La Marzocco Linea Mini intermittent boiler refill fails

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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#1: Post by BAEvans »

Need a bit of advice.
After 6 weeks of non-use while gone (machine off) noted new problem. No difficulty pulling shots but when machine idling during the day intermittently boiler refill fails with pump running until (safety?) cuts it off and red light begins flashing. Turning off power and back on usually results in immediate normal refill and both LEDs on ready to function. A tech here for an unrelated issue checked the tubing and valves- fine. Absolutely no scale in the machine. He surmised the solenoid controlling refill might be failing. Machine is about 4 years old. Thoughts?
It is a part I can easily replace myself if that is the issue.

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Team HB

#2: Post by Jake_G »

Greetings Bruce,

The solenoid is certainly something you could change with basic tools, but intermittent issues are always a bit tougher to solve.

The basic troubleshooting steps involved with this one would involve determining whether or not the solenoid is being told to open when the problem arises.

To do this, you would need someone with the sensibility of a qualified electrician to probe the connections on the solenoid valve with a voltage meter when the problem is occurring. If the solenoid valve is getting 120V and not opening, it should be replaced. If the solenoid valve is not getting voltage, then the problem is more likely a failing relay on the logic board. With LM selling the new "connected" logic boards, they may have an older one they can provide at a discount, but I would not count on it, so you need to understand where the problem lies to know how to proceed.

An alternative to probing the connections with the machine powered up is to unplug it and wire in a 120V lamp into the solenoid circuit. I like to use a simple lighted switch I have laying around from old projects (probably an old Starbucks Barista machine) and plug one of the wires that goes to the solenoid into the prong on one side of the light and then crimp on a few female spade connectors onto a jumper wire to go from the lamp back to the terminal on the solenoid that you pulled the wire off of. This way, the light will shine whenever the solenoid has power going to it.

Once that's done, power back on and draw some water out of the steam boiler and see if it refills properly. If it times out and the light you wired in turns on, you know the solenoid valve is faulty. If it times out and the light doesn't turn on, then the logic board needs looked at. Final case is that the boiler fills properly and the light doesn't turn on, which means you wired the light wrong or the light is no good, so it is important to verify that when a boiler fill goes well that your test instrument is working.

The qualified electrician-type approach with a voltage meter is far easier, but wiring in a test light with the machine unplugged is safer if you don't have the know-how nor the friends with it to safely troubleshoot energized electrical equipment.


- Jake
LMWDP #704