Pump works but won't pump.

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PeppercornEspresso
Posts: 8
Joined: 9 years ago

#1: Post by PeppercornEspresso »

Hello, I am restoring a Cimbali M21 plus 2 group (Very similar to dosatron M30).

I bought it from somebody who had gotten a quote to have it repaired. They told me that the pump and motor needed replacing.

I was hoping this was not the case so i cleaned the pump and then tested the pump and motor. they both work when i plug them into mains directly.

This leaves me with a conundrum though because the pump works but it doesn't activate when i hit one of the brewing buttons. water comes through but at the pressure from the mains supply.

So anyone want to help me troubleshoot?

So far as I can imagine the problem is either a failed part, or some kind of check that the machine is doing that is preventing it from activating the pump.

Does anyone know if there are circumstances it is checking for that would cause it not to fire the pump? (I heard something about the pressurestat needing to be at pressure? I havent found any help in any of the manuals for similar cimbali machines).

Is it likely to be a relay from the control board? is there like a fuse or something I can replace.

ira
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#2: Post by ira »

Follow the wires to see what switches power to the motor. Possibly a relay in the control box, possibly a external SSR or contactor somewhere else.

You're in Australia so I think it's 220 and the machine should be switching both wires to the motor, but don't quote me on that.

Ira

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erics
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#3: Post by erics »

There exists several La Cimbali manuals in the downloads section. Perhaps they will be of some use.

/downloads/
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

PeppercornEspresso (original poster)
Posts: 8
Joined: 9 years ago

#4: Post by PeppercornEspresso (original poster) »

Hey thanks guys for the replies! I am going to learn how to use a multimeter and report back. Yeah those manuals are great and there is literally nothing like them on the whole of the net. none of them are for my exact machine though and don't go into much detail as to what is going in the things brain.

PeppercornEspresso (original poster)
Posts: 8
Joined: 9 years ago

#5: Post by PeppercornEspresso (original poster) »

Hey I just bought a multimeter today so I should have a better answer. Also I emailed both the Cimbali Factory through their online form and Coffex in Australia who both promptly sent me a copy of the Manual! I was so impressed. I would recommend to anyone looking for Manuals that are not already cataloged on this site to try emailing the factory. Should know tonight what the issue was....

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tohenk2
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#6: Post by tohenk2 »

PeppercornEspresso wrote:Should know tonight what the issue was....
:wink: and the answer is ...[rollin drum]...?

PeppercornEspresso (original poster)
Posts: 8
Joined: 9 years ago

#7: Post by PeppercornEspresso (original poster) »

The issues was.... Different to what I thought. So the relay is not the issue. I mocked up a new relay in with alligator clips. And it is not actually receiving any signal to pump when I hit a brew button. There is ac going through the relay, it actually powered on at first which made me hopeful, but this was because I had the relay wired normally open instead of normally closed.


The upside- the relay might be fine after all... The downside I have to look further up the chain than I was before. The wiring diagram is doesn't give me much help with the brain of my machine so I'm just going to have to follow as best I can. Perhaps what is wrong is that there is another bank if relays on the main board and I just need to replace one of them. I don't know why there would be a relay there in addition to the relay closer to the pump. But hey it's been a fun learning process anyhow.


Worst case scenario I end up with a more manual machine than before I guess. But I am confident I can find out what is wrong the board looks in good shape more generally. I might have to call in a favour from a an engineer friend.

PeppercornEspresso (original poster)
Posts: 8
Joined: 9 years ago

#8: Post by PeppercornEspresso (original poster) »

Alright completely disregard the above post it was the relay.

So for those with pump problems the diaristic matrix should go (or at least it did for me):

It won't pump>
Is the motor working?(test it by giving it energy the same as it's rated amount)
If it is not check the capacitor doesn't need replacing.
If it is making noise but not turning check that the pump has not siezed ( if it has try soaking it in citric acid and then turning it-it should be hard to turn)

If the capacitor motor and pump all work then our problem is at the brains of the machine.

Check to see if there is a fuse for the motor in the wiring diagram in the manual.(email the factory or the local distributor for the manual)
If there is a fuse find it using the wiring diagram as a map( mine was on a second pcb hidden under a piece of plastic)
Google what a blown fuse looks like (they look blown, ie you will know from looking if it is)


If it's blown replace it, if it's not we need to look further...(at this point it's worth saying that it is safer to ask a electrically minded friend or employee to do the next part, there is real risk of electrocution and death if safety precautions are not taken)
Using a multimeter check that the relay (should be rectangle shaped and have voltage ratings eg 250v 10a 12vdc) is receiving the rated volts ( 12v for mine probably yours too). Mine was zetler branded. I checked the volts with a cheap multimeter it was receiving 13v (do) which seemed close enough to me. It was hard to disconnect the pcb from the frame of the machine and to see under it to get to the pins I needed to test. I used alligator clips so that I could set it all up, step away from the electricity plug it in, hit the brew button and watch the multimeter display the volts. Electricucion is a real possibility if you fiddle with the wires while its fired up.

If it is getting 12v you are in luck! The relay is broken. It can't be fixed according t the guy from the espresso restorations website. So you need to replace it. Unlike your pump and motor which are worth a lot of coin, a relay is a very cheap component, I picked up a very beefy looking one from a local electronics store, make sure it is rated the same as the one you are replacing( in my case it needed to be 10a 240v ac and 12vdc). You could replace it with an identical part if you want, I'm sure they come cheap on the Internet. I didn't and my part didn't fit in the board so I desoldered the part and soldered on some terminals which I attached wires to (making sure the wires are beefy enough to take the amps they need to without getting hot). I attached the wires to the relay, I googled the part number so I could work out how to wire it. I put the pub back in the machine and hooray it worked.

If you are not getting 12v to the board (for about 2hrs I was sure I wasn't but this was user error on the multimeter) you have to entertain more difficult possibilities. I felt a bit out of my depth at this point but I started chasing the 12v signal back to where it was supposed to be coming from. If I had not re tested the relay I would have gone about testing the components in the pcb in and the wiring until I found what actually needed replacing. Good luck I hope it goes well, maybe consider manually firing the pump and call it preinfusion.

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tohenk2
Posts: 314
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#9: Post by tohenk2 »

Glad you could fix it with a new relay.

In general the most common fault with PCB's are:
- connectors not making proper contact anymore (reseat those, maybe clean them as well)
- bad soldering. Recently lead-free soldering is mandatory in some parts of the world, but there are some real quality issues with that. (resolder the spots you don't trust)
- blown capacitors (if you see any capacitors with a round top you should replace those)