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Thread: UNIC Rumba - 2 group machine

  1. #1
    Junior Member
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    UNIC Rumba - 2 group machine

    Hey Coffee Snobs,

    Couple of issues

    We bought the above machine for our house and it had an issue with one of the group panels/modules (so only one group was working). I may be able to get a new one from Unic (but would cost as much as we paid for the machine). Is there anywhere that has second hand/used coffee machine parts? (The solenoid for that group seems it will also need replacing as there is no 'click' when we put the working panel in that side).

    Other than that the machine was functioning beautifully and making exceptional coffee, but now does not seem to fill the boiler automatically on start-up - is there a way to re-set the machine? (in case it is something electonic/electromechanical) ?

    Thank you in advance.

    Will

  2. #2
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    Will,
    Two things you could try that won't cost,swap over the solenoid from the working group to the non functioning one and see if the previously working group behaves differently.
    The auto fill problem may be simply due to probe contamination/ corrosion, (both checks need caution regarding electrical wiring so ensure the machine is unplugged before fiddling in there) remove the probe and using a fine emery paper to give it a clean to improve water level detection.
    Try these simple checks and see how things go...fingers crossed,then we can go to the next level of checking if necessary.
    ok...?
    cheers,
    Mick.
    Last edited by mulquemi; 19th June 2017 at 06:51 PM. Reason: Typo
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  3. #3
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    Thank you Mulquemi for the reply.

    I will have a look at the probe and see how I go.

    Just to be clear about the unit, when we bought it both the controllers/panels/modules were working when it was first powered up along with both steam arms and the hot water outlet. the RHS group worked perfectly but while the LHS group butons all functioned, there was no 'click' or waterflow through the group head which lead us to believe the solenoid on that side was probably gone.

    When the installation was complete we switched it back on, but only the LHS controller/panel/module worked and since the RHS was the only one with water flow we swapped the controller so that on the RHS was the working controller and the working group (solenoid and water flow).

    So for a week that all functioned really well (and made amazing coffee, provided hot water and endless steam).

    Then yesterday, it stopped filling when you switch it on, no steam and the water flowing through the group is cold. Tried pressing the red re-set button which was on the side of the boiler (perhaps on a solenoid for the element?).

    The machine cost $300.00 (which is double what I paid for the last one, which is a FAEMA FaemaTronic from about 1990, which according to a repairer needed a motor and a pump among other things). So, although we haven't spent a lot we were hoping it would last longer than a week...

    I will get some emery paper and have a look at the probe. with any luck we can get it back to functioning on the one group like it had been. It was certainly lovely coffee. WE bought an $80 grinder (A Beraldo which must be about 10 years old) and after a good clean out and some fiddling, grinds the beans fine enough to make a great brew.

  4. #4
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    Huntercoffeelover,
    Bit difficult to diagnose from my location however,
    "Then yesterday, it stopped filling when you switch it on, no steam and the water flowing through the group is cold. Tried pressing the red re-set button which was on the side of the boiler (perhaps on a solenoid for the element?)."
    I would check the electrical contactor (giant relay) .
    My understanding of your description is the machine is now unresponsive to being turned on,perhaps you have a neon glowing indicating power to the contactor although with a possible failed 240 volt solenoid (inside the contactor),could be checked out by confirming solenoid magnetically applying the contacts for power/pump activation,easy to observe with top cover off.
    Please watch out for live conductors in there!
    Hope that helps.
    Cheers,
    Mick.
    Last edited by mulquemi; 21st June 2017 at 01:06 PM. Reason: clarification
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  5. #5
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    Thanks so much for the reply, Mulquemi,

    It is responsive (in that the display lights up on the group that works and it pumps cold water through the group head which I assume would normally be heat-exchangedand hot) I think it does not make steam or boil water because there is no water in it to boil - but I'm not a coffee machine technician. Just a coffee drinker :-)

    I think something is wrong with the auto fill facility - which (now I am totally guessing) could be something to do with the modules that form the controls for each group (As that appears to be the only PCBs in the machine) or the probe as another poster had mentioned.

