Rocket Appartamento Scorching Wire Connectors

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
achosid
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#1: Post by achosid »

There are clearly some manner of electrical gremlins living in my Appartamento. I previously had a blocked thermosiphon preventing the grouphead from heating up, but I had the machined looked over by a local tech and the grouphead is perfect now. Previously, however, I had issues with the machine overheating, tripping the hi-temp resets, and when I look to click the reset finding that the wire connectors are scorched, insulation is melted, or the spade connector cover is melted. I've been through three pressurestats and at least eight hi-temp sensors (almost always because the wire melted onto them and I couldn't remove the spade). I'm running out of ideas here: is there anything else to do here besides trying to replace the entire control board?

jwmelvin
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#2: Post by jwmelvin »

Melted connector at the spade indicates excess resistance in the spade connection. I had the same thing in my Gaggia Classic, to the point that the insulator burned. I had to slightly crimp the female spade connector to improve the fit and shortly thereafter had to get a new thermostat (where the connection was). Some electrical contact cleaner to remove oxidation may also help.

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BaristaBoy E61
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#3: Post by BaristaBoy E61 »

Spade lugs have to fit tightly !
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

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Jeff
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#4: Post by Jeff »

Unless something has changed, they route the full heater current through the pressurestat without an SSR. While this may work on 230 V, it is a common failure point with 120 V machines that run roughly twice the current. Installing a SSR seems a better alternative to keeping a stock of pressurestats on hand. Search should find several threads on how to do this.

(Clean, well crimped connectors and wire of sufficient gauge are needed in any event.)

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homeburrero
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#5: Post by homeburrero »

achosid wrote:I've been through three pressurestats and at least eight hi-temp sensors (almost always because the wire melted onto them and I couldn't remove the spade). I'm running out of ideas here: is there anything else to do here besides trying to replace the entire control board?
I don't think the control board is involved in these failures. I agree with others that bad connections or crimps are more likely. If your pressurestat is switching full heater current* then it may not last long on the 110V machines, but most people just replace them and typically they don't show signs of burning at the connector when they go bad. The fact that you are also frying thermal switches implies that your problem is likely faulty connections.


Instead of crimping a failed connector I think you should cut back or replace the burnt wires, and crimp on new connectors with a quality crimping tool. Do a tug test of the wire and connector, clean the spades of the pStat and thermofuse, and make sure the connector fits tightly to the spades.


* If you can trace both of those wires that attach at the pStat back to the control board, then you have a wiring version where a control board relay does the heavy current switching rather than the pStat. If you have one wire at the pStat going to the controller and the other going to the thermofuse or element, then your pStat is handling the full current and is more likely to fail early. The latter is preferred and used on later Appartamentos because it's cheap and easy to replace a pStat, but expensive or difficult to replace or repair a controller.
Pat
nínádiishʼnahgo gohwééh náshdlį́į́h

achosid (original poster)
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#6: Post by achosid (original poster) »

I was about to order new wire and spade connectors from Stefano's. Am I correct that 14 AWG is appropriate for this application?

I've checked my machine before: I have the model where the heavy work is on the pStat. Current one is only a few months old, so I imagine it's unlikely I already need to replace it. I may order one to have it on hand, just in case.

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GregoryJ
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#7: Post by GregoryJ »

I think 14 gauge is good. I've had a very similar problem on my Profitec. WLL said they couldn't send a replacement wire harness, but they sent some blue insulated spade connectors, which are typically for 14-16 gauge wire. They said over many heating cycles the spade connectors can come loose, which creates the high resistance and heat. It's really alarming to smell the burning plastic, and it's happened to me twice in 2 years.


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BaristaBoy E61
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#8: Post by BaristaBoy E61 »

Jeff wrote:Unless something has changed, they route the full heater current through the pressurestat without an SSR. While this may work on 230 V, it is a common failure point with 120 V machines that run roughly twice the current. Installing a SSR seems a better alternative to keeping a stock of pressurestats on hand. Search should find several threads on how to do this.

(Clean, well crimped connectors and wire of sufficient gauge are needed in any event.)
+1

While there's a lot of good advice in this thread, if this were my machine this is the direction I'd be going in, as well as beefing up the wire gauge.
"You didn't buy an Espresso Machine - You bought a Chemistry Set!"

achosid (original poster)
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#9: Post by achosid (original poster) »

Do you think 14 AWG is sufficient, or thicker?

If I were planning on keeping this machine long term I'd do the SSR upgrade, but I'm planning on upgrading this spring.

Davi-L
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#10: Post by Davi-L »

I have repaired 2 or 3 Italian espresso machines. The wiring is the weak point indeed. Going from 230V to 120 American voltage is a problem. Do upgrade the wires to 14G if they carry high currents.
Do install high quality crimp-on connectors. Cheaper crimp-ons from hardware stores do not cut it.
They come in many flavours and T&B are my preferred professional connectors. I use a simple hand powered crimp tool. But I know exactly how how hard to squeeze it. Pick what works for you. The tighter the better. Always crimp on shiny copper wire. Not greyed out stuff. and do check once a year to see if there is any colour changes in the crimps or wires. If so, replace them. The plastic over covers are just for looks, they do nothing but warn you that the connector below is way beyond over temp. Time to replace. After 10 years, I've not had to repair the wiring on my Alexia.
It can be done, and there's no magic in it.
Dave