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Gaggia Classic - general troubleshooting/improvement

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  • JojoS
    replied
    Originally posted by cwhiteley View Post
    Hello! Newbie here. I pulled my Gaggia Classic apart and cleaned it after buying it used. It hasn't seen a lot of action in its lifetime but was pouring very slow shots. I took it apart and cleaned every possible part according to recommendations here. I unscrewed my OPV valve but did not record how many turns it took to remove from the body. Anyone have any idea how far it should be turned down to function. So far I have been trial and error and no luck. I don't have a pressure gauge or blind cup to test? Any suggestions or know factory settings????
    Best to just get hold of a pressure gauge. Trial and error even with a blind filter is a roll of a dice at best by measuring output. Tighten it up clockwise and back out 2 or 3 revolutions should get you somewhere ideal but that is just a guess.

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  • cwhiteley
    replied
    Hello! Newbie here. I pulled my Gaggia Classic apart and cleaned it after buying it used. It hasn't seen a lot of action in its lifetime but was pouring very slow shots. I took it apart and cleaned every possible part according to recommendations here. I unscrewed my OPV valve but did not record how many turns it took to remove from the body. Anyone have any idea how far it should be turned down to function. So far I have been trial and error and no luck. I don't have a pressure gauge or blind cup to test? Any suggestions or know factory settings????

    Leave a comment:


  • pcqypcqy
    replied
    I've been playing with an arduino lately and have finally worked out how to measure the voltage coming from the PID controller to the SSR, i.e. how often it gets switched on and for how long each time. Will play around with some settings and do some more measurements and put an update on here in a few days.

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  • Dimal
    replied
    It's up to you mate but what would I know...

    Mal.

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  • pcqypcqy
    replied
    It's a different problem. CPU cooler needs good thermal contact to transfer heat into a heat pipe/sink and fan arrangement, and needs to continue doing so whenever it's on. I'm simply trying to measure a temperature. I know it's not a permanent fix, but the blob of thermal paste and the tape are still there so I'm happy with it for now, at least until I can assess how the pid is performing before I commit to drilling out the thermostat hole.

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  • Dimal
    replied
    Originally posted by pcqypcqy View Post
    so long as it's reasonably secure and thermally connected to the boiler, isn't it going to give you consistent results?
    Well mate, would you tape your CPU Cooler down and reckon it's good enough?

    You can't get a reliable thermal connection using the amount of force that a piece of tape provides. You want reliability, you need to have it properly fixed to the boiler. Up to you of course...

    Mal.

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  • pcqypcqy
    replied
    Borrowed a Mini Mazzer. Is pretty good!

    Still getting some jetting out the naked portafilter and very wet pucks. Almost looks like there are 4 spots where channeling occurred, corresponding to the 4 holes in the shower screen holding disc.

    Any tips on where to go from here?

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  • pcqypcqy
    replied
    Ha ha, I solved this problem.

    The thermocouple as a braided metal outer covering over the wires. Turned out this was brushing one of the SSR contacts, so every time the PID was powered, it was getting an extra 40mV through the thermocouple, which turned sensible temperatures around 3mV / 90 degrees C up to around 1200. I re-ran the wires ensuring no contact and problem sorted.

    Why do you say you need to screw it in - so long as it's reasonably secure and thermally connected to the boiler, isn't it going to give you consistent results?
    Last edited by pcqypcqy; 21 September 2015, 08:53 PM.

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  • Dimal
    replied
    Yep....

    Sounds like your t/c has gone "open circuit". May be easily rectified depending on where the break is. Best to do a close inspection along the t/c from whoa to go to see if you can locate it, otherwise a new t/c will be the only way out... By the way, you can't join a broken t/c cable/wire as such, rather you need to shorten the t/c back to the break and create a new t/c junction.

    Also, just taping the t/c to the Boiler somewhere is not a great idea, regardless that you've used thermal interface compound. You really need to screw it to the top of the Boiler using one of the t/stat mounting screws if possible; and the TIC too of course.

    Those PID parameters all look a bit odd to me also but until you have a working t/c and it is mounted solidly and securely, will be better to wait until you've fixed that side of things up.

