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EM6910 power light keeps flashing green and group head gets heat

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  • EM6910 power light keeps flashing green and group head gets heat

    I recently bought a well used EM6910. This machine was $20 on the basis that it has this issue and that it should be a replacement of the thermostat that should fix it.

    I thought it would be best to get a second opinion before I order a new part and muck around with it.

    When I power it on, it seems to work OK, the power light flashes green indicating it is warming up, I can feel the group head gets warm so it appears to be heating up OK, and I can hear what I think is the thermostat click on and off periodically after about a little over a minute. The power light remains flashing though as though it never gets up to the right temperature.

    Does this sound like the thermostat is faulty? I have a bit of an uneasy feeling that a thermostat would not cause this issue and it is something else, I'm hoping others have seen this before and can help.

    I have opened up the machine and it looks pretty good inside with the exception of a couple of wires which has some fraying of the outer protective layer, I attached a couple of photos.

    Any help would be much appreciated.
    Attached Files

  • #2
    Does the steam thermoblock also heat up? You only mentioned the grouphead heating. I can't offer an explanation for the frayed wires unless someone has worked on the machine previously but it should not be much of a problem and would not be affecting the way it works. If the steam thermoblock is not getting hot that would stop the machine from getting to the 'ready' state. Most likely to be caused by a blown thermal fuse. The white section of the cable shown in your second photo is the thermal fuse. It can be tested with a multi-meter on 'ohms' or 'continuity buzzer' but double, and even triple, check that the machine is off and unplugged first as most of the internal wiring is 'live' with just being plugged in to a power point.

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    • #3
      Thanks for the post Xanthine, I got hold of a multimeter and tested that fuse out, and it appears to be the problem. The "continuity" beep does not sound when the fuse is in between it, but does when it is across the wire just on one side of it so that indicates that is the issue.

      Replacement looks to be about $20. I have attached a photo of the fuse, is there an equivalent from an electronics shop I could get a bit quicker and cheaper? I Googled 240C thermal fuse and came up with a few options, about $2 each, which I would be happy to use. Would 10A work in this?
      Attached Files

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      • #4
        I've been doing a bit more reading, and it looks like it is best to replace the thermostat as well as the thermal fuse, as a faulty thermostat is likely the cause of the fuse blowing.

        Another question I had, there are thermal fuses which are 229C at RS Electronics, which are quicker to get. Would the 10C difference likely result in the fuse blowing under normal usage, or is there a bit of leeway with this rating? I'm thinking it will be OK based on other posts I have read.

        I need to replace the fuse anyway, so I think I will try the 10 pack thermal fuse from RS electronics, and see if the machine works OK then before I replace the thermostat.

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        • #5
          I'm glad to hear you found the problem. As to a replacement, you will notice that the fuse is crimp connected to the leads and can not be soldered in, so unless you have some means of doing the same with the new fuse I would suggest using a replacement part. I believe this would have the wires with a spade connector already attached but you would still have the crimp wire joiner at the other end to deal with. I have seen repairs with an insulated screw joiner used here (not on the thermal fuse itself). I would not bother to change the thermal switch unless it is open circuit as this only operates as a backup to the temperature sensor/control board system which does the temperature regulation under normal operating conditions. It would probably be worth refreshing the thermal grease under the temperature sensor as this tends to dry out and loose effectiveness over time and is more likely to be the cause of thermal fuse failure. Also, this type of thermal fuse tends to 'wear out' with age due to constant heat stress. The temperature sensor is the white ceramic button with a pair of white wires. It is attached to the thermoblock with screws and a clamp. If you do decide to change just the thermal fuse I would be inclined to use an exact replacement. Keep in mind that this part of the circuit is connected to un-switched active with the relay switching in the neutral side of the circuit so it is constantly 'live' when the machine is plugged in to an 'on' power point.
          Hope this helps.
          Trev

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          • #6
            Hi I have the same dilemma and a new fuse here in melbourne if i drive across town is $25!!!!!
            I could get one online but by the time i pay exorbitant postage and wait it will be the same cost.
            I have looked at the thermal grease as suggested and it is still "wet" "pliable" so hasnt dried out. I have some computer thermal grease for under the processor if that would suffice to replace if necessary.

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            • #7
              I got a pack of 10, pm me your address and I can post you one. Once I have put it on I'll let you know how it goes and any issues etc.

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              • #8
                Re thermal paste, I usually use Unick which is a non-conductive silicone grease based compound. I have had a tube of this which has lasted many years as only a tiny amount spread over the mating surfaces is required. I would suggest you avoid the conductive greases which contain finely powdered metals. Non-conductive greases are often called 'dielectric'.

                I'm probably stating the obvious but don't forget to fit the white sleeve over the thermal fuse before re-fitting it.

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                • #9
                  I bought 2 from jaycar this morning, 229c which was the same as the original, though very faded. just putting things back together now, fingers crossed. thanks for the offer thats good of you.

                  ok i am back to coffee again yay.
                  Last edited by roscored1000; 6 days ago.

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                  • #10
                    Out of interest what type of crimps are best to use when replacing the thermal fuse? Don’t really see any of the original type being sold anywhere

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                    • #11
                      Originally posted by tez1 View Post
                      what type of crimps are best to use when replacing the thermal fuse?
                      RS Components part number 809-2369

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                      • #12
                        What is the safest way of removing the thermostat on the steam thermoblock? I cannot get to the back screw of the thermostat because other parts are in the way, so I thought I should remove the thermoblock, but I am not sure if that is the right way to go either.

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                        • #13
                          Originally posted by tez1 View Post
                          Out of interest what type of crimps are best to use when replacing the thermal fuse? Don’t really see any of the original type being sold anywhere
                          Hi I didn't use any crimps, I cut them off and just used solder, I attached a few alligator clips to act as heat sink and soldered quickly, works fine. That also meant I didn't have to disconnect anything or disturb anything.

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                          • #14
                            Originally posted by roscored1000 View Post

                            Hi I didn't use any crimps, I cut them off and just used solder, I attached a few alligator clips to act as heat sink and soldered quickly, works fine. That also meant I didn't have to disconnect anything or disturb anything.
                            I think from previous posts, solder is a no no as it will melt due to the temps.

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                            • #15
                              Yes I just read that too will if it comes apart I know what to do, where did you get your crimps from

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