Conversion of a 110V cheap soldering iron to 220V

[Koray]

Hi all,

I received a 110V cheap soldering iron with my aliexpress purchase and I want to convert it to 220V. It has a very simple circuit. Can anyone help me with how to proceed? It uses a BT136S-600E triac and some passives to control the temperature. It is a neat little thing so I don't want to dump it. Photos below.

Thanks in advance, and kind regards.

Koray

[Ian.M]

Its not temperature controlled, as there is no temperature sensor, and the TRIAC circuit is no more than a simple power controller like a light dimmer, and its unsafe for use on 220V and unfit for general electronics use as the shaft isn't  grounded.  Even if it passes a 1KV Hi-Pot test when hot from element to shaft, you'd still have the problem of rewiring it to reliably ground the shaft, and rebuilding the dimmer circuit to work at double the voltage and limit the max power, not to exceed the element's ratings.  The end result would still be a 'firestick' on a dimmer so barely worth the effort.

[Koray]

Thanks Ian!

There is ground line that can be attached to the shaft easily and it is not connected to the lead. I will replace the lead anyway. I can do it with a grounded mains cable to ground the barrel, so grounding can be sorted out. But if the existing dimmer circuit cannot be altered with a simple replacement of existing resistors, then you are right I shouldn't waste time on it. 

K.

[Gyro]

It's likely that they use a higher resistance element for a 220V version. You will possibly find that the firing angle of the triac needs to be too short for predictable temperature setting (as if you were using a 110V lamp on a 220V supply dimmer).

An isolated 220V - 110V step down transformer would be the best solution, but probably not economical in this case - unless you already have one.

You would probably do better using an unregulated 220V iron and a lamp dimmer.

[tunk]

Assuming the electronics are the same for the 110V
and 220V irons, then you could replace the heating
element with a 220V version.

[akimpowerscr]

Try to use it with a 220V 100W incandescent bulb in serie with the main voltage

NB: the triac of the fase control must be shorted with a jumper.

[Koray]

Thanks for all suggestions and comments.
Kind regards, K.

[bob91343]

Use a variac.

[Greybeard]

I would sell it on ebay and buy a new cheap 220/240V iron.

[janoc]

Throw it away and buy a proper iron for 220V. This thing cost maybe $10 shipped and trying to fix it to be safe to use at 220V is going to cost you at least 2-3x as much + work, if it is even possible.

[TonyOldTimer]

Aliexpress main line products are for 220-240V.  Looking at the silkscreen of the circuit board, R3 should be 82K but actual install is 62.3K.  It could be a special adaptation for 110V.  You can trace the circuit to see if this makes sense - put a real 82K in there for 220V.

[janoc]

Aliexpress main line products are for 220-240V. 

I do wonder what makes you say that. First, AliExpress does not make any products, it is only a marketplace with thousands of individual sellers selling who knows what.
Second, there are many 110V products there, you often get a choice of both mains plugs and mains voltage if the device isn't universal.

And finally, while you could swap some resistors around, what makes you sure that the device has also adequate clearances and creepage for 220V, along with proper insulation? Why would you risk your life for a cheap piece of junk? If nothing else, the iron is not grounded and is powered directly from the mains - if the heater has a fault, you get live voltage directly on the tip. Wonderful ...

[TheMG]

More effort to modify than it's worth. This is not even a temperature controlled iron, it's just variable power that's it. The temperature markings on the control dial are just decorations, the real temperature is going to be all over the place: too cold when doing lots of soldering or large joints, too hot when it's sitting plugged in for a while.

Like most cheap irons, the tip quality is likely junk too, and won't last long with any serious use, especially without temperature regulation.

[TonyOldTimer]

Aliexpress main line products are for 220-240V. 

I do wonder what makes you say that. First, AliExpress does not make any products, it is only a marketplace with thousands of individual sellers selling who knows what.
Second, there are many 110V products there, you often get a choice of both mains plugs and mains voltage if the device isn't universal.

And finally, while you could swap some resistors around, what makes you sure that the device has also adequate clearances and creepage for 220V, along with proper insulation? Why would you risk your life for a cheap piece of junk? If nothing else, the iron is not grounded and is powered directly from the mains - if the heater has a fault, you get live voltage directly on the tip. Wonderful ...

Peace! I know Aliexpress does not make any products.  But, the products sold through Aliexpress are mainly for mainland china and mostly 220V countries.  I am just doing an engineer's guess, that the designer just create a quick and dirty version for 110V countries.
  The OP asked for way to modify it to work with 220V, and that is the way that "I think" can be done.  Any modification in the primary main circuit is dangerous, so "buyers beware".  However, if the product was designed for 220-240V (a BIG if), then I would "assume" that it is OK.  Whether it is worth the effort or not is just another question.

[tunk]

I don't have this iron, but I do have two similar irons
with temperature control. The the element of the 110V
version is 260ohm, and the 230V is 816ohm. So I think
you at least have to replace the element.

