Deception In Soldering Iron Ratings

[JimB]

Test table may be flawed with Average power vs peak power In PWM controlled heaters

What!

PWM does not come in to the measurements at all.
None of these soldering irons has ANY kind of electronic control.
Both the Oryx and the Weller use good old fashioned on/off control with a period of several seconds.

JimB

 

[Tony Stewart]

I did not see a model # for Weller but we know it was a major source of EMI every 10 seconds or so cycle, so new ones are soft L PWM switch, but I"ll accept the report for what it's considering no source voltage tolerance tests were performed.

In my first R&D days , the shop supervisor taught NASA soldering methods to staff from a 6" thick Bible. The techs met all technical requirements with a 30W fixed power iron and a dimmer.


Thanks to Weller ! i cut my teeth on random glitch immunity.

 

[MrAl]

Hi Tony and JimB,

Nicely put Jim

It is not real PWM, it's just on/off multiple cycle control where the 'on' time can be 15 seconds or more as it is heating up for the first time from a cold start. This gives plenty of time to measure the input current and power, both to the input of the station itself and also to the iron element alone. The 'on' duration is controlled with a triac because it is AC powered not DC, which stays 'on' for many cycles spanning several seconds.

I suppose there could be some DC real PWM units out there, but this isnt one of them and another unit by another company turned out to be the same. Also, the elements themselves are all similar except for the power rating, and some of them even have the power rating stamped right on the side of them, and that is for the element itself, and the measured current and voltage do not produce the stamped power. For example, one was stamped with "50 watts" yet a DC current and voltage test had shown only 36 watts, and there's no inductive component that can cause it to go higher than 36 watts if driven by AC instead of DC.

BTW, both stations i tested were sold as having "60 watt" soldering irons. Some of them out there have true 50 watt irons (the other model iron) but the ones sold that have 36 watters cant drive the true 50 watters, so we cant get new irons to get more power either. Too bad. The drive circuits on these true higher power units have different type sensors and probably heavier duty transformers for the higher current.

I have to add that the irons do in fact work to solder many things, but they are just not as good as we would like to see since they are advertised as higher. Id' say they are best for PC boards with regular sized components, maybe up to the standard 2 watt resistors depending on the pad size.

 

[Nigel Goodwin]

It is not real PWM, it's just on/off multiple cycle control where the 'on' time can be 15 seconds or more as it is heating up for the first time from a cold start. This gives plenty of time to measure the input current and power, both to the input of the station itself and also to the iron element alone. The 'on' duration is controlled with a triac because it is AC powered not DC, which stays 'on' for many cycles spanning several seconds.

I think you're missing the point, it's not 'real' PWM as there's no need (or point) in doing that, it's 'burst fire control' - a far more sensible system for controlling heating (including a soldering iron). I would imagine all electronically controlled soldering irons use this method of control?, as it does everything that's required.

 

[MrAl]

I think you're missing the point, it's not 'real' PWM as there's no need (or point) in doing that, it's 'burst fire control' - a far more sensible system for controlling heating (including a soldering iron). I would imagine all electronically controlled soldering irons use this method of control?, as it does everything that's required.

Hi,

Well actually that was what i was stating, that it is not true PWM and i am not arguing that we 'need' true PWM, just that on/off control does not interfere with the power measurement as it might in a true PWM system where RMS values would be different than extrapolating from average values. So we have plenty of time to measure the true power.

BTW, we can measure the element itself for a more direct reading.

 

[Tony Stewart]

Keep in mind line tolerances vary with location and time of day and affect results of those that use poor specmanship E.g best case voltage rating and worst case unspecified test reports.

So criteria may be mismatched in all honesty, but point taken.

But there are irons for many purposes , RF types for fastest desoldering (I got 22 SMD memory chips extracted in 30 sec in a Comdex test) to stained glass types with large mass 150W for removing RF ground shields from ground planes ) to vacuum de-soldering for GP repair work.

But again you can do NASA Quality soldering with skill and a cheap iron.

Dont forget the 1M to ground .. Save money on an ESD station.

 

[JimB]

Tony Stewart wrote:

but I"ll accept the report for what it's considering no source voltage tolerance tests were performed.

Am I being particularly thick here or what?
What have "source voltage tolerance tests" got to do with the price of fish?

