La Marzocco Linea: Coffee boiler not receiving power from SSR and PID troubleshooting

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

#1: Post by jakedelaselva »


I'm currently trying to get an unloved and unserviced 'La Marzocco Linea 2 AV' built in October 2007 to work properly.

After quite a lot of cleaning and checking for blocked pipes, the largest problem that has me stuck at a dead end is that the coffee boiler element will not turn on (it's not receiving any kind of power, but the cables are ok)

Using a multimeter, I have checked and confirmed that all of the cables can receive power, although I can also see that the PID controller is not sending any electricity to the SSR (Solid State Relay), and the SSR's power light will not turn on. From what I can see the SSR sends electricity first to the coffee boiler safety thermostat (which I just replaced) on top of the groups and then to the Coffee boiler element.

So, before I order a new and expensive PID or a new SSR, is there any kind of troubleshooting that I could perform on the PID? I would like to note that while the machine is on, the PID is displaying what I assume are zeros but are displayed as U's. When I use the arrows to change the temperature or hold the select button, I am able to change parameters.

Looking online, I can't seem to find any sort of clear PID troubleshooting online other than the basic La Marzocco PID manual which doesn't explain if there's a problem with a boiler not turning on. I know that there should be a green light that shows if the coffee boiler is on, that light is not on. I obtained a set of instructions from an espresso repair shop to set up a PID as if it were new and I was able to set the parameters as stated, though the coffee boiler problem continues. :(

Here are the images of the SSR and the PID display

Team HB

#2: Post by ira »

If you pull the input wires to the SSR and connect a small power supply or 9V battery across it, it should turn on. I keep all my old router and similar power supplies for things like this. That way i don't feel bad about cutting the connectors off to get power for some project.


#3: Post by PaulTheRoaster »

The Us are not zeroes.
Look in the troubleshooting section of: ... manual.pdf

jakedelaselva (original poster)

#4: Post by jakedelaselva (original poster) »

Do you mean I should unplug the connection from the PID to the SSR and connect a power supply or a battery to test the SSR's function?

Team HB

#5: Post by ira »

Yes, that is an easy way to test the SSR.

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Team HB

#6: Post by cannonfodder »

I have had UUUU before on other controllers. It could be several things, but I had a broken thermocouple.
Dave Stephens

jakedelaselva (original poster)

#7: Post by jakedelaselva (original poster) »

What would be the best way to test if the thermocouple is broken and could that be the cause as to why the coffee boiler heating element will not turn on?

jakedelaselva (original poster)

#8: Post by jakedelaselva (original poster) »

Great news! There was something with the PID programming that I had to change. Whoever designed the PID controller must have been someone who hated anyone who wasn't a professional programmer, talk about least intuitive design ever created. Now my temp for the coffee boiler is way too high, back to the 80 page manual on how to simply lower the temp. :lol: