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Thread: La Pavoni undressed

  1. #1
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    La Pavoni undressed

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Here she is in all her glory. Ive pulled a few things off and it looks pretty good inside. Theres definitely scale, but the level is pretty low, consistent with running with filtered water. Ive seen far worse. In fact I drained the boiler and the boiler drain absolutely gushed out. This means that the scale build-up is reasonably light. The water from the boiler smelled like wet carpet, but was completely clear. I also drained some water from the heat exchangers and it too was clear and tasted completely neutral... This is a good sign that the machine hasnt been too abused in its past life. The groups are great. They are La Pavonis version of an E61 group, but the shower screen is held in with a screw and is easily removable. The water dispersion block is a two part affair. There is a large amount of empty space in the head of the group. This is very different from the Bezzera group, which has very little empty space. The most unexpected thing about this group is that when I worked the dispersion block loose, the group seal actually came out with one of them, it remained in the other, but was easily dislodeged with fingers. Now I have both group seals out without having to recourse to an icepick/screw driver type brute force and destruction. Ive been on the alert from one of these Pavoni groups for just this reason. Ive heard some stories about major struggles in getting the seal/shower screen out of a standard E61 group, and this was one of the reasons I avoided.

    The photo is a collage of images, showing the front twin E61, the rear nickel plated 14l boiler, under the group heads with the gasket and dispersion blocks removed (not too dirty at all, but still in need of a clean) The insert in the red box is the rusted pump. Thats the one item that isnt in working condition. I suspect one of the E61 microswitches is also cactus, but thats minor. The motor does run, but there is a bit of bearing noise. I have another nearly identical motor which Ill probably use in its place, although Im sure itll run as is.

    Ive popped the top of one of the E61 groups and its pretty clean inside. Some scale build-up but again rather minor. Im sure that I could get it up and running without a major descale, but it might be worth getting it back to spotless condition before running it. Im still debating this one.

    Anyway, Im pretty happy with the machine. The seller has agreed to reimburse me a large portion of the cost for a new pump, so the machine will have cost me $520 plus pump. Restoration costs might not be too high, but the E61 groups are rather expensive groups to refurb. Ill see how it goes.

    I cant wait till I pull my first shot on the beast.

    On a sad note: The BZ35 has pulled its last shot. Im going to clean it up and sell it off to finance the new machine and some of the refurb. The farewell was about as good as it can get. It was a tight ristretto with a light tamp. The espresso just dripped out with a beautiful red colour... just what I was after.
    After about a year and a half, Ive really learned to drive this machine. With care, its shots are as good as anyything out there. Its solid as hell, easy to work on and is built with commercial quality components and it steams like a demon. I think Ive come full circle with the steaming as Im back on the 4-hole tip and happy as hell. Soft silky microfoam every time and only about 8-10 seconds required for a single cups worth....

    Oh well, on with the Pav restoration... the lack of coffee will drive me... ;D

    Cheers,

    Mark


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    Re: La Pavoni undressed

    Mark,

    She looks good - really good. You have done well!

    Id say refurb wont be very expensive judging by your description and the photos..... maybe just seals, group filters etc...

    If it were me - Id do a full refurb.... she certainly is worth it!

    You have yourself a very attractive piece of kit!

  3. #3
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    Re: La Pavoni undressed

    Sure is [smiley=thumbsup.gif]

    Mal.

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    Re: La Pavoni undressed

    Heres an update. I finally had her dressed a few days ago and got her up and running.

    First things first.

    I pulled her down to the frame. All the pipes were easily removed by gently tapping the compression fitting nut to crack open the seal. Each pipe was individually descaled in citric acid solution until it looked like a tube of pink salmon.

    The boiler was more difficult. I removed the entire unit. It is a closed boiler (unlike most commercials with an end-plate), so access is only via the various holes. The element screws in and I took the entire boiler to a coffee tek place to have it descaled. Unfortunately they werent able to do the descale, but did remove the element for me. So I went to super-cheap and bought a 40 l bin which was a good fit for the boiler. I used the bin to descale the boiler and HX units. The boiler actually wasnt too badly scaled in any case. I let it sit in the citric acid solution overnight and then rinsed it and soaked it in fresh water to try and get rid of any acid residue. I also descaled the element by fitting a baloon over the element terminals and dropping the entire thing in the acid bath.

    I also removed the steam and hot water wands and cleaned/descaled them. I bought new seats for all the wands from coffeeparts (overnight service is awesome). I didnt open the valve bodies, as unless theyre leaking, I could see no reason to do so.

    I also got really intimate with the two E61 groups. To open these up requires a 36mm spanner, so I had to buy one. I actually bought a 1 7/16" spanner which is 0.5 mm too big, but is the size needed for the element. In any case the slight size difference is negligible at this size.

