I got a 110V version of the Aoyue 968A+ soldering station by mistake and shipping the station for a replacement or selling it is not an option. I reverse engineered part of the station looking for the cheapest way to convert it to 220V input capable (instead of using a 220V to 110V transformer).

This is the bit of the pump and hot air gun driving circuit that I reverse engineered. I'm wandering if it could be "fixed" by placing a diode between say the TRIAC and the hot air gun heating element therefore chopping half the 220VAC mains sinewave. The pump seems to be the same for both 220VAC and 110VAC versions of the soldering station though, so I'm thinking how could I find out if 220VAC was to damage the pump.


simulate this circuit – Schematic created using CircuitLab

Hot Air Gun Heating Element:

Hot Air Gun Heating Element

On the other hand, there's also a transformer with 110VAC input and 24V and 9V outputs for the soldering iron and the 5V linear regulator tied to the logic circuitry respectively. Is chopping half of the 220VAC sinewave before the transformer input a solution too? I saw a post about half wave rectifying and a hefty discussion about its effects on the transformer, so another option would be trying to wind more turns into the primary winding, would this be advisable or too much work / space required to achieve it?. I have yet to reverse engineer this part of the cricuitry but there's also an optocoupled BTA12-600C TRIAC that's controlling the soldering iron heating element.

Transformer Label:

Transformer label

Transformers Remaining Space for Extra Winding:

Transformer remaining space

This is the PCB with the heaters and pump controlling circuitry:

Component Side

Bottom Layer

On a side note: I'm willing to upload a schematic of the remaining circuits if the MCU on the bottom layer was to be identified. It's a 7mmx7mm 32 pin ~0.7 pitch TQFP marked as " REN10 509 H3G1 " with the following pinout ->

Pin 1 - 5V

Pin 2 - "M" programming?

Pin 3 - "R" programming?

Pin 4 - NC (in this PCB)

Pin 5 - GND

Pin 6 - NC (in this PCB)

Pin 7 - 5V

Pin 8 - NC

Rest of the pins - apparently GPIO

  • 2
    \$\begingroup\$ Buy a 1000W transformer for 220VAC to 110VAC and be done with it. You will probably have to order parts to modify the soldering station anyway. If you live anywhere near one of the US military posts in Europe, you might be able to get a used transformer cheap. \$\endgroup\$
    – JRE
    Commented May 30, 2018 at 16:03
  • \$\begingroup\$ I notice some red wires on the primary side of your transformer. How many are there? If there are more than 2, could you show a schematic? \$\endgroup\$
    – user148298
    Commented Jan 22, 2019 at 20:05

3 Answers 3


Using diode in series with primary transformer winding is very bad idea. AC transformer may work only with sinusoidal (AC) voltage. The only solution for transformer is to make new primary winding, doubling it's turns by thiner wire. But! The other parts of scheme remains. Triacs are 600V rated, so the questions is: are heater element and pump motor capable to run at 230 V? I guess they aren't. I guess pump motor for 220 V would have double turns (comparing to 110 V version) in it's winding (as transformer have). And heating element would have 4x resistance. Putting diode in series with heater will cut only half of power, while doubling the voltage increases power by factor of 4, so diode is not a solution.

So, the choice is: (1). Change ctransformer (or rebuild it's primary winding), heating element and pump, or (2). Just bye 600W+ 230-110 transformer.

I think the last one is much better.

  • \$\begingroup\$ There a chance the transformer supports 230V. If you look at the photos, there are several red wire pairs on the primary side and two pairs of blue and black wires. Perhaps, fhe primary side can be rewired to support 220V and the secondary rewired to 5 or 10V? \$\endgroup\$
    – user148298
    Commented Feb 3, 2019 at 21:50

Your transformer will not survive chopping the mains waveform in half with a rectifier.

Use a 240:110 autotransformer to power the complete solder station.


If you put 220VAC on the primary of a 110VAC transformer it will very promptly run down the curtain and join the choir invisible.

Your best bet is an external transformer. You cannot even use an external 24VDC supply because the triacs will never switch off.

  • 2
    \$\begingroup\$ +1 for literary merit. \$\endgroup\$
    – user133493
    Commented May 31, 2018 at 7:21
  • \$\begingroup\$ Out of curiosity, if he powered the primary side with 220VAC, wouldn't the output be 12V instead of 24 and the 10V be 5V? \$\endgroup\$
    – user148298
    Commented Jan 22, 2019 at 19:16
  • \$\begingroup\$ @user148298 if the transformer was ideal, double in would give double out, but a real transformer designed for 110V will saturate badly with more than double the design voltage, and will quickly heat up and fail. \$\endgroup\$ Commented Jan 22, 2019 at 19:19
  • \$\begingroup\$ It's been a while. LOL! I noticed the photos he added of the transformer. There appears more than 2 red wires on the primary. I suspect there are 4. Bare in mind, the manufacturer will likely optimize their BOM costs by using dual primary transformer. There's a good chance it's a dual primary, which requires wiring it in series for 220V. \$\endgroup\$
    – user148298
    Commented Jun 26, 2021 at 16:01

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