Hi all,

I'm wondering if you can help me. I rebuilt a Nuova Simonelli Appia with volumetric dosing and I am now at the point where I'm putting it through its paces. I noticed the power button is stuck in the "on" position, a few of the LEDs are not illuminating including the one over the power button, and when I first started the machine the pump motor would continue to run after the autofill probe had shut off the autofill solenoid. I had to unplug the machine a few times to make this symptom disappear. The machine will continue to heat whether the keypad is plugged in or not. All other functions are normal including the pressurestat, it will cycle the element on and off according to boiler pressure.

I was very careful to only remove as many wires as was required to remove the harness from the frame. Everything was labeled, and put back in its proper place. It is possible a wire may be crossed but everything matches visually to the photographs I took before disassembly.

I wonder if anyone knows how I could narrow the problem down to the keypad or control card, and what points to check with my meter. The pump was seized when I bought the unit, so I did not run it up completely before disassembly, but I'm pretty sure the power button worked as it should. Also, is there anywhere I can send either the keypad or control card for repair, or am I stuck buying new units. Thanks very much

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First off, unplug the machine and do not plug it in again until you know for sure it is wired correctly.  It is possible that you are in danger.

It sounds like you're getting some electricity where it shouldn't be.  Or, at least, it's leaking through the CPU for some reason.  The only thing I can recommend, and I've rebuilt several Appias, is to get the electrical schematic and then go through the circuits, starting at the terminal block, and trace forward using continuity.  Mark the wires with sharpie or tape as you go, keeping leg 1, leg 2, and ground separate and make sure everything is connected properly.  Also double check the way the cord cap is wired, if you are using a three prong twist lock plug, or any plug, then make sure you don't have a hot leg feeding into the ground.  Decoding the wiring schematic when looking at the CPU hook-ups can be confusing so you should make sure the wiring harness connections that feed into things like solenoids, probes, and pumps are in the correct socket.

If I had to guess what the issue was, beyond a blown CPU board, is that Ground and one of the Hot legs has been switched.  220vac machines like that typically route one of the hot legs directly to all electrical components and route the other through the CPU to control the components.  If the control leg was switched with ground you'd supply many of the components with both legs through their ground connections which would feed the pump motor via the chassis and rob the CPU and buttons of the leg they used to control the machine.  So some things would always be on and some others would never function.  The other issue with this is that when you back feed 120vac into the Ground you can shock yourself pretty bad, possibly lethally, if you touch the frame and ground the voltage, and you can blow up some of the electrical components on the CPU as many ICs don't like voltage where they aren't expecting it.

Pictures can be a good reference tool but you cannot depend on them.  The only thing that really matters is being able to use your meter and trace your way through the schematic.  Something I always tell myself, and anyone who I've ever trained, is that you cannot forget that there is enough electricity in those things to kill you.  Triple checking your connections based on a thorough understanding of the schematic is not unwarranted before you ever plug the unit in and certainly before you turn the unit on.

Once you have verified the connections via schematic the only other thing is that the CPU is blown and you'll have to replace it.  It would be possible to repair these items, theoretically, but would cost more than a new one.

I can't really tell you what "points" to check.  That knowledge comes from knowing how electricity works in general and how it functions specifically with each component of the machine.  When you understand that and have the schematic in front of you then you can test any point you need.  Be careful.  Call Nuova Simonelli if you get really stuck.  They are super helpful and really knowledgeable.

Hi Mike,

Thank you so much for your long and well thought-out reply. I paid more than I'm comfortable with to purchase this core, and while there was very little wrong with it, this problem has me very concerned about my investment. I'll clarify a few details:

It is a 2007 model, 110V 1500W.

Disconnected from the control card were:

-the original cord and plug (plug is a molded assembly)

-connector for the doser keypad

-connector for the autosteam sensor

-connector to the pump motor

-heating element

No other wiring connections were disturbed. Harness and solenoid coils, pressurestat, thermal safety switch were all removed as an assembly. I've included pictures of the power cord wiring connection terminal strip before disassembly and after reassembly, they're identical. Brown is hot and blue is neutral if I remember correctly. So I guess the only question is how this control card could have gone to pot just sitting in a parts bin for two weeks? And am I really into a control card or is it possible the keypad is causing these problems? It would seem not, as it continues to run with the keypad unplugged. I'll definitely call NSusa in the morning and see if they can shed some light. Thanks again for your advice. Cheers


I like Mike's post - some good considerations. Double-check all of the electrical connections and verify that things are as expected at the terminal block.

The switches on the volumetric Appia are momentary, so the fact that the unit continues to send power to the pressurestat and pump after unplugging the keypad doesn't really tell us much. What would be really useful to know is what happens when you plug the unit in with the keypad disconnected. If the unit begins heating right away, it seems unlikely that the problem is the pad.

If it was on my bench, my first suspicion would be welded relay(s) on the main board. If that were the case, the machine would send power to various components any time it was plugged in, even if the touchpad were disconnected. I don't think this unit has a big block-style relay (contactor) like the larger 208-240V ones, but if it does that would also be a possible culprit.

Remember that seized pump can be a primary failure or a secondary failure. If the pump relay had welded shut the pump would burn itself out pretty quickly.

Good luck.

Hi Brady,

Thanks for your interest. The machine powers up with keypad removed. It's odd to me that a couple of LEDs are blown on the keypad as well, because I would think that they would all be powered from one source but I suppose they could be switched from transistors on the control card as well. In any case, the power LED and single and double tall LEDs never illuminate. I tried to measure voltage with my DVOM, but was getting very low voltages on both the lit and unlit LEDs, like 1.75 to 2.3VDC (I tried AC as well with no change in the numbers).

