Fiorenzato Doge Conico jamming after switch from single dosing to hopper - Page 3

#21: Post by **OldNuc** » March 29th, 2015, 10:40 am

If you connect a 50/60 Hz AC motor rated for 120vAC to a 240vAC source, wall or transformer, you will promptly let the magic smoke out of it. No motor theory required. The motor may have a failed start cap or open start winding or both. If unclear how to proceed then the local electric motor shop is the place to go.

A motor insulated for 50 Hz will run fine on 60 Hz but run 6/5 x rated RPM @ 50 Hz faster. Start and run cap valuse should be adjusted as required. Stalling is an indication of a failed run cap.

#22: Post by **drgary** » March 29th, 2015, 10:59 am

Rich,

Are "start cap" and "run cap" start and run capacitors? The technician checked the installed capacitor that was mounted on the bottom plate and said it was working fine. He was unable to improve performance by switching that out.

So you're saying one of the windings on the motor may be broken or that there's another capacitor in there that wasn't checked?

#23: Post by **drgary** » March 29th, 2015, 11:02 am

Here is an exploded parts diagram that shows two versions of the motor, and one of them may have an additional capacitor installed. I wonder if we got a version without that? Of course the part isn't listed (see parts 35 and 36).

http://www.cafeparts.com/productDetail2 ... emID=73075

Here's a screen shot of the salient parts from that page.

#24: Post by **OldNuc** » March 29th, 2015, 2:25 pm

Yes, starting and/or run capacitor.

Part numbers 31 and 32 are of interest.

With the beans removed and the burrs opened up the armature/center burr should spin freely. If not that alone may stall the motor. These things are now designed to be Energy Star compliant(or EU equivalent) and have next to no starting torque, will not pull the skin off of a rice pudding.

If the capacitor has degraded at all from the spec the motor will very likely stall.

Part 31 appears to be a run capacitor. If degraded motor will stall.

#25: Post by **drgary** » March 30th, 2015, 9:17 am

The burr does spin freely. Next I'll have to check the apparent run capacitor.

#26: Post by **OldNuc** » March 30th, 2015, 9:28 am

The low cost import capacitor testers measure the ESR of the capacitor and this is only a faint representation of capacitor condition. That is a 12.5 mfd 450v run cap and these ratings are for a 220v 50Hz capacitor. The one in the machine should be adjusted for voltage/frequency differences for best results. You need a good old time motor shop.

#27: Post by **drgary** » March 30th, 2015, 9:43 am

Absolutely. I wasn't going to attempt DIY testing here. What's interesting is the motor shop guy didn't look for the second capacitor in any way that was obvious to me. If a run capacitor is at fault, could his tests on the start capacitor have come up puzzlingly ineffective?

#28: Post by **OldNuc** » March 30th, 2015, 11:28 am

From the drawing that is providing incomplete info I suspect this motor only has a run capacitor which it stalls easily. A real drawing would be very helpful. You have to find the well aged motor person to actually understand the run cap size issue. What was initially installed could be slightly undersized and plain old age has done it in. The individual capacitor test should have been as valid as they usually are. Are there any markings on the capacitor?

#29: Post by **drgary** » March 30th, 2015, 12:29 pm

There's no useful drawing, so I took the bottom plate off after unplugging the machine and didn't touch any leads because capacitors hold charge. This grinder has only one capacitor, and it's this one, which checked out up to spec.

Looking inside from the bottom I could clearly see the motor has no capacitor hitchhiking on the side. That's different than what's seen in this part of the illustration. I don't know if adding Part 31 could give it the extra torque it needs, but again that's beyond my understanding. I've written to Fiorenzato and others and don't yet have a response.

#30: Post by **DaveC** » March 30th, 2015, 1:26 pm

dmw010 wrote:I emailed the vendor, and his only suggestions were that I'm either underdosing/grinding too fine or need new burrs. I've only put maybe 30-40 pounds of beans through, so I don't see how the burrs could be worn out. As for underdosing, I'm generally getting around 30g of espresso in 25-30 seconds with an 18g dose, which seems pretty typical to me.

I also ran a couple of doses of Grindz through it this afternoon, just in case there was any residue gumming things up. Though it looked pretty clean in there from what I could see. It isn't simple to remove the burr carrier and open up the grinding chamber, so I've never done it - the manufacturer definitely did not intend for users to open it up for cleaning.

By the way, single-dosing worked fine today, so the problem only seems to happen when starting the grinder with beans already in the grind path.

I'd like to bring you back to basics, because it's all got a bit esoteric for it's own good.

1. It's totally unlikely your burrs are worn, a conical like that is going to do 500-800Kg+ before the burrs need changing
2. The motor should have more than adequate power
3. 50/60Hz operation on that AC motor will make no significant difference.

Things that don't seem normal....30g of espresso in 25-30s sounds dreadfully slow, however, I'm hoping you're going to say something like it grinds the beans in 4 or 5 seconds, but it takes a further 20 seconds for them all to come out when single dosing, not because it's grinding, because it just takes this long for the coffee to work its way out? If your not saying this.....then that's absolutely 100% not right.

Logically this means 2 things are possible, as conical grinders don't tend to require as much force as flat burrs for a given grinding area.

(a). The ground coffee is building up in the exit path of the burr chamber and when you grind with beans in the hopper, the chamber fills, can't empty fast enough and the coffee is compacted by the sweep arms and stops the grinder. When single dosing, you don't get this as the coffee has more time.

Solution - ensure the exit path from the burr chamber is absolutely clean of grinds and not restricted in any way, check any flap, or other anti clumping device is not jammed in a partially closed position or stiff.

(b). The motor is indeed damaged (it could be a start run capacitor, or a failed winding). You have checked the capacitor, but without a lot of work, failed/shorted windings are not so easy to check. When a motor jams, it becomes a heater and it may have jammed before if you were not the first owner and burnt out part of the windings. if you are the only owner, you will know for how long it jammed....and if you switched the power off pretty quickly, it's not usual for windings to short out....but it can happen quickly, especially if the motor was not well constructed (e.g. factory defect).

Solution - run the grinder with nothing in it....the motor should run absolutely smooth, a slight roughness could indicate defective windings. note this type of test is not conclusive as depending on design a motor with defective windings might still run quite smoothly, but not give the required run torque.

My guess would be a problem (a) above....If you have checked it and it's completely clean and functional, the motor can be spun by hand and is not jamming...then it could well be a defective motor and your Vendor and grinder manufacturer should be eager to replace it and investigate exactly what the problem is in this unit. if I were the manufacturer, I would absolutely want to know if there was a problem with a batch of motors!!