Edit: I'm no expert on this, but TonyOldTimer could be
right - i.e. that the Triac circuit is trimmed by resistors
for use with 110 or 230V.

[janoc]

Peace! I know Aliexpress does not make any products.  But, the products sold through Aliexpress are mainly for mainland china and mostly 220V countries.  I am just doing an engineer's guess, that the designer just create a quick and dirty version for 110V countries.
  The OP asked for way to modify it to work with 220V, and that is the way that "I think" can be done.  Any modification in the primary main circuit is dangerous, so "buyers beware".  However, if the product was designed for 220-240V (a BIG if), then I would "assume" that it is OK.  Whether it is worth the effort or not is just another question.

The thing is that you are here giving an advice to a beginner based on a few pictures, one possibly mislabeled resistor and rather dangerous assumptions about what is and isn't sold on AliExpress**.

If he takes you up on your advice and does the mod, he could easily construct a deathtrap or set his house on fire by modifying what looks like a pretty sketchy device already. If the OP knew what they are doing the question would not have been asked.

It must be clear to you from the pictures that that device couldn't be safe for 220V use (and neither for 110V) due to the total lack of earthing as a minimum. It has been mentioned by others before as well. So there is not "BIG if" there and it is not OK to just swap resistors and assume it was "designed for 220V". Maybe in China such thing would be considered safe enough but I doubt that's the case elsewhere in the civilized world. 


** AliExpress is selling stuff "for export", targeting non-Chinese clients, and not for mainland China - they have other marketplaces for that (Taobao), with a lot of things not available on AliBaba/AliExpress. So there is plenty of 110V gear targeting mainly the US market being sold there.

[Koray]

Hi again, thanks for all suggestions and the discussion. After the first comments on the dimmer circuit with triac, I understood that the heating element was specced for 110V. I measured the resistance and achieved 60W rating as labelled at 110V (194Ohms). A replacement heating element is unnecessarily expensive, since this unit came to me as a free gift with another purchase. I have since broken it down for spare parts box.

Kind regards, and thanks for the educative discussion.

Koray.

[TonyOldTimer]

I am sorry for pointing out my observation of the mismatch of the component and the silkscreen.
Peace and happy holidays.

[Koray]

Happy holidays, Tony! No need to apologize. I was also thinking that there might be a simple way to convert the iron, but with this thread I learned how triac dimmers worked and understood how the heating element was specced for 110V regardless of the dimmer. Thanks for suggestions!

Koray

[Ian.M]

Fixed output TRIAC dimmer style circuits to run 115V heating type appliances on 230V, mostly for the travel market  used to be fairly common, so, ignoring the safety issues, there is nothing fundamental that prevents it being converted successfully- its just a matter of limiting the max. power to the element to be no greater than its maximum when running from 115V.  However simply swapping one resistor is unlikely to be the solution, because a 230V version of the iron, although it might use the same dimmer PCB with a few component changes, it would almost certainly use a 115V element.   

However in real life one *MUST* consider the safety issues.  If you were going to attempt to modify it, the first thing to do would be to check if it could be done safely.   Start with a 1KV Hi-Pot test between both pins of the mains plug shorted together and the shaft.  You are looking for a high insulation resistance - tens of \$M\Omega\$ when cold.  Then heat it up to max on a 115V supply from a Variac or autotransformer, to max temperature and immediately reconnect it for the Hi-pot test, monitoring the resistance as it cools.  If it drops below 2\$M\Omega\$ at any point, or flashes over, that's a fail, as the limit for a class 1 handheld heating appliance is 1\$M\Omega\$ at 500V and you need a safety margin, hence 1KV and 2 \$M\Omega\$.  A low voltage insulation test is inadequate as you need to know if the insulation will withstand 1KV safely before connecting it to a 230V supply, and cant reasonably disassemble the element to check insulation types and thicknesses, and creepage distances.   I'm expecting it to fail the high temperature Hi-POT testing .  If it passes, you've still got to sort out adequate grounding for the shaft that wont be compromised by the possible high temperatures, and will remain attached even if the shaft starts to come loose from the handle.

Next would be to run it with the temperature control board removed or bypassed, and a 1.5A 250V fast blow fuse in series with the element, on a 230V dimmer running from an energy meter, and soak test it at 60 watts for a couple of hours.   Let it cool off a bit then briefly connect it to the full 230V supply.  What you are checking is whether the element's insulation can withstand 230V across the element. If you are unlucky, it may flash over and take out the fuse.  If you are really unlucky it may take out the dimmer as well.

You can now start reverse engineering the power control board, checking creepage distances and deciding what component changes will need to be made to make it safe to run on 230V, to limit the power to 60W max, and to give it an acceptable control response.

Anyone competent to do the above will realise there's many hours of work involved, and no certainty of a usable iron at the end of it, so its just not economic for a piece of cr@p firestick maybe worth $10 bucks.

*ALWAYS* be suspicious of 'free gifts' - TANSTAAFL applies!