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Thread: Giotto Premium Plus (approx. 2009 model) turning off after 10-15mins

  1. #1
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    Giotto Premium Plus (approx. 2009 model) turning off after 10-15mins

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hello Coffee Snob experts out there,

    I would be very appreciative of any advice you may have on the problem I am having with my Giotto Premium Plus (approx. 2009 model). I recently had an issue where it was over filling and thanks to advice on this forum, I resolved this by removing the overfill probe and removing scale build up.

    However, it is now turning off after 10-15mins. It heats up as normal and the pressure gauge goes to around 1.4 bars of pressure. I can see that the heating element switches off at this point and then comes back on again at around 1.1 bars of pressure. I assume this is relatively normal cycling of the heating element to keep the boiler pressure within the correct range? I can't work out why it would turn off though after sitting idle for 10-15 mins. I can see that the green power light turns off and the pressure slowly drops back to zero.

    For the time being I have a very limited window of opportunity between heating up to the correct temperature and pulling a shot before it powers off...quite frustrating!

    Open to any ideas or suggestions and happy to provide any more details which may help to diagnose the issue. I have an electronics background and multimeter available so can do some tests if needed.

    Thanks in advance!

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    Jonny, when you removed the scale from the boiler level probe, did you also do a full descale of the machine?

    Also, how scale up was the level probe?

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    Just noticed that you have stated that the gauge ranges from 1.1 to 1.4, this seems a bit wide, the dead and should be narrower.

    Probably a good place to start, if you feel confident is to check that all the connectors have a good clean connection.

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    Hi Marke and thanks for your repsonse!, Yes, I did a full descale first which improved things slightly but I still had an occasional over fill. I then went the next step and removed the boiler level probe and cleaned it with steel wool. I actually couldn't see much scale build up but it hasn't over filled since. I will double check all connectors and ensure they have a good connection. Any specific connectors I should focus on that are more likely to cause this type of behaviour? Cheers, Jonny

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    Sounds like a bit like my Premium that I upgraded to a hybrid Plus. My problem was the switch (not sure what they are called) that turns the boiler elements on and off in the electronic module was worn. I replaced the module and it has not missed a beat since. The module replacement might be best done by a technician as the wiring must be correct

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    Senior Member sprezzatura's Avatar
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    Sounds like a bad controller. If your thermal cut out isn't popping and the pstat is working there isn't a whole lot left to check unless some water is shorting something out.

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    Senior Member sprezzatura's Avatar
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    Unfortunately there's a mechanical relay in the controller that wears out on the heating element circuit and pump sometimes. Some people replace this relay. My soldering skills aren't very good so I don't replace these. But if you're electronics savvy it's possible - the Giotto controller is pretty basic: the h.e. circuit is the black wire on the high-voltage side. There are three mechanical relays inside. When you slide the PCB out of the cover it opens like a book.

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    If you do a bit of a search on the forums, there is a guy who is offering a relay replacement service. Let me know if you can't find it and I'll try to dig it up for you.

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    Have a look at the top of the boiler. You will see a thermostat with two male spade terminals. With the machine off and unplugged from the power point, remove the female terminals. With your DMM check for continuity across the thermostat. Pull gently up on the red reset plug and check for OL. Sometimes the bimetallic thermostat fails or corrosion causes a fault. A cheap repair compared to a new level/h.e. controller.

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    After thinking about it some more and drinking a couple of beers, you might have a faulty pstat. The membrane may be worn out. The contacts carbonised. Turn off machine and unplug. Take a look at those contacts. Turn the pstat pressure down to 1.0 bar and see if the dead band gap decreases.

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    My original pstat had a wide range of 2-3 bars. It was metal cased. I replaced it with an all black plastic one which has a narrower band. I still think it is going be a module replacement. I tried/replaced every thing else but ended up replacing the module.

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    Quote Originally Posted by sprezzatura View Post
    Have a look at the top of the boiler. You will see a thermostat with two male spade terminals. With the machine off and unplugged from the power point, remove the female terminals. With your DMM check for continuity across the thermostat. Pull gently up on the red reset plug and check for OL. Sometimes the bimetallic thermostat fails or corrosion causes a fault. A cheap repair compared to a new level/h.e. controller.
    Hi Sprezzatura and thanks so much for your advice.

    I found the two terminals on top of a small, black, round device with a red button on top. Sorry if this is silly question but is this called the pressurestat or thermostat?

    As instructed, I turned the machine off and unplugged. I removed the two black terminals on top of the thermostat and measured the resistance which was around 20 ohms. When I pulled the red button up it went to open circuit (O/C). Is this a good sign?

    The contacts looked pretty clean but I gave them a further clean just in case. I then plugged the two black plugs back in and turned the machine on. I measured around 2 ohms resistance across the two terminals when I first turned the machine on. The resistance then varies between 1 ohm and 2 ohms during the normal operating cycle (i.e. as the pressure varies between approx. 1.2 - 1.4 bars).

    After around 15 minutes, as normal the machine turned itself off (and the power light went off) and the pressure slowly dropped back to zero. At this point the resistance on the thermostat was around 1.5 ohms. Not sure if that helps :-(

    Anyway, I'll try turning the pressure down to 1 bar as suggested and see what that reveals.

    Update - after turning the pressure down to between 1.1 - 1.3 bar the same thing happened although it appeared to take a bit longer to occur. I'll try turning it down a little more to see what effect it has.
    Last edited by Jonny; 3rd November 2015 at 07:45 PM.

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    Thanks for your response Dumiya. It's fantastic having some options to consider! Are you referring to the mechanical relay that Sprezzatura mentions below? Just trying to narrow down the next thing to check. Also, did you replace it yourself and if so, was it relatively straight forward?

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    Quote Originally Posted by dumiya View Post
    My original pstat had a wide range of 2-3 bars. It was metal cased. I replaced it with an all black plastic one which has a narrower band. I still think it is going be a module replacement. I tried/replaced every thing else but ended up replacing the module.
    Mine is the black plastic one.

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    Quote Originally Posted by sprezzatura View Post
    Sounds like a bad controller. If your thermal cut out isn't popping and the pstat is working there isn't a whole lot left to check unless some water is shorting something out.
    I don't believe the thermal cutout is tripping for two reasons:

    1.) the resistance across the two thermostat remains at around 1-2 ohms when the machine switches off
    2.) when I pull one of the connectors off to simulate an open circuit, the heating element turns off but the power light remains on (when the issue that I have experienced occurs, the power light goes off also).

    So I'm guessing it's sounding more like a bad controller.

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    I agree, your thermal cut out is working (this is the black thing on top of the boiler with the red button that pops out if there's an overheat situation). If it's working the button doesn't pop out. Don't worry about Ohms - just need continuity when the button is down. If you pull it up you will sever the circuit and get O/L on your DMM.

    Sounds like a bad controller. If you're interested in having a look you can remove the PCB and take a look inside. Sometimes there's carbon around a bad relay or a burned out transistor/TRIAC. Possibly the transformer. Some people here on CS refurbish them. You can put out a request - heck, if it's a heating element relay you could solder a new one in yourself if that's in your repertoire.

    Otherwise site sponsors Talk Coffee and ECA have controllers. I replaced a Giotto controller with a Pro El Ind. earlier this year.
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    Addendum: that was from ECA (Espresso Company Australia) - the coffee company I was working for at the time had an account with them.

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    Quote Originally Posted by sprezzatura View Post
    I agree, your thermal cut out is working (this is the black thing on top of the boiler with the red button that pops out if there's an overheat situation). If it's working the button doesn't pop out. Don't worry about Ohms - just need continuity when the button is down. If you pull it up you will sever the circuit and get O/L on your DMM.

    Sounds like a bad controller. If you're interested in having a look you can remove the PCB and take a look inside. Sometimes there's carbon around a bad relay or a burned out transistor/TRIAC. Possibly the transformer. Some people here on CS refurbish them. You can put out a request - heck, if it's a heating element relay you could solder a new one in yourself if that's in your repertoire.

    Otherwise site sponsors Talk Coffee and ECA have controllers. I replaced a Giotto controller with a Pro El Ind. earlier this year.
    Thanks again Sprezzatura! I see what you mean now about only looking for continuity. I had initially thought that the themal cut out device would vary resistance based on temperature but it did just stay within a very low impedance range, for all intents and purposes, full continuity. I'm guessing once it gets to a pre-determined temperature it becomes O/C (as simulated by pulling the red button).

    I removed the Pro.El.Ind controller last night after taking some "before" photos and labelling each connection. I have found the appropriate transformer and large black relay on RS Components...haven't looked for the transistor yet. Before I ordered the parts I wanted to do a multimeter test after it "turns itself off" and see if the transformer is faulty (i.e. not showing the correct secondary voltage)...only problem is that since removing and re-installing the controller the problem hasn't re-appeared!!! Haha!!! Further testing to come :-)

    If all fails, I'll be planning a trip to see Chris @ Talk Coffee for sure. I would have done so sooner except we live quite a drive from Melbourne so I'm trying to be more self sufficient :-)
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    Jonny,

    Maybe it's the electrician coming out in me, and the memories of my last little tingle are still fresh in my mind, but you need to be very careful where you stick your test prongs, the wires and terminal your playing with will have 240v on them when your machine is on and running, you must also have a different multimeter to me, mine doesn't like to measure resistance while having voltage applied to it, you won't get a correct reading, and you can also damage your meter.

