I have a two group Faema Due Automatic that I just rebuilt, new gaskets, seals, heater and a good cleaning. Now its up and running but recently (yesterday) when I turn the machine on (to either position one or two) after 8 second, the pump turns on and continues to run until I turn the power switch off.

I did some trouble shooting,
-group solenoid connected/disconnected
-flowmeter connected/disconnected
-Wiring harness to flowmeter and group solenoid at the motherboard connected/disconnected
-Hot water switch connected/disconnected
-Level sensor grounded/ungrounded
-Level sensor disconnected
-Boiler Fill solenoid disabled (unplugged)
-Cycle both groups, both start and stop, start and stop buttons still control the pump and solenoid if I cycle them during the 8 second period before the pump turns itself on.
-Disconnect pump leads, pump does not turn on (duh), but relay still clicks at 8 seconds.
-It still makes espresso, the pump just doesn't stop when the shot is over.

Based on eliminating all the other things that could cause the pump to turn on it leads me to believe that it is something on the motherboard that is sending the signal to energize the pump. I did an inspection of the pump, nothing is obviously burned/melted, the jumper diagram on top of the transformer is normal, and the dip switches appear to be set properly.

Is there a way to reset the processor? Jumper terminals, push a button?
If the only solution is to replace the motherboard I'll just wire in a switch to manually control the pump.

First never turn it on again on II so you will not take the chances to burn the heating element
if there is not water in the boiler
second
if you are familiar with this part (otherwise do not attempt)
locate the 2 autofill wires one ground one to the probe
(one is the ground one is the one going at the probe)
using some alligator jumpers
you can simulate the boiler
putting them in a glass of water

insert ground one
in glass
leave probe out
turn machine on
pump should run
insert probe wire in water
pump should stop within few seconds
this test will give you and idea if your control box is good/bad
if your water has enough conductivity or not

then move to the rest of possibilities
eventually if your autofill valve is getting

I have seen some machines that tie in all the ground wires to one common ground (which of course eventually runs to the ground wire in your power cord), and if one of those junctions is corroded, disconnected, or if the path is broken somewhere, the water level probe does not ground properly. This can cause the pump to run non-stop.

Is it only the pump and none of the solenoids that are being energised? The reason I ask is because the pump is always commanded to run at the same time a solenoid is activated. If it is the pump and a solenoid, which solenoid and you can then determine where the signal is coming from. A bad touchpad will cause a signal to be sent continuously. Second scenario: I have repaired a couple of boards that have had burnt paths under the relay and would run the pump continuous. Normally a stuck/welded relay will start the pump immediately as the power is applied. Is the 8 second delay the same time that it always took for the computer to cycle on? Seems too long for the computer to come up. Other than the 8 second delay, it sounds like a welded pump relay. One last thought, Does the pump run if the level lead is grounded prior to energizing the machine? One more thing to check, something that I've never been able to verify but have suspected on Faemas, Disconnect the leads to the heating element and check for continuity from the element to ground. It should read infinite. On occasion I see Faema elements with leaks to ground and I suspect that the injection of voltage to ground is messing with the auto level signal. But of course this would be accompanied with the opening of the fill solenoid.
James

I thought that autofill was line pressure only? If it is based off the pump that would make sense, The autofill circuit was one of the first things I checked, had it disconnected for most of the testing.

I did find a loose ground nut but tightening it did not make a difference, but by the time I found the loose ground nut I had disconnected the autofill.

All the solenoids are good and work properly. (one group does leak a little and I need to replace the valve guide, but the solenoid still cycles properly). I mostly disconnect things to ensure that its not a wiring issue, the group solenoids still cycle if the flowmeters are disconnected.

One button board is broken, but I played with it and a continuity tester and made push buttons to replace it, that cycles fine, on the button board that still works I leave it disconnected for testing and cycle the group by shorting the pins.

I switch between having the heater energized and not energized, the overload thermostat is there (I think it works) and the pressurestat cycles. I am careful to make sure that the boiler is full of water before energizing the heater.

Tonight I'll test it again and report back on results. Oh, and it still makes some pretty decent espresso (by disconnecting the pump long enough for it to get to temp, turning it off to plug in the pump, power up, pull shot, then power off when shot is over.

I'm a mechanic in a nuclear power plant so I am fairly familiar with trouble shooting things. When electronics get beyond relays and motors and move on to circuit cards and microprocessors is where I get lost (magic boxes).

Chris Charron

vashonz wrote:The autofill circuit was one of the first things I checked, had it disconnected for most of the testing.

if you had it disconnected
and I'm reading correctly what you are saying
then the autofill/pump/inlet solenoid should be turned ON
and filling the boiler

I played with the machine when I got home last night.
I connected the fill level and ground connection together, powered it up, and everything was normal. The frusterating part was that when I first started trying to find the problem I -thought- that I checked the autofill level circuit.

I proceeded to try to get the shots dialed in, I'm not exactly sure if I'm doing it right, pressure seems on, I have no idea about temperature. I'll be buying some sort of temperature measuring device soon so I can tell if anything I'm doing is moving temp in the correct way.