    For the E61s I did a descale in citric acid as well as a soak in caustic soda to remove any residue in the brew path. This cleans them up really well. I did the caustic soda soak first followed by the citric acid soak. I also had to recondition the three valves in each group. Again coffee parts came in with the valve seats. I also needed some pins that had been worn down by the cam. I got the pins from coffeeparts but they had the wrong thread!!! So I had to work around this. Rather than try to tap the correct thread, I went and bought the valve seats and a few other pins and built up entirely new valves. To save some money, I ordered some pins that I knew were the wrong length (too long) and shortened them to the correct spec in a lathe.
    After all that it was time to put it back together again.

    As for the dead pump, I decided to use one Id been running for nearly a year as an outboard pump.

    So that was everything. Then to put it all back together. No real drama. I only wired in two of the elements to drop the current draw to a manageable 12.5 A.

    Once I got it back together I fired it up and waited.... It looks like the pressurestat was set to 1.1 bar, which is pretty standard. Both pressure gauges worked, which is good. The pump that I had set to 9 bar read 9 bar on the Pav gauge. The boiler filled in no time, using about 7-8l of water (theres plenty of head room for steam).

    The groups use thermosyphon restrictors to keep the group temperature from overheating (3mm apertures). The group heads reached between 91-97oC. The fluctuations due to the pressurestat cycle. Ive already decided to PID this away in the near future.

    I loved how quiet the thing runs. The rotary pump is/was very quiet and the loudest sound is the Sirai pressurestat switching(clunking). But these are 30A switching monsters.

    A pressure check to make sure all the fittings were tight revealed a leak in one fitting. This wasnt a tightening problem, so probably meant some damage on the seat of the compression fitting or the olive. I noticed the leak was via the threads of the compression nut, so a few winds of teflon tape and viola, all tight and no leaks since.

    As soon as I was satisfied I got me some beans and went to work. I made two straight shots. The first was too light, under xtracted. The next was awesome. It hit the red crema zone and came out with caramels and sugars detectable in the rather old beans. Then a couple of cappas. The first was very smokey... I burnt the milk. Man this thing steams fast compared to the BZ... maybe 5 secs for 200 ml of milk. The next was better, but the shot was off. However there was still a taint in the milk due to the descale of the boiler. Ive since refilled the boiler a couple more times, but before I could taste some more of this red crema madness, the pump died...(it started going very squeaky and the pressure was fluctuating). I have yet another pump, which I tried, but this one was also cactus (worn seals couldnt get up to pressure). I also tested the motors (I have a couple) and they were fine. So its off to buy a new pump before this machine can be brought back to life again.

    Then I noticed one more thing. The seals around the lever rod leaked when using a blind filter basket. It looks like another coffeeparts order is about to take place....

    So there it goes. All the really important parts run fine. But the pump will cost me a new replacement pump.

    Ill also add PID control of the boiler temperature pretty soon, as Id like to limit the fluctuations in the group temperature.

    Cheers,

    Mark.

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    Re: La Pavoni undressed

    Mark....

    When you say:

    The groups use thermosyphon restrictors to keep the group temperature from overheating (3mm apertures). The group heads reached between 91-97oC. The fluctuations due to the pressurestat cycle. Ive already decided to PID this away in the near future.

    Im a little (actually a lot) surprised you blame the pressurestat cycle. :-/

    It sounds to me more like variation in the thermosyphon than boiler temp variation.

    My pressurestat has an on/off hysteresis of about 0.15 Bar .
    Now if we assume it is 0.2 Bar that equates to a temperature variation of less than two degrees Celsius........ (from my BP temperature / pressure graph.)

    So unless your pressurestat is wildly off.... it should be maintaining pretty close to what you would get from a PID (infact I thought PIDs are only used on the brew boilers of machines like LMs - the pressurestat being sensitive enough for single boiler HX machines).

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    Re: La Pavoni undressed

    Looks like all is going really well!

    Like JavaB says, Id be surprised if the temp fluctuation were solved by PIDding it ... you did descale the thermosyphon, right?

    Just a few ideas, presuming that the group is very similar to an e61; how about replacing the 3mm thermosyphon restrictors with 2mm restrictors? That should be enough that it doesnt mess with your preinfusion, but it will lower the group temp relative to the boiler so that you can crank the boiler up and cut your steaming time to four seconds instead of 5 ;P More importantly, seeing as the preinfusion restrictor is so easily accessible, you could have one 0.8 and one 0.6 for the hell of it. Of course, if its plumbed in, I guess that youll be able to regulate the preinfusion using the middle position of the lever anyway. Im sure that you have seen the M6 thermocouple adaptor.

    If you want to PID the machine, you might find that running the PID off a pressure transducer eliminates the headache of trying to work out where to put the thermocouple!

    Sounds like youre going to have a blast with this machine.