    I'm all for tinkering and fixing your own problems, but we need to be careful when giving advice to people, we think we may of explained it correctly, but it is easy to misunderstand what is being instructed, I have seen some scary stuff when it comes to electricity and people who think they know what there are doing, it doesn't take much to hurt yourself, someone else, or do more damage to your machine than it already has.

    Not trying to step on any toes here or upset people, just wanted to bring it to your attention, be careful. Sorry I can't offer any help with your machine, hope you get it sorted out soon.
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    Yes, Tony's correct. I usually don't delve too deep into the electrical diagnosis but if someone seems competent there are some simple tests you can do with your DMM. I try not to do too much with the machine hot myself. The TCO is something that can be tested with no load on as well as coil tests, earth leakage, and bi-pole switch function. Please remember it is 240VAC 10amp and one slip with conducting material and you'll being doing the 240 volt shuffle. You may blow up the board. I suggest having a portable residual current device to plug into unless you have one installed on your mains power.

    On another note, removing the PCB and connections may have jostled one of the relays. If the transistor was blown it would not have improved the function of the h.e. relay. It's a good bet it's the relay.
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    Quote Originally Posted by tonyh View Post
    Jonny,

    Maybe it's the electrician coming out in me, and the memories of my last little tingle are still fresh in my mind, but you need to be very careful where you stick your test prongs, the wires and terminal your playing with will have 240v on them when your machine is on and running, you must also have a different multimeter to me, mine doesn't like to measure resistance while having voltage applied to it, you won't get a correct reading, and you can also damage your meter.

    I'm all for tinkering and fixing your own problems, but we need to be careful when giving advice to people, we think we may of explained it correctly, but it is easy to misunderstand what is being instructed, I have seen some scary stuff when it comes to electricity and people who think they know what there are doing, it doesn't take much to hurt yourself, someone else, or do more damage to your machine than it already has.

    Not trying to step on any toes here or upset people, just wanted to bring it to your attention, be careful. Sorry I can't offer any help with your machine, hope you get it sorted out soon.
    Thanks for the words of warning Tony, appreciated and yes I was very careful. I have an electronic engineering degree but haven't dabbled much with electronics in recent years so it has been good to get back into it...cautiously :-)

    So a quick update from this morning, the machine eventually did turn itself off and I then checked the voltage on the secondary winding of the transformer and it was approx. 1V (prior to shutting itself off it was reading 12V - which matches the "no load" output voltage of the 9V transformer). So at this stage I am thinking it is more likely the transformer that's at fault, but happy to take other opinions.

    In the mean time I have ordered a replacement transformer and relay from RS components as they were pretty cheap (<$15 including delivery).

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    Quote Originally Posted by sprezzatura View Post
    Yes, Tony's correct. I usually don't delve too deep into the electrical diagnosis but if someone seems competent there are some simple tests you can do with your DMM. I try not to do too much with the machine hot myself. The TCO is something that can be tested with no load on as well as coil tests, earth leakage, and bi-pole switch function. Please remember it is 240VAC 10amp and one slip with conducting material and you'll being doing the 240 volt shuffle. You may blow up the board. I suggest having a portable residual current device to plug into unless you have one installed on your mains power.

    On another note, removing the PCB and connections may have jostled one of the relays. If the transistor was blown it would not have improved the function of the h.e. relay. It's a good bet it's the relay.
    Totally agree Sprezzatura and I always exercise the utmost caution when working on any 240V circuit. Yes, the house does have an RCD but I'm hoping I won't be testing it...but glad to know it's there. Famous last words!!
    sprezzatura likes this.

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    Great news, it's fixed. Replaced the transformer and all was well in the world. I couldn't find the exact part number so just made sure it was 240V primary, 9V secondary, 1.5VA and single output. The model I chose was 9 V ac 1 Output Through Hole PCB Transformer, 1.5VA purchased through RS components. RS stock number is 732-0342.Total cost was $6.51. Much cheaper than a new controller board :-)

    HUGE THANKS to all those who offered support & advice through this forum. That means you Sprezzatura, TonyH, Dumiya & Marke! I really appreciated your time in responding to my calls for assistance and as a result I learnt a lot.

    NOTE: As mentioned quite correctly by TonyH, anyone attempting this repair should have sufficient competence, exercise caution and take necessary steps to ensure that power is isolated prior to working on the machine due to the risk of electric shock. If in doubt, send the machine to a trained technician.
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    Pleased you got it fixed! Your back to the world of awesome espresso again!

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    Great outcome, always satisfying when you can put your skills to work and solve problems using them, and at minimal cost too, enjoy your next brew.

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    Nice work! Nothing like NOT having to buy a new PCB if you can get away with it.

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    Good work, lacking the technical expertise I simply replaced the whole controller. I took pictures before of the wiring and carefully followed the photo. Doubled checked, Yes I got it right. Even this way is not for the feint hearted. And like wise all is good but it cost about 50 times more than your transformer .... Ah well, good outcomes all round and in the cup!



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