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Thread: La Cimbali M21 Junior Issue

  1. #1
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    La Cimbali M21 Junior Issue

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Posting for advice from the forum on the next steps on a new toy Iíve just purchased.

    Itís a 2006 M21 Junior - tank version. Previous owner indicated the unit was used in a cafe but has since sat in the store room since it was replaced by new machine. No further details and machine was said to be functioning. Knowing from the forum that M21 is built solidly and would last. I thought itíll be a nice upgrade from my silvia - bought it.....without testing !

    The machine looks pretty good but a bit dirty. Fired it up, heater was boiling ok, steam wand and hot water were functioning, run the water through the group head - all good until the pressure relief valve blew. Switched machine off immediately and checked pressure gauge reading was in the red zone.

    Did another test a day later - now very careful (eyes tight on the pressure gauge). Few observations:
    - boiler refilling operating well
    - during heating up, a bit of water was draining from the 3-way valve thru the drain tube into the drip tray (for a few secs only)
    - while pressure is building up (still not in the green zone), opened the steam wand and observed pressure dropping. Shut steam. Heating seemed to then stop.
    - switched off and restarted machine, heating resumed.
    - allowed boiler to heat. Pressure continued to rise and heating failed to stop.
    - switched off machine when pressure got into the red zone (didnít want another pressure valve lifting)

    From reading the forum, I think the likely fault is the pressure switch.

    i then stripped the machine to have a look - a bit dirty / dusty but wasnít too bad:
    - some gunks around the pressure gauge (external surfaces)
    - black/dirty tip on drain from the three way valve
    - minor scales on joints of the boilers (minor leaks over time ?)

    Trying to attach some photos of the machine for reference but Iím unsure how to or may not have permission.

    I was thinking of removing the pressures switch (Sirai xp110) and tubing to check for scales/blockages but considering the others observations above, I was wondering if itís recommended to do more.

    I also plan to clean the 3-w valve tubings, grouphead screen and a general cleaning of the whole unit - then perform a general descaling after fixing (hopefully) the fault above.

    Just not sure if Iím on the right track or if itís necessary to remove the boilers for descend in acid etc. Have read numureous posts inc restoration for mostly older units vs this 2006 unit.

    Appreciate advice and thoughts.....

    ps-hope to be able to post some photos soon.

  2. #2
    Senior Member Jackster's Avatar
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    Id be opening the boiler and cleaning that out.
    Also inside all the piping. Wouldnt think about drinking the crud saved inside.

    You can use imgur to host pics, others are using google pics

    I agree, i think you have issues with the pressurestat. Bad contacts or blockages. Something

  3. #3
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    Quote Originally Posted by Jackster View Post
    Id be opening the boiler and cleaning that out.
    Also inside all the piping. Wouldnt think about drinking the crud saved inside.

    You can use imgur to host pics, others are using google pics

    I agree, i think you have issues with the pressurestat. Bad contacts or blockages. Something
    Donít know the arrangement on the Cimbali, but if the pstat switches via a relay, that could also be the culprit.

  4. #4
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    Thanks Jackster.

    Here are some photos (hope they will come through). I’ve cleaned machine external and some internal sections so it looks cleaner than when received.

    My plan of attack:
    - drain boiler
    - remove all tubings to descale
    - clean pressurestat, 3 way-valve, group head screen
    - remove heater and check condition of scales. If not bad, box up and possibly do a normal descale (after reinstall tubings) or leave as is
    - if bad, remove boiler and descale (in citric acid?), reinstate, test and tune pressures. Will do a good clean of the internals as well

    What do I do with the scales on the fittings/connections on the boiler? Do I need to remove to descale as well or can I just clean externally without removing fittings (esp in the case I don’t have to remove the boiler to descale)?

    Required parts - I guess gaskets for the heater, and connection to grouphead. Do I need any other parts for the small tubings/fittings/connections to the boiler in case these are disconnected.

    Any idea if the boiler is SS or nickel plated copper ?

    Noted the heater is rated 1800-2050 W and the power lead is 10amp. Not sure if this is ok as I’ve seen 1200W for other Junior on the internet (some only used 4 out of the 6 connections - i assume 2 out of the three elements?)

    https://photos.app.goo.gl/UgNTloGi2gJH45i53

    https://photos.app.goo.gl/UlQUJ7JjoW3QUjGA2
    https://photos.app.goo.gl/LGkwi5Lm30RoiM7C3
    https://photos.app.goo.gl/bHMwX0I73OBzIpCQ2
    https://photos.app.goo.gl/H9ZLBrHoSaJs1b2s2
    https://photos.app.goo.gl/n3bNRU7gYeitcgb22
    Last edited by Timm; 26th March 2018 at 12:15 PM. Reason: Corrected photo link

  5. #5
    Mal Dimal's Avatar
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    G'day Timm...

