Faema Compact A 2 Group Rebuild - Need your help

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
3BABY
Posts: 8
Joined: 12 years ago

#1: Post by 3BABY »

Hi Guys,

So Finally i have got a machine (i didnt have much luck with the Euro 2000 the other day) nevertheless i picked up up a "not currently working" Faema Compact A 2 Group machine yesterday, i haven't had a chance to plug it in and see whats going on but will hopefully get the chance in the next few days, and after fixing the issue will strip the machine for a good clean / rebuild.. but firstly i need your help to name a few of the components in the machine im not too sure about (please see below pics).. i understand the fundamentals of how an espresso machine works & im pretty good on the tools and have a background in electronics/electrical engineering but all this plumbing is got me a little confused, if some one could explain the process the water goes through from inlet to group/steam wand (in this machine) it would muchly appreciate it.

what is the part in Red?

is the part in Purple the heat exchanger obviously attached to the boiler, but the groups arnt getting fed from it.. so im a little lost the smaller pipe that comes off the top of it goes down and along the bottom of the machine to the part i circled in red (marked with "A").

what is the "black box" under the flow meter in the the front corner of the machine? circled in green. it has a small brass pipe going into it that goes to the boiler element area, and has brown/blue wires in it... maybe some sort of cut-off or supply to the unit.. as it has a electrical mains supply going into it.











thanks guys :-)

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allon
Posts: 1639
Joined: 13 years ago

#2: Post by allon »

The purple is a pre-heater; the heat exchanges are inside the main boiler.
The red is the water distribution block "valve block". It has a solenoid that controls the autofill, expansion valve, and manual fill valve.

Check your PMs...
LMWDP #331

3BABY (original poster)
Posts: 8
Joined: 12 years ago

#3: Post by 3BABY (original poster) »

I called the guy that i got the machine off and he told me one group wasn't working and the machine wasn't heating,

i tested the resistance across the element at 19.00 ohms.. this sounds about right.. so it wouldnt be burnt out, i originally thought hmmm now i must have a control board problem.. but after a little more thinking and reading of the manuals i did notice that (the black box i circled in green above) is a pressure switch and it has a button on the from of the machine, which was in the "popd out" position when i got the unit.. i was (being a curious male) wandering what it did and pushed it in.. it stayed in and didnt pop out.. so maybe it wasnt heating because of this pressure sensor ? we will see when i turn it on..

and maybe the reason a group isnt working could come down to a control board or solenoid ?

so if i understand correctly please correct me here if im wrong:

the solenoid on the value block only lets water to pass through the valve block when the level sensor is activates the control logic that turns on the pump and also the solenoid, and thus the cold water goes into the preheater and gets mixed with hot water and eventually gets pumped into the boiler until the level sensor shuts off the pump and the solenoid.

otherwise when you hit the "gimme a shot" button the control logic starts the pump releases the valve solenoids on the group head.. the cold water goes into the valve block.. with nowhere to go because the solenoid has shut the "to the boiler" path it goes through the flow meters through the heat exchangers into the groups until the control logic says stop.. shuts down the pump and group solenoid..

.. question .. when the boiler is getting filled by the pump water in cant go anywhere in the valve block (because the group head solenoids are closing) so the cold water coming in goes to the path of less resistance to fill the boiler ?



thanks guys :-)

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allon
Posts: 1639
Joined: 13 years ago

#4: Post by allon »

3BABY wrote: so if i understand correctly please correct me here if im wrong:

