[*]Hi
New to the forum and in desperate need of help! I have a trusty old cimbali junior d which has served me well over the years.
The problem is that the boiler overflow valve started spewing water when I turned it on one morning. I think that the boiler is constantly filling up either because the solenoid valve to fill the boiler is dead or that the boiler sensor is dirty, the sensor was in good shape but I cleaned it anyway and moved onto the solenoid. If I unplug the solenoid and turn the machine on water does not flow into the boiler, but when it is plugged in water continually flows. I guess this means at least that the solenoid valve works as it behaves differently with current or without. Trying to follow the logic as I have no experience here!

This leads to conclude that between the now clean sensor, the control box and the solenoid valve there is an electrics issue. Im no electrician but have followed the wires and inspected around the machine (including disconnecting and taking the control box out) and can see no obvious signs of loose cables, corrosion or damage. I've banged my head over this and can get no further. Please if there's anyone out there who could help me diagnose the problem I'd be eternally grateful. Thanks for reading.

P.s ive read other threads about milar issues on the site to guide me so far. apologies if this is throwing up the same topics!

I assume you've tried grounding the probe and that didn't help, have you tried replacing its wire and grounding that new wire?

Have you checked the powerboard's ground connection with the lowest setting on your ohmeter to a distant ground point on the machine's body? To boiler? To component grounds (ie. third spade on a solenoid valve)?

Assuming that you have the "normal" style filling level circuit and not the one in the container with multiple probes,

if the machine is plumbed in:
water can push through from the line pressure and open an tired solenoid 2-way valve plunger or can have little sediments or worn sat and is not sealing properly,
with the above in mind no electrical components such as the coil or the pump should be activated.
If not plumbed in the above will happen only when there is active components activated.

If you actually hear the filling kicking in then test the probe circuit to ground, you can jump it to sre-produce it out from the boiler just to test the wires, ground and the control box,
if even simulating you get the same result and further you can jump directly on the ground and probe on the control box itself,
the box can be the final issue.

Thanks for your reply. I have indeed tried grounding the wire to the probe and will take the next steps and let you know how I get on

The probe probably has lime scale

It's shiney as can be

Samseventhorizon wrote:Thanks for your reply. I have indeed tried grounding the wire to the probe and will take the next steps and let you know how I get on

Just to be on the same page... You have tried directly grounding the probe and that doesn't stop the auto-fill (Pump on, Solenoid energized) from running?

That's correct. So far the only way I can stop the auto fill is to disconnect the wires to the solenoid

Not sure if this manual is of any use, but wiring is on p23
La Cimbali Junior M21

Heat kills electrical parts, particularly electrolytic capacitors, of which there are usually a few in the control box. A competent electronics tech could test and repair. He doesn't need to be an espresso machine expert. The newer Aluminum caps have amazing properties, so if you go that route, make sure to request.

If you can take a picture of the control box model, that could help find the exact print.

Unfortunately, Gicar recently made most of the manuals inaccessible.

Blue circle - water floods out when auto fill won't stop
Red circle - solenoid valve that unplugged has a good seal and let's no water through, when plugged in will not shut off
Green circle - the clean probe that when I ground does not shut off the autofill
Here my control box

With an electrical tester I have checked that there are no wiring problems between the probe and the control box.

Am I missing any other obvious problems or can I safely assume the control box is reached it's end

Thanks for reading im totally new to this kind of project but totally unwilling to let this machine go to scrap!