Deception In Soldering Iron Ratings

[picbits]

Hi picbits,
it looks so nice to handle! Probably it's costly high enough! I have an inron rated just $1.

This one cost around £280 / $440 USD - quite an investment but it has probably saved half of that in labour time since we bought it. When you are soldering large terminals or ground planes it really shines.

 

[MrAl]

Thank you Al for what is proving to be a very enlightening thread. So sitting here with one of my inexpensive soldering pencils, inexpensive is a nice way to say cheap. This is labeled Radio Shack and has a selector switch for 15 Watt or 30 Watt. So I place it in the 30 watt position and I read ~479.5 Ohms, I reverse my ohmmeter leads and read 479.5 Ohms (same reading). I select the 15 Watt position and read open circuit on my Fluke 87 but when I reverse the leads I read ~256.8 Ohms. My guess would be there is a diode lurking about in there.

Ron

Hi,

Yes it sounds like a diode. If the measuring current was 2.5ma and the diode drop 0.5575 and the test voltage 1.2v then those readings would come about (480 ohms and 257 ohms).

If you instead test with a 70v DC power supply and measure the current, the two resistances should come out much closer to each other if there is a diode because the diode voltage drop will become less significant. With the diode drop being near 0.6v it competes with the test voltage too much which skews the resistance measurement.

 

[Willen]

This one cost around £280 / $440 USD - quite an investment but it has probably saved half of that in labour time since we bought it. When you are soldering large terminals or ground planes it really shines.

Hee hee hee then I need to spend my whole 3 months salary! Thank you anyway!

 

[audioguru]

"$440 USD" Hee hee hee then I need to spend my whole 3 months salary!

I am sorry to hear that you are in poverty, Willen.
Then your annual salary is only $1760 USD. Today on TV they said the average annual wage of a registered nurse in Canada or USA is $65,000 which is 37 times more than yours.

The minimum wage in Canada today is $11.00 per hour. If the person works 40 hours per week then his annual wage is $22,880, 13 times more than yours. At least 2 weeks of paid vacation time is included. A clerk in a fast food restaurant (do you want French fries with your hamburger?) or a cashier in a food store makes minimum wage, but they might get paid more if they have been there a long time.

 

[MrAl]

Hello again,

Well when comparing salaries in different parts of the world we also have to compare to the local economic conditions, such as the price of a loaf of bread, gallon of milk, etc.

But back to soldering stuff...

I measured the input power to my station and it measures 55 watts with the soldering iron still heating up. That's nuts. The soldering iron itself clearly takes only 36 watts so i wonder where that extra 20 watts is. I might have to "tear it down" and find out for myself.
Some others on the web have torn down their stations to examine the guts. Very interesting stuff. Quite simple circuits. Some have found dangerous wiring errors.

 

[JimB]

I measured the input power to my station and it measures 55 watts with the soldering iron still heating up. That's nuts. The soldering iron itself clearly takes only 36 watts so i wonder where that extra 20 watts is.

My first thought is "how did you MEASURE the power" ?
Did you use a real power meter, or, did you measure the voltage and the current an then multiply together?
If so, could the "extra" 20 watts be due to bad power factor from the transformer in the soldering station?

JimB

 

[Willen]

I am sorry to hear that you are in poverty, Willen.
Then your annual salary is only $1760 USD. Today on TV they said the average annual wage of a registered nurse in Canada or USA is $65,000 which is 37 times more than yours.

The minimum wage in Canada today is $11.00 per hour. If the person works 40 hours per week then his annual wage is $22,880, 13 times more than yours. At least 2 weeks of paid vacation time is included. A clerk in a fast food restaurant (do you want French fries with your hamburger?) or a cashier in a food store makes minimum wage, but they might get paid more if they have been there a long time.

Hi, actually I am in 'cheap' part of the world instead of 'poverty' place. Yes, as MrAl said- local economic condition is suitable little with the salary I am getting. I can survibe within a month normally using my salary here. But getting comparatively (to international standard) less salary, it affects badly while buying non-local (international) stuff like motor bike, computer, electronics components, TVs, DVDs etc. I need to work full 8 months to buy a simple 110cc motor bike.

 

[audioguru]

I was in poverty when I was in university but I did not starve. I did not fly home to visit my parents, instead I rode a train for 3 days and 4 nights for one-way.
When I was 22 years old I got my first job and I parked my bicycle for the last time. Then I bought a very cheap brand new car. I never had a motorbike.
I bought my first home and color TV when I was 26.

Today my wife and I are comfortable with old age pensions paid by our government. We also have investments.
I do not waste money like some of my neighbours. I have a home phone that dials "dial-pulses" so I do not pay the touch-tone fee (month after month after month) but I pay my bills with touch-tone for free. I do not have a cell phone anymore.

I do not eat in restaurants often. I do not travel much but I have vacationed in Europe, Mexico, Jamaica and Cuba. I will have a vacation in Mexico in 3 weeks where my son will get married.

 

[tvtech]

I do not have a cell phone anymore.

I hate cellphones too. Intrusive things that always demand your attention. No matter what you are doing at the time.

