The Hacker Diary


Repairing A Flat Iron ( Thermal Fuse Fun! )


My fiance mentioned this morning that her imitation "Chi" was borked' after less then a year of use.

For those of you who aren't in the know ( aka male ), the Chi is a highly regarded flat-iron that many women claim are known to be reliable.

Where's that scientific data when you need it eh?

When I bought the generic flat iron for my fiance, I did so because I couldn't justify the expense of a CHI. ( It just figures that I drive a Honda S2000 ). Anyways, I was able to repair the flat iron and I have detailed how to perform the repair below.

WARNING / DISCLAIMER: If you don't know what a soldering gun is or better yet don't have one, steer clear of performing this repair. Bottom line is I am not responsible what-so-ever for your actions. By continuing beyond this point you agree to the above terms.

Great, so I see you agree. Let's get to it.

The problem at hand with most flat irons "breaking" is that once the thermal fuse goes (ie. Excessive heat from being left on all day / overnight / etc), the circuit is open, the ceramic plates will not heat and you will have a broken flat iron.


Wire Crimps or a Soldering Iron & Electrical Solder
Phillips screwdriver
Thermal Cutoff Fuse (depends on Iron. See details below)
Volt Meter


To begin, we need to confirm that the issue is the thermal cutoff fuse. The thermal cutoff fuse is a little electrical component fuse that will open the circuit when a certain temperature is exceeded.

This is what it looks like:

looks pretty innocuous right?

Taking apart the imitation CHI is fairly simple and straight forward. As you get it apart you'll find that the ceramic plate has a plastic backing that slips on and in the space between the thermal fuse is housed. In the picture below, you can see the thermal fuse inside a protective (plastic??) housing with thermal paste pressed against the back plate. In the picture below, I have taken of the plastic backing and exposed the thermal fuse.

To test the fuse, I set my volt meter for continuity and tested the thermal fuse. As you can see below, no continuity.

From here you need to identify what the flat irons thermal fuse specifications are by reading the part number and googling it. In my case, the thermal fuse was available at the local Radio Shack.
I soldered it it and was good to go. My thermal fuse was SEFUSE SF226E rated for 227°C, 10A and 250V~.


My soldering gun is battery powered and is just below what the fuse is rated however I would recommend using crimps instead as an extremely hot soldering iron will destroy the fuse before your wife / girlfriend / mother get's a chance to use it.

UPDATE: Over at JoeDotCom.Com there is a great write up on fixing a switch of a flat iron.

Tell me what you think?

Comments (32) Trackbacks (1)
  1. Ok so I am going to attempt this on my CHI (the ridiculously priced one) But before I take it apart, ALL flat irons have these thermal fuses right? And would this be the problem if the reset button on the cord is still working?
    Thanks for your tutorial!

  2. Hi There. It is good to see someone else who is not afraid to tech-out on a womans haircare product… and also not afraid to blog about it. :)

    I made a page detailing my Chi repair (for my wife, of course) a while back and have been getting a steady flow of comments with folks asking follow up questions. One such question was related to Thermal Fuses. My researching an answer led me to your page and I have since added a link to your article on my page in the hopes that it will help other people as well.

    Check me out (perhaps your readers would find my page useful when they tackle their own thermal fuses):

    Together we can keep these damn, expensive things running! :)

  3. Wow, I hadn't seen these comments till just now!

    To Godfrey:

    You are correct. All flat irons have thermal fuses. As for your reset button question: It's hard to determine with just that much information. It would be a true statement to say that it is entirely possible that the thermal fuse went if the reset button still works but the ceramic plates do not get hot.

    To Pines:
    I noticed you linked the other day to my site and I appreciate that very much. I'll link back to yours as well.

  4. Great post. These type of posts are awesome. I have narrowed down that it is my thermal fuse. Problem is the print on the fuse is all blurred and/or too small to read. Any ideas? It is a true CHI iron. I beleive named the CHI WEE.

