I have a Ponte Vecchio Lusso that has served me well for several years. Lately, however, the electrical system has been misbehaving.

The most recent symptom is that one of the wires is overheating. I replaced the switch after it melted, assuming, incorrectly, that the problem was with the contacts of the switch itself. Now, with the new switch in place, the wire coming into the same contact that melted away (see the dark blue wire in the attached image) quickly becomes extremely hot. The light brown wire (coming out the other side of the switch) also heats up. This light brown wire connects to slot 4 in the electronic brain (see picture).

Any insights would be appreciated.

For context, I replaced the brain about six weeks ago after the machine stopped heating.

Hi
Do you have a pic of the switch original wiring configuration before you replaced it?
What I can see is that you have active and neutral connected together through the switch, which will overheat when you activate it. They need something between them such as a light, element, motor, solenoid etc to use the current flowing between the wires.

Usually on the switch in the pic, the wires are connected brown (on top) with brown (below) and then blue(on top) with blue(below).
The switch connects the wires and completes the circuit when switched on( brown on brown, blue on blue), which then powers the item it is connected to such as pump, light, heating element etc.

It seems you might have a short circuit the way it is wired in the pic above.

Cheers
Gor

The brown wire out of the control box is 'hot' and is connected to dark blue which is neutral(power wire coming into machine).
As soon as you press switch on, the connection between 'hot' brown wire from control box, and neutral blue wire from power cord coming into machine is creating a short circuit.

How your machine is working at all is a pure fluke.

gor wrote:Usually on the switch in the pic, the wires are connected brown (on top) with brown (below) and then blue(on top) with blue(below).

Yes. That is the convention (brown/black wires are generally line, blue/white are neutral.)

However, I disagree that this odd wiring is causing a short when the switch is turned on. (If it was, you would have major fireworks and no coffee when you flipped the switch on.)

If we assume that the brown wire from the cord is Line (hot) and the blue wire from the cord is Neutral, then when the switch is on, the lavender wires inside the machine become Line (hot) and that brown wire that goes from the switch to the controller carries Neutral. Not a good color choice, but would not create a direct line-to-neutral short. (It's true that you have a blue wire connected to a brown wire at the switch when it's flipped on, but they are both neutral, so no fireworks.)

The machine will work fine with Line and Neutral reversed, as long as it's consistently reversed. If you have a picture of the original wiring, take a good look - you may have reversed two of those switch wires when you made the change. You can simply swap the position of the brown and blue wires from the cord and then your machine's wiring (and wire colors) should be more conventional.

As to what's causing the burnt terminals/switch, I suspect the connector on that blue wire is bad, which generates a lot of heat, which spreads through the switch contacts to that brown wire's terminal. I'd replace the connector on that brown wire as well, just to be sure, as well as any others that are looking overheated and discolored. Your new switch may be damaged as well.

When replacing you need high quality connectors and a good crimping tool (and good technique.) Some people advise carefully done solder in addition to crimping. You can search here on HB and on the internet for technical guidance about crimping connectors. Here's an informative recent thread about a similar issue in which some electical experts have weighed in with advice about terminals, crimping, soldering, etc.: La Pavoni Europiccola melted electrical connection - What happened here?

This is the diagram for the simple level controller that is in the machine ( image source from the net and HB).

Homeburrero you are right in saying that the reversing of the line and neutral will have no effect in the way the machine operates since the level control portion is via the transformer (probably 12 volt) which will continue to operate if lines are reversed. Whether the relays switch a hot or neutral doesn't really matter.

You are most probably right that loose spade connections have created heat that is the cause of this problem.

I found another pic on HB with the wiring connected the same (reversed).

Thanks to everyone for their helpful feedback. The issue seems to be resolved now.

Long story short: it was the contacts

Long story slightly longer:

I tried swapping the dark brown and dark blue wires and saw the exact same behavior: wires too hot to touch within a few seconds.

(side note: the machine was working fine for quite some time with them swapped: Dk Bl connected through switch to Lt Br and Dk Br connected through switch to Lt Bl. Based on faint memories from a circuits class taken many years ago, this makes sense to me. However, looking back to some old photos taken when I started tinkering with the machine, I did see that these leads were reversed when I installed to new brains and new switch a few months ago. Interestingly, I think I used the photo @gor posted as my reference when I put everything back together - note to self about photos from the internet, ymmv)

A quick trip to the hardware store and an outlay of $0.51 produced four shiny new connectors, which, after installed, resulted in cool, happy wires.

(note 2: all four wires were rather corroded and I ended up cutting back 0.5" to get to shiny copper for the connectors)

Here's a pic of the new assembly:

Yes. glad too see this is working out. We had a thread a while ago on just these types of connectors, which apparently all fail eventually. I had the same problem on my Lusso and thought it was the switch itself. But when I changed to wires it seemed to fixed the problem also.

Good to hear from another Lusso user.
PC

I had a similar problem a year or two ago. For me, it was the brown wire getting so hot it would melt the plastic connectors. I noticed the wire was very corroded and cut off a few inches to get to some bright copper. This solved it for a couple of months and then it came back (I could always detect it early due to the smell of burning plastic). I performed the same fix (a couple of more inches) and bought another two months. During this time I purchased a roll of high temp wire and when it died again, I replaced the whole wire and no issues since.

I mention this because I think once you notice some corrosion on the wires, it would be best to replace the entire wire - you have time now to find what you need on ebay.

Thanks bmac. As you predicted, here I am three weeks later with the smell of roasting wires coming from the system. Time to look for new wires.

I purchased a roll of high temp wire

I searched quite a bit and couldn't find a good source for high-temp wire. Could you post a link and some specs for it?

PC