Author Topic: Soldering iron that won't melt?  (Read 1422 times)

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Offline Jookia

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Soldering iron that won't melt?
« on: August 30, 2019, 11:14:38 am »
I bought my first soldering iron (a Duratech TS-1620) in 2017, and I've been using it to practice soldering now and then since.
Today it's handle melted as I left it it on its stand for a few minutes while I tried to place a through-hole resistor.
I'm not exactly sure why this happened. Maybe the stand got too hot. I've attached some photos if anyone's interested.
But evidently the soldering iron was not able to cope with this task.

Is there any other soldering irons in Australia suitable for a beginner that can be left on in its stand while placing components?
Am I doing something wrong? It's a little annoying to have to wait a while for it to heat back up.
 

Online Ian.M

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Re: Soldering iron that won't melt?
« Reply #1 on: August 30, 2019, 11:34:05 am »
The Duratech TS-1620 is advertised as being temperature controlled so what probably happened is the temperature controller failed shorted leaving the element on 100% of the time.

Lets see a picture of the stand it was in at the time to eliminate the possibility that you had done something stupid to it or used an inappropriate one.

If you got the iron from an Australian supplier, I'd contact them and see what they can do as I'm sure they don't want the Accc  all over them calling for a compulsory recall. 

If you imported it yourself you are probably S.O.L.
« Last Edit: August 30, 2019, 11:40:06 am by Ian.M »
 

Offline Jookia

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Re: Soldering iron that won't melt?
« Reply #2 on: August 30, 2019, 12:03:11 pm »
It's likely that it's my fault then if it's a defect: I burned off some of the insulation of the cable between the station and soldering iron in 2017 and wrapped it with electrical tape then thought nothing of it since everything worked. I think I also had some power draw issues once when I used a sketchy power board too. I'm surprised it would melt itself at its own temperature, unless it decided to draw as much current as possible.

I just wasn't sure if this was normal or something I was supposed to do when soldering. Here's a picture of the stand, it seems fine still.
 
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Offline Ice-Tea

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Re: Soldering iron that won't melt?
« Reply #3 on: August 30, 2019, 12:12:01 pm »
Just to keep its temperature, the iron will turn the element way down. Maybe 10-20% or so. So I'd say its fairly normal it would 'melt itself' if left @100%.
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Offline magic

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Re: Soldering iron that won't melt?
« Reply #4 on: August 30, 2019, 12:12:30 pm »
Nothing to do with cables or mains outlets unless you connect it to wrong voltage (like a 110V unit at 240V).
 

Offline Ice-Tea

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Re: Soldering iron that won't melt?
« Reply #5 on: August 30, 2019, 12:17:29 pm »
... but he mentioned the cable between station and iron. You know, the one that carries the temp sensor information..
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Online Zero999

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Re: Soldering iron that won't melt?
« Reply #6 on: August 30, 2019, 12:40:41 pm »
It looks suspiciously like an open loop phase controlled soldering iron, i.e. just a lamp dimmer connected to a heating element. If so, it will have no feedback, so will cool down or heat up a lot, depending on what it is soldering i.e. how much heat is being sunk.

Does the brightness of the LED change, as the knob is adjusted by any chance? If so, it's definitely phase controlled.

I have one. It's fine for soldering small components, but not much else. Set the temperature so it just starts to melt the solder and not much more.

In the long term, I recommend getting a proper temperature controlled iron.
 

Offline Jookia

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Re: Soldering iron that won't melt?
« Reply #7 on: August 30, 2019, 12:55:20 pm »
Someone else did a bit of a tear down of the station itself but there's no pictures: https://www.eevblog.com/forum/beginners/duratech-ts-1620-soldering-station/ It may be an older revision however.

The brightness of the LED does change as the knob is adjusted, but it's very bright to begin with and I didn't notice until I looked just now.
Would it even be possible or a good idea for the iron to report its temperature back given it only has a positive and negative wire to it?

