My beloved Pavoni Eurobar has a serious ailment. She heated water yesterday as usual until the pressure read about 0.5 bar (set at 0.9) and then she stopped. The power switch remained lit but the element was cold. I disassembled the machine, and cleaned the pressurestat and pressurestat pipe leading from the boiler. The microswitch clicks when pressed, though I have not checked it with a volt/ammeter to see if there is an internal short or burnout. I saw no evidence of cracks or discoloration in the element, though I will be more thorough when next I disassemble the machine. When reassembled the machine again heated water until 0.5 bar and then stopped. Today there is no activity at all. Any clues? Doug, are you out there in the ether?

Cheers,
Colin

Hi Colin, yes I am out here under ether mostly. I have spent the past couple of days puzzling over a Faemina with a lot of glitches so electrical gremlins are close to my heart at the moment. Take a deep breath and start fresh by disconnecting all the wires to the element and pstat and test each component. Test the ohm reading across the element terminals and verify that this reading is stable. Test from the element terminal to the base plate to verify that there is no short in the element. Test the pstat with probes on the terminals (no wires hooked up) and it should give continuity (switch closed) when cold. Once you get all of the electricals diagnosed as positive function it seems that you will need to zero in on the pstat....as I recall it has a rubber membrane inside a brass housing that can possibly be replaced. This is rather than change it out to a Mater or other since the geometry of the pstat is critical to be able to adjust it from the outside of the machine through the tube on the side. If it is not repairable it seems that it could be replaced with a new Mater with the loss of the adjust on the fly feature. But then, it could be that the microswitch on the pstat is either sticking or defective (the .5 bar then shutoff followed by no heat). As I said, do some tests with an ohm meter and this starts the process of sorting it all out. On the machine there are very few components so unhook them and test separately to avoid any false leads which one has a tendency to follow even when they go nowhere but into this brain pounding zone of confusion.
And by the way....ANY short in the element of any kind will throw a GFI breaker at the receptacle, or the main breaker in your house panel, or shock the you know what out of you and visual inspection or not, you will definitely know it if there is a short. Something funky here with the pstat.

Thanks. I'll let you know what I find. Tis a puzzlement ...

By the way, Doug, I actually have tubing available to bend into a new P-stat pipe, so as long as any new p-stat has an adjustment screw I think I can get it lined up with the adjustment port and preserve that functionality. I have some candidate P-stats I am looking at. Thanks for the help so far. I'll see what the ohmmeter says.

Colin

Hi Doug, I tested the element and it reads about 48 ohms, which is spot on for a 1000W element at 220V. No shorts evident. The readings on the microswitch on the pstat were unstable. The male spades on this switch attach via screws that thread into terminals. I disconnected the male spades and tested the screw receptacles on the switch and got an over limit reading with the switch unengaged and a low (0.3) reading when it was engaged. This suggested the switch was fine and the contacts dirty. So, I cleaned the spades. After that the meter read the same with the spades screwed in as with them out of the switch. I figured I had fixed the problem. However, I still get no heat. I can adjust the set screw on the pstat and hear the switch engage and disengage and still no heat. I will go over the rest of the wiring harness tomorrow, but I am a bit confused. Any ideas, or should I just plug away with the main switch (which does light), and the rest of the harness? There is the issue that this element has an odd receptable in the element base in addition to the two main leads. You can see it in the picture. The red wires lead into this receptacle, which is a copper tube that contacts the main element in the interior of the boiler. I am unsure if this could be part of the problem. However, with the main two boiler leads detached the element tested fine.

Cheers,
Colin

OH MAN!!!! Your temp safety fuse is blown! The overtemp fuse is soldered on the wire that is covered by the orange wrap and is stuffed up in the cavity. You can test this by removing that wire from the circut and test for continuity. I bet it is blown and you will have no continuity. You likely just need a new fuse. This is sounding like a happy ending!

Spot-on, Doug, that was it. No current is passing through the fusible link. I began to wonder if there was a fusible link stuffed up there when I went to bed last night. It makes sense. I knew there was no resettable hi-limit thermostat. The copper tube into which the fuse was stuffed contacts the element so it can sense the temperature. What maybe happened is the dirty pstat stayed on too long, the element briefly overheated while I was grinding shots and it blew the link. Why it worked again once after that I don't know, it might not have completely gone the first time. It is also possible that it blew the previous time I used the machine. I like to flush some left-over water through the group screen right after I turn off the machine but before it cools down. It is possible I flushed too much, exposed the tip of the off, but still hot element and fuse housing, and it blew.

By the way, Doug, where do you get your teflon-coated wire for espresso machine rewiring? I was going to try the auto parts shop. I might replace the harness for fun, or at least make a spare harness to have on hand.

Great news there...pstat ok and heating element ok, that's the main thing! The teflon wire is really nice to use...rated at 700F vs silicone wire rating of 400 so generally can be used without covering with a fiberglass sleeve or something. McMaster is a good source to get the complete amp/gauge rating specs for the wire but ebay is where we get the best deals for small (100ft or less) amounts. The PTFE coated wire is quite expensive to buy by the complete spool and since we use a lot of colors we generally get 25 or 50 foot coils from an ebay seller who has a lot of gauges and colors.

I found some wire, maybe even the same seller. Thanks.

Hello all, (Doug in particuluar),

I finally replaced the thermal fuse in my Eurobar and made a spare wiring harness just for the heck of it, and I am happy to report that she is back in the business of making espresso. I used this as an opportunity to clean the group and lube the piston and so she is quite clean and all is right with the world. After cleaning and adjusting the pressurestat the deadband is now at .05 bar! I'm not sure I actually would have chosen that, as the element now cycles very frequently. I may fiddle with it a bit more later. Doug, thanks for the help. The only bad thing is now I need to give back my brother his Cremina.

Cheers,
Colin