    What do you think about that?

    What does the contactor look like (I was a phone tech so know something about electonics but that was a long time ago). I can't see any obvious relays, but there is something which looks a bit like a junction box/wiring connection loom - is that what it would be?

    Thanks so much for the reply.

    Will

  6. #6
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    Huntercoffeelover,
    "It is responsive (in that the display lights up on the group that works and it pumps cold water through the group head which I assume would normally be heat-exchangedand hot) I think it does not make steam or boil water because there is no water in it to boil"
    This statement suggests to me that your contactor is operational otherwise no pump activation would occur,so too is your group solenoid.
    Your pressure stat (device that controls the heating element activation) is powered via the main contactor output.
    Although similar in operation to the main electrical contactor ,the pressure stat controls the movement of its contacts by pressure delivered from the boiler rather then the magnetic movement of contacts.
    Pressure stats can fail due to a number of reasons , resulting in stuck closed contacts that will boil dry the machines boiler (unless a fail safe option is installed) or remain open with sounds more likely your machines fault.
    No heating equals no heated water or steam....sounds like your machine ?
    If you or someone handy (with a serious sense of electrical safety) can use a multi-meter to confirm that pressure stats output contact connections are closed when (closed circuit) cold and open when at set temperature (pressure stats are adjustable over a range).
    Your pressure stat can be easily removed (brass hex joiner) and once disconnected from input /output conductors ,checked out for proper operation.
    Some espresso machines have a glass sight level which clearly shows your boilers water level, some don't.
    Good idea to remove the water level probe and after cleaning it then use something to dip into the boiler (via the probe opening ) to confirm the presence of water.
    The fact you have water coming out cold suggests the boiler is fine and full.
    Hoping yours is a simple fix,
    Cheers,
    Mick.
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  7. #7
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    Thanks, Mick - I appreciate your reply.

    I'm not sure I understand enough to do this, but I will try and give it a go. So just to triple check you don't think it has anything to do with the electonics, but rather some of the electro-mechanical stuff?

    I can see what I recon is the pressure stat (something hooked up to the boiler via a single brass pipe with electical wires connected to the bottom), I will try and work out a way of seeing if this is faulty - How do we get it to think there is a raised temperature (when it is disconnected) to test if the circuit opens? I'm guessing it is easy enough to check that the circuit is close when it is cold, as long as the terminals on it are intuitive. We do not have a schematic for the machine.

    Would photos of all this help you ?

    Will

  8. #8
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    Huntercoffeelover,
    Photos are always worthwhile,another confirmation of the pressure stat working is to check the terminals of the boiler element ( carefully as power will be on and is lethal).
    When pressure stat is functioning power should register on the multi-meter when connected to boiler terminals (if heating elements are working correctly).
    You may simply have failed heating elements and everything else could be operational!
    Heating elements can be checked by first disconnecting wiring lugs and measuring resistance ( ohms) of each element...depending how many you have (1-3 possibly).
    No heating means no current flowing through elements!
    Cheers,
    Mick.
    Last edited by mulquemi; 22nd June 2017 at 09:15 PM. Reason: Wrong choice of words!
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  9. #9
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    Hey Everyone - just thought I'd let you know we ended up going to a coffee machine repairer and getting a control panel for the LHS group off another wrecked UNIC Rumba and... IT WORKED! Even the LHS group now works (which we though had a solenoid issue). The machine has been humming along for nearly 2 weeks now making delicious coffee.

    So I guess, overall the machine was $300 and the second hand part was $100 - so we have still only spent $400 to get a working two group machine for home (plus a filter and some pipes and fittings for under the sink).

    The coffee this machine makes is delicious! Have only had one disgusting burnt/gritty coffee since we bought it.

    I"d never heard of a UNIC Rumba before, but I'm reliably informed that Bela Roma used them as part of their coffee distribution, so hopefully this means parts will be around for a while.

    Yours in good coffee,

    Will
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  10. #10
    Mal Dimal's Avatar
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    Great outcome mate....

    Onward and upward now, eh...

    Mal.
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