Hi HB'rs

I'm new to HB, and this weekend I became the owner of a sick little La Cimbali M28 Select over the weekend, I picked up the machine for rather cheap as it's motherboard is fried (literately, smoke is coming out of the IC's).

What I'm going to attempt is to fix the motherboard and attempt restore the machine. But as I've never attempted to fix an Espresso Machine before I have a few questions.

I could not turn this machine on, due to the fried motherboard.

1. How can I test/inspect the motor / pump is working fine? Without the motherboard.
2. The previous owner of the machine did say the pump is a little noisy and might need a descale, any tips suggestions, resources I can look at regards to that process.
3. If I where to say convert this machine into a manual machine (run without flow meters), has any one attempted such task, any resources available?


Cheerio,
Barend

Barend,
You should be able to check the motor by running it directly from mains power. Even in a three-phase machine, the motor should be single phase. Check all voltages etc before you do, and if you are in any doubt about rigging up a temporary switch etc. get help.

There is lots about descaling pumps on this site.

Converting to manual would involve replacing the conrtol circuitry with something that can switch your solenoids and activate the pump simultaneously. Basic logic and a contactor might well do. Or perhaps an Arduino/Pi project?
Check the voltage of the solenoids too. You might need to swap them for mains voltage versions..

Alternatively, get hold or the circuit diagram for any similar cimbali machine and make a direct copy.

Does your machine have auto-fill? that would have been controlled by the motherboard.
My machine will also only operate when it is up to working temp. So beware - there may be more functions being controlled than just stop/go. You should understand all the safety features and make sure they will still work if you make a modification.

Good luck with the machine.
Be safe.
Thom.

Hey Thom

Thanks for your input.

I will try rig something up this weekend to test the pump.
But before I throw some juice at it, should one be able to spin the pump spindle by hand?

Does your machine have auto-fill?

Yup does look like it, cool I'll take those things into consideration. Hopefully I can just fix the circuitry and keep it original

Barend,
The motor should turn freely. The pump should have some resistance.
It is easy enough to separate them to find out. they are coupled together with a clamp/collar, and don't worry, the pump is self contained. It won't leak or break any seals. Don't strip the pump though! They are not considered servicable at home. If it is stiff, descale first. If that doesn't work, consider refurb/replace.

Again, search this site and elsewhere for info on pumps. These questions have been asked before..

Good luck with it.
Best,
Thom.

Thanks again Thom

Got an idea something might be up with the pump, as I can't turn it by hand at all and don't want to forcibly turn it with pliers or the like. Will remove it in the week, soak it in some citric acid and try again, worst case it's toast too and I need a new one.

I did some "debugging" on the machine yesterday.



By using a little USB Inspection camera I poked around in the boiler to see what I'm up for... As suspected there is quite a bit of calcium buildup.



This is on top of the HX, yikes...


The water mixer must be leaking, hopefully I can just find the seals for it.

I tested all the solenoids with a 24VAC power supply and they all activate nicely so that's a bonus one less thing to replace.



My girlfriend's dad is getting his head around the circuit board, trying to figure out why one of the IC's lit up. At this point we suspect it's a faulty relay, as the IC is driver for the relays.

Fun fun... will keep updating the thread with my progress.

I got the motherboard fixed... Needed one 50c (NZ) chip to be replaced.

I also removed the pump over the weekend and let it sit in a citric acid solution for a wee while till I could turn the pump by hand (as I could not do that before).

However now I face another problem, the machine turns on fine and the pump starts, but it's not drawing any water (trying to get it to draw from a bucket)

Here is what I've tried
* Pre-infusing the line, by filling it with water
* Removed the water mixer screw to see make sure it's not air pockets/blockages preventing it from pumping.
* Did a basic inspection on the inlet / outlet hoses to make sure water can flow and that there is no twists and kinks blocking water.

I obviously don't want to keep it running longer than 30seconds at a time as I don't want to hurt the pump if there is no water flowing through it.

Any other tips? Tricks? Suggestions?

Will try disconnecting the outlet hose, this weekend. Think I'll make a little water tank with a one-way valve, and lift it above the coffee machine to make sure it's got some positive pressure.

Well the machine is working

The problem with the pump was cavitation. I just forced some water down the line (basically poured water into the line, and blew on it ) it started pumping immediately.

Here is a little video of the machine running, as you can hear the pump is noisy as hell, that's after descaling it, it will probably need to be replaced.
I'm not even going to try and pull a shot. The water was milky lime green with colour.

Over the next few weeks I'm going to dismantle the machine and clean it out.

I also picked up another el-cheapo over the weekend, a Brasilia Maxi-America this machine is complete, owners could not tell me if it's working or not, they inherited with a business, but it does seem to be in good nick, from my quick inspection it has a few minor leaks and the hot-water tap needs to be repaired.