    Luca

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    Senior Member robusto's Avatar
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    Re: La Pavoni undressed

    Good to see that the problems were little manageable surprises rather than shocks, Sparky.

    Dont you just love that salmon copper colour? Its almost a pity that it has to be hidden by the panels!

    Good luck with the pump. Any chance you can rebuild it yourself?

    -Robusto

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    Re: La Pavoni undressed

    The temp variation is real. Ive been monitoring the boiler wall and there is a 6.2 oC variation during the pressurestat cycle. I havent checked the steam charts yet, but if Java is correct, then the Sirai pressurestat needs an overhaul. Thats one of the things that I didnt do during the refurb. Membrane kits are available for coffeeparts, so its no drama. My boiler pressure gauge isnt calibrated below 1 bar, so the low point may be quite a bit lower than the 1.5 bar deadband that JavaB has.

    Luca, firstly its a real E61, just with a different shape and an easily detachable shower screen (OK slightly different). Otherwise its parts compatible with the E61. As for the gicleur, it has 0.7mm ones fitted and they give a really nice flow, so I dont see the need swap em about. Also the E61 has a pre-infusion chamber, which seems to work pretty well. No need to "middle position the lever", which is not really possible anyway as the microswitch is actuated pretty much as soon as the top valve is opened by the cam.

    As for the high group temp, the water dance from the group seems to go on forever. Thats telling me to lower the pstat first. Once thats happening (given the pstat is operating correctly) then Ill revisit the group temp. If it is still too hot, even when the water dance is manageable, then its time to look at 2.5 mm thermosyphon restrictors, which Ill probably make myself, as I love the DIY stuff on the lathe.

    Im aware of Eric S M6 thermocouple adaptor, thanks. Its a mod for down the tracks.

    PID with a pressure transducer is definitely the go, if a cheap transducer can be sourced. I know of one supplier and might look that up again. JavaB, there are PIDed commercial HX machines currently available, such as the Reneka that Pioneer Coffee recently bought. It may not be the best use of a PID, as you suggest. Again, Ill check the pstat operation first.

    Yeah, Robusto, no show stoppers yet. I do have a sticking anti-vacuum valve though and the possibly dodgy pstat (that can be refurbed for cheap) and now my latest pump seems to have completely gone caput. It was getting up to 8 bar this morning, and now nothing.... New pump coming.

    Yeah its all fun if you like that sort of thing. I was just tantalised by the *momentary operation of the beast before the pump upped stumps on me....

    Cheers,

    Mark.

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    Re: La Pavoni undressed

    Mark,

    Sounds like the procons were a bit old and tired..... they have a reputation of being excellent pumps - even happy to draw from a reservoir.

    I was amazed at the capacity of the La Cimbali pump - greater than most 4 group machines..... but it certainly comes into its own when you are extracting from both groups and the autofill cuts in..... the group pressure barely moves from 9 no matter what I do. They certainly have over engineered the machine (which aside from the weight - Im real happy about).

    Sounds like your restoration is really going very well- with only a few minor annoyances along the way - as there always are.

    According to my chart with a total pressure of 1.9 Bar BP is 119C and at 2.1 Bar it is 121C ..... and my boiler varies from 1.1 to 0.95 above atmospheric.... so only 0.15 dead band- which should give <2 deg C variation.

    It will be interesting to see what the dead band on your is... 6C variation is approximately 0.4Bar variation around 1.1 Bar...... mmm me thinks overhaul time for the pressurestat!

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    Re: La Pavoni undressed


    Yep 0.4 bar looks to be about what Im getting. I was going to overhaul the sucker, but thought Id suck it and see. But it is usually recommended that you replace all the rubber parts on an old machine, and that includes the pressurestat membrane.

    A few other things have popped up. One of the thermosyphon lines is now leaking. I think this is just a case of a few thermal cycles loosening up the fitting. Ill retighten and see. Otherwise zi noticed the large relay that switches on the element seems to be humming. Im not intimately familiar with relay failure, but audible humming from the switching coil doesnt sound right.... maybe itll be best to just wait and see....


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    Re: La Pavoni undressed

    Quote Originally Posted by Sparky link=1170566881/0#9 date=1173185227
    Im not intimately familiar with relay failure, but audible humming from the switching coil doesnt sound right.... maybe itll be best to just wait and see....
    Many of the high current relays (contactors) are operated on AC rather than DC...... and loose laminations (or even the coil being loose on the former) can cause that hum...... fingers crossed

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    Re: La Pavoni undressed


    Fingers crossed indeed. Thats a pretty expensive part (although I do have a spare kicking around).


