Announcement

Collapse
No announcement yet.

Alternative PID for Expobar III?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    An idea that I've been toying around with is exchanging the brew SSR with a dimmable relay. In this scenario, whenever the steam boiler is off the brew element can operate at the full 2000W. However, when the steam boiler energises this could auto-dim the brew boiler SSR down to say 600W. However looking at dimmable SSRs they are expensive (around $90 on RS components).



    Once the brew boiler is up to temp, you don't really need 2000W especially if you have pre-heat through the steam boiler. Obviously this may cause issues with pid tuning.

    Comment


    • #17
      Originally posted by Dimal View Post
      That one was only by way of an example, not knowing what your budget was mate. And, for what it's worth, this particular manufacturer makes units that perform well above their price point, so don't be too hasty...

      Mal.
      No haste to be had Mal. It's all good.

      There's good stuff and not so good stuff. I actually liked the PIDs you mentioned because they offer different colour options. Doesn't mean much to most, but when you go out of your way to build something, it's the small details that make something nice.

      Budget? It's good to have a budget, But having bought it in the first place, I expected it to work for a reasonable period of time. There's what is called "implied warranty", which mean that if you pay a lot of money for an items worth, then there is a reasonable expectation to a reasonable period of warranty. Spending good money after bad is never good. But I don't want to pay $260 for something that could fail in the same sort of period, only to have to go through it all over again. I could post youtube links of other people who have had the same issue, and that includes the current BLUE LED model. So what do I do, chuck it out and get something else?

      So, a reasonable budget cost would be even with the correct replacement. Say I spent $260 in parts and built something, as long as the functionality was same or better, I'm still better off. Even if I do have something hanging off the side. I could even incorporate the grinder timer, water level meter and sms controller. Have it all as one coffee station. House the grinder into box for sound-proofing and make a larger hopper with thermal insulation etc. Only limit is the imagination.

      MrMcSteam,
      That idea is pretty wild, for me anyway at this stage. If you do get around to doing it, post it on the forum. Will be good to see the progress of it.

      When I devise something I'll need to be able to break it down and build it back pretty quick as it's my only machine and we use it everyday.

      Comment


      • #18
        Hi again BM...

        It really is difficult to make any kind of recommendation of this type over the Net - Too many implications. Best bet is to stick with Coffee_Machinist's advice, he knows these machines backwards and is better placed than most to advise you on the best outcome. I'm a tech-head and sometimes forget that not everyone possesses the same knowledge and experience. If you don't possess similar knowledge and experience, then Rick Bond from C_M is your best bet...

        Mal.

        Comment


        • #19
          Originally posted by MrMcSteam View Post
          An idea that I've been toying around with is exchanging the brew SSR with a dimmable relay. In this scenario, whenever the steam boiler is off the brew element can operate at the full 2000W. However, when the steam boiler energises this could auto-dim the brew boiler SSR down to say 600W. However looking at dimmable SSRs they are expensive (around $90 on RS components).



          Once the brew boiler is up to temp, you don't really need 2000W especially if you have pre-heat through the steam boiler. Obviously this may cause issues with pid tuning.
          Hi mmac.
          Whilst a creative idea using a dimmer it would in practical terms not be very efficient. The ssd uses duty cycle to effectively achieve the same outcome with the benifit of switching off at the zero crossing point.

          This gives a robust and almost infinately variable solution which is no coincifence is pretty widely adopted.

          Comment


          • #20
            Originally posted by koshari View Post
            Hi mmac.
            Whilst a creative idea using a dimmer it would in practical terms not be very efficient. The ssd uses duty cycle to effectively achieve the same outcome with the benifit of switching off at the zero crossing point.

            This gives a robust and almost infinately variable solution which is no coincifence is pretty widely adopted.
            Hi Koshari,

            I wasn't talking about a resistive dimmer which would be inefficient. I was talking about these microprocessor based solid state relays that modify the ac sine wave. These ssrs take a 0-5v signal that is proportional to the desired output power.

            http://www.crydom.com/en/Products/Ca...eter%20control

            These could be interfaced with arduino and a dac easily to give actual proportional output as opposed to time divided proportional output.

            Cheers

            Comment


            • #21
              Ok. Sorry for my assumption.

              Comment


              • #22
                Originally posted by koshari View Post
                Ok. Sorry for my assumption.
                No worries, sorry my reply was terse. I was replying from my mobile.

                I have a lot of experience with the electronics side of things but no experience with the plumbing side of espresso machine mods.

                Comment


                • #23
                  Thats ok.

                  Imo with temperature control being a relatively slow function such a high resolution of control would possibly be a bit of a waste of effort unless you increased the wattage of the element therefore increasing the heating ability early in the error detection period.

