How to convert the Hakko FR301-82 for North America - Page 1
Forum section: electronics / general

author: Logg
author_rank: Newbie
timestamp: July 24, 2024, 04:52:03 pm
content: MotivationFirst of all, WHY would anyone want to do this? The answer is that right now, you can import this tool from Japan to America for only $160 (just check eBay). By contrast, the American variant sells from Home Depot currently for $278.48, and direct from Hakko USA for $340.67. If you buy from Amazon, the reviews there say you will most likely get the Japanese variant anyway, but at a more premium price of $204.Most likely, the cause for the majority of this price difference is the "Weak Yen". Lately, you get a lot more Yen than you used to when you convert $1 USD to the currency used Japan, which means that $1 USD in Japan has more buying power than is normal, and this is a situation that has been ongoing for at least a year now.There are very few differences between the Japanese FR301-82 and the North American FR301, which makes the conversion viable & desirable.Background informationThe Hakko FR301-82 is a variant of the well-knownHakko FR-301 desoldering ironproduced for the Japanese market. Two variants are sold in Japan. The FR301-82 is a 3-prong grounded variant, and the FR301-81 is a 2-prong ungrounded variant, compatible with the more common 2-prong outlets in Japan. Needless to say, the grounded FR301-82 is preferable, since the ground wire is connected to the tip of the iron, which might otherwise transmit rogue voltages to the component you are desoldering & damage it.It is possible to use the FR301-82 outside of Japan, and some people do in fact just plug it directly into 120VAC and are happy (for a while), but it is relatively trivial to make the conversion proper. The easiest thing to do is to just use a step-down converter to 100VAC, and since the tool doesn't use that many watts (around 100w), most any step-down converter can do it. But that's not what this thread is about. I'd like to document the differences between the Japanese Hakko FR301-82 and the North American Hakko FR301 to help those who want to run the FR301-82 safely & without failure, as designed, on 120VAC.Foreground informationNearly all components of the FR301 and FR301-82 are the same. The chassis is the same, the suction motor is the same, the circuit board is the same (only one circuit board used world-wide, see attached pictures). The heating element is technically a different part number, (replacement part# A5047 for North America & A5046 for Japan), but it has the same ohms resistance across the two red heating element wires (per Hakko documentation), and from what I can find online, no one has had any issue using the heating element part of the FR301-82 circuit on 120VAC without modification. The North American version is said to use 140watts to heat, and the Japanese version is said to use 98 watts to heat. The math says that this difference in peak wattage is due to the increased voltage available in North America, and not due to a difference in components used. Nevertheless, if you are nervous, just don't do this modification and use a step-down converter instead; you'll still save money over buying the North American FR301.I bought the FR301-82 from Japan and a B5189 replacement PCB from Hakko USA to inspect every single component on the circuit board and confirm: There is only one difference between the FR301 and the FR301-82 apparent to me. Resistors in position R21 and R20 have values of 300 ohms in the North American controller PCB, and only 10 ohms resistance in R21 in the Japanese controller PCB (R20 is empty). There is also a black sharpie mark in the "120 vac" silk screened checkbox instead of the "100 vac" box. There are no other changes on the board.TipsHypothetically, you should be able to use eight "normal" 1/4th watt 1.2kohm resistors in parallel instead, if you are more likely to have those smaller resistors laying around in your workshop.Be careful not to lose the small spring which goes on the yellow button piece near the collection tube, or the small plastic washer that goes on the screw of the yellow back-piece, or the small captive nut that that screw screws into. Take pictures as you disassemble for easy reference.You may need to calibrate the temperature control, which can be done by tweaking the phillips-head variable-resistor directly above the part of the tool which lists the temperature settings. I did this by comparing my trusted Weller WES51 temperature controlled soldering iron with the un-calibrated FR-301 under a thermal imaging camera. The value that was correct for me and my specific FR301 heating element was 4.94kohms across the legs of that variable resistor, but your value may vary. By the way, I believe this calibration step is why Hakko put the "Element is heating" LED indicator on the "wrong side" of the tool; it does make calibration easier to be able to see the tip & the LED at the same time.If you're not sure about any part of this, just use a cheap low-wattage step-down converter & you'll still save money.Too Long; Didn't ReadReplace resistor R20 (which is a 1 watt 10 ohm resistor in the Japanese Variant) with two 1 watt 300 ohm resistors in positions R20 and R21 (as done on the North American version). These resistors limit current to the suction motor. Congratulations! You just saved over $100 by replacing a resistor.The heater section of the tool seems to have been designed by Hakko to use either 100VAC or 120VAC without modification.

