Mr Coffee won’t brew

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We used to have Krupp’s Coffee maker which worked great for many years, but at some point the coffee pot cracked. Unfortunately, it was not possible to buy just the pot. Although the coffee maker was working fine, we had to recycle it. Before recycling it, I took out the heating element thinking that it might be useful some day.

Last Christmas we got Mr Coffee coffee maker because you could buy the coffee pot separately if it cracked. It worked fine until last week July 22nd, 2012, then stopped brewing. After pressing the Start button, the lights would come on, and you could hear a ‘click’, but then it would not brew.

When I wanted to open it up, six Phillips screws underneath it came out without any problems. However, there was also a locking Torque screw which was impossible to open. We checked on the warranty and it turns out the unit was still under warranty. When I called the local office about it, they simply did not want to deal with it and I don’t blame them. It is just easier to buy another one. :)

But in my case it is more of a challenge to see if it is possible to fix Mr Coffee. I drilled through the locking Torque screw to find out why it was not brewing.

Mr CoffeeVoiding the warranty.

Here is how the underneath of the MrCoffee looked like.

Mr CoffeePower Connection 1

The black cable marked “in” with the yellow arrow in the picture above shows the power coming in from the wall plug. There are three connections: the first one (marked “1″) is the neutral, the second one marked as “2″ is the hot side. Through the relay, the power travels to the third connection marked as “3″.

Here is a better view.

Mr CoffeePower Connection 2

The heating element terminals are shown with red arrows “1″ and “2″. One side of the heating element (red “1″) is permanently connected to the neutral line with the white wire. The hot side (“1″) after passing through a relay (“2″) is connected to point “3″, then “4″, and “5″, and to the other side of the heating element. When I measured the hot side voltage, the current was flowing all the way to “5″, but there was no voltage at the other end of the heating element (red “2″). This meant that the “diode looking” part connected from yellow “5″ to red “2″ was defective.

Here is a better view of the relevant parts.

Mr CoffeeThermal fuses

I cut these two parts out and tried to read the markings on them. “MICROTEMP G4A01 TF216C” was stamped on both. It turns out they were thermal fuses to protect the heating element. If you think about it for a minute, you can see that at any one time only one of them would break the circuit, which meant that the other one was spare.

I soldered the parts back in and short circuited the defective one (the one on the right). And that was it! MrCoffee has been brewing fine now without any problems.

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27 Responses to Mr Coffee won’t brew

  1. Gary says:

    How do you go about short circuiting the defective one?

  2. nev says:

    You can take a piece of wire and solder both ends across the defective device. In my case, I guess there was enough heat that while brewing the solder melted causing the same problem. So, make sure to wrap the wire before soldering so it does not open. Actually you may not even have to solder it, just wrap the wire across the bad part.

  3. jimbotis says:

    The thermal fuses are there for a reason.
    Shorting that circuit is not such a good idea. Burning down your house — also not a good idea.
    Why not replace the thermal fuse.
    A good electronics parts store, or online supplier will have the fuses and crimps to install.
    Easy to do it right, so…………..

  4. nev says:

    Thank you for your comment jimbotis.

    An equivalent circuit for two fuses in series is a single fuse. In other words, connecting five fuses in series to the device, will not protect the device 5 times. When there is something wrong with the device, only one of the fuses will blow.
    If there is a single fuse protecting the device, DO NOT short circuit it. You can use a very very thin wire as a fuse. This is a trial and error method.
    Your suggestion of replacing the second failed fuse of course is harmless (I shorted it). Adding even more fuses will not cause any damage (except to your pocketbook).
    Our coffee maker is still working fine as of 04/08/2013.

  5. Kwaaaa says:

    I have the same coffee maker model and mine went out too, it was also the thermal fuse. As for why they have two, it is in case one is a dud or didn’t perform as expected (didn’t break the circuit in the event of overheating). But it’s a trade off for safety versus reliability, but now it has doubled the chances of one going bad prematurely.

  6. Pid Jones says:

    Or, as on our four-month old Mr. Coffee, both fuses are open. To me, this indicates a true over-heat event (probably the cliks-on switch that controls the element stuck). One fuse I might replace or even bypass and watch carefully. Two and I’m headed to Walmart after work for another new pot. The Nuclear Navy taught us resourcefulness, but also to believe our indications.

    Once upon a time, there was a store in about every town where you could buy such parts. Now all you can find in them is cell phones, radio-controlled toys, and batteries.

  7. Mark says:

    On my Mr Coffee model FTX43 it turns out the heating element is open circuit (infinite ohms), I expected the thermal cut-outs but unfortunately the element is shot after less than a year.