    Mal.

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  • pcqypcqy
    replied
    So now in installing the project box I've somehow stuffed something up. I think there may be a loose connection somewhere in the thermocouple. The screen is reading some temperature above 1200 deg C and flashing. If I reverse the polarity of the thermocouple wires it just flashes "oooo" at me. I had some issues like this when I first installed it the other day and jiggling the wires at the PID end seemed to help, but now I've stripped the dodgy crimped connections off and have just put the wires into the mounting screws. My multimeter tells me there's a voltage across the wires, so I'm not sure what's going on.

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  • pcqypcqy
    replied
    I've attached a photo of my pid for reference. I will get a project box for it today. Values are below. I did a few auto tune routines, most were near the set temp to begin with. My theory is that it needed some sensible values to begin with so it could home in on something that works, so each auto tune got me a bit closer.

    Set Value is 95 currently. My probe is taped to the side of the boiler, away from the elements, with a big blob of thermal paste. Most people seem to have temps set in the low 100's, but that just gives me boiling water or steam out the group. I'm varying the temp a few degrees to find the sweet spot, and I'll dig out a glass thermometer to try and measure the temp coming out of my naked portafilter.

    I think the probe placement away from the elements means that the boiler shell at that location is more influenced by the water inside rather than the elements. I'm not saying that this is better, just noting the difference.

    I did it this way so I could reverse my installation and out the thermostat back in if I want. The thermocouple is much larger than the thermostat was, so didn't want to drill and tap just yet.

    P 67
    I 527
    d 131
    Ar 6
    T 1
    Sc 0
    Attached Files

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  • CaffeinatedAndrew
    replied
    http://www.fmfranklin.com.au/products/data/rkc/c100inst.pdf

    Not sure if this is your exact one but the symbols for the settings should all be similar. Out of interest what did the auto tune set the PID settings to?


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  • Dimal
    replied
    With machines like the Classic that use a particularly small Boiler, you're probably better off using the Autotune feature after the machine has warmed up somewhere close to normal operating temperature, rather than from cold. You can do this more than once, as you've already tried, and then as a matter of interest, you can then go into setup and see what final parameter settings have been settled on, and record these for reference.

    After using the machine for a few days, you can then determine if further fine tuning may be required. The main thing to remember when attempting this, is to only adjust one parameter at a time and perhaps use something like this or this as an aid to determining what needs to be adjusted...

    Or, you could just head back in here and see if one of us can help you out...

    Mal.

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  • pcqypcqy
    replied
    EDIT - did another autotune and it seems to have settled down now and holds the set temperature better without overshooting.

    PID went on yesterday. I'm struggling to tune it. I've let it warm up to about the operating temperature, and then selected auto tune. It doesn't seem to realise that if it heats at full power right up to the set point that it will overshoot by 10 to 15 degrees celcius. It seems to be quite good at catching the falling temperature, clicking on and off as the temperature falls to the set point, at most dipping 1 degree below, but the overshoot is killing me at the moment - spouting steamy water out the group everywhere.

    Anyone familiar with this device? I feel like there's a setting somewhere that I can change so that it will undershoot rather than overshoot.

    It's a cheap knock off Berme Rex C100 from china. The manual I have is in mandarin, and the other manuals I've seen online are all in Engrish so I'm struggling to understand what each parameter is actually for.
    Last edited by pcqypcqy; 19 September 2015, 12:00 PM. Reason: for fun

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  • Dimal
    replied
    Originally posted by pcqypcqy View Post
    We used to do them nearly back to back, but now I'm trying to leave more time between shots, occasionally flipping the steam switch on for a few seconds to help recover the temperature. Though without a readout of the temp, this is all guesswork. The pid will help with this a little bit.
    A PID Controller, properly installed and setup, will obviate the requirement to wait between pulling shots. The Classic responds particularly well to this type of Mod' as it has a high Power to Water Volume ratio in the Boiler which allows it to be very responsive to a PID Controller's outputs. This is also the case for (dry) Steam production too...

    Mal.

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