  5. I'd imagine that the thermal fuse I posted would be more than adequate for your purposes. Thanks for writing!

  6. My CHI was a 240 c fuse. Radio Shack didn't have it so I had to order online.

  7. Good write up, Wife complained her chi stopped working. I only had to go as far as the power cord. Swivel Contacts were bent, she had the cord wrapped around the iron.

    Bent it back and works now. Good info to know when the iron breaks tho. I'll keep it handy.


    • Hi there Gjaime,
      I think I have the same problem with my iron. It’s been sitting in my cupboard for over a year, I could never bear to part with it, and I’ve hated the replacement since day 1. I think my chi has the same problem, I used to wrap the cord around the iron to keep it tidy. If I spend a lot of time bending the cord just so.. it will light up and work, but then as soon as the cord moves, it’s off again.

      None of the fixes I’ve found so far show how to realign the wires or whatever from the power cord to fix this. Could you please tell me more of your process?


  8. my girlfriend is a professional hairstylist and has gone through three of these chi flat irons in the the last 2 years. she leaves them on all day causing the thermal fuse to blow. i have fixed them for her and she is happy to have not had to buy yet another iron. i was actually just looking for a schematic for the iron when i stumbled upon your page. just wanted to give kudos to you and all of the others who have jumped in and fixed your woman friends iron.

  9. Does anyone know what what the connectors are called that are permanent. Both ends looks like they roll in over on both sides of the wire when crimped. wire===fuse==wire. Thanks. I am searching thru tons of connectors.

    BTW: If you don't know what kind of fuse. Buy one that has a low rating. If it blows quickly try one rated a little higher. If you buy one rated too high it may not blow in time to save he appliance or cause it to catch fire.

  10. How do you get the fuse out.
    Do you just pull on the wires or have to seperate
    the ceramic from the metal back?

  11. I need to buy a replacement power cord for my gf’s Chi Iron.. Please advise where I can buy one online.

  12. Also my gf has another Chi iron that gets hot on the back part of the ceramic plates.. Even if the iron as not been on for too long.. Could it be the thermal fuse?

  13. Hello, I know this post is old but I wanted to try anyway…
    I bought an expensive flat iron form USA and I live in EU. Mine’s a CROC Classic.
    I didn’t know about the difference in voltage so I used it and almost fried it.
    Do you think the only thing burned inside would be the fuse?
    Is it possible, if I open it, to change the engine in a way to have a flat iron compatible with 220v???
    Thank you.

  14. Ahoy there! It seems that this here is the place of refuge for those who are sufferin’ from their loss of “Chi”. Everyone is easily identified by their full-bodied, curly, puffy,unkempt or otherwise, non-straight manes. Ain’t we a motley looking crew..actually more like Motley Crue with that big 80’s hair! Poor souls. AAARGH!
    Anywhoo, Good information & good photos on the site. All of it is worthy of a look-see, even if you think you know what yer doin’ odds are you just might learn something. Unfortunatley for me I tripped and fell into this place after I had spent an evening replacing a burned (actually flattenned )and broken cord (shut in the door too many times), removing and rewiring the rotating connector (frayed and exposed wire) only to end up with a open thermal fuse as the final hurdle. Continuity check proved it but I put in a jumper wire in place of the suspect fuse for just a second and it came to life. Now I am looking for that fuse. Momma didn’t lke my idea of hopping her ass up the kitchen counter and I would move teh ironing board over and just use that nice teflon coated iron on her hair. What? I bet it’d work! HAA!
    SO a Huge slice of Raisin Pie for the originators of ths site & all those that comment and enlighten us poor souls that dare to walk along the path of repair. Keep up the good work.
    Remember, no one man knows everything, so remain teachable. One should try to find something new each day to learn in order to keep your mind from the perils of stagnation and know-it-all-ism!
    Yo Ho Yo Ho….a pirates life for me! AAAARGH

  15. My electrical engineer friend did this for me, however it doesnt spring back appropriately after it was put back together. Did you have this problem? Using silicon teflon lube helped but not entirely. It is functionable, but Im a little annoyed.

