doesn't tin properly anymore. I have a pile like that. :( :)

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I

long

barely

the

Remember to replace the shroud that screws on and retains the tip, it is part of the magnetic "circuit" and if absent causes that sort of problem.

Also if you're careful , ie parallel jaw pliers, you can pull off the magnastat of a worn tip and change the temp on another good but wrong temp tip.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Does this unit have a temperature-calibration pot?

I used to find that my 700 deg tips lasted for months with my Weller PTC on

10-12 hours a day, but recently, I've found them to be burning out in just a few weeks. At first, I thought it might be that the Magnastat was seized shut, overheating the tip, but it is clicking on and off quite normally. Unless Weller have done something to change the tip plating, I can't really think of any other reason that this is occuring. This iron has been the workhorse of my workshop for years, and like the OP on this thread, I am extremely familiar with all aspects of its normal functioning.

About the only other possibility that I can think of is that I am doing more lead-free work now than I was, and just maybe, the more aggressive fluxes that are incorporated in this hateful stuff, are attacking the tip plating. I'm actually still not doing anything like as much lead-free soldering as I am leaded, but I guess that after making lead-free joints, solder is still sitting on the tip perhaps for hours at a time. Another slight possibility is that a mix of leaded and lead-free sitting on the tip, is causing problems for the plating. The only reason that I say this, is that when I was researching an article that I wrote on lead-free, I spoke with an expert on the subject, and one of his papers stated quite clearly that leaded and lead-free should not be mixed in the same joint, as it was likely to result in long term compromise of the joint integrity. I'm not sufficiently versed in metalurgy or chemistry to understand why this might be, but maybe a factor ?

Arfa

I had a similar problem a few years ago. At the time, I had 3 Weller WTCPT irons deployed. Two at my house and one at the office. The one in my shop kept eating tips. They would slowly turn black and refuse to tin. All my tips came from the same batch so it wasn't the tip. I bought about 25 of these stations plus parts at an auction perhaps 20 years ago. I rotated the 3 irons between locations and found that the problem remained with the shop location. Then, I realized that the one thing that I was doing in the shop, but not at the other locations, was using the iron to melt plastic parts. I tended to use it for plastic welding and drilling. I would clean and tin the tip immediately afterwards, but apparently the damage was already done. I'm not sure of the exact mechanism, but something in the plastic might be removing or trashing the plating on the tip.

Most of the rework I do in the office is with the evil lead-free solder. If the board used lead-free, my resoldering should use the same. I have both types of solders and use them as required by the type of board. I haven't seen any such tip problems with lead-free.

I dunno. I've been told the same thing. That's why I have two rolls of solder at each workstation. I don't really understand the failure mechanism when mixing solder and flux types. However, now that you mention it, I have been replacing tips at a faster rate since I've started using some lead-free solders.

I did some Googling for soldering iron tips that were specifically designed for lead-free soldering. I found several, but none that bothered to mention the difference between ordinary and lead-free tips. I'll guess that it's pure marketing and that there's no real difference in construction, other than operating at about 50F higher in temperature.

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
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Skype: JeffLiebermann     AE6KS    831-336-2558

No. The Weller WTCPT has no controls or adjustments. The primary temperature determining component is the curie point of the magnet in the tip. At low temperatures, the magnet holds a piston, which pulls a pair of relay type contacts closed, which then runs the heating element. When the tip temperature reaches the curie point, the magnetism disappears, opening the contacts. There's nothing in the contact assembly that would affect the temperature, except perhaps if the piston were stuck. That's unlikely because of the huge clearances involved. If it's cycling, then only the tip can affect the temperature threshold.

Weller manuals:

WTCPT manual: (215KB) See section on "Principle of Operation".

--
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558

My guess is that the breakdown of the plastic was releasing a halogen-rich vapor, either from the plastic itself (e.g. PVC is polyvinyl chloride and can release chlorine-rich combustion products) or from a fire retardant (often chlorine- or bromine-based).

It would not surprise me if such halogen-rich compounds would be chemically-active enough to corrode the iron plating on a soldering tip, and eventually expose the underlying copper.

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

I prefer 800 degrees. Always have done. Esp with small tips. The idea is to get the soldering done as fast as quickly, not leave the joint cooking until the solder finally melts.

I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F tips. I even told the manufacturing dept of a certain company to change to 800F tips for a certain process but they moaned that 'the tips wear out faster'. So the returns rate went up again Bloody idiots.

Graham

Well there is the issue of lead-free solder too which requires a 50C (90F) or so hotter tip.

Graham

Your reply address suggests you are in Italy. But why are you using dizum ?

Are you unaware of the extra temperature required to melt the lead-free solder now mandated in the EU ?

Graha,

Which is why they formulate compounds used for conductor to not do that these days.

My place of employment uses non halogen compounds and low if no chlorine type chemicals in the plastics used in common cable and wire products.

I've seen many times copper wire eroded inside just from its own PVC insulation due to older chemical mixes which we don't use any more.

--
http://webpages.charter.net/jamie_5"

Just to be clear though, only mandated for items placed on the market after June 2006, and which don't have a waiver. Items manufactured prior to that using conventional leaded solder, can continue to be repaired / reworked / modified with leaded solder and non RoHS compliant components. New items for non commercial i.e. amateur use, can still be constructed in whatever component and solder technology you like.

Arfa