I repaired my Lelit Combi PL042QE coffee machine

Today I finally got some free time to look at the Lelit coffee machine. It had stopped working a few weeks back with a complete loss of power. At the time, I remember thinking the machine was extremely hot and suspected the worse.  None of the lights on the front (power etc) would subsequently activate and I was expecting some costly repairs. I sent an email to Alan Frew from coffeeco where the machine was originally purchased (I’m the second owner).  Alan quickly responded with a useful link to his website for steps on troubleshooting:

http://www.coffeeco.com.au/articles/repair.html

Unfortunately, according to Alan’s flow chart “When I turn it on nothing happens” indicates “Your problem is serious. Return your machine for expert service”. 

Anyway, I decided to pull the machine apart (which ultimately takes the removal of just 2 screws), to see if I could spot something visually that could indicate the cause.

Nothing!

Next, I did a search on google for multimeter and Lelit coffee machine to see if someone much smarter than I had done similar troubleshooting in the past.

Nothing!

I finally stumbled on an excellent guide for troubleshooting Rancilio Silvia machines http://www.coffeegeek.com/forums/espresso/machines/312139 which gave me a basis to get started.

BEFORE CONTINUING – ENSURE THE MACHINE IS COMPLETELY DISCONNECTED FROM THE POWER SOURCE

The Lelit that I’m in possession of is fitted with three thermostats:

1. 95°C thermostat for coffee
2. 125°C thermostat for steam
3. 165°C thermostat for safety over-temperature cut-off (red push button)

I first set my cheap $20 DickSmith multimeter to test for continuity. I set test leads on each side of the thermostat (having removed the active (brown)/netural (blue) cables). The buzzer sounded on each thermostat (which for my multimeter indicates the resistance is less than 70Ω). Pulling the little red push button upwards on the 165°C thermostat causes the buzzer to stop indicating an open circuit (which is expected).

Just to be doubly sure that the thermostats appeared to be good (and not measuring more than a few ohms), I set the multimeter to measure resistance.  There is a note in the manual of my multimeter stating to short-circuit the test leads/input terminals before taking measurements where low-resistance precise measurement is required and record the resulting value. The value should then be subtracted from the measurement obtained when testing the particular object in question. Taking the above adjustment in to account, the resistance readings for the 95, 125, and 165 thermostats were 0.1, 0.1, and 1.x ohms respectively – all well within the “few” ohms range. The fact that the 165 thermostat was reading slightly higher had me wondering whether it was possibly bad??

Next, the Silvia troubleshooting article states to test the heating coil (element) by obtaining a resistance reading across the heater terminals. Once again we remove the connecting cables and perform our test against the bare terminals. The resistance reading across the heater terminals on my machine was 50Ω . Fantastic!!! It thus looks like I hadn’t burned my element out!

At this stage, I decided to give Alan a call suspecting that maybe it was the 165 thermostat that could be the issue.  I provided him the resistance readings from the thermostat and heater, and Alan seemed to think they were fine. He mentioned a few additional troubleshooting steps that I could perform, and also told me a story of how a customer the day before had brought in to the shop a $2000  coffee machine for servicing that had just stopped working. The machine that had died turned out just to have a faulty main power switch.  A faulty power switch I thought – surely that couldn’t be my issue - switches don’t just break. 

Anyway I persisted with my charge that it must be the thermostat and decided to find out if there was a simple way to bypass it to see if the machine would momentarily turn on (to prove the thermostat was the issue!).  It turns out it is as simple as (carefully) just shorting the thermostat’s two terminals with a wire to keep the circuit closed.

I gingerly shorted the two terminals of the thermostat and carefully plugged the machine in to the power source and pushed the main switch.  NOTE – my place is fitted with a residual current device (RDC) – also known as a safety switch.  I would not have attempted this without such a backup.

Nothing!  No lights.  Still broken.

BEFORE CONTINUING – ENSURE THE MACHINE IS COMPLETELY DISCONNECTED FROM THE POWER SOURCE

At this point with nothing to lose and facing the thought of packaging my machine up and getting it serviced by the professionals, I decided to test if the main switch could be the fault.  The switch fitted to the machine is a DPST (double pole, single throw) – meaning two separate circuits are controlled by the switch, and the switch can either be closed (on), or open (off).

I set the multimeter back to continuity and inserted each lead in to the terminals controlling the active circuit (brown wires). The buzzer sounded as I flicked the switch from off to on. So this particular circuit was intact. I next inserted the leads in to the terminals controlling the neutral circuit(blue wires). This time, the buzzer would NOT sound as I repeatedly flicked the switch from on to off (and vice-versa).  Wow – the switch was broken!  Who would have thought?  Maybe Alan had intentionally mentioned this switch thing for a reason (in fact I bet he did!!!).

I decided to set the switch to the on position and remove the neutral connecting leads and manually short them together carefully using a wire. I once again plugged the machine in to the power source. 

LIGHTS – ACTION.

The boiler light came on and a bit of excess water spat out the tubes. It worked!  I quickly disconnected the power source.

BEFORE CONTINUING – ENSURE THE MACHINE IS COMPLETELY DISCONNECTED FROM THE POWER SOURCE

OK – so the broken switch was the reason the machine would not power up. But what had caused the switch to break in the first place? The switch is easily removed by pushing the spring-like clips on the top/bottom of the switch whilst at the same time pushing from the rear so that it pops out the front of the machine. On inspection of the switch terminals, I could see the lower terminal that accepts the incoming neutral (blue) cable from the power source was slightly melted. Why this was, I do not know. The machine had been left on for quite a considerable time (90 minutes or so) without any use. I’ll have to wait and see if the issue reproduces – and if so, get the experts involved.

The rocker switch itself is rated for 16A/250V AC and T120/55 (ambient temperature). Tracking down a replacement DPST switch in Australia with similar specs was proving reasonably tricky.

I found the following rocker switch SCHURTER 1301.9224  (red illumination) that matched the specs perfectly. The green illumination model is 1301.9215.  Farnell (aka element14) sell both switches for about $5 each – but there is a minimum credit card order of $10 required and a 5 day wait. http://au.element14.com

Jaycar also sells a similar switch – although it is a DPDT! http://jaycar.com.au/productView.asp?ID=SK0982

Eager to get my coffee machine back in order, I decided to buy switches from both places.I picked the switch up from Jaycar and installed it, and everything appears to work perfectly. I have also ordered the Schurter 1301.9224 from element14, and if motivated will probably switch the Jaycar out and replace it.

Below is a pic of before and after:

A big thankyou to both Alan Frew from coffeeco, and also Jim Galt (author of troubleshooting Rancilio Silvia post).