What proper temperature controlled iron would you recommend? Is there a list somewhere?
It would also be nice to have one that doesn't have exposed wiring inside like that.
« Last Edit: August 30, 2019, 12:56:57 pm by Jookia »
 

Online Rerouter

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Re: Soldering iron that won't melt?
« Reply #8 on: August 30, 2019, 01:01:41 pm »
Had one of those at my work when I started, they are very painful to use compared to even the plug in irons, as at least those tend to hold a somewhat consistent temperature due to the thermal mass.

A Hakko 936 clone would be the next step in the right direction, with an actual Hakko 888 as being the norm for me these days. but the clone of the earlier model is a lot cheaper for a beginner.
 

Online Ian.M

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Re: Soldering iron that won't melt?
« Reply #9 on: August 30, 2019, 01:04:35 pm »
The stand looks OK and original although as there have been several stand design changes, I cant be certain.   

Also, I couldn't find any internal photos of the base unit.  Please open it and take some, as it would be interesting to know for certain if the iron is an isolated low voltage one with a transformer or SMPSU in the base unit, or if its got a mains voltage element, in which case making the handle out of a thermoplastic would be a critical safety flaw as any overheat would risk leaving live conductors exposed.

If its confirmed that it isn't a proper temperature controlled iron, I would be unhappy if the supplier offered an exchange - hold out for a refund or if they have a better model, or other stuff you want, store credit.

@Jookia: Thanks for that link. 
 

Offline Jookia

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Re: Soldering iron that won't melt?
« Reply #10 on: August 30, 2019, 01:25:37 pm »
Here's a photo of inside. Yes, there was a large unconnected piece of metal to make it feel heavy.

Edit: Uh, does this mean I had mains voltage isolated by just electrical tape?  :-\
« Last Edit: August 30, 2019, 01:32:39 pm by Jookia »
 

Online Zero999

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Re: Soldering iron that won't melt?
« Reply #11 on: August 30, 2019, 02:27:40 pm »
Yes, it's just a lamp dimmer. If you looked at the other side of the PCB and reverse engineered it, you'll find it's a standard lamp dimmer circuit, consisting of a TRIAC, DIAC, potentiometer and a couple of resistors and capacitors.

The weight is essential to stop it from tipping over, when the soldering iron is in the stand.

The soldering iron itself runs off the mains voltage, so insulating the cable with electrical tape is a bad idea. The entire cable should be replaced, preferably with a heat resistant one. Indeed the first thing I did with mine was replace the crappy PVC cable, with silicone one, before I got the chance to burn it.
 

Online Ian.M

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Re: Soldering iron that won't melt?
« Reply #12 on: August 30, 2019, 02:48:41 pm »
The soldering iron itself runs off the mains voltage, so insulating the cable with electrical tape is a bad idea. The entire cable should be replaced, preferably with a heat resistant one.
Bit late for that now. 

The handle should *NEVER* have melted like that, exposing live connections, as that's a major electrical safety fail.  It should either be made of a thermoset plastic that can't remelt, or there should be a thermal fuse on the back of the mounting flange that blows before it reaches the handle melting point, or the connections should be touch proof even with the handle missing.  Therefore I believe you have a good case that the device was potentially unsafe and therefore 'not fit for purpose' at the date of purchase.
N.B. IANAL nor qualified to do electrical inspections, especially not in Australia.
« Last Edit: August 30, 2019, 04:03:37 pm by Ian.M »
 

Offline ArthurDent

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Re: Soldering iron that won't melt?
« Reply #13 on: August 30, 2019, 03:53:19 pm »
There are a lot of similar irons and lots of rebranding so the name and model doesn't mean that much. Here is a photo of my base that has the same blue plastic case but a different dimmer circuit board and a connector so the iron itself can be unplugged from the base.

I have turned mine up to 100% to heat some solder joints that were probably too massive for this size iron and left the iron at full for some time with no problem. If your iron got hot enough to do the damage shown I would guess that there was some shorted sections in the heater and that allowed the iron to get far hotter than it could if set to 100% and working normally. This problem could also occur if you had a 120 volt iron like I do and ran it from 220 volts.