author: digger
author_rank: Regular Contributor
timestamp: July 24, 2024, 08:03:46 pm
content: excellent, well written post. thanks

author: rsjsouza
author_rank: Super Contributor
timestamp: July 26, 2024, 12:46:08 am
content: Thank you! This is great info!

author: charamstwo
author_rank: Newbie
timestamp: July 31, 2024, 11:28:00 pm
content: Great post! I'm considering whether i should grab a FR-301 for cheap from Japan and convert it to 240V or run it with a step-down transformer i could build myself for a project. I was wondering if you could measure the powerfactor for me. There is this super nice used transformer i spotted, but it might be just to tight on VA.

author: Logg
author_rank: Newbie
timestamp: August 01, 2024, 03:44:28 am
content: Quote from: charamstwo on July 31, 2024, 11:28:00 pmThe 240v conversion I think is a lot less trivial. Hakko uses model number "FR301-22" for at least the UK market. The FR301-22 has a different suction motor for 240v, and the heating element I've heard is also different, but I can't find a source direct from Hakko for that; they don't seem to sell those replacement parts. I can't recommend trying to convert the tool from 100vac to 240vac since aside from any circuit board changes (which I don't know the details of either), the critical components are most likely not going to function unless you bring the voltage down. A standard step-down transformer is probably the go-to option for import from Japan for usage in 240/220vac countries.The rated power draw is 98 watts on 100VAC or 140 watts on 120VAC, though I haven't measured it myself.

author: Waky79
author_rank: Newbie
timestamp: December 13, 2024, 01:28:59 am
content: Finally an answer on the differences.Excellent info, thank you.for your efforts.I don't think those are 1 Watt resistors.Based on appearance and physical dimensions(12mmx4mm), I believe those are 2W metal oxide KOA Speer. They're an exact match.https://www.koaspeer.com/catimages/Products/MOS/MOS.pdf

author: Fried Chicken
author_rank: Regular Contributor
timestamp: December 24, 2024, 12:41:40 am
content: Fantastic information!

author: jheissjr
author_rank: Contributor
timestamp: December 24, 2024, 03:26:43 am
content: Excellent! What was the voltage drop across the individual 300Ω resistors for power dissipation?

author: def45
author_rank: Newbie
timestamp: January 08, 2025, 10:10:56 pm
content: can someone measure the tip temperature of the Japanese Hakko on Hi before any modifications on 120volts, wondering how close to 500C it is. Mine will be here in a month and will also check wattage consumption.

author: Crang76
author_rank: Newbie
timestamp: February 02, 2025, 10:18:14 pm
content: Thanks for posting this. I just converted my Japanese one to 120v following this using identical KOA resistors and all. They were 2W. Worked like a charm. Two observations and hints to add. First, as you are pulling it apart if you take a Sharpie and make a witness mark on the temperature adjust wheel before it pops off the pot its on, it will save you a bit of a headache putting it back together.The other is after reading this I adjusted the trim pot to 5k Ohms. I bought a $20 solder iron thermometer off Amazon to dial them temp in. At 5k the 660F setting was well over 900F. I had to dial it up to 12.22k running off my 122.7V wall voltage to get it dead on at 660F. Totally repeatable now and I finally got my Hakko FX888 calibrated as well- it was well over 100F off due to user error when I first set it up....KOA resistors-https://www.mouser.com/ProductDetail/KOA-Speer/MOS2CT52R301J?qs=gw9ytUtHRwMiFI0XWMUBow%3D%3D

author: reagle
author_rank: Unknown
timestamp: February 15, 2025, 04:21:52 am
content: Thank you for the post- I was just contemplating buying the US version but for my use case it's way too much money.. Japanese version is about half the price.Silly question- how does math work here? We had a 10 Ohm in series with the motor and are now putting 150 Ohm. Input supply did not change that much, so why such a large jump- what am I missing?

author: Zoli
author_rank: Frequent Contributor
timestamp: February 15, 2025, 06:58:09 am
content: Quote from: reagle on February 15, 2025, 04:21:52 amThe motor running on ~85V - do the math.

