This is a La Marzocco GB5 from 2005 that i found at an Italian restaurant for very little money, not very well taken care of. I have striped her down and done a thorough cleaning/descaling, replaced heating elements, pipes and couple other pieces. After putting it back together and starting her for the first time, this is what happened:

First the steam boiler wouldn't stop heating. I thought pressure stat went out. Replaced and was still overheating. Then realized the coffee boiler was not heating while the steam boiler overheats...this machine has the old type of triacs..they sort of function like a relay, I think...so I switched the main wires of the coffee boiler and steam boiler on the triacs and the opposite was happening coffee boiler overheating, steam boiler not working. Figured the steam boiler triac must have been stock in the open position and coffee boiler triacs in closed position. A friend found me a SSR with equal amperage but multi pole. Connected the wires and now neither the steam boiler nor the coffee boiler kicked.

Question: if with the original triac it was overheating, wouldn't that be a sign that at least the mother board was passing the signal to the it? Or could it be possible that something in the mother board is malfunctioning? If I get a proper DC voltage reading from the multi pole relay DC pole, wouldn't that mean the relay is okay? But why is it not opening the circuit and allowing the boilers to heat up?

Any suggestions?

Ricardo,
Can you post a picture of the SSR's? If they are the ones LM makes then they will fail in the ON condition causing the boiler to overheat. Check the voltage on small connector it should read 5-9 volts dc when energized. If you have power here then you can make sure the electronics are working correctly.

BillC

this first image is the triacs the unit had which was causing the boiler to overheat.

This is the SSR that was installed afterwards. With this one the boilers are not heating at all even though am getting the correct DC voltage.

Looks like you may have to do some troubleshooting.

1st I would check to make sure the wiring is correct. Make sure one boiler is on the "A" side and the other is one the "B" Side. Then you have to determine which boiler each of the smaller (red and Black) wires control "what" boiler. Then make sure they are connected to appropriate side. You might want to verify that the red wires are actually positive just in case someone messed with the wires. When they are connected to the small pins make sure the pins are not touching each other (can't tell if you have a connector on the pins or not or if they are insulated).


BillC

Hello,
Just for some brain food. Triacs tend to fail in a shorted condition. That being in a conductive state rather than an non-conductive. A Triac blocks current up to a rated voltage level. Using a water analogy, it is more like a valve than the mechanical relay equivalent of hooking up a hose.That leaves you with a "I shut the valve" rather than a "I unhooked the line." So what traditionally happens is that the level of voltage and current blocking decrease to a point where there is a voltage threshold that is less than your line voltage. The Triac becomes a component in a voltage divider equation. This leads to a final failure of the Triac as you are dropping voltage over a resistance and that equates to heat which finally kills the Triac. This is now happening without the triac being triggered.
The circuit that you see on the little board is about as simple a Triac firing circuit as one will see. An optocoupler firing a Triac. A triac works on a voltage differential between pin 1 and pin 3. This is accomplished by supplying line voltage to the optocoupler with a resistor inline to cause a voltage difference. The optocoupler is fed low voltage DC and is grounded at the microcontroller to light the internal infra-red led. When the led is lit,the optical transistor opposite the led changes state and provides the voltage differential to fire the triac. A word of caution, don't ground out the led to see if it is working as you will smoke it as you have bypassed the resistor that limits the current to the led. You can test a triac by shorting between the two high voltage legs of the optocoupler when the circuit is energized. Carefully of course.

And thinking out loud here, I suspect that the reason your SSR doesn't work is that it is needing voltage and a certain amount of current. The circuit that you are trying to fire the SSR with has very little current available as it is intended to run an optocoupler with it's reduced current requirements. I haven't had enough coffee yet to wade through the data sheets...
If I had to repair one of these and I didn't have the older style triac, I would find a Triac with a 25amp+ and 800 volt rating. B or C at the end of the part number determines triac sensitivity. W in the part determine whether or not there is an internal snubber circuit. Inductor devices (think motor or solenoid) normally need the snubber. Resistance items like heating elements don't. Coffee is done...
jpboyt

Correction: Voltage is sourced at A2 not A1 as I stated above.
jpboyt

A triac that fails internally almost always fails in the on condition. However, a solid state relay that can switch an AC load (a component that contains a triac) can fail in the on or off condition depending upon what component has failed.


BillC

Wanted to end this post by letting everyone know that after checking the wire connections, I realized I had them in the wrong configuration. The relay is now working and both boilers are kept at proper temperature/pressure. Now I have an issue with the pump motor not kicking in but gonna try a few things before I create a new post. Thanks everyone!