In post #2 of this thread, I clearly stated:

I measured the resistance of the heating element, hot and cold, and calculated the power at both maximum and minimum rated supply voltages.
The results are presented in the table below

.
Which in general terms means that I measured the heating element resistance when the iron was cold, and again when hot, I then CALCULATED the wattage based on the manufacturers rated minumum and maximum supply voltages.
I then presented those results in a table so that the reader may compare my calculated values of heating element power with those stamped on the soldering iron its self.

What is so difficult about that?


Tony Stewart also wrote:

the shop supervisor taught NASA soldering methods to staff from a 6" thick Bible

Thereby lies the problem perhaps, the shop supervisor should have used a 6" thick book on soldering instead of a 6" thick religious text.

JimB

 

[Tony Stewart]

To clear the smoke, some ODM's may use nominal Vac, others appear to have used max Vac for ac switched iron ratings.
Vac has a 20% tolerance , except places like India.

Believe what you like, be it any religion, but NASA soldering is based on Physics and pre-empted Industry Standards from IPC but more details. Like how to desolder the centre wire and rewire pins with suitable heatshrink for a Mil-Std high density circular connector. Not easy surrounded by natives circling the wagon.

 

[Nigel Goodwin]

Vac has a 20% tolerance

Not in the civilised world!

 

[MrAl]

To clear the smoke, some ODM's may use nominal Vac, others appear to have used max Vac for ac switched iron ratings.
Vac has a 20% tolerance , except places like India.

Believe what you like, be it any religion, but NASA soldering is based on Physics and pre-empted Industry Standards from IPC but more details. Like how to desolder the centre wire and rewire pins with suitable heatshrink for a Mil-Std high density circular connector. Not easy surrounded by natives circling the wagon.

Hi,

Whenever something like this comes up, we hear all kinds of excuses come out of the woodwork. Some will try to claim that the wattage rating is based on input power to the entire station rather than just the iron, but that does not fly with me either. Also, to think that they would base their soldering iron power rating on the max line voltage is just downright crazy. That would in fact bring the rating up near 50 watts, but then for low line it would be as low as 23 watts, which is less than half the rating.
When i worked in the industry we were always well aware of the effect of line voltage tolerances and there were test procedures that included at least three tests: one for low line, one for nominal, and one for high line. There was never a question about how something would work because it was always tested, and that was because we were always aware of the effects of different line conditions.
That's how design work goes for things that run off of the line. We know the tolerance, and we design with that in mind. We dont assume that the line is always as one particular level. If we did that, some things would not work right at all, and other things would even blow up.
Also, everything else is rated based on the nominal line voltage. Other irons will measure much closer to the rating at the nominal voltage, so i cant see any good reason why these particular irons can not measure close too.

As i was saying in another post, one element had "50 watts" stamped right on it, and at 24vdc it tested at only 36 watts. Now maybe they meant at a higher voltage? If so, then it should not have been included as part of the package that comes with the soldering stations, especially when the state the operating voltage is 120vac 60 Hz.

Your point is interesting though, so that maybe if we applied another 20 percent voltage (somewhat over 28 volts) we'd get around 50 watts. I wonder if the element could take it without burning up.
I actually now have the test equipment to test this either AC or DC, but i fear that it could burn out the station or the iron element, or just the iron element if i test it with a DC power supply. I guess the triac should be able to take it, but I'd have to risk loosing an element just for the test.
I guess there is also the chance that better quality (more expensive) stations put out a higher voltage and thus attain a higher power level. The costs of the two stations tested was about $80 USD and the other about $150 USD.

 

[Tony Stewart]

Hey Mr Al,
I was actually making fun of marketing guys who translate good Engineer Specs and cherry pick the ones that sells more like GiB and GB of binary vs decimal memory on a HDD and then neglect parts used by OS backup etc. in laptops.

As a former Test Engineering Mgr, I understand any valid test must indicate operating conditions.

On the burnup part.. 20% over no overtemp immediate problem , since it has a thermal cutout to regulate fixed temp or variable temp with thermistor... except exterior oxidizing and coil aging would be degraded by 2x per 10 degree C over nominal * d.f.

 

[MrAl]

Hey Mr Al,
I was actually making fun of marketing guys who translate good Engineer Specs and cherry pick the ones that sells more like GiB and GB of binary vs decimal memory on a HDD and then neglect parts used by OS backup etc. in laptops.

