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Thread: Grimac La Uno (Mia) Electrical problems

  1. #1
    Junior Member
    Join Date
    Oct 2017

    Grimac La Uno (Mia) Electrical problems

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    I have owned my Grimac machine for the last ten months without a problem. when i bought it there were a few things to fix including the heating element. until yesterday i hadn't turned my machine on for three weeks and then after heating up for a little bit it tripped the fuses on the switchboard.
    I had a little look around the machine and after unplugging the heating element the switched did not trip.
    One of the electrodes had considerable rust build up (i'll insert a photo if i can figure it out) and after cleaning it up it would let the machine run for a little longer but it still tripped the switches.
    It's pretty clear either the heating element is shot or there is a grounding issue in the machine, I am yet to pull the heating element out but that's my next priority.

    I was looking for a wiring diagram for the machine if anybody has one as i can't seem to find one online.

    Also, my boiler level probe seems to have an electrical connection that is stupidly just connected to the frame by one of the previous owners so i'm not sure if it actually functions. If anybody has one of these machines it would be great to get a couple of photos of where this wire should be running to. (SOLVED): I got a little confused with where this wire was running and its to the Gicar electrical box

    Link to images:

    Any help would be much appreciated as i am starting to crave coffee but not at the cost of a damn cafe!!!
    Last edited by Spencersmagas; 27th November 2018 at 12:41 PM. Reason: adding link

  2. #2
    Join Date
    May 2005

    I donít have a wiring diagram but I do have a working Grimac Mia for comparison...


  3. #3
    Senior Member Lyrebird's Avatar
    Join Date
    Jun 2018
    It is usual for one side of the boiler level to be connected to a ground point and the other to the boiler level probe. The presence of water* reduces the resistance between the probe and the chassis, pulling the probe low which is then detected by the comparator on the controller board. The absence of water increases the resistance pulling the probe high and the comparator detects this as a low water condition.

    I don't know the Grimac but if it's like every other Italian machine I've seen all the info you need to rewire it will be on the Gicar controller box (in Italian of course).

    * Technically it's the ions in the water not the water itself.

  4. #4
    Junior Member
    Join Date
    Oct 2017
    Thanks for the help guys.
    I ended up finding a wiring diagram that someone had posted online : Inside The Grimac Mia by Mario Marchadesch | Photobucket
    Unfortunately i think my heating element will need to be replaced at this stage however i am yet to pull it out but that is on the list of jobs for today.
    Dimal likes this.

  5. #5
    Junior Member
    Join Date
    Oct 2017
    randomly good news. I went to bed last night thinking that it could be possible that the water level of the boiler was sitting just under the top of the heating element leaving the element slightly exposed and as a result when the element heated up it would overheat after a minute or so.
    I had the water level set as low as possible to try and get some dry steam and i raised it up about 2-3 cm and guess what its heating up properly and not tripping the switches!!!

    Hopefully this excitement isn't short lived by a $73 demise of having to buy a new element in a couple of days but things are looking good!

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