Hakko FR-300-05 desoldering iron - 120V -> 240V

[mark41]

Hi folks,

I've just got the desoldering iron from Hakko (second handed). It's 120V 60Hz model. I live in the area with 230V 50Hz. I opened the iron to see the circuit. I am posting a photo of the insides. Does anybody have an idea what changes should be made in order to transform it into 240V model so I could plug it in to the wall without stepdown transformer ? All inputs welcomed. Thank you ! :-)

Marek

[kPATm]

Maybe something similar to this??




Im not saying for you to do this as it may cause big bang bang but hey, its an option

[mark41]

Really ?  I hope that was meant to be a joke.  There is no transformer in the desoldering iron apparently. It's easy to convert the soldering iron, I actually have done it, using different transformer, but this is kinda different story.

[nanofrog]

It looks to use a voltage divider via the power resistors to my eyes. Just swap the two 300 ohm resistors for 150 ohm units instead. That's the good news.

Bad news is you also have to swap the heating element for the 220 - 240V 50/60Hz version (P/N A5001), which tacks on . ~50EUR + VAT and shipping.

[mark41]

Thank you nanofrog. It seems that you are correct about the heating element. I will try to contact a look for the best offer and see.

Are you sure about the voltage divider? The 300ohm resistors are connected in parallel (BOTH ends of resistors are connected to each other). The 18k ohm resistors are connected the same way...

or I am misreading something

[nanofrog]

Whether the pairs are in series or parallel, just calculate it out as configured to find the output voltage. Or just measure it if you prefer. Keep that value for Vout alone and change Vsource to 240V. Then solve for the correct R2 for the new mains input.

Online Voltage divider calculator.

Regarding pricing, Batterfly is the least expensive source for Hakko in the EU that I'm aware of (A5001 text above is a direct link). Not sure if a suitable step-down transformer is cheaper or not, but you won't need a big one (only draws ~114W @ 230VAC according to the manual). 

Best of luck. 

[mark41]

After some "research", I will stay with my 120V version and order the transformer for 120V. Less money then new heater and it might be useful in the future... Thanks for the input! 

[nanofrog]

To be on the safe side, I'd recommend a 300W unit to be sure you won't overheat the transformer when used full-tilt in order to allow you to keep working however long you need to use it (takes into account power factor, and that the W ratings of the transformer are typically peak/max, not nominal).

And as you mention, it's useful for other 110 - 125V tools you may be able to get for less than their 230V mains versions. 

[simone.pignatti]

Thank you nanofrog. It seems that you are correct about the heating element. I will try to contact a look for the best offer and see.

Are you sure about the voltage divider? The 300ohm resistors are connected in parallel (BOTH ends of resistors are connected to each other). The 18k ohm resistors are connected the same way...

or I am misreading something

here is the list of the heating elements, we are happy to support you in case of needs.

[mark41]

I would like to share my final solution. A few months ago the heating element died because I forgot to set my autotransformer to 120V. Then I decided to convert it to 230V so I could use it anywhere easily. I bought the A5001 heating element for 230V and installed it. I searched for the view of the PCB of the 230V version. I found it on youtube. Then I swapped the power resistors based on the video. The voltages for the control circuit were ok (lower), but I really couldn’t go over 120V because of the voltage at the motor. I found out that motor is for 120V and that it is kind of impossible to separately buy the 230V version. Later I analyzed the circuit and found out that the power resistors were just voltage droppers, not dividers as thought. I tried to use it with voltage divider but the heat losses on the resistors when used at 230V were so huge that it was impossible to use it for a long time. I measured the power and current of the motor when running on 120V. I ended up using capacitor dropper for the motor with the value around 2.5uF. This solution works flawlessly. After that I took out the red LED and replaced it with small high luminance LED and I also added a green LED that would light all the time so I couldn’t forget to switch it off (I was inspired by an article). Last change was the cable. I got myself a silicon power cable that is heat resistant and has great elasticity (the normal cable is clumsy in my view). Finally everything works fine.
Thanks you, nanofrog from this forum, who helped me to think about the solution.

Video with 220V PCB:
LED hack: http://quan-diy.com/misc/hakko_mod/fr300.htm

Capacitors used:
330nF https://www.digikey.com/product-detail/en/kemet/F862BS334K310ALR0L/399-11693-ND/5125417
2.2uF https://uk.farnell.com/kemet/f862fn225k310zlh0j/cap-sup-x2-2-2uf-310vac/dp/2533553

LEDs:
http://www.optosupply.com/uppic/2016817786216.pdf
http://www.optosupply.com/uppic/2016817242214.pdf

Cable: https://www.omnical.co/products/helukabel/22990/183011900

[nanofrog]

Glad you finally got it sorted. 

FWIW, I was hoping you could've gotten away with squeezing the X2's internally, but that's clearly not possible with the larger one (2.2uF).

That said, you came up with a very nice external mounting solution IMHO.   

[Dd]

I measured the power and current of the motor when running on 120V.

Could you please share the measured values? What was the voltage on the motor terminals?

I've attached FR-301 Japanese PCB version for 100 V mains. There only 10 Ohm single resistor installed in series with the motor instead of two 300 Ohm (150 Ohm total) in 120 V PCB.  And there 160 Ohm resistor on 220V version in this video https://youtu.be/PRwGHpnZC_E

From Hakko Japan: "The motor is not available by itself, and it is an integral part of 'Pump Assembly' which is available for repair purpose by distributors who had repair training and got authorized by Hakko."

[scroeffie]

is it possible to do this with a hakko fr 301 100v version and convert it to 240v ? prices are insane for the 240v version