Lelit PL41EM blows fuse - wrong wiring or broken thermostat?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by sigissmondo »

For 10 years i've been the happy owner of the basic Lelit PL41EM. The one without a PID. Now after 10 years the gasket has worn out inside the boiler which I discovered after some research. Unfortunately, in my enthusiasm to take a better look what the problem was, I forgot to note down some of the wiring. I took some pictures, but since it's a bit too busy due to so many cables I had a hard time to figure out what goes where. Normally the cables of on the boiler sit quite right, but the one's going to the buttons are a mystery. I did follow my intuition and connected the wires to my best knowledge.
End result? it powers on, the pump works when pressing the switch... but then, when I leave it on for a minute or 2, fuse goes out! :shock:

I'm all but an expert, but my gut feeling tells me that as soon it reaches a certain temperature it sends a signal to the thermostat and ... things go wrong. I know it's a lot to ask, but if anybody could map me the wiring, that would be a great help. If you need pictures or an image how I wired it, I'll gladly post it here.

Funny detail: Since the gasket gradually got worn out, limescale had the time to gradually seal the upcoming cavity between the boiler parts. So, when I tried to remove the limescale, the seal broke. The inside of the boiler was pretty clean, unlike some videos I've seen on the Lelit insider youtube channel.

sigissmondo (original poster)

#2: Post by sigissmondo (original poster) »

Here is the current situation

sigissmondo (original poster)

#3: Post by sigissmondo (original poster) »

here you have my wrongfully put scheme. maybe somebody technical will be able to see my wrongdoings? Either way, I've found others who were looking for this scheme. So it can be useful for other owners of the PL41EM

On an additional note: I placed a new 125° thermostat.

Alan Frew

#4: Post by Alan Frew »

This might help.


sigissmondo (original poster)

#5: Post by sigissmondo (original poster) »

Thank you Alan, I appreciate it. unfortunately this one has a different setup than mine. I'm guessing it's the pl42em

Team HB

#6: Post by JRising »

In your picture, you have the blue with the un-connected end. Part of the multi-connection conductor that has a "2" on it where it connects to a thermostat... In the schematic, that's gotta be (From the far end to the close/disconnected end) Element, to Safety-T-Stat, to pump, to steam switch upper blue side... So that disconnected end is steam switch upper blue side... BUT, the terminal with the 2 on it is connected to the middle t-stat, and if I'm not incorrect the safety(165 with a red button) looks to be the t-stat to the left in the picture. Make sure you know which is which, they do have to be connected properly.

Look at each conductor in the schematic, find that conductor in the machine and make sure it's properly connected. Start with the easiest. The bottom-most one in the schematic is neutral (blue), long and has only the 2 connections (one at each end of course). It goes from steam switch blue to Steam Solenoid. Make sure it's correct.

Next, the phase(brown) conductor above it. About as long as the last one, but with three connections on it. Same Solenoid Valve, Pump and Brown, lower side of PUMP switch this time, (not steam switch). Make sure that one's correct.

Then the blue that I spoke of in the first paragraph, 4 connections, element(labeled boiler in schematic) the resettable (safety 165) thermostat, pump, and upper blue side of steam switch. Make sure it's correct.

Then the next blue above it, also on the safety t-stat, simple, only 2 connections, safety to powerswitch. (Yes, I see that the schematic has the power switch wired phase to neutral and vise-versa). If you can wire it the way it was from the factory it's not your fault. I strongly suggest matching the black wire from the powercord to the brown wire going to that safety t-stat, just so that the neutral blues aren't live) This will let a ruptured element overheat the boiler once, pop the safety and alert you that there's an issue with the machine rather than having the phase on the self-resetting side of the thermostats.

You can continue from here, only 3 conductors left. Make sure they're correct. Enjoy your espresso.

If this DOESN'T make sense to you, or you're uncomfortable, it can be dangerous to do it incorrectly. Print the schematic and have an electrically inclined friend or even a professional do it for you. Injuring yourself isn't worth saving $60.

sigissmondo (original poster)

#7: Post by sigissmondo (original poster) »

Hello JSRising, maybe its important to note I drew the schematic to make it easier to spot the fault in it :D in my initial image I have indeed switched a multi connection cable. the picture was from before I realised I connected at least that one wrongfully. The current setup is like the one in the schematic, but with no luck.

Team HB

#8: Post by JRising »

Oh Crap, sorry... I see what you're doing now.

After a three minute study of your schematic, it appears functionally good to me. (Not to mention better than a lot of professional schematics, good job).

Regarding your issue, it's strange. No new connections are made when a thermostat clicks off, so for a machine to short to ground or draw more power when a thermostat clicks is difficult to believe. I suppose that with the 95 degree t-stat conducting, the resistance through the heating circuit could be so low as to hide a very minor ground fault in the element. Then with 92 open and no good path to neuitral, the amperage at the element fault gets above the 5mA needed to trip the GFCI. I find it hard to believe, but without a megger to find the fault, I can't rule it out. I believe in an element ground fault only going above 5mA with the t-stat open more than I believe that a ghost might be messing with your machine.

sigissmondo (original poster)

#9: Post by sigissmondo (original poster) »

Thanks again for replying, the good news is that I just received the schematics of the PL41EM from Lelit. This might really come in handy for others who have the same issue. Now it's time to compare I guess.. I'll see where this goes and keep you posted.
- I'll have to be honest though, the schematic seems more daunting to read than I expected. I don't know if anybody would be willing to compare it to my drawing

Team HB

#10: Post by JRising »

Side by side, it checks out.
Your schematic was good.
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