Jura Z5 tripping GFI - need advice

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

#1: Post by 3ddesigns »

Hey guys,

Picked up an older Jura Impressa Z5 that trips the GFI when the pump is about to come on.
It's happening either when I press the hot water or the espresso button, so my guess is that the pump is shorting it.
Any advice on how to troubleshoot this and test the pump to find out what exactly the issue is?

Thanks in advance!


#2: Post by WWWired »

Hi 3ddesigns :) Often a single component in an appliance or machine can trip a breaker if the component is failing or developing a fault.

A very awesome machine by Jura, a company that started out as a channel partner of SAECO and then when SAECO was sold (the first time) Jura developed its incredible machines based on Arthur Schmed's brilliant engineering and patents that revolutionized the coffee industry and developed the foundations of super-automatics and their exceptional focus on sanitary/health engineering design in coffee equipment that has even affected semi-automatics and other coffee machines.

Here's a few things to try possibly (be sure to take numerous pictures and even video for your records):
  1. Try the machine on a completely different Electrical Circuit (be sure its not just another plug-in/outlet on the same circuit);
  2. Here's a video link how to open the machine for a look inside to see if anything is obvious How To Open Jura Z5-Z6-Z7-Z9
  3. If you don't have a clamp meter, that Harbor that's sells Freight place sells a great little clamp multimeter for about $14 Bucks recently (sad they don't sell in Canada :( ). This can be used to not only probe contacts and check a pump's diode and coil but solenoids etc. and the clamp allows for monitoring of some current on wires without having to risk a nasty shocking experience that will result in having to relearn how to count to ten or grow back some eyebrows;
  4. Take photos at all stages from two or three different angles when removing any component . . . have little baggies and a Sharpie to mark where screws come from right on the bag.
And most importantly, share your journey here with your new friends! :)

Here's another pretty awesome video by a YouTuber channel "Spare Time Worshop" that also shows what a Jura Z5 looks like and some of the disassembly and inner workings . . . There's a lot of very expert folks here that can diagnose issues just by looking at or hearing what's happening in a video or pictures of a machine . . .
Credit: YouTube and "Spare Time Workshop" channel

Team HB

#3: Post by JRising »

Disconnect the pump's electrical leads and wrap them or stow them in a way that they can not touch anything. Try brewing. Of course, the pump won't run but you want to see if the GFCI still trips, if it does trip, then the pump isn't the culprit.
Repeat with each of the components that would be energized at exactly that point. You say it's precisely when the pump should energize so that's the logical starting point.
You can basically rule out grinder, boiler, steam valve, multifunction valve, brew-unit motor and all sorts of things if you know that everything works perfectly until the point where the pump engages. Good luck.

3ddesigns (original poster)

#4: Post by 3ddesigns (original poster) »

Thank you both. I got as far as pulling the badge off the back side, when I realized they use a special oval key for the oval head screws. Ordered one and it should arrive tomorrow. Keep you guys posted.


#5: Post by WWWired »

Very awesome! JRising and several of the long time Home-Barista members have made this the best coffee community on the internet and mentored many of us here! He's awesome and his insights are always fantastic :) You'll be an expert before long! :)

3ddesigns (original poster)

#6: Post by 3ddesigns (original poster) »

I wanted to give you guys a quick update. Upon removing the rear and side panels and turning the machine on, I discovered a major leak from somewhere under the boilers. While I could not pinpoint where exactly the leak was, I think it would be a good idea to address this first before moving on to the short issue.

A quick question - how do I remove those clamps from the braided plastic hoses? Do I simply squeeze them with plyers, or another special tool is required?

User avatar
BaristaBoy E61

#7: Post by BaristaBoy E61 »

3ddesigns wrote:A quick question - how do I remove those clamps from the braided plastic hoses? Do I simply squeeze them with plyers, or another special tool is required?
Posting a picture would be helpful. If it's what I think it might be, a pair of pliers should do the trick. Release the compression of the clamp with the pliers and manipulate it with the pliers to a part of the hose where it will no longer have its clamping effect.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

Team HB

#8: Post by JRising »

Major leakage inside is probably the cause of the ground fault... But I'm with BaristaBoy on this one. Please post a picture of what you're finding.

I haven't been inside a Z5 since 2018, I can't remember if the multifunction-valve is down on the floor in those... If I remember correctly, the multi-function valve and the pre-heater/heat exchanger are both down on the floor of the machine. The pre-heater is probably so pitted and disintegrated that it's going to be the leak you're seeing. If so, with all of multi-valve's microswitches mounted to the bottom of the multi-valve's bracket, your switches will be soaked and you'll find the problem easily.

3ddesigns (original poster)

#9: Post by 3ddesigns (original poster) »

I recorded a short video of when turning it on. I can't really tell where the water is coming from, but it appears it might be the aluminum cast of the small (left side) boiler itself.


- a couple of pictures as well.

Team HB

#10: Post by JRising »

Ahh, yes... Those hose clamps.

There is a special tool for them, but you can do it with just small lineman's pliers or needle-nose pliers (I'd use the angled ones). You can pop the little "lock plate" off of the clamp with just your thumb and fore-finger, and with practice you can out it back on that way, too, if you have a decent angle at it. It takes practice, but it's possible. With the plate off, yes, just squeeze the clamp by it's looped end and forked end together to make it larger and slide it up the hose away from the boiler.
I agree that it looks like the boiler itself is leaking. The machine was probably frozen at some point.

In your photo your pre-heater looks good. You may want to lift that multi-valve to see if the switches on the bottom are soaked.

Remove a screw by the red arrow if there is one, then push down the tab by the red arrow, slide the multi-valve's bracket back over the tab and lift it up off the floor. Dry everything up, put it back, and it might be good once you've replaced that leaking brew-boiler.