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    Re: La Pavoni undressed

    Quote Originally Posted by Sparky link=1170566881/0#9 date=1173185227
    Otherwise zi noticed the large relay that switches on the element seems to be humming. Im not intimately familiar with relay failure, but audible humming from the switching coil doesnt sound right.... maybe itll be best to just wait and see....
    Another culprit with AC armatures is contamination on the main faces where the armature poles make contact..... quite a common problem and easily dealt with by cleaning with a suitable solvent and thoroughly drying out. This is the most common mode of failure for burning out the relay/contactor coil, as the less than optimum mating of the pole faces increases the reluctance in the magnetic path causing current flow in the coil to increase. Over time this leads to over-heating and accelerated degradation of the coil winding insulation and ultimately failure.

    Always plenty of ways to skin a cat with these things ;)

    Mal.

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    Re: La Pavoni undressed

    Thanks for those tips on the relay. Ill have a look and see what I can do.

    Good news on the pump front. The pump I was originally using seems to be ok. I had a chat with a coffee tek this morning and he pronounced the pump good, but diagnosed the real culprit...

    Whether by design or later modification, there is a check valve missing from the brew path, which means that hot water flows back into the pump and even further into the reservoir... The odd thing is that the machine didnt show any signs of being modified, so how this happened, Im not sure. But as soon as we got to chatting it all made sense, the pump and motor body getting too hot to touch and the reservoir water getting quite warm. I even noticed a couple of steam burps back into the reservoir...

    I have a couple of check valves kicking around, so this will be sorted out asap.

    Id like to have this thing up and running by the weekend... fingers crossed.

    Cheers,

    Mark.

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    Re: La Pavoni undressed

    Mark...

    Just a guess on my part..... but if using a reservoir then there is no positive pressure ..... whereas if connected to mains you would have 3.5 - 5.5 Bar pressure on the supply side of the pump....

    Which would prevent and water flowing back from the brew path.... as it would have to overcome that pressure... For example - I always have 5 Bar in the heat exchanger which is a good idea so that the water doesnt boil- and deposit scale!!)

    The machine was probably designed only to be plumbed in (hence no sign of a mod).

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    Re: La Pavoni undressed


    I though that as well, but the thermal expansion can manage a great deal more than mains pressure, so there will still be some back flow. The coffee tek (who knows just about every machine ever made) reckons there was a check valve in that machine. He was actually quite adamant on this point. Anyway way problem diagnosed and it will be resolved.

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    Re: La Pavoni undressed

    Mark,

    I just checked my drawings and mine doesnt have a check valve in the path either.... so it does rely on the mains pressure....

    You are right- some water will be forced back by the expansion in the heat exchanger.... but unlike yours where it will be boiling (no pressure in the heat exchanger) therefore a far greater volume will be expelled- mine is at 5 Bar and wont boil- so a relatively small volume will be expelled.

    Wont a check valve cause a build up of pressure in the heat exchanger as the water heats up - expands- and has no where to go? And it will start at 9 Bar pressure at a temp of about 93C and heat up to 125C - quite a bit of expansion = extra pressure in the sealed system possibly causing strain on the brew solenoid :-/ :-/

  18. #18
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/15#16 date=1173229091
    Wont a check valve cause a build up of pressure in the heat exchanger as the water heats up - expands- and has no where to go? And it will start at 9 Bar pressure at a temp of about 93C and heat up to 125C - quite a bit of expansion = extra pressure in the sealed system possibly causing strain on the brew solenoid :-/ :-/
    Unless the machine is a very different design than most any water left in the heat exchanger will do the same thing it does on your Cimbali JavaB, exit via the grouphead and (assumming the machine has one) the 3-way pressure relief valve.

    The brew solenoid regulates the water flowing into the HX, not out of it. The HX is not a sealed system. :)


    Java "Hhhmmm....Hydraulics" phile

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    Re: La Pavoni undressed

    Java....

    Now youve got me more confused than normal!

    Ive just checked my hydrologics drawing...... and water goes from the pump, appears to loop through the group head, into the heat exchanger, back to the group, through the 3 way and if the three way is on- out via the group head.... if the three way is off..... the water passage from the HX is blocked i.e. a sealed system.... the group is however vented via the three way - but not the HX. :-/ :-/

    What have I got wrong?

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    Re: La Pavoni undressed


    JavaB, the 3-way will usually hold back about 12 bar before being forced open. This acts as an expansion valve and does the job. Other machines have dedicated expansion valves (like the Pav as the E61 group wont work as an expansion valve).

    Its true that with mains pressure, the initial expansion will occure until the pressure is equalized and then the flow will stop. Thats probably good enough to stop excessive hot water reaching the pump.

    Ive seen a few Bezzeras and they all include a separate exapnsion valve and check valve to prevent any flow back to the pump. This is common for most commercial and prosumer machines according to the tek whose brain I pick on occasion.

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    Re: La Pavoni undressed

    Ah....

    Done some more checking....

    There is a pressure relief valve (11.5 Bar) on the run to the groups.... just after the pump with a vent line into the drain collector....

    And on the output side of the pump (shown on the pump drawing!!) is a non return valve....