As a former Test Engineering Mgr, I understand any valid test must indicate operating conditions.

On the burnup part.. 20% over no overtemp immediate problem , since it has a thermal cutout to regulate fixed temp or variable temp with thermistor... except exterior oxidizing and coil aging would be degraded by 2x per 10 degree C over nominal * d.f.

Hi there Tony,

Oh ok, ha ha, i see where you were coming from now. I agree fully

I appreciate your informative input here too as your past experience sheds light on many topics of interest to many people.

I was going to build my own station originally, then decided to buy one because i found one at a good price around $80 USD, and that included a hot air rework too also with several tips. The soldering iron circuit looked interesting though, so i thought that one day i might build a higher powered circuit that could handle the higher rated irons. I found some that were really around 50 watts (i think) but they are advertised as 70 watts (ha ha). 50 watts would probably be very good for a lot of stuff i do. I get by with 36 watts for now, and have other irons for higher powered stuff.

Another interesting problem that came up was with the soldering 'gun' from Harbor Freight. I may have mentioned this already, but the tip melted in half after only a few uses, and this problem was verified because a friend bought the same gun and that one melted too. I now use a heavy duty copper tip, which draws too much power from the internal transformer so it overheats the transformer if used for too long, unless i use a variac to lower the power manually. Strange, but at least i can use it again now
Before the transformer overheats that darn thing probably works at 200 watts or so, for maybe five minutes use only.

And again, thanks for your input here as it is always interesting to hear what you have to say.

 

[Tony Stewart]

Another interesting problem that came up was with the soldering 'gun' from Harbor Freight. I may have mentioned this already, but the tip melted in half after only a few uses, and this problem was verified because a friend bought the same gun and that one melted too. .

This is a design flaw in the process.
Copper is very brittle and can easily break after 2 bends.

When a sharp bend is made the incremental ESR can easily increase at the bend due to crystalline weakening.

A special process Weller used is need to reduce the crystalline stress on the copper bending process yet distribute the increased resistance over a greater length like 10mm centred around the tip.


If it were tinned with solder that would help. Wasn't that in the instructions?

Get a Weller tip.

 

[MrAl]

Hello Tony,

The tip that came with it was made of some other metal, rather than copper. It had a higher resistance than copper too. I dont know what metal it was, but with a pure copper tip the iron draws more current from the line and thus more power.
I thought about increasing the resistance by cutting small grooves into the tip along it's length but didnt get around to that, and then i got the variac which seems to solve the problem.

Any idea what kind of other metal that was? Fairly light colored almost like 'white' metal.

 

[Tony Stewart]

What happens if you twist the tip a few turns between two pliers? If the resistance is high like some aluminum or nichrome mix alloy, that would explain it.

I think copper guns are around 100 turns primary so 100A secondary.

This one being higher resistance, could be only 75 turns primary so impedance being root(N) of secondary. copper would be too low on primary impedance and power double.
PRimary needs 25 more turns for Copper tip on 1 turn secondary.

 

[MrAl]

Hi,

Well the tip cant be aluminum because it tins too easily. It would have to be something that accepts solder readily, but not copper.
Unfortunately i dont think the transformer can be modified too easily, although i could check if there is room for more turns.
Now that it is like that however, i kinda like the idea of having a higher power even for a short time, but yeah i guess that option should be switchable.

 

[Rich D.]

In my cynical opinion you can't trust anybody when there is money involved, including me. These days there is so much anonymity between the retailers and distributors and the manufacturing (often overseas) and the owners of those companies that those execs can pretty much get away with whatever lies they want to and few people actually call their 'bluff'. And with technical claims, there is a lot of number-fudging that most of us (in the general public) don't really understand completely. Maybe 0.1% of the people find out and get a simple refund, but they still make money from the other 99.9% and can afford very good lawyers. They know that virtually all of us don't have the time or energy to pursue these rip-offs. Maybe if a few dozen people or more were killed they might be held accountable. We regular folks are kept too busy with our full time jobs, family, etc...

Anybody remember the big conspiracy of almost every lawn mower manufacturer that got together to collectively raise their horsepower ratings? At the time (late 90's) lawnmowers had huge stickers on the side touting their horsepower ratings. So many people bought new mowers based on the belief that they were getting better performance - including me. They lost a class-action suit but there were so many victims of the ripoff that I never saw a dime. Meanwhile at the time they were lobbying the US government to re-define the standard horsepower, but I suppose they were a little short of bribe money.