Is there any condition you can think of that could cause welded contacts? Or an overcurrent to overload and burn contacts? I could swear these symptoms didn't exist when I first powered-up the machine, but perhaps the unit was hit with a power surge?

Thanks again for all your help. Will be calling NSusa as soon as they open. In the meantime, I'll try and map-out the relay pins and check continuity on them. Cheers

*cue funeral music*

Sounds like the main board to me. Disconnected the ribbon cable from the board side, right?

I've always suspected stuck relays result from a power surge or heat issue, but really don't know. I once had to replace a melted block relay after a squirrel decided to check out the building's main electrical transformer...

Good luck!

Latté 911 said:

Hi Brady,

Thanks for your interest. The machine powers up with keypad removed...

Sorry if my post was a bit hyperbolic but I tend to be a safety weenie...

It does sound like some voltage got into the CPU, perhaps some static, and blew out some transistors on an IC or something.  As for the lights on the keypad you should compare the good ones to the bad ones and see if the bad ones are getting sent the same amount of juice as the good ones are.  If they are then the light on the keypad is bad.  If not then it's all in the CPU.  I would use DC and check one side of the LED and have the other probe on ground. It's possible that what ever got into the CPU to blow it got into the keypads too and took out a few of the LEDs.

Thanks guys,

I've got the local dealer checking price and availability for me right now. I already know the list price, and as a tech I should be getting a bit of a break on it, so I'm not as concerned as I was last night. It does seem like the relay contacts might be sticky but I was out all day on admin duties, so I'll start to poke around again tonight with the meter and see if I can isolate whether I have a shorted relay or a constant trip voltage.

Have you guys tried replacing board components? The main relay is an ERA, and the other smaller relays are I believe CHF. I have an old single-sweep oscilloscope that I can blow the dust off of if need be. Though at $100 and $300 respectively, I can't see how I'd get in under that if I needed an IC with the time it'd take. I think you're right, Mike, into the bin with them. What a shame.

Edit: I think I may know what happened. I installed the harness and cards into the machine while it was sitting on my stainless sideboard. The machine frame is insulated from that with its rubber legs, but there's a possibility I may have touched a wire going into the card before I touched the sideboard and caused some ESD damage. I'm going to have to either rethink using a stainless work surface or modify it with a static wriststrap or something. What do you guys do? I just wanted a sanitary work surface.

Thanks again

Huh. I don't do anything special regarding ESD, just touch something metal before messing with the board. ESD isn't gonna weld a relay, but you already knew that.

I'm not talented enough to even consider repairing a board, and always replace. I kinda figure anything that's big enough to fry a relay probably did more than that while it was in there anyway.

Local dealer? If you're doing tech work you ought to try to get set up with all of the manufacturers whose machines you deal with and buy parts from them. There's really no other practical way to buy the amount of inventory you're going to go through. Reseller and/or service partner discounts have changed a bit with some manufacturers recently, but you should still be able to get enough of a discount from all of your suppliers to be able to cover shipping and make a little bit when you charge list.

Hi Brady,

I was just off the phone with the Simonelli dealer *closest* to the Toronto area. I won't give their name, but you could find out easily enough.

Simonelli has the price of the main control card published on nuovadistribution at $319.30 USD plus taxes and shipping. The *local* dealer said straight out they price above list at $449.21 CAD plus taxes. They were willing to give me a 25% discount off their price at $359.21 CAD plus taxes. Gee, thanks. So much for a local partnership. For comparison, ECM Parts in BC quoted me $275 CAD plus taxes and shipping for the same card. There's Espresso Mali in Montreal that I can try tomorrow, but the ECM price will be pretty tough to beat. I have already set up accounts with a couple manufacturers with Canadian distributors, but most of the best sources for them are in the US so it's a bit more difficult to make a profit on parts with brokerage on top of shipping unless buying in huge orders. I will be doing more of that as I become established and a bit further into the black. Right now it's long hours, Kraft Dinner and hotdogs. Cheers

I've had success with getting control boards repaired, but only if I knew what the problem was.   Usually the cost of repair has been far less then the cost of the board, though I've probably only done this with very expensive boards.  I'm not sure this is a board problem.  Could you restate all the issues you are having now, in a list and in the order of occurrence?  Like this-

1 - problem one

2 - problem two

3 - etc.......

Since you did take the wiring apart, I'm highly suspicious of that.  One of my techs, who has a degree in electronics no less, wired a control board wrong a couple of weeks ago.   So it happens.    

Hi all,

Thanks for the help. It appears both the control board and the keypad board were damaged by ESD. The new control board solved the autofill problem, but replacement of the keypad was necessary to return function to the power switch and burnt-out LEDs. Luckily I found a supplier in Canada that gave me a very good price on OEM control boards. If anyone knows a supplier that can repair these boards, it might be worthwhile to have them rebuilt as spares. Cheers

So I've had the Appia sitting in my showroom unplugged for a month now. I recently powered it up to demo it, and two of the LEDs are out again!

The unit has a new control board, keypad board, and ribbon cable. I was very careful to observe proper ESD protocol e.g. hooked a wriststrap to the ground peg inside the control box. No other machine I've ever worked on has had cards this fragile, and as a former electric forklift tech I've handled hundreds. I'm now having a problem with the control board on a Faema Due that's been in my shop for a couple of months: the manual start/stop buttons on the volumetric keypad (which I replaced with brand new) do not work but everything else does.

I know enough now not to handle the board while I have the machine up on the stainless sideboard. But that didn't stop these boards from failing. I'm at my wit's end - this is getting expensive.

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