    So all is again good in La Cimbali land!

  22. #22
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/15#18 date=1173242893
    Java....

    Now youve got me more confused than normal!

    Ive just checked my hydrologics drawing......
    The drawings in the Cimbali manuals leave a lot to be desired. They bear only a passing resemblance to the physical item.

    On Cimbalis the water comes up in a copper pipe and passes through a hole in the bottom rear of the grouphead into another copper pipe which makes a loop and feeds the water through the top front of the grouphead into another copper pipe where it then goes into the 3-way valve. From the 3-way valve the water then goes into another copper pipe which feeds it through a hole in the upper rear of the grouphead, coming out a copper pipe on the other side which then loops around and injects the water into the HX at the top center of the rear of the grouphead. The water from there goes down a poly pipe to be dumped into the bottom of the HXs tube where it is flash heated to steam and exits the HX via a small hole in the grouphead. It travels the length of the grouphead and exits via the showerscreen. There is a 3rd line attached to the 3-way valve. That is the pressure relief line which vents into the drip tray.

    As you can see from that description with the brew switch turned off the HX is open directly to the atmosphere via the pressure relief line and the showerscreen on the grouphead. There is no way short of a faulty 3-way valve and a packed portafilter (or the channel that feeds the showerscreen) that any water heated in the HX can make its way back to the pump or the rest of the system.


    Java "A little less confuzzled?" phile

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    Re: La Pavoni undressed

    Java,

    Got to agree with your comments re drawings..

    But my reality is different to the drawings - and your description....

    Copper pipe up to the top left side of each group (about the centre).... through a hole in the casting and out the other side (right) where it loops via a copper pipe back to the centre rear of the group assembly and then out through a copper pipe into the centre of the heat exchanger "cavity".... It then returns via a channel cast/drilled into the brass to the three way mounted on the right side (near the front)..... the other side of the three way goes via a machined channel into the group head above the showerscreen.... with the third leg going into the drip tray.....

    TOTALLY different :o :o.... OK it is a dossatron but that shouldnt make any difference...

    Go Figure??????? :-/ :-/ :o :o

  24. #24
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Heres a pic of the grouphead on my Cimbali. The green dot is the waterline from the pump. The white line is the route of the incoming room temp water with the arrows showing its direction of flow. The red arrows show the direction of flow of the water at the end of the shot when the 3-way valve closes off the inflow of cool water and opens the path to the pressure relief line. In this pic the relief line was already disconnected from the 3-way valve assembly.


    Java "A picture is worth, well a few words anyways!" phile


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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/15#20 date=1173245351
    Ah....

    Done some more checking....

    There is a pressure relief valve (11.5 Bar) on the run to the groups.... just after the pump with a vent line into the drain collector....

    And on the output side of the pump (shown on the pump drawing!!) is a non return valve....

    So all is again good in La Cimbali land!
    On the Grimac there is a massive valve, and one of the smallish 6 mm? pipes from it goes to the drain collector.

    The valve obviously is operated electronically on demand for the boiler and heat exchangers. But I can also operate it manually by pushing in, and holding, a knob on the front of the machine.

    --Robusto

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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/15#22 date=1173247436
    Java,

    Got to agree with your comments re drawings..

    But my reality is different to the drawings - and your description....
    Got a pic?


    Java "Wants to see" phile

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    Re: La Pavoni undressed

    Quote Originally Posted by Javaphile link=1170566881/15#25 date=1173248081
    Got a pic?


    Java "Wants to see" phile
    Mmmm -didnt photograph this area whilst doing restoration..... will have to take some....

    Check your mail.... sent you some pages from the service manual.



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    Re: La Pavoni undressed


    Im pretty sure Javaphile has confused the brew path a bit. If I follow the description of the brew path, then when the 3-way opens at the end of the shot, the pressure from the group will force coffee crud through the HX first before it gets to the 3-way. Theres no manufacturer that would use such a design. The 3-way is usually as close to the group as possible to minimise the path that coffee crud will travel before it is ejected. The diagram shown on the coffeeparts web page is consistent with a 3-way close to the brew head.

    JavaBs explanation is what Id expect. The the expansion valve and check valve close to the pump seems pretty common. The expansion valve often has some silicone hose feeding into the drain.

    Theres not too many elements in a coffee machine, but most are there for a reason and its important to know what does what and why, so you can diagnose any problems and fix them. Its clear that none of us has the wealth of experience that a professional coffee tek has. Thats why my trip to the coffee tek this morning was invaluable.

    Cheers,

    Mark.

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    Re: La Pavoni undressed

    Quote Originally Posted by Sparky link=1170566881/15#27 date=1173250363
    If I follow the description of the brew path, then when the 3-way opens at the end of the shot, the pressure from the group will force coffee crud through the HX first before it gets to the 3-way. Theres no manufacturer that would use such a design. The 3-way is usually as close to the group as possible to minimise the path that coffee crud will travel before it is ejected. The diagram shown on the coffeeparts web page is consistent with a 3-way close to the brew head.