the solenoid on the valve block only lets water to pass through the valve block when the level sensor is activates the control logic that turns on the pump and also the solenoid, and thus the cold water goes into the preheater and gets mixed with hot water and eventually gets pumped into the boiler until the level sensor shuts off the pump and the solenoid.
I think that's correct. I think there's also a valve which limits the flow to the boiler such that if the boiler calls for refill during a shot, it won't take all of the water supply to fill the boiler; it will leave some heading to the pump for the group(s).
3BABY wrote: otherwise when you hit the "gimme a shot" button the control logic starts the pump releases the valve solenoids on the group head.. the cold water goes into the valve block.. with nowhere to go because the solenoid has shut the "to the boiler" path it goes through the flow meters through the heat exchangers into the groups until the control logic says stop.. shuts down the pump and group solenoid..
Yup. When you call for a shot, it turns on the pump AND opens the 3-way-valve on the solenoid, which opens the heat exchanger loop to the chosen group head(s).
3BABY wrote: .. question .. when the boiler is getting filled by the pump water in cant go anywhere in the valve block (because the group head solenoids are closing) so the cold water coming in goes to the path of less resistance to fill the boiler ?
The pump is in front of the valve block; when the boiler is getting filled by the pump, water is going from the pump to the valve block, through a valve (which can be used to reduce or shut off the path to the solenoid), through the solenoid, through a check valve, and to the preheating tank, which is connected to a heat exchanger in the boiler on top and bottom, and heats through a thermosyphoning action, I would guess. Because the group solenoids are closed, it just pressurizes the HX loops, but doesn't let any water out of the group heads. There is a check valve between the valve block and the loops, so they probably won't drop much in pressure anyway...

Got it?
LMWDP #331

3BABY (original poster)
Posts: 8
Joined: 12 years ago

#5: Post by 3BABY (original poster) »

Yeah i think it got it.. thanks :-)


So anyways, after a partial re-wire of the boiler circuit i have the unit heating and coming up to pressure and then clicking off as expected...

so in an effort to find out why one of my group buttons did nothing (right hand side) and i had no pump etc.. i pulled the electrics box down, everything looked ok checked one of the fuses on one of the boards (the middle control card was hard to get to).. but i did notice that the wiring was a little backwards.. so i put the connectors as the should be and turnd the unit on.. POP.. yep.. fuses blew right away.. so after thinking for a little and checking all the wires.. i thought it must be a overload to cause the fuses to blow.. what was connected to the board to make it go pop.. the pump... pulled it out and yep you guessed it.. seized.. so i went and got a few more fuses.. and separated both the control board and both fuses were blown.. that must have been why only one group solenoid was working (it looked like someone had had a muck around with it before me).. so i replaced the fuses.. but only installed one board.. the main one that connects to the right group buttons.. took the pump unit off the motor and had the motor connected (also disconnected the boiler circuit).. turnd the machine on.. the motor spun up and then i heard a pop from that side of the machine (quickly turnd the machine off).. Hmmm not loooking good.. i think i may have burnd the motor out running it with no load? maby? i disconnected the motor and turnd the machine back on to check the right hand side group buttons and they all worked.. so.. everything it working except the pump (witch looks like it needs a rebuild or replace it solid as i can just turn it a little with a pair of monkey grips).. and i havnt had a chance to test the solenoid on the valve block..

.. so i pulled the top off the pump and the wires going to the phase shifting capacitor are burnt out.. but the windings look ok.. i have checked the resistance and one (the winding not with the capacitor) is: 18 ohms. and the winding that has the capacitor connected in series is: 34 ohms.. does that sound right? should they both be the same?

so a little bit of a google around $279.00 for a rotary pump assembly? anyone know of any places that would be cheaper? or possibly offer a rebuild? (before it start to get out the 10 Tonne Press)..

and if in the case my motor is fried... take it to a re-winder or replace? i imagine it would be super expensive!? or maby a pump/motor assembly off another machine would work ?

your opinions guys :-)

jpboyt
Posts: 220
Joined: 14 years ago

#6: Post by jpboyt »

Resistance readings for the primary and secondary windings sound about right. Secondary windings in series with the run capacitor, as far as espresso induction motors go, have a higher impedance than the primary windings. Motor has a couple of bearings, both on one end of the armature, cantilever style. Common bearing numbers available at most industrial supply houses. Remove small snap ring and the armature taps out the back of the case. Most motors fail from the pump leaking and the front bearing, which is for some dumb reason a shielded bearing not a sealed unit, getting dosed with the worlds most common solvent. Water. Iron mixed with oxygen makes Iron oxide I think. No chemist but I recognize rust when I see it. Burnt wires indicate overcurrent but if you still have a decent resistance reading the windings are probably ok. Rewinding is probably cost prohibitive. Used motor needing a set of bearings might be your cheapest route.
jpboyt

jpboyt
Posts: 220
Joined: 14 years ago

#7: Post by jpboyt »