The only way that they were found out was that somebody happened to send the true power ratings of the various models to the EPA that were enforcing power vs. emission limits. Some observant fellow noticed those power ratings did not match the marketing claims, so they had documented proof of their lies. (At least that's how I remember it.) I mean, really...who here has the ability to measure lawn mower horsepower? Sure, some guys may have access to a dyno-meter, but how many of them can be hooked up to a lawnmower?

I noticed the following spring when all the new models came out suddenly NO lawnmower had horsepower ratings. Instead they all had torque ratings all over the mowers! You can be pretty sure those numbers are all made up. Maybe some day there will be a law that requires stamping the parent company of any manufactured product on the product, combined with a law holding the executives of those companies personally liable for fraud. And maybe someday there will be no more hunger, disease, war, poverty, it will always be sunny, unicorns will roam the earth...

 

[Tony Stewart]

Torque is more important anyways when it comes to load rather than load* RPM

I can imagine with RPM adjustments that may increase HP, you can cheat but at the expense of torque and engine life.
So torque is more important for maintaining constant speed when the RPM's may be different in each case.... unless you start comparing 16" vs 23"

Companies with the most to lose by brand recognition and public fraud, will attempt to be more honest.

getting back to iron specs. I believe it may be vague to some who decide to give the breaker rating for worst case line voltage like+10%Vnom, then choose that for actual power level which might explain +20% in power rating to nominal.

wheras breaker rating and nominal power rating should be worst case and nominal respectively, rather than worst case and best case.

 

[MrAl]

Hi,

Nice writeup Rich. That is a good summary of the state of manufacturing vs sales in the USA today. The gov seems to ignore anything that pertains to the consumer and allows companies to get away with way too much.

The last unicorn was probably shot and sold as regular cow meat (steak) <chuckle>.

Tony:
I should mention that i have soldered a lot of stuff now with one of the units i tested, but the heavier gauge wire takes longer as you have to keep the iron on the joint longer. I tried soldering some heavier wires together (stranded) and it took longer than usual. It would have been much faster with a true 60 watt iron. It did solder however, given a little more time, so it's not like the units are useless, they still work for most things but dont plan on doing it in a hurry if you are dealing with maybe #14 gauge AWG wires or heavier.
I guess the key is to have a heavy duty soldering gun on hand as well.
I have that Harbor Freight gun but i can only use it for a few minutes at a time or it will overheat and start to smell bad. Alternately i have to turn down the voltage to it, and live with a lower power rating. That happened because the original tip melted after a couple uses so i had to use a different replacement tip which has lower resistance. Pretty nutty, but it has a lot of power now, at least for a few minutes

 

[Rich D.]

With soldering iron stations, I never really took to the idea of adjustable outputs. I use a good ol' Weller that uses the magnetics of the tip to regulate temperature. Worked well enough for decades and still does. I figure if the temperature is right for small electronics, there's no need to adjust it. (I do need a bigger one to solder heat sinks though.)

Given that now I know that manufacturers tweak the power ratings, I figure if I ever need a new soldering iron station, I'll choose one with maybe 30-50% more wattage than I really need, so I have the opportunity to adjust-out their "adjustment" of the power ratings. That is of course if my Weller WCTP(?) ever should die on me.

With the lawnmowers, I was basing my decision on the ratio of power/cutting area because I always seemed to have a problem cutting thick grass at the normal self-propelled rate. So I chose a Toro, which was 6.5 hp / 22", and it was also the lightest except for Lawn-Boy's 2-stroke (which I had a lot of experience with, and don't like mixing oil that much). I can say for sure that Toro was part of the Class action, but I do remember MANY other big-name brands, probably all of them, at least those that used Briggs & Stratton and Honda motors. (I'll refrain from naming them, not absolutely sure now.) Point is you can't trust brand names anymore. More often than not, they are commodities that are sold and traded just like any other commodity. Like gas stations... it is irrelevant what sign is on the lot, (Exxon, Sunoco, Hess, Mobil -er-Lukoil...) they are all free to buy and sell whatever gas they can get delivered cheapest.

Heck, there is even a growing counterfeit industry for electronic components! Is that Panasonic capacitor really a Panasonic or some knock-off brand manufactured in China?