    Mark.
    Not to mention all that Caffetto in the HX :( :( And it would sure take several blind shots for any to appear from the relief pipe - which I know is not the case.

    Theres not too many elements in a coffee machine, but most are there for a reason and its important to know what does what and why, so you can diagnose any problems and fix them. Its clear that none of us has the wealth of experience that a professional coffee tek has. Thats why my trip to the coffee tek this morning was invaluable.
    And thats the great advantage of this site..... we can all share our knowledge - and between the lot if us - hopefully get it right! ;)

  30. #30
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by Sparky link=1170566881/15#27 date=1173250363
    Im pretty sure Javaphile has confused the brew path a bit. If I follow the description of the brew path, then when the 3-way opens at the end of the shot, the pressure from the group will force coffee crud through the HX first before it gets to the 3-way. Theres no manufacturer that would use such a design. The 3-way is usually as close to the group as possible to minimise the path that coffee crud will travel before it is ejected.
    Thinking about it (I know I shouldnt be doing that this late at night!) youre absolutely right. And as I study the pic more and think back to when I had it all apart I remember now being confused as to the exact path the water took through the grouphead. The 3-way valve actually sits in front of the pipe that in that pic appears to go through it and is mounted directly to the side of the grouphead with the only pipe connecting to it being the pressure relief drain line.

    This would allow the water (and backflush chemicals) to go from the shower screen a short distance through the grouphead and then out via the 3-way valve, before it reaches the HX.

    The question that then of course begs to be answered is what is the path of the water through the grouphead between all the different pipes and the 3-way valve?

    Has anyone ever seen a cutaway view of one of these groupheads?

    The diagram shown on the coffeeparts web page is consistent with a 3-way close to the brew head.
    Got a link? I cant find any hydraulic diagrams there.


    Java "Going to sleep before he confuzzles even more people" phile

  31. #31
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/15#26 date=1173249356
    Check your mail.... sent you some pages from the service manual.
    Havent gotten them yet. Ill check again in the morning.


    Java "Really going to bed this time!" phile

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    Re: La Pavoni undressed

    Java,

    Sent them to your CoffeeSnobs address.... so they SHOULD be there....

    One shows a cutaway of the group showing the machined channels within.

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    Re: La Pavoni undressed

    It looks like Robusto will beat me to a working machine. :(

    The oneway valve may take a day or two to sort out.

    On the pressurestat side, the membrane was cactus (and home to a small cockroach family), so a new membrane will cure this 0.4 bar pressurestat swing, I hope.

    Im still endevouring to get it running by the weekend.... fingers crossed.

  34. #34
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/30#31 date=1173255390
    Java,

    Sent them to your CoffeeSnobs address.... so they SHOULD be there....

    One shows a cutaway of the group showing the machined channels within.
    Hhhmmmm....Still nothing in the mailbox. Ill have to do some digging to see what the problem is.

    On a happier note, now that Im awake and thinking/seeing clearly Ive redone the flow path picture showing the correct path.

    The water comes in starting at the big green dot. Following the green line the water then goes up the pipe which passes under (not through) the grouphead and into the top left side towards the front of the grouphead passing straight through to the upper right foward pipe where the pipe then loops around and passes behind the 3-way valve/solenoid and into the right side of the grouphead towards the rear. It then passes straight through the grouphead and out the pipe on the rear left side where it then loops around and is injected into the HX above and centered on the grouphead. The water is flash heated there and then follows the red line straight through the grouphead into the 3-way valve and from there it follows the yellow line to the showerscreen. At the end of the shot when the pressure relief (backflush) valve is opened the water then flows back following the yellow line from the showerscreen to the 3-way valve and then along the blue line from the 3-way valve out the flush pipe to the drip tray. :)


    Java "I can see clearly now..." phile


  35. #35
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/30#31 date=1173255390
    Java,

    Sent them to your CoffeeSnobs address.... so they SHOULD be there....
    It looks like Ive got the problem sussed and it should all be sorted out and working properly sometime today. :)


    Java "One more problem solved!" phile

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    Re: La Pavoni undressed

    OK JavaB, fire that email at me again there please. Everything should all be sorted out now. :)


    Java "Problem solved!" phile

  37. #37
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    Re: La Pavoni undressed

    FYI on a side note Cimbali is now touting their no tamp feature on their newer model expresso machines.

    I was out doing a repair not to far from the local Cimbali dealer yesterday afternoon and decided to swing through just to verify that I had the water path correct and to pick up a new o-ring and gasket for my gravity valve.