Oops, I lied. You may have a bearing on each end after looking at the pictures. Faema never could settle on a decent pump, motor, or drive method.
Anyway it all still taps not presses apart. As in gently...
jpboyt

3BABY (original poster)
Posts: 8
Joined: 12 years ago

#8: Post by 3BABY (original poster) »

Hey Guys,

So abit of time has gone by and I've managed to rebuild one side of the Machine.. So far what was wrong with the machine was: A Seized Pump, blown motor, the left hand Flowmeter was busted, both groups were in need of a rebuild/clean.. the shower screens were disgusting! The boiler was rewired, 1 of the control boards is ok. The other is half working. I have rebuild the left hand side group and swapped the flowmeters over so I can use the automatic buttons.. I have disconnected the solenoid form the right hand group, the motor and pump was replaced with a Procon pump and a GE motor.. I chose this option because to get a genuine Faema motor/pump was going to be expensive and trying to rebuild the existing unit(s) would have just cost me even more. I have rebuilt the valve block and the boiler water level indicator and now the machine is running, heating up correctly and auto filling the boiler when It gets below level,

I have connected a pressure gauge via a "T" to where the feed from the pump goes into the valve block (as the standard double scale gauge is ½ broken and only displaying the boiler pressure). This is kinda where things start to go a little funny.. As you can see in the pics below I set the pump to 130 PSI and started to pull a couple shots.. as soon as I hit the "2 short" button I get a gush of shot and then it tapers off the a constant stream and eventually blonds off and then clicks off (this is after me setting the appropriate potentiometer on the control card to count enough pulses from the flowmeter to give me 60ml of liquid).. and this is all over in the space of about 12 seconds.. I though this is definitely too short.. Thinking it must be the grind I go a finer grind and done the same procedure.. it slowed a little but I still get an initial gush of liquid as soon as I hit the button and the stream off spouts seemed a little "watery looking".. after a couple days of messing around with grinds and lowering the pump pressure and testing from 115-125psi im still getting the initial gush and watery shots.. so I went to my friends place and had a go on his Wega after playing for a good 30mins I got a good grind and a nice shot coming off, the pump gauge on the Wega said it was producing 9.5 bar.. so I got a container and packed up a bit of the same ground coffee and took it home to put the Faema through some diagnosis.. after the same procedure of dosing and tamping I hit the button on the Faema and again I get the gush and then the shot is over in about 12 seconds.. What the Hell? So I cut the bottom out of one of my portafilters and pull another shot.. still comes out prity quickly and there is noticeable splashing of coffee in and around the cup, so now I adjust the pump pressure down to about 90 PSI.. and pull another shot (this is all with the same coffee grounds I brought home) the shot comes out a little slower but still too fast.. I take it down to around 55 ish PSI and the result is the video below.. and this shot did taste "ok" ... my question is.. when every other machine is set to 9bar to pull shots why am I having to crank it down to just over 3.7bar? is there a pressure vs flow problem? I thought about this but the flowmeter has a very small hole probably only 1.5mm max to direct a jet of water to the impeller this should certainly restrict the flow enough regardless of pressure.. where is my problem? Even with a finer grind (that chocked the Wega I cant choke the Faema on the same 130PSI pump setting).. Your opinions please!!










and the below was this mornings debug session:

dose and level off with a straight edge:


tamp:


boiler pressure good & clean Group:


and this is the "loaded up" pressure



the longer term plan is to make a custom control board for the machine .. .after the mechanical stuff is sorted..

3BABY (original poster)
Posts: 8
Joined: 12 years ago

#9: Post by 3BABY (original poster) »

ok so i managed to fix the standard double scale gauge and its reading a value of 4bar (+ or - around 3-5 PSI compared to the other gauge i added in before the valve block) while pulling a shot or fully loaded up with a blank filter in.

i am however still stuck at pulling shots at around 4 bar.. i cant seem to work out what the problem is, im starting to think that you cant treat every machine as the same "black box" that produces the same 90-100 degC worth of water temp and a pump pressure of 8-10 bar.. .. and the only real way we can get the correct flow/volume to a shot is to adjust the grind.. and the same grind on one machine wont give the same results on another machine.. any opinions on this hypothesis guys?

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barry
Posts: 637
Joined: 19 years ago

#10: Post by barry »

what grinder are you using? how old are the burrs?

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