    • as a double-E, I can tell you that most of us lack in mechanical engineering prowess. take it back to your buddy / friend-with-you-know-what and make him move the spring around until it works right, there’s only a couple of ways that it fits.

  16. I am 7 months past my warranty, nobody will believe that my shiny pink flattening iron broke down in less than a year by looking at it. I loved my limited edition pink CHI. It’s such an expensive iron and it does not make sense for me to buy a new one. At the time I purchased this CHI, I had other recommendations for Avante and GHD but I choose this CHI in good faith. I am so disappointed that paying the premium price failed me so early! I have a $60 iron that I’ve been using for 4+ years!! This was the most expensive flat iron I’ve ever purchased it is the most short-lived. WILL NOT BUY AGAIN.WILL NOT RECOMMEND.

  17. thank you so much for your website. with the information you provided my chi was successfully repaired. taking up less time than an hour to fix! the problem was: my chi would come on after i plugged it in then once it got hot the thing would cut off and not come back on. now my chi works better than before with the fuse purchased from radio shack that cost only $2. we were able to follow the power flow up to the metal plates, which ment it was the fuse causing my chi not to work, replacted the fuse, works perfect.
    thank you so much again!

    • nikki – my wife’s chi also heats up a little and then stops. Did you have any continuity on your thermal fuse that you replaced? I do. Isn’t the fuse simply a working or not device? Thanks.

  18. Where is this CHI thermal fuse??? My wife has the CHI 1 inch. Stopped working. I took it apart and everything looks fine. I follow the leads to the ceramic heating plates. Taking off the cover to the plates the wires just stop there… no inline fuse. the wires are connected to a little “plate” that appears to be glued to the back of the ceramic plate… both look the same… PLEASE HELP! If I can get the fuse at Radio Shack for 2 bucks that would be awesome
    thanks, jim

  19. I have replaced the inline fuse twice but it keeps blowing up. The original fuse looked like it was incased in a ceramic material. Operating Temp. is +109C Max or +229F Max I’m wondering if the heat from the iron is overheating the fuse or do I have the wrong fuse? I don’t know.

  20. Just had the same issue with the Thermal Fuse on my wife’s real CHI. You can test the fuse on the PCB connections without digging it out of the back of the ceramic heater. The part I ordered was from Newark Electronics NTE8226 at $1.60 each. It will be at my house in 3 days! Wish me luck!!!

  21. I just returned from Europe and I believe it got zapped. Anybody have a idea what part I need to replace.

  22. I replaced the thermal fuse and that side gets hot, but the other side doesn’t.. Is there 2 fuses?

  23. Just replaced thermal fuses. The one I took apart had two fuses and both were bad! We will see how long they last…..

  24. My girlfriend returned from europe too and hers was also fried while she was over there. I just pulled it apart and the resistor (the only one that I can see) is fried and I have no idea what it was.

    Does anyone know the value of this resistor or have a good close up picture of the circuit board?

    Ang, I’m assuming that you have the same problem. If I can fix this Í’ll let you know what the problem was.

  25. hey Josh, yo probably don’t need an answer to your quuestionn. since its been about 23 months ago but maybe someone else has a question similar to yours…. anyone who has ever found themselves completely lost about resisitors …. here is the 411: the purpose for them is they act as a passive electrical component that limits the flow of electrical current. I’ll assume you are referring to the fixed type which is the long one withbthe bands of colors because they were the most common. Of course there are still 4 main types of fixed resistors… squared and dark brown or black base is carbon composite > tan base is carbon film> blue base is metal film> grey base is metal oxide film > foil agree the black squared ones with no color band. The purpose for the colored bands are to determine resistance value and tolerance. The first band= first. significant digit …..second= second significant digit….third= multiplication factor … fourth give the tolerance of the resistor. Look up the resistor color code chart or resistor offers as calculator to help ( or just suck at math like me …although I went to school for this so this math is a piece of cake for me) it’s really not as complicated as I might be explaining it. thhe website I gave is very helpful.. it is important to now the current flow to prevent frying the object youre trying to repair.. hope I was of help

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