    While waiting for them to pull the parts I made myself some drinks on their demo 3-group Dosatron. I did my usual dose and tamp only to discover that there was no way the portafilter was going to lock onto the grouphead. I commented to the tech on how much lower the showerscreen was than on my M28 and he stated that Cimbali had lowered the showerscreen so that it acted as a tamper when you locked the portafilter on. Eliminating the need to tamp before locking on and brewing. Ugh!

    A classical DOH! moment presented itself as I was grinding the beans and asked their new secretary who they were from as they looked and smelled old. She said they were Lavazza and I commented that they should really hook up with a local roaster and use good quality fresh beans for their demos. Her comment? "Oh no! We cant do that! These are espresso beans!!" DOH!!


    Java "Shaking his head in amazement" phile

  38. #38
    Senior Member robusto's Avatar
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    Re: La Pavoni undressed

    Geez, Javaphile, youd expect that sort of attitude from the receptionist at the local new car showroom where they make you a coffee while the transfer papers are prepared....

    But from a Cimbali dealership? >:( On second thoughts, it makes sense. The offing is supposed to closely match that would-be customers, i.e., cafe owners, are accustomed to. ;D

    The "inbuilt tamper" is a worry. What would Greg Pullman say to that method. Seems like the puck is being screwed down by a shower screen rather than tamped.

    Speaking of which....what a mess tht screen is going to become pronto.
    Stick to the tried and proven traditional way, I say.

    --Robusto

  39. #39
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    Re: La Pavoni undressed

    Quote Originally Posted by robusto link=1170566881/30#37 date=1173380564
    Stick to the tried and proven traditional way, I say.

    --Robusto
    Yup, I agree!

    Its sad to see the dealers reflecting the speed is more important than quality attitude you see in most cafes. They are doing absolutely nothing to increase the quality in the cup, only to increase the bucks in the cafes pockets.

    The owner made the comment that you cant taste the difference in the cup between doing a manual tamp and letting the showerscreen do the tamp. He looked totally lost and confused when I pointed out that of course you couldnt, using the beans and equipment they had there. They use an automatic tamper (not a manual tamper in sight) that has a 52mm head to tamp a 58mm basket to far less then 30 pounds (maybe 10 pounds?), and theyre using stale old beans. Is it any surprise that you cant taste the difference?!

    One of these days Im going to go over there with some fresh beans and my tamper to show them just how bad their espressos taste. They may know espresso machines like the back of their hands, but they obviously dont know sh!t about coffee.


    Java "Gee, am I a snob or what?!" phile

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    Senior Member robusto's Avatar
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    Re: La Pavoni undressed

    I dread to think what the ultimate outcome would be if you traced the thinking backwards .... from the attitude of the dealership...to the factory...to the engineers ... to the designers.

    Temperature control? Pre-infusion? "Nah, they wont taste the difference. Use that thermoplastic for the group, its cheaper."

    --Robusto

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    Re: La Pavoni undressed

    It seems all the advances and tweaks the designers put into the machines to produce a better cup are rendered useless by the idiots on the end of the portafilter in most cafes.


    Java "Doesnt order out for a reason." phile

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    Re: La Pavoni undressed

    Quote Originally Posted by Javaphile link=1170566881/30#35 date=1173376180
    OK JavaB, fire that email at me again there please. Everything should all be sorted out now. :)
    Java "Problem solved!" phile

    Java,
    Email sent - better luck this time.

    Robin.

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    Re: La Pavoni undressed

    Quote Originally Posted by Javaphile link=1170566881/30#36 date=1173377847
    FYI on a side note Cimbali is now touting their no tamp feature on their newer model expresso machines.

    While waiting for them to pull the parts I made myself some drinks on their demo 3-group Dosatron. I did my usual dose and tamp only to discover that there was no way the portafilter was going to lock onto the grouphead. I commented to the tech on how much lower the showerscreen was than on my M28 and he stated that Cimbali had lowered the showerscreen so that it acted as a tamper when you locked the portafilter on. Eliminating the need to tamp before locking on and brewing. Ugh!

    Java "Shaking his head in amazement" phile
    No..... not another manufacturer of fine equipment succumbing to the almighty profit dollar- in this case their customers rather than their own..... :o :o

    Its a pity someone who has - at least in the past - made excellent over engineered machines (like a two group with a 250L per hour pump :o :o) has seen fit to support such shoddy cafe driven procedures....

    More coffees per hour - more cr@p coffees that is...... but the punters wouldnt know a good coffee if it bit them as most have never had a good coffee as a bench mark....

    The replacement dosertron board wasnt built to the same standard as the original either.... more "cost cutting"?

    I guess La Cimbali will join the other disposable coffee machines before too long - certainly the groups will have to be with all that "self tamped coffee" - which wont be cleaned out properly by the cafe owners.....

