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Breville BES920 - Not reaching temperature

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  • #16
    Originally posted by PeteRepeat View Post

    After fixing the thermal fuse on the boiler, it's now only over temp on the boiler. All other temps (group head and steam boiler) checked in diagnostics are ok.. The bubbling I hear and the obvious positive pressure indicated by the leaking orings seem to indicate boiling occurs approaching 100 degrees ?

    So who knows maybe I could have replaced triac only (??) but decided a board was only like $40 so less risk.

    hopefully all ntc sensors are fine... couldn't remove them from the boiler without brute force.

    Thanks for all your info. very informative..

    ​​​​​
    There's a "thermal fuse" (the bottle cap sized white-ish thing) and then there's a NTC Sensor that is used by the Brew Boiler's PID controller. There are two types of these NTC Sensors that insert into your Brew Boiler . . . the new NTC Sensor has a Retainer hitch/hair pin clip that secures the NTC Sensor in place after being pushed into place, and the older version of NTC Sensor is threaded into place. As with many things Breville, after their warranty parts inventory is depleted, Breville legacy model owners must find generic part sources (something being done increasingly and shared as information on sites like this). Your Brain Box is likely not the issue. The NTC Sensor on your Brew Boiler is the possible source for this fault.

    Do you have any photos of your brew boiler from when you opened it up and did previous replacements of components? While you likely didn't need to replace any of the components you mentioned above, it's excellent maintenance and will extend your BES' life and basically turn it into a new machine at those component locations

    If you have the old style NTC Sensor, it will be screwed into place, and sits just to the posterior (on the side) of the brew boiler from the Thermal Fuse (whitish bottlle cap, slightly smaller than actually, sized item) . . . its not on top of the boiler but on the right side of the brew boiler (the smaller boiler) if you are facing the machine from the front).

    Looking at the picture above, you can see the NTC version that has the hitch/hair/pin clip (that has to be carefully pulled out first) before removing the NTC Sensor, which actually is in contact with the Brew Boilers water. If you have one that looks like it has a box wrench fitting, you'll have to screw it out carefully. Before you do that, you'll want to test it for continuity etc. using a Digital Multimeter (DMM) if you've got one?

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    • #17
      Here's an example of what failed seals on a Brew Boiler can inflict on a Grouphead in a BES900XL or BES920XL Double Boiler system if not checked on annually or every other year . . . two pictures, one showing the corrosion that can occur on the Grouphead's NTC Sensor and the second showing the over all Corrosion on the Grouphead area due to water intrusions from the leaking seals on the Brew Boiler . . .
      Breville BES900XL BES920XL Grouphead NTC Sensor showing Corrosion due to Brew Boiler Seals leaks
      Breville BES900XL BES920XL Grouphead NTC Sensor showing Corrosion due to Brew Boiler Seals leaks

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      • #18
        Thankfully the insides of mine look good, no corrosion on top of the old group head when I replaced it just now (only due to old single piece collar = very early 920).

        Thanks. I realised I only replaced the fuse.

        Seems I have the original NTC sensor as well from your good description. Does that mean a new boiler if that goes? Like my group head when the collar went... However there's no signs that has a problem is there, more for future proofing it? I know the triac board has issues as I can hear the heat element turn on say a second after the system turns on, then it doesn't turn off when at temp (confirmed with volt meter as well). Also confirmed the element hasn't shorted to ground and it has the correct resistance, well I think.
        ​​
        ​​​​Yeh I have a multi meter and know how to use it without blowing myself or the machine up ?

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        • #19
          Oh so that connection on the top of the group head is the NTC sensor? I thought it was a ground when I pit it back on just recently to the new group head. I t looked ok re corrosion but I thought it was a ground when I pit it back on.

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          • WWWifi
            WWWifi commented
            Editing a comment
            yes indeed, that is the temperature sensor that is feeding your Groupheads PID controller data The lug (the metal terminal with the screw hole in it) is wrapped around what appears to be a square-ish item. That square just between the wires and the screw hole is the NTC Sensor. The NTC Sensor is likely encased in a heat resistant, water resistant, polymer. The metal of the lug (the terminal connector you screw onto your Grouphead) transmits the thermal energy from the Grouphead to the NTC Sensor (the square-ish thing the shoulder of the metal lug is wrapped around).

            It definitely looks like a Ground Wire . . . the give away that is more than a Ground wire is the square electronic component (the NTC Sensor) that has two wires (not one), one sending current in, and one receiving current out (both going to a connection on your brain-box of your BES.

        • #20
          Hmm. Whne I took the NTC sensor off it had a seperate loose metal tab, that I just put between the NTC sensor and the group head... I wasn't sure what order it went on, and I originally thought it was just a ground wire I figured it'd be fine (yes I know grounding is also important, but if I had realised it was for temperature I could have paid more attention.

          Do you know if it was meant to be two pieces plus the screw and in what order they should have gone on?
          ​​​​

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          • #21
            We have success.

            ​​​​​​Replaced the triac board and a few orings (I got limited supplied so to be continued).

            The good old bes 920 (7+ years old I think) is back to life.

            However the brew head heats up slower than the steam boiler on cold start which is unusual. Does the pid learn or are they fixed gains?

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