author: reagle
author_rank: Unknown
timestamp: February 15, 2025, 12:40:11 pm
content: That's the problem. I cant't make sense of the math or am missing something. Any ideas of the motor internal resistance or actual current? If I am dropping 15 V across 10 ohm in the original version that's 1.5A , way exceeding the 2 W rating. I also get vastly different motor properties for both cases so something is missing in my assumptions (done both manually and with a bit of AI assist )Scenario 1: 100V, 50HzVoltage across the resistor: The voltage across the resistor is the difference between the source voltage and the voltage across the motor. V_R = V_source - V_motor = 100V - 85V = 15VMotor Current: The current through the resistor is the same as the current through the motor since they are in series.1 I = V_R / R = 15V / 10Ω = 1.5AResistor Power Dissipation: P_R = I^2 * R = (1.5A)^2 * 10Ω = 22.5WMotor Impedance: Z_motor = V_motor / I = 85V / 1.5A = 56.67ΩMotor Inductance: We know the impedance is a combination of resistance (which we'll assume is internal to the motor and not given) and inductive reactance. Z_motor = sqrt(R_motor^2 + (2πfL)^2). Since we don't know the motor's internal resistance (R_motor), we can only calculate the apparent inductance assuming the entire impedance is due to inductance. This will be an overestimate of the true inductance.L = Z_motor / (2πf) = 56.67Ω / (2π * 50Hz) = 0.18H (approximately)Scenario 2: 120V, 60HzVoltage across the resistor: V_R = V_source - V_motor = 120V - 85V = 35VMotor Current: I = V_R / R = 35V / 150Ω = 0.233AResistor Power Dissipation: P_R = I^2 * R = (0.233A)^2 * 150Ω = 8.16W (approximately)Motor Impedance: Z_motor = V_motor / I = 85V / 0.233A = 364.81Ω (approximately)Motor Inductance: Again, we will overestimate inductance because we don't know the motor's internal resistance.L = Z_motor / (2πf) = 364.81Ω / (2π * 60Hz) = 0.97H (approximately)

author: Zoli
author_rank: Frequent Contributor
timestamp: February 15, 2025, 03:45:16 pm
content: Sorry, I was wrong in the first place: the motor should run on 98.5V, not 85V. In this case the 10Ω resistor is more protection/fuse then real dropper.

author: reagle
author_rank: Unknown
timestamp: February 15, 2025, 05:25:15 pm
content: Oh that makes way more sense, thank you! So they come out to 150 mA in 100V and 143 mA in the 120, while dissipating 3 W in the resistors in the latter case.After starting at it for a moment, its basically (100-Vm)/10=(120-Vm)/150 , which makes Vm 1380/14 or 98.57V

author: leighcorrigall
author_rank: Frequent Contributor
timestamp: March 23, 2025, 11:52:39 pm
content: Quote from: Crang76 on February 02, 2025, 10:18:14 pmThis is really important!An alternative is to set the dial to 350 C and then carefully remove it from the trim resistor, but this is not always possible.I also recommend making sure that the blue and red wires leading to the heating element assembly are well placed or there will be pinching. Note the position of the solder chamber latching assembly too. I had to take it apart because the spring was not in position. Make note of all spring positions.After an initial inspection of the instrument, I could quickly perform the 100 to 120 VAC conversion. R20 was replaced with a 150R 5W resistor and everything seems good now.Thank you, Logg. Well done.

author: FiveTau
author_rank: Newbie
timestamp: April 23, 2025, 02:48:44 am
content: I ordered one from Japan but was sent the FR301-81 by accident (the two-prong variety). I've done the mod to convert it to US voltages and it's working just fine. On the Hakko website you can order the 3-prong cable as a replacement part, so I was wondering if it was as simple as swapping out the cable and running the wire to the nozzle as it is in the FR301-82. Would I need to recalibrate the temperature setting? Any idea?

author: thm_w
author_rank: Super Contributor
timestamp: April 23, 2025, 09:31:06 pm
content: Quote from: FiveTau on April 23, 2025, 02:48:44 amYou can see in the first photo here how its connected to a post:https://www.eevblog.com/forum/reviews/hakko-fr-300-05-desoldering-iron-120v-gt-240v/msg1309916/#msg1309916Does yours not have any green wires inside at all?

author: jheissjr
author_rank: Contributor
timestamp: April 27, 2025, 05:06:59 am
content: I also converted a 100V version of the FT-301 into the 120V version. It looks like the two 300Ω, 2W resistors are underrated for reasons I can’t explain. The resistors should be at least 3.2W and instead are 2W. One might suggest the motor has a duty cycle from the operator but that is a poor design. Does Hakko depend on the operators of the thousands of FT-301 in the field to never exceed the 62% duty rating of the pump? (2W/3.2W).Secondly and for more unknown reasons, the two parallel 300Ω resistors reduce the pump motor power in the 120V version compared to the 100V version. The motor output for the 100V version is 22.5W and the motor output for the 120V version is 18.5W. The 120V version is operating at 90% of the 100V version. I used to 180Ω resistors instead of two 300Ω to maintain the motor power equal to the 100V version.Finally, I made two changes to the tool. First, the plastic tube was replaced with a glass tube. Second, a power-on light was installed on the back of the handle.