 

[MrAl]

My first thought is "how did you MEASURE the power" ?
Did you use a real power meter, or, did you measure the voltage and the current an then multiply together?
If so, could the "extra" 20 watts be due to bad power factor from the transformer in the soldering station?

JimB

Hi there Jim,

I tried to think of a snappy comeback for this question but i couldnt think of a very good one right now as i am kinda beat from todays outings and such. I wanted to add a little levity to the conversation and at the same time get the point across. I was thinking maybe something like:
"I put my tongue across the line and can tell the wattage by how much it tingles" (he he he).

But really if i dont know how to measure real power by now after some 45 years or so in electronics and electrical engineering for several years professionally involved no less in power electronics and control systems in the past and still immersed almost daily as a hobby, then i would be in really bad shape "Power electronics" involves power supplies and stuff like that, like supplies from like 1 watt to 30KW. I think more inexperienced workers would have more difficulty with this kind of measurement.

So the answer is yes, i used a watt meter. But it is nice that you asked this because you got me to think a little more about this, about how this can happen. One thing i didnt do this time was compare the VA to the true Wattage, as i usually do that too so i can estimate the power factor, and you made me realize i didnt do that this time. I can also add a little more data to the meld now too, because i have a second station measurement with a watt meter and that is a different kind of station with the same iron. This second reading was 40 watts.
So what does this tell me?
It tells me that it is starting to look like they under designed the transformer (as i have seen far too many times in the past now) so that it is partially saturating with the normal 120vac line voltage. That would explain how i got some much MORE power around 20 watts. That's a lot of power to loose somewhere, and it takes a large volume/surface area to dissipate that. The only thing that could be taking that much power is the transformer, because nothing else could be designed that poorly and still live without a decent size heatsink.

I am almost ready now to 'tear it down' and see what is inside. My curiosity is high now especially after reading some more stuff on the web about this. I found some cute soldering iron controller circuits on the web and they are super simple in design. I'd like to see how they are doing this station, as well as get a rough estimate of the rating of the transformer they used because i'd like to go to a higher rated iron at some point, maybe 100 watts if i can. I think at least 60 watts real power should be minimum, and i would be happy with that. Once i dig into the guts i'll post some information. I'll probably also check the waveform of the transformer a little better to see if it looks like it is saturating.

Thanks again for the question because it got me thinking a little more deeply about what is going on with this thing. I intend to find out sooner or later where that 20 watts is going.

 

[JimB]

MrAl, I am glad that I was able to channel your thinking. I did not mean to imply that you did not know the effects of reactance and power factor, it is just that we all make "an assumption too far" sometimes.

So, it is looking like there is a (design) problem with the transformer. I look forward to reading about your further investigations.

Whatever started you on this crusade into soldering iron power ratings in the first place?

It would never have occured to me to question the power rating of a soldering iron.
Although having said that, I once bought an iron which was supposedly rated at 15 watts, it was not temperature controlled in any way, it was made by Weller, and it was rubbish, a real piece of nasty. I was slow to heat up, when it was up to (its own) temperature it was sluggish melting 60/40 solder. I soon abandoned it in favour of the little 15 watt Antex which features in my table of results.
The Antex was not temperature controlled, but was a superb little iron which I only put aside when I got the temperature controlled Oryx.

JimB

 

[Willen]

Sorry for interrupting again! Recently I measured my another $3.5 iron, was rated 60watt. Label has- "Goot" as a brand name and Made in Japan. With unstable DMM, in diode test/continuity mood, the element's resistance I got is 780 ohms and I got 62 watt in this way.

EDIT:
Watt= (220V^2)/780 ohms

 

[JimB]

...I got is 780 ohms...
...Watt= (220Vx220V)/680 ohms...

Which is it, 680 or 780 ohms? Attention to detail is important.

JimB

 

[MrAl]

Hello again,

JimB:
Yes we make assumptions and ever forget sometimes so it is good to be reminded, and other readers would want to be aware of this too
So you had a Well-er that did not perform Well, ha ha, i wonder if it could have been an imitation?
I saw some nice Wellers on the web but they were like 300 bucks and i didnt want to pay that much.
What started this was i got a soldering station and soldered with it once with the iron, then the next time i went to use it it started going crazy because it would indicate "5-E" or "S-E" on the seven segment display, which is an error code for "Bad soldering iron". That made me take the iron apart to see what the problem was, and that meant i had to measure the resistances. I found the heater element to only measure 16 Ohms and the 'sensor' was open circuit. I connected the element to a DC power supply and it did heat up, so the problem was the sensor blew open. But since the current was too low (like 1.5 amps) i knew it could not be a 50 watt element, so that got be looking into this matter (1.5^2*16=36 watts).
To make matters worse, yesterday i received a new heating element that is supposed to be "50 watt 24 volt" also, but when i measure that heater resistance i read about 4 ohms !. That's nowhere near the right resistance, but i havent checked it 'hot' yet. I'll have to check that better today some time.