                  This slowness is likely the reason a good deal of temp specific controllers only have a single digital output. You could consider a controller with a 4-20 ma output and drive your variable ssr with simply a presision resistor across its input giving you 1-5v across its input.

                  Also keep in mind it would then have to pay off pretty quickly to prevent excessive overshoot in temperature.

                  The algorithms in a pid controller are pretty advanced at modeling rate of change. I personally havnt had any experience in arduino firmwares that acheave this. I also have no reason to doubt they exist.

                  Comment


                  • #24
                    Originally posted by koshari View Post
                    Thats ok.

                    Imo with temperature control being a relatively slow function such a high resolution of control would possibly be a bit of a waste of effort unless you increased the wattage of the element therefore increasing the heating ability early in the error detection period.

                    This slowness is likely the reason a good deal of temp specific controllers only have a single digital output. You could consider a controller with a 4-20 ma output and drive your variable ssr with simply a presision resistor across its input giving you 1-5v across its input.

                    Also keep in mind it would then have to pay off pretty quickly to prevent excessive overshoot in temperature.

                    The algorithms in a pid controller are pretty advanced at modeling rate of change. I personally havnt had any experience in arduino firmwares that acheave this. I also have no reason to doubt they exist.
                    You're correct there is little benefit, other than being able to have both elements on at the same time. As the elements are both 2000W, using the dimming ssr the brew boiler could be dimmed to 400-600W thereby keeping total power draw under 10amp. Then when the steam boiler isn't needed the brew element can utilise the full 2000W available.

                    Anyway definitely something I wouldn't bother doing unless I had to replace the PID and or relay anyway. The Minore performs well as delivered.

                    Comment


                    • #25
                      Originally posted by MrMcSteam View Post
                      The Minore performs well as delivered.
                      Not for me it doesn't :/

                      Comment


                      • #26
                        Just been inside Minores all day again, and I realised another issue with going to a different controller - there is only roughly 50mm depth available behind the front panel until you hit the internal water tank panel. That rules out any 1/32 DIN controller that I know of.

                        Comment


                        • #27
                          Yep, I'm ok with an external PID.

                          So, if I was to want...

                          To be able to have just the steam on
                          To be able to have just the Brew on
                          Have some form of warm or standby function. Let's say 20% power.
                          Buttons for single shot, double shot, triple shot, stop, flush, water tap

                          Physical Mods
                          Flick tap for steam
                          Flick tap for water if electromechanical option isn't possible for timed pours


                          Other than buy another machine, what do I need to know that is specific to the Minore III? Is there a service manual for it?

                          Coffee_Machinist, you said that the steam has priority, does it make sense to change this behaviour?

                          Comment


                          • #28
                            Bringing up this old thread because I recently encountered and addressed this problem. See the post at: CoffeeGeek - Espresso: Espresso Mods and Restorations, Expobar Brewtus IV-R PID Controller Replacement

                            Comment


                            • #29
                              Alright, Friday housekeeping and I'm going to detail my fixes over the years. I've owned an Expobar Minore 4 for nearly a decade I think and they're really good, but spoiler alert. They break.
                              In relation to this particular issue, I've been through the first unit that totally lost all output but still worked...until it didn't. I replaced it with my current one in which one segment is now dead after 36 months (seems like a common issue with no fix), but otherwise was working fine, until it spazzed out and quit completely. The below will NOT fix the issue where the LCD slowly shits the bed, one segment by one segment. I've tested the fix graciously provided by coffee_machinist and my findings/experience is as below.

                              The exact part on my Gicar was a HAHN BV 202 0154 Transformer: encapsulated; 0.5VA; 230VAC; 6V; as detailed here https://www.tme.eu/en/details/bv2020...n/bv-202-0154/

                              The part cost ~$10 shipped from the UK, so really I was saved over $300! To desolder the exisiting 4 connections, ideally use a solder sucker, or if you're a tightarse like me, I had some old desoldering wick which is shithouse, but works in a pinch. Then it's just a matter of slotting the new transformer in and re-soldering. My old one visually looked fine with no bulges, magic smoke smell or otherwise. But when I fired it back up it worked perfectly!

                              Comment


                              • peetdevos
                                peetdevos commented
                                Editing a comment
                                I've owned an Expobar 1-Group with the same PID (blue LCD) for more than 10 years. The PID started going blank after a few minutes once the machine reaches ideal temperature. I've diagnosed the issue by removing the PID from the housing and tapping it with a screwdriver when it goes dead. That often times brings it back to life. I assumed that it may be the transformer. I was quite happy to see the issue explained by coffee_machinist in this thread (thanks !!. I'll order a replacement transformer and report back on how it worked out.
                            Working...
                            X