    The tamper resistant torx screws under the rubbers are annoying, until you realize you can EASILY remove them (and replace) with a simple small slotted screwdriver!
    HA!

    I agree with previous posts that it’s OK to short ONE of the thermal cutouts in series but NOT BOTH. You can find them cheap on ebay or radio shack anyways.

    Wish I’d saved the last Mr Coffee identical model we had for parts – dang.

  8. Marcus says:

    I had the same exact problem Nev did. I bypassed the fuse with a solid core wire with the insulation cut off. I most likely used too small of a gauge for the current, but a solid core with no insulation has less chance of burning up.

    Be careful when choosing your wire. I tried Elenco TL-6 Standard Alligator Lead Set in the past with other heating elements and burned em up. I tried them with the Mr. Coffee heating element, but watched it closely, and it would burn up as well if I didn’t pull the plug.

    The temperature of the water was perfect for coffee before the problem. Hopefully the temperature remains the same after this fix. I don’t see why it wouldn’t….

    thanks for the easy fix, Nev!!

  9. Eric L says:

    I followed your instructions to the letter and my coffee maker still does not brew.

  10. john winder says:

    Thanks a million for doing all that work on your coffeemaker and posting your results online with great illustrations. We really appreciate your contribution: it was a great help to us in working on our old Mr.Coffee CGX23. In our case, the fuses were good (unfortunately); it’s the relay, or something else in the circuitry (the On light does come on). Since the main water-boiling element is in series with the plate heater, hopefully it will not be too dangerous to by-pass the circuitry; we might try that. (A schematic in the Owner’s Manual would have been a help, too.)

    Thanks again!

  11. Anonymous says:

    I bypassed a defective fuse in the same manner. But then the element got WAY too hot. It actually burned the thermal paste. I decided to replace the burned out fuse. heh

  12. coffeedrunk says:

    Please do not jumper these fuses. They’re not only temperature protection but also current protection. They will open up if the temperature gets to high, but also will open up if the current draw is to high. If the heating element develops a shorted winding, the current will increase thus opening one or both of the thermal fuses. Also, the warming plate not only keeps your coffee hot it also acts somewhat as a heatsink for the heating coil so keep it clean. Dirt and old coffee act as an insulator. Finally the white material you see between the heating element and the bottom of the warming plate is heatsink compound. It helps to transfer the heat from the heater to the plate.

  13. nev says:

    I agree with lot of the things that you mention in your comment, thank you. Jumpering both fuses
    would not be a good idea. As I suggested earlier, only jumper the blown out fuse. I have done
    this with our coffee maker, and our coffee maker is still working as of this writing (after 10 months)
    without any problems. I only report here what worked for me hoping that it will be useful
    to somebody else. It it doesn’t make sense to you, then of course you can do whatever you want
    with your Mr Coffee. :0

  14. Les W. says:

    I work in instrument safety and compliance and have some insight into this fire protection scheme. Fuses are used for fire prevention. The reason for the 2 thermal cutout fuses in series is because the safety standards requires double fault protection for single use over temperature protection devices. Just in case one device fails to operate correctly the other has a chance of working. That is because heater elements are notorious for going bad. By bypassing the open fuse your putting full reliance into the used second fuse for fire protection. You should replace both fuses at the same time with the same ratings and if they blow again suspect the element is bad and you should replace the coffee maker unless you have a source to purchase a new element. With special equipment you can diagnose the heater has an insulation breakdown instead of simply and open circuit element. My Mr. Coffee maker died today. I’m deciding if I want to try fixing or replace it. Probably replacing it.

  15. nev says:

    Hi Les-
    Thank you for your comment. I like your recommendation (from safety standpoint) and support it.

  16. Moondog says:

    I Had the same problem and narrowed it down with a multi meter. I was wondering if it would be alright to remove the bad fuse. I found a new fuse assembly on line for 15 dollars. Too much. Thanks for the info

  17. Anthony Vavala says:

    My Mr Coffee maker blew BOTH fuses so I replaced both and it worked for one brew and burnt out again. Any help will be greatly appreciated.

  18. Chris B says:

    This same thing happened on my Mr. Coffee bean grinder. It got stuck on a bean for about a second and then died. I did the same thing- removed the thermal fuse and soldered the connections, and it works fine now. I came across this post because (apparently) this same fate has befallen my Mr. Coffee coffee maker- seems they are using crappy or overly-sensitive fuses.

  19. L Neumeier says:

    Thank you! I just fixed mine by cutting out the fuse on the right and hooking the ends of the wires together.