author: Fried Chicken
author_rank: Regular Contributor
timestamp: April 29, 2025, 03:41:33 am
content: Quote from: jheissjr on April 27, 2025, 05:06:59 amI mean... yeah? Think about how the tool is used. I don't know how someone would exceed a 62% duty rating... but if they did, they would know it, and I think hakko makes a bigger/better/badder vacuum desolder tool.

author: alex843
author_rank: Contributor
timestamp: May 04, 2025, 07:10:46 am
content: Quote from: charamstwo on July 31, 2024, 11:28:00 pmDid you buy a transformer or build one?I just took delivery of a Hakko FR301-82 from Amazon Japan and I'm looking for a step-down transformer. You need to be careful of some of the voltage converters you see on eBay and elsewhere. Some of them take a 230-240V sine-wave, chop it up and turn it into something that might not resemble a sine-wave. These are intended for Japanese sourced heating devices and not for electronics or anything containing an electric pump or electric motor.I'm in New Zealand and will most likely get a step-down transformer from TorTech in Australia:https://www.tortech.com.au/product/voltage-converters/step-down/economy/economy-japanese-step-down-transformer/

author: FiveTau
author_rank: Newbie
timestamp: May 05, 2025, 01:27:57 am
content: Thanks for the photos. No, no green wire in mine, but the posts for hooking it up are still there, so I added the wire myself. It seems to work fine, though I swear it gives off more of a burning smell than before, so I wonder if I need to recalibrate the temperature setting.

author: jnkirk71
author_rank: Newbie
timestamp: May 18, 2025, 04:20:22 am
content: Hi, Im looking at buying a Japanese 100v Hakko FR-301.I live in Australia and have a step down transformer 110v (puts out 113v)Do I need to adjust the Japanese 10ohm resistor value or should it be OK to just leave it stock?

author: rsjsouza
author_rank: Super Contributor
timestamp: May 19, 2025, 08:02:49 pm
content: Hi, the 113V is unloaded? I imagine so.At any rate, an excess of 10% should not be considered critical for this type of product.

author: jnkirk71
author_rank: Newbie
timestamp: May 19, 2025, 10:37:09 pm
content: yes unloaded, the stepdown transformer is labelled at 110v, i checked the ohms calculator conversion webpage and the difference was not huge in resistance value, just wanted to double check that I wasn't going to stuff it up and could avoid by replacing a resistor!

author: jheissjr
author_rank: Contributor
timestamp: May 23, 2025, 10:42:21 pm
content: Changing R20 from 10 ohm to two 300 ohm resistors in parallel doesn't seem to account for the 42W difference between the 100V and 120 models. Where is the 42W difference?

author: Zoli
author_rank: Frequent Contributor
timestamp: May 24, 2025, 05:48:36 am
content: Quote from: jheissjr on May 23, 2025, 10:42:21 pmHeater.

author: NYG
author_rank: Contributor
timestamp: May 29, 2025, 07:14:52 pm
content: Not sure if I have any 2 watt/300 ohm resistors but I have plenty of 5 watt//220 ohm. I might give this a go later.edit: 5W are much too large. oh well.

author: gica69
author_rank: Contributor
timestamp: June 05, 2025, 08:14:14 am
content: So, is it recommended to use the two 180ohms resistors at 3W instead of the 2X300ohms at 2W? Going with the chart for pump motor efficiency to reach the 22.5W at different voltages it seems to allow for better duty cycle rating as stated by jheissjr . Do KOA make the 180ohms at 3W? Thanks

author: jheissjr
author_rank: Contributor
timestamp: June 12, 2025, 11:45:36 pm
content: Quote from: NYG on May 29, 2025, 07:14:52 pmHow are you powering your 100V version?

author: onesystem
author_rank: Regular Contributor
timestamp: August 21, 2025, 07:13:39 pm
content: Received Japanse Hakko today, swapped the resistor. Works amazing in USA. Thank you for your detailed post!

author: BillyO
author_rank: Super Contributor
timestamp: August 22, 2025, 10:46:09 pm
content: Quote from: gica69 on June 05, 2025, 08:14:14 amYou need to look at the wattage through the resistors, not the motor. The motor draws about 0.15A @ 98.5V and two 300 ohm resistors 2 2W in parallel will give 150 ohms @ 4W.So: 0.15 x 0.15 x 150 = 3.375WTherefore two 300 ohm 2W resistors are rated for continuous duty.

author: Southerner
author_rank: Regular Contributor
timestamp: October 18, 2025 12:13:11 am
content: Quote from: jheissjr on April 27, 2025, 05:06:59 amThank you for the information. It saves me a lot of hassle. Also I always replace the plastic catch tube with a Hakko glass tube.