The waveform out to the iron (with 16 ohm heater element) looks severely flat topped, which indicates that the transformer could be saturating near the peaks, a typical low end design or a design in a product meant to be used for short time periods only on an intermittent basis. More testing will be required on this too.
I cant wait to see what it looks like inside, like the control circuit and transformer size.

SHORT UPDATE LATER:
Ok, i measured the new 4 ohm element when it gets hot. At 4 volts it draws 1 amp, but then the current starts to decrease significantly indicating that the element resistance is rising. Running it up to 20vdc it draws only 2 amps, which of course indicates that the resistance is now around 10 ohms and it is probably still increasing a little. I suspect that running it up to 24vdc would mean the resistance would increase to 12 ohms which is just about right for a 50 watt element. So this is truly a 50 watt element.
The name brand is "Hakco" and the package is stamped "50 w, 24v".
The element is just stamped "Hakco 003".
So this element changes resistance a lot when heated, the other element does not do this or at least not very much.
Unfortunately i am not sure if this element can work with my rework station. The iron that comes with that station is 16 ohms cold, and while this new element is heating up it will draw much more current than usual. I dont want to take a chance and blow the station, so i'll have to see how they make this station first (parts used, ratings of the parts, etc.).
If anyone happens to have any info on this, it is a:
"W.E.P. 852D+ SMD Rework Station" (hot air and soldering iron).


Willen:
Yes your iron sounds like it is up to par, working as it should (assuming 780 ohms that is).
That's certainly a good price too
I paid a little over $70 (USD) for my rework station,which was also a good price here in this country.

 

[Willen]

Yes dear JimB and MrAl, I meant to say 780 ohms I measured.

 

[JimB]

So you had a Well-er that did not perform Well, ha ha, i wonder if it could have been an imitation?

I don't think that it was an imitation, the iron was advertised quite widely in the hobby electronics press with allusions to the "real deal" Weller irons used in a industrial environment.
So whether my Well-er was just the runt of the litter, or, Weller made a bit of a lemon, I don't know. Not that it matters any more, I think it went into the bin many years ago.

JimB

 

[Scotophor]

Speaking of imitations, and attention to detail:

The name brand is "Hakco" and the package is stamped "50 w, 24v".
The element is just stamped "Hakco 003".

Do they really say "Hakco"? There is a well-regarded brand of soldering equipment called "Hakko". If yours is spelled "Hakco" I would assume it's a knock-off and should probably go in the garbage.

 

[MrAl]

Speaking of imitations, and attention to detail:


Do they really say "Hakco"? There is a well-regarded brand of soldering equipment called "Hakko". If yours is spelled "Hakco" I would assume it's a knock-off and should probably go in the garbage.

Hi,

Yes good point. But in this case it was my fault because when the write the intended correct name "Hakko" they make that second 'k' very close to the first one, so it looks like a "C" if you dont look closely. I didnt look closely enough so i wrote "Hakco" when it is really "Hakko".
I saw some pictures on the web and it looks the same. It also appears to be of decent quality.
I'll get the pic off my camera and post here hopefully in a few minutes.
Thanks for bringing this up because sometimes a 'slightly' different name is used by the fakers to make it look like the real thing as you noted. My intent with this thread is to bring out the good and the bad with soldering irons and stations.

This element is also interesting because the cold resistance is 4 ohms while the hot resistance would be around 12 ohms. That means it heats up faster than one that was just 12 ohms all the time, given the right drive circuit that is. It will not work in my rework station unfortunately because the initial resistance is too low, but mostly because it uses a PTC thermistor (Positive Temperature Coefficient Thermistor) while mine uses a K type thermocouple. That seems to separate the two main types of elements in the iron itself, and the stations from what they can deal with. Some stations require one and some the other.

Here are the pictures. You will see the element slightly blackened due to testing as it gets pretty hot.

 

[throbscottle]

With reference to fake Hakko irons, the real ones afaict have a good quality crimp on the cable clamp in the handle, the fakes just have the metal wrapped round. Of course I could be wrong...

 

[MrAl]

Hi,

Oh ok well that's interesting too. This was just the element as that's all i ordered. Any information that adds to the pile is good i think so we all learn more about this.

I measured another iron resistance, and it reads about 6 Ohms. It's made for the automobile 12v system. The resistance does not change much either, and it takes a long while to heat up (a good 5 minutes). Once it heats up it draws about 2 amps at 12v. At 14 volts it draws about 2.3 amps. Its the Radio Shack Cat 64-2105 rated 30 watts at 12vdc, which of course isnt true, but it's not too far off being closer to 24 or 25 watts as measured. At 14 volts though it will be 32 watts so if the car is running then it meets the spec.
Certainly only made for small connections and the tip is very long which means it would be better with a shorter tip.
This was purchased quite a long time ago, cant remember the date now.

I am starting to look at the 'torch' flame style soldering tools. Apparently they have come a long way with them. All shapes and sizes which are equivalent to about 30 to 150 watts depending on model and of course the price to go with that ranging from about $10 USD to about $85 USD.
I think they would be much better for times when we are away from the electrical outlet rather than the 12v iron above. I had trouble soldering connections when it was just a little cold outside, and had to go get the gun and inverter to be able to solder anything.