  20. Warren says:

    Thank you! I was just about to give up fixing it and go buy a new one when I thought to do one more google search and found this site. No Coffee on a Sunday morning is an emergency and this fix did it! I plan on replacing the thermal fuse eventually but I will enjoy hot coffee until then. Thanks again!

  21. Stephen Barr says:

    Does this fix help with the no brew problem or the no heating pad problem or are they the same? My light turns on but nothing happens.

    Also, could someone who has replaced the fuses please share the specs and maybe even an online link to purchase.

    Thanks a bunch!

  22. dennis perry says:

    hopefully, the link will work, it’s ebay about the usual over temp fuses needed. I advise pairs if the unit you have has two. They have crimp connectors that work best for these, as it’s supposed that soldering them can be problematic, as we see that they’re actually spot welded and/or crimped from the factory. Older heater elements should be just replaced if the unit is really old(approaching or past warranty) bypassing the fuses are/is reckless. Depending on the price of the coffee maker, probably just best to replace it, but I’ve actually got another on warranty for this same problem and am attempting to fix the left over units the company didn’t want back, as it’s very new, didn’t go but for two months. Any way, hope this helps.

  23. John says:

    Couple months ago I fixed my daughter’s Cuisinart with a ONE thermal fuse from Amazon (10 for ~$7). It has 2 fuses essentially in series too but not connected to each other (1 on heating element input and 1 on the output). A short while later the other one failed and now it’s working ok, but for how long? Now my Mr. Coffee 33 blew one. I replaced that one and had coffee the next morning but not the following day…. It turned out to be the one I replaced???? There’s no way of knowing if it was a thermal failure (240 °C) or a current failure (15 amps at 110 VAC). If there’s another failure I’ll put 2 in parallel to double the current capacity (I understand the risk but I’ll learn something)??? My diagnosis consists of measured resistance across the fuse.

  24. Jack Nichols says:

    If you want to know why there are two thermal fuses in series, it’s because of all the lawsuits that Mr Coffee and other manufacturers got in the 80′s for fires, deaths, and serious injuries.

    The UL standard for household coffee makers is: UL 1082 – “Standard for Household Electric Coffee Makers and Brewing-Type Appliances”. Edition 6 was published in March of 2009. For drip coffee makers, UL 1082 requires a limiting-type device. The usual limiting device is a thermal cutoff. It is easier to meet the specifications if two thermal cutoffs are used.

    I usually encounter one or both of the 214c/216c fuses blown.

    These fuses and such have to be crimped on solidly in some fashion, as soldering them will result in the solder melting when it is running. That’s why they are tack welded from factory.

    After replacing them, if they fail again you have some other issue at fault. Either the Bimetal Thermostat is stuck closed and running the heating element too long and hot, or the heating element has gone bad and is running too warm.

    I will try a new set of fuses for a few bucks and a bit of time just to see if it was some kind of current surge that tripped them, and if they blow again I’ll replace the Bimetal thermostat and some new fuses a second time after checking the ohms on the element.

    Beyond that, I consider it a lost cause and save the coffee pot to use with a new purchased unit.

    I have grown to hate this design because of how often it fails. I have heard of numerous (Brand New units) failing within the first week of use. I have decided to go with an older style Percolator unit like a Farberware or something.

    Check out this site to see why you need these safety components and why it is dangerous to circumvent them.

    http://www.electrical-forensics.com/Coffeemakers/CoffeeMakers.html

  25. William Shutt says:

    Your solution solved my problem. I now have hot water for my coffee again. THANKS!!!

  26. Brian Edwards says:

    The author states that “the current was flowing all the way to “5″, but there was no voltage at the other end of the heating element (red “2″).” Current WAS NOT FLOWING because the fuse was blown and the circuit was open. Yes, VOLTAGE was present. There are two fuses in case one fails to blow and your house burns down due to the lack of a second/redundant $2 part. People also make the mistake of calling an OPEN circuit a SHORT. I often make comparisons of water and electricity to explain what is wrong, but plumbers and electricians get along like clowns and mimes.

  27. Tiger Joe says:

    My friend , both of those thermal overloads should have blown. The reason there are two is incase a single overload fuse is shorted out within — meaning, it is fused connected inside itself and will not open when overheated. There is no such thing as a spare. What you did is very unsafe. You may have no thermal protection now. You may have shorted around the good overload that worked when your devise overheated It could be that the one that blew was weak, but never err on the side of the most dangerous probability. Better to call the one that did not blow defective and replace both overloads

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