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Expobar Minore (Brewtus) ii Repair/Rebuild

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  • Expobar Minore (Brewtus) ii Repair/Rebuild

    I recently acquired an Expobar Minore ii in an 'electrically unrepairable' state. Having qualifications and experience in repairing electrical equipment I figured I'd give repairing it a go, if it was really dead I'd design a custom control system anyway. I figured I'd take some photos and document my experience here in case it might be useful to anyone looking at repair of a similar Expobar machine in future.

    If you have any questions or comments, please feel free to post.

    Here is the machine after I got it home. Will begin the repair/rebuild soon!
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  • #2
    Good luck!

    I did a pretty big rebuild on a Minore III recently so if you need a hand let me know. I think they are pretty similar just use a different model PID, I would be tempted to use the newer PID (if the PID is dead) from the Minore IV but they are pretty savage price wise I think it was about $250.

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    • #3
      You Little Bewdy Aaron!. The more rebuild / 'pimp my pumper' ( goodness Is that allowed Jp?) threads the Better.
      Imho. These have been sadly lacking in recent times.
      Com'on guys give Aaron a round of applause and encouragement.
      And a big thanks for the entertaining read !
      G.L.

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      • #4
        Go for it. There is not much electrically to go wrong in them. Even at $250 for a pid it is a cheap rebuild. There are some good youtube videos somewhere that shows all about the insides and what is connected to where,

        Regards
        Geoff

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        • #5
          Whole Lot Latte have some excellent stuff on Minore called Brewtus in the US;
          https://wiki.wholelattelove.com/Expo...roubleshooting

          Not sure if it is linked there but they have technical walk through of checking major components one by one.

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          • #6
            Thanks to everyone for the well wishes ?.

            First step is to turn it on and see if we can see what works and what doesn't. Then come up with a plan of action.

            I turned it on and to my surprise the temp controller came on (displaying E1), the pump ran and the steam boiler started heating. Steam pressure closed the anti vac valve and it built up pressure until the pressure stat kicked in. I ran some water out of the hot water tap and the steam tap. I also lifted the E61 lever and tried pressurizing the group head with a blind basket, but the group seal did not hold any pressure (gushed out the sides). The steam boiler cycled a few times before tripping out the RCD (I had connected it via an RCD and MCB separately to diagnose ground faults). Looks like the main controller is OK, and the temperature controller could also be OK (maybe just a temperature probe problem). Time to unplug and let it cool down before removing the cover.

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            It is marked October 2007 inside. Generally looks OK; obviously not new, but no signs of any big issues. There are no signs at all of water leaks.

            First odd thing I noticed was the temperature controller was connected via a small transformer. The specs for the temperature controller indicate 240VAC should be OK, so I'm wondering if this was a fix for a previous issue (burned out transformer inside the unit itself). Google seems to indicate this might be a common problem. If the internal transformer to the controller has been bypassed, then I should be able to supply DC instead of AC to the controller (will investigate further later).

            Second thing I noticed was the temperature sensor is completely... errr.... disintegrated? There appears to be remnants of it stuck in the thermowell.

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            The next thing I noticed was the controller was just freely hanging in the space below the temperature sensor. I'm surprised it is not suspended with a bracket or something to reduce the vibrations from the pump bumping it around.

            I am now planning to take the whole thing apart (everything that can easily go back together at least) and give everything a good clean / descale in the process. Then fix anything that is broken (e.g. seals and electrical problems) whilst re-assembling. I suspect the issue with the RCD could be a ground fault through the brew boiler heating element; but will get to proving that shortly. I've taken a bunch of photos during disassembly to document the wiring and plumbing connections / orientation. Now the cleaning begins!

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            • #7
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              • #8
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                • #9
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                  • #10
                    Originally posted by aaron2 View Post
                    The steam boiler cycled a few times before tripping out the RCD (I had connected it via an RCD and MCB separately to diagnose ground faults). Looks like the main controller is OK, and the temperature controller could also be OK (maybe just a temperature probe problem). Time to unplug and let it cool down before removing the cover.


                    then I should be able to supply DC instead of AC to the controller (will investigate further later).

                    Second thing I noticed was the temperature sensor is completely... errr.... disintegrated? There appears to be remnants of it stuck in the thermowell.

                    I suspect the issue with the RCD could be a ground fault through the brew boiler heating element; but will get to proving that shortly.
                    Well by the looks of it the temp sensor might not be working..Just a feeling not completely sure.
                    If the controller had a transformer bypassed and a new transformer was installed the transformer will still put out AC and will need to be rectified before being used in the controller. Check the output ACV from the transformer

                    Heating element does sound a bit doge. Disconnecting the element and retesting would have been my testing method but now you have it out of the machine measure with a meter and see what it says.

                    I look forward to seeing this project completed. Even if you updated the control and PID it will serve you well for quite a few years.

                    Regards

                    Geoff

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                    • #11
                      Thanks Crisp_image I'll check the element tomorrow. Cursory check with my crappy home multimeter suggests some leakage to earth. The transformer still works, so the rectification must still be in place in the temp controller. I'd rather use a SMPS instead, so will test that tomorrow to see if it works, then order some parts accordingly.

                      I'm going to order some other bits and pieces to tidy the internals up while I'm at it. Anyone have any ideas where to get new shrouds for the electrical connectors (quick disconnects)? Would be nice to replace the old brittle ones, or maybe heat shrink?

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                      • #12
                        From memory most / all of those spade terminal covers need to be put on before the lug is crimped. Nothing wrong with heat shrink to recreate something like below. I would use something like RS Components part number 4580695, but I'm into overengineering things.

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                        • #13
                          I found some on eBay if you search for "Slip On Cover for Female 6.3mm Spade Terminals" they aren't cheap but I grabbed some as you often get cooked ones from the heat inside machines. They slip on fine on an existing cable from the end.

                          I would link but eBay links aren't allowed.

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                          • level3ninja
                            level3ninja commented
                            Editing a comment
                            You can post the item number

                          • roosterben
                            roosterben commented
                            Editing a comment
                            Thanks level3ninja I will post the item number next time for any eBay parts.

                        • #14
                          Originally posted by roosterben View Post
                          ... eBay if you search for "Slip On Cover for Female 6.3mm Spade Terminals" ... post the item number ...
                          Thanks to roosterben and level3ninja : The eBay item number is 133444694067 for that part. From that listing I've found the part number and have ordered a pack of 100 from RS (RS part number 688-1029).

                          Also level3ninja I use those shrouded quick disconnects at work and not sure the plastic shroud would stand up to 100C+ for very long. I can't find any info anywhere on their rated temperature limit; that being said the stock ones also obviously exceeded their limit. As I have now found the stock ones and they are cheap (and easy; no re-termination required) I'll go with that for now. Thanks for the suggestion though; might be a good alternative (looks better and more compact) for future mods ?.

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                          • #15
                            Originally posted by Crisp_image View Post
                            ... Well by the looks of it the temp sensor might not be working..Just a feeling not completely sure ...
                            Just saw this ? love it!

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