In my photo you can see that the 3 wires coming from the iron are ground/earth, 120 volt low, and 120 volt high through the dimmer circuit, there is no sensor on either mine or yours. In my photo you can see a small heat sink on the TO-220 triac on the side of the dimmer board. Even if you had damaged the dimmer circuit when you melted through the wires and the board shorted the iron would only see the line voltage and should be o.k. at 100% power.

If it makes you feel any better I'd bet it was a problem with the iron and you had nothing to do with the problem.
 

Offline Audioguru again

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Re: Soldering iron that won't melt?
« Reply #14 on: August 30, 2019, 04:02:52 pm »
The soldering iron is cheap, Chinese and maybe was never certified to be safe. If it caused a fire then your insurance company would laugh that you bought a cheap Chinese soldering iron. Claim denied!
 

Offline Audioguru again

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Re: Soldering iron that won't melt?
« Reply #15 on: August 30, 2019, 04:06:53 pm »
I forgot to say that my electrical utility company gave free compact fluorescent light bulbs to show consumers how to reduce electrical wattage. But reports came in that some dripped burning plastic. They were all recalled and replaced. They found that the Chinese manufacturer stole the safety certificate number from a competitor so these cheap ones were never certified to be safe.
 

Offline Jookia

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Re: Soldering iron that won't melt?
« Reply #16 on: September 01, 2019, 06:38:15 am »
I'm going to ask for a refund from Jaycar, who sells these on their website and in the physical store I bought it at.

There's no photos of the other side of the PCB, so here's one. I the flipped underside to match.

I'm not sure which iron to buy next, but that might be a topic for another thread. An EEVblog episode comparing a Hakko and Weller soldering iron did a burn test on the cables showing how the iron can't burn through them. Is that a common safety feature?

Though, with some Weller stations not having fuses it's a bit concerning how safe these things are.
« Last Edit: September 01, 2019, 06:41:08 am by Jookia »
 

Online Rerouter

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Re: Soldering iron that won't melt?
« Reply #17 on: September 01, 2019, 06:47:30 am »
your going to be more happy with the hakko, if cost is really a concern, an older hakko clone will still beat out the iron you currently have.
 

Offline amyk

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Re: Soldering iron that won't melt?
« Reply #18 on: September 01, 2019, 07:27:30 am »
Edit: Uh, does this mean I had mains voltage isolated by just electrical tape?  :-\
That is what electrical tape is meant to do, so not really a problem...

You'll find even a 936 clones to be a significant upgrade from that iron. There are several cases where the triac failed shorted and the tip will glow red, but I don't recall anyone saying they melted the handle that way. For a cord that won't melt through, find one with a silicone cord.
 

Online Zero999

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Re: Soldering iron that won't melt?
« Reply #19 on: September 01, 2019, 08:10:51 am »
The soldering iron itself runs off the mains voltage, so insulating the cable with electrical tape is a bad idea. The entire cable should be replaced, preferably with a heat resistant one.
Bit late for that now. 

The handle should *NEVER* have melted like that, exposing live connections, as that's a major electrical safety fail.  It should either be made of a thermoset plastic that can't remelt, or there should be a thermal fuse on the back of the mounting flange that blows before it reaches the handle melting point, or the connections should be touch proof even with the handle missing.  Therefore I believe you have a good case that the device was potentially unsafe and therefore 'not fit for purpose' at the date of purchase.
N.B. IANAL nor qualified to do electrical inspections, especially not in Australia.
I agree. I think there's a fault in the element causing it to get too hot. A thermal fuse is a must, since any case material, be it thermoset or not, will present a fire/burn hazard once it gets past a certain temperature.
I'm going to ask for a refund from Jaycar, who sells these on their website and in the physical store I bought it at.

There's no photos of the other side of the PCB, so here's one. I the flipped underside to match.

I'm not sure which iron to buy next, but that might be a topic for another thread. An EEVblog episode comparing a Hakko and Weller soldering iron did a burn test on the cables showing how the iron can't burn through them. Is that a common safety feature?