    UNBELIEVABLE :o :o :o :( :( :(

  44. #44
    Sleep is overrated Thundergod's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by Javaphile link=1170566881/30#38 date=1173383969
    One of these days Im going to go over there with some fresh beans and my tamper to show them just how bad their espressos taste.
    Do it!

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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/30#41 date=1173395018
    Quote Originally Posted by Javaphile link=1170566881/30#35 date=1173376180
    OK JavaB, fire that email at me again there please. Everything should all be sorted out now. :)
    Java "Problem solved!" phile

    Java,
    Email sent - better luck this time.

    Robin.
    Nope, hasnt arrived. :-/

    Youll need to send it by clicking on the email link on here again. Remove any old addy you may have for me from your address book. The link here had an incomplete address in it.


    Java "It pays to check the simple things" phile

  46. #46
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    Re: La Pavoni undressed

    Quote Originally Posted by JavaB link=1170566881/30#42 date=1173395763
    The replacement dosertron board wasnt built to the same standard as the original either.... more "cost cutting"?

    I guess La Cimbali will join the other disposable coffee machines before too long - certainly the groups will have to be with all that "self tamped coffee" - which wont be cleaned out properly by the cafe owners.....

    UNBELIEVABLE :o :o :o :( :( :(
    I wouldnt say the machines are becoming disposable. Theyre still being made every bit as heavyduty as they used to be it appears. They may in fact be getting better as the head tech there told me that the techs were more heavily involved in the designing of their new machines and as a result such things as a good mask is being used on their PCBs and the electronics are being given better protection now. :)


    Java "Gotta love the simplicity of the old M28!" phile

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    Re: La Pavoni undressed

    Quote Originally Posted by Javaphile link=1170566881/30#44 date=1173409977

    Youll need to send it by clicking on the email link on here again. Remove any old addy you may have for me from your address book. The link here had an incomplete address in it.

    Java "It pays to check the simple things" phile
    Ahhhh.... no .au on the end of the address.... updated address book ;)

    OK take 3 has been sent.

  48. #48
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    Re: La Pavoni undressed


    Er people this is going seriously OT. How about using PMs?


    Back OT. I bough a few check valves (actually one too many) to give me the option of fitting it in the water inlet point before the pump or directly in the path of the HX feed line after the pump. Ill start with the check valve fitted before the pump as its easy to install. The other option may mean getting an adaptor if I dont already have it. Both methods should work, but Id prefer to put the check valve after the pump when using a tank, because the pump doesnt have too much suction pawer to start with.

    A new pressurestat mambrane kit has arrived and compared to the old one its all thin and floppy. The old one was very hard and cracked. No wonder the pressurestat was varying so much.

    The last thing to sort out is the slight taint in the steam boiler. The steam has a slightly acrid metallic smell, reminiscent of acid on metal. When I opened up the pressurestat, it also had this smell, so Im wondering if the smell is from its prior life or the result of my descaling. I remember this type of smell from the BZ after its descaling and it went away soon enough. But the Pav boiler is 7 times larger in volume.... The water drained from the boiler also has this smell and a very slight taste. It will have to be removed for milk drinks. So more flushing is in order, or maybe another descale...

    Cheers,

    Mark.

  49. #49
    Super Moderator Javaphile's Avatar
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    Re: La Pavoni undressed

    Quote Originally Posted by Sparky link=1170566881/45#47 date=1173410912
    Er people this is going seriously OT. How about using PMs?
    Id normally have done just that, but seeing as Im a Mod on here others needed to know to throw away any old addy they may have gotten for me from the email link on here and to get a new one. :)

    The last thing to sort out is the slight taint in the steam boiler. The steam has a slightly acrid metallic smell, reminiscent of acid on metal. When I opened up the pressurestat, it also had this smell, so Im wondering if the smell is from its prior life or the result of my descaling. I remember this type of smell from the BZ after its descaling and it went away soon enough. But the Pav boiler is 7 times larger in volume.... The water drained from the boiler also has this smell and a very slight taste. It will have to be removed for milk drinks. So more flushing is in order, or maybe another descale...

    Cheers,

    Mark.
    More flushing never hurts, but you may find that this smell/taste will be there for a bit until the inside of your boiler and piping gets a new oxidization/sealer layer on it. As I recall it took a couple of weeks for it to go away in my M28 after a descaling.

    Not that this is the case here but water can also go stale in the boiler if its not being used and hence replaced frequently enough.


    Java "Dont like no smelly water!" phile

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    Re: La Pavoni undressed

    Mark,

    I had a similar smell with the smaller single boiler machines I had previously after a descale...... but it disappeared after a few flushes.

    The La Cimbali has a stainless steel boiler..... so I had no problems even though it is massive..... I suspect its the pink exposed copper after descaling in your type of boiler..... and it only goes away when you get that passive copper layer.....

    Probably more flushing will sort it out..... together with an extended time on idle... I think another descale might just prolong the process even more.



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