    Yes mate, I don't believe that all three elements are required in a home setting and you could safely disconnect one of them. Re: the overpressure problem, it does sound as though the p/stat has had its day. A new unit is not very expensive and if coupled through an SSR (also not expensive), it will last many, many years...

    Mal.

  6. #6
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    Thanks degaulle and Mal.

    WRT the heater, I assume I just need to disconnect 2 connectors and tape them away safely..leaving the other ends of the cables undisturbed right?

    An update - I’ve removed the pressurestat and found scales on the tubing (see photo). Scale was ‘soft’ but was sealing. It broke pretty easy by poking and was easily removed. Not hard at all. Some scales at the nozzle of the pstat. See photos.

    Plan to fire up to test soon. Will revert with results.

    https://photos.app.goo.gl/gq576PTerjAToPYe2
    https://photos.app.goo.gl/15c5A8DtWBfmOYAi2

  7. #7
    Senior Member artman's Avatar
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    That looks like a very clean unit!

    I would check the tube going to the pressure stat for blockage, unlikely as it is large diameter. You could disconnect machine, check that the PS is closed circuit with no pressure. then us a bike pump/compressor to pressursise boiler and see if PS goes open circuit. will help you pin point the issue. Not expenive to replace and as above, SSR upgrade would be worthwhile.

    EDIT: jsut saw your updated post. if you have a decent amount of scale it would be worthwhile to do a descale. very easy. Your boiler has a drain valve (non element side of the boiler, bottom fitting). yOu can fit a hose over the barb and crack open the end part/barb for simple draining/flushing.

    Cheers
    Last edited by artman; 27th March 2018 at 02:35 AM. Reason: more info added
    Dimal and bigdaddy like this.

  8. #8
    Senior Member artman's Avatar
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    I wouldnt worry about the small deosits on the fittings, give them a clean and monitor for weeps, you probably wont notice anything.

    These machines are great beasts and produce fantastic brews!

    Cheers
    Dimal and bigdaddy like this.

  9. #9
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    Thanks Artman. I will clean up deposits at the fittings as recommended and monitor and will check/ descale tubings before doing anything further. Forgot to mention that the soft white scale noted yesterday at the tubing end (shown in photo of post#7)was just a small thin layer and I couldn’t see scales further into the tubing.

    Just fired up the machine (after the quick unblocking of the pressurestat) and boiler cut off at around 1.1-1.2 bar. Really pleased with that.

    I’ll continue with the rest of the checks and fixes as necessary and hope to be able to pull a shot soon.

    Just observed the black plastic drip tray has minor crack. Would a heat gun be good to ‘melt’ and ‘reseal’ the cracks? Or do I need to build up with sealant (some heat resistant sealant from Bunnings?)

    Mal, Artman, would you still recommend the upgrade with an SSR? I tried to find past posts on M21 SSR upgrade but there were no details on how. Is there a guide for ‘dummies’ on this upgrade ? Note I have installed a PID on my Silvia (thanks to WSullivan for his Step by Step Guide on PIDing Silvia in the forum) and that’s my only experience with an SSR. Still a ‘dummy’ but never afraid to learn from the many ‘gurus’ in this forum.

  10. #10
    Senior Member artman's Avatar
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    SSR will just save you burning out contacts on the PS. If it is working fine you could just leave it. If you are electrically inclined it is should be very easy. Basically the PS turns the SSR on and off and the SSR does the high current switching.

    I have repaired plastic cracks from the non visible side by melting together with soldering iron. If you are careful you can make it almost invisible, or very hard to spot. Did it on a car glove box cover years ago and you could hardly notice it, looked like a tiny scratch.

    Cheers
    Dimal likes this.

  11. #11
    Mal Dimal's Avatar
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    Do you have an Electrical Schematic for the LC Timm?
    If so, if you could scan and post back in here, one of us should be able to help you out Ok...

    Mal.

  12. #12
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    Thank you Artman. I will use the soldering iron to seal the cracks - brilliant tips here I must say !! And now I get to use a unit I bought 2 -3 years ago

    Here is the e schematic I found from the internet. Would appreciate some guidance here Mal.

    cheers

    https://photos.app.goo.gl/yjc0FqQ1DjJRjZGJ2

  13. #13
    Mal Dimal's Avatar
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    PM sent Timm...

    Mal.

  14. #14
    Senior Member Jackster's Avatar
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    Id loctite 401 or 406 the crack. My plastic soldering isnt the best.
    Maybe a wipe of black silicone after if its required.

    Also baking powder sprinkled in the loctite will allow it to be built up as reinforcing.

  15. #15
    Senior Member artman's Avatar
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    Itís not really plastic soldering as such. Itís just using the tip of the iron across the crack in a cris cross sort of pattern to melt the two sides together. Just donít go deep and you should be fine. It doesnít take much to fuse the two halves together.

    Cheers



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