Though, with some Weller stations not having fuses it's a bit concerning how safe these things are.
Yes, it's a lamp dimmer. The TO-92 package is a TRIAC and the little blue cylindrical component with axial leads is a DIAC. One of the capacitors will be for timing when the TRIAC fires, depending on the potentiometer setting, another capacitor might be as a ballast for the LED and the rest will be for RFI filtering. The inductors and transformer-like component, which is a common mode choke, again will be for RFI filtering, as phase controllers are noisy and can interfere with radio reception.

Of course they should give you a refund. They should also stop selling such a dangerous PoS. Tell them they should investigate this further, before it burns someone's house down.

I've had a good experience with Hakko. I have the US model and run it from a 110V transformer and it works fine, even though it's 50Hz where I live and it's designed for 60Hz.

Edit: Uh, does this mean I had mains voltage isolated by just electrical tape?  :-\
That is what electrical tape is meant to do, so not really a problem...
Not really. It's never a good idea to insulate something with electrical tape. It's not so much of a problem if there's something else already providing protection against shock, such as a plastic or earthed metal enclosure or device is run at a non-hazardous voltage, but is completely unacceptable otherwise. Electrical tape peels far too easily. The adhesive is nowhere near reliable enough for anything safety critical. Just replace the whole cable, rather than splicing it.
 

Offline vk6zgo

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Re: Soldering iron that won't melt?
« Reply #20 on: September 01, 2019, 10:31:01 am »
I turns out to have the same internal "guts" as the one I bought from Jaycar some years back to use while I was fixing my Weller WTCP.

That one had a base a bit like the older Wellers , but quite small.
As soon as I saw the uncalibrated knob, I knew it wasn't really temperature controlled.
I suppose you could use "weasel words" & say,"Well, you can control the temp with the knob", but that is seriously sleazy.

In my case, I thought "It is what it is" & would probably be useable, was cheap, so bought it on the "like a fuse" basis that you buy most stuff these days-----If it dies, you throw it away & get a new one!

Well, it was lousy, though I did a few jobs with it-------too hot for really small jobs, not hot enough for average work, only about one third of the control rotation gave enough heat to solder.

It felt heavy, as if it had a transformer, which could maybe be salvaged, so I decided to pop it open, only to find my "transformer" was a weight, & the same cruddy little lamp dimmer as in the OP's one was inside.

I would advise the OP to buy an old WTCP, but if they do, make sure it cycles on & off, as sometimes the Magnastat switch gets old & becomes stuck "on" making the iron run "full on" continuously.
I've never seen a Weller melt its handle  though! ;D
« Last Edit: September 01, 2019, 10:33:40 am by vk6zgo »
 

Offline Old Printer

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Re: Soldering iron that won't melt?
« Reply #21 on: September 01, 2019, 06:02:46 pm »
The soldering iron is cheap, Chinese and maybe was never certified to be safe. If it caused a fire then your insurance company would laugh that you bought a cheap Chinese soldering iron. Claim denied!
This is just plain wrong. As consumers, our insurance companies cannot hold us responsible for evaluating the integrity or safety of products we buy. To deny a claim, an insurance company would have to prove you did something willfully negligent. Depending on the laws in your country they can sue the maker, distributor, dealer, etc.. Even a half-assed repair to the cord like the OP admits to would likely not get them off the hook. Not being pompous, I have wrapped more than my share of electrical cords with cheap tape or worse.
 

Offline Audioguru again

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Re: Soldering iron that won't melt?
« Reply #22 on: September 01, 2019, 08:31:32 pm »
I suspect that the manufacturer of that cheap soldering iron that gets too hot has no quality control and never tested it. They probably make 120V and 240V ones and got the heaters mixed up.
 

Offline Jwillis

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Re: Soldering iron that won't melt?
« Reply #23 on: September 01, 2019, 10:45:47 pm »
Did you check the thermistor in the handle.They do fail over time .Although thermistors fail open circuit  more often , there is a chance that they can fail closed circuit. Drift in the resistance value is the second most likely failure.Maybe check for possible short in the control circuit.
 

Offline ArthurDent

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Re: Soldering iron that won't melt?
« Reply #24 on: September 02, 2019, 12:18:32 am »
Did you check the thermistor in the handle.

There is no thermistor in this iron. It is just a 'dimmer' circuit and there is no feedback to regulate temperature. 
 


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