# La Pavoni Pro wiring problem



## Batian (Oct 23, 2017)

Today I started to dismantle a recently acquired La Pav Pro.

On removing the base I found that the wiring was nothing like the previous model I had worked on!

The safety thermostat is not wired in and there is a totaly different pressure stat arrangement.

Should the safety stat be wired or is replaced by the black box attached to the pressure stat gubbins shown in first pic and connectors labelled in red 3 and 4?


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## jimbojohn55 (Jan 15, 2016)

Hi - the lead to the element terminal should be attached to one side of the safety thermostat and then from the thermostat to the terminal, I suspect the thermostat is faulty as they have taken it out of the loop - best get a new one first:good:


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## Batian (Oct 23, 2017)

Thanks. The problem has just got worse.

The thermostat is unlike the previous two. There was no retaining screw.









In trying to wiggle it undone the plastic 'barrel' neatly snapped.









This is the underside view of where the stat is seated.









What do I do now?


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## El carajillo (Mar 16, 2013)

It looks like the threaded screw in type (similar to Gaggia Classic) .Try gripping the remaining plastic and try unscrewing.

If plastic breaks away, gently tap a small FLAT screwdriver tip into the brass pin to form a screw head, then try unscrewing.

If all this fails it may require a small screw extractor or drill out and re-tap thread.


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## Batian (Oct 23, 2017)

@El carajillo

@jimbojohn55

Thanks for your help El C.

I have found this on www:

https://www.home-barista.com/levers/replacing-fuse-in-la-pavoni-europiccola-t17076.html

It looks the same as my busted fuse. The above says it is glued in. It would appear to be glued in to the casr holder part of the heater element base plate??? (see 3rd pic above) There is no brass pin as per yours above.

Does your advice now change?

What should I order to replace the busted fuse ?


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## ashcroc (Oct 28, 2016)

Batian said:


> @El carajillo
> 
> @jimbojohn55
> 
> ...


If it's glued in then you're looking at getting something under it to lever it off or maybe even knocking it out with a chisel or punch.


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## El carajillo (Mar 16, 2013)

Depending on how hard the plastic is you may be able to pick it out with a small screwdriver or pointed awl. I suspect if it has been subjected to heat it may be quite brittle and break out in small pieces.

If it will not pick out possibly use a small drill / dremel to remove it If you use a drill, drill a hole in a piece of dowel to fit over the drill bit to restrict how deep you can drill (you do not want to drill through the bottom of the boiler)

Alternative to a dowel you can use a cable connector (hollow brass) screwed to the drill as a depth gauge.


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## jimbojohn55 (Jan 15, 2016)

agree ^ best to carefully drill - also you could apply a little heat, its tricky because of the proximity of the pressurestat pipe, also the sealant is heat resistant, as above one alternative is to heat up the tip of an old blunt screwdriver that's ready for the bin then plunge it into the plastic so it melts a slot, let it cool for 5 minutes then use the screwdriver to try and twist it out.


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## Batian (Oct 23, 2017)

With BF&BI I have got the u/s stat out. It appeared to be epoxy resin rather than Krazy/Super Glue as suggested in the thread link above.

I had a light bulb moment and used a couple of bits of 3"X 3" to anchor and protect.









The link above also suggests these stats are probably off the shelf and have a range of applications.

Anybody got an any ideas about a replacement to fir the hole? And what the trip temp is going to be?

I have looked at several La Pav parts suppliers and they all seem to supply this:

https://www.theespressoshop.co.uk/en/Thermostat/pg-1-13.aspx

Could I use one of the hex bolts to anchor this part to the casing?

I will ring The Espresso Shop on Monday and see if they know the solution unless someone comes up with a suggestion for a more exact replacement!.

On the plus side...

I was just going to 'touch up' the few rust spots on the underside, but now I have fully exposed the underside, I will do an overall spray-can re paint!


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## ashcroc (Oct 28, 2016)

A resettable one is a good idea so you don't need to replace it again if it kicks in. It's so much easier just pushing the red button.


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## coffeechap (Apr 5, 2012)

I believe it's a thermal fuse as opposed to a stat, a resettable one one be better provided it fits, I can check for you on Monday and let you know


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## Batian (Oct 23, 2017)

coffeechap said:


> I believe it's a thermal fuse as opposed to a stat, a resettable one one be better provided it fits, I can check for you on Monday and let you know


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## Batian (Oct 23, 2017)

The plot thickens.

There was no seal/gasket between the boiler and the heating element. The element base appears to be grooved for them, but there was definitely not one when I took the element off!

Now, I ran the boiler up to the point when the pressure stat cut out to check what was or was not leaking. The pressure gauge was not working, but when the lever was lifted, it was like an upside down 'Old Faithful' geyser. I suspect way over normal pressure and certainly more than my other La Pav.

So I would have thought that an absent gasket/seal that was meant to be there would have meant a flood in the base?

Or was there some La Pavs that were made without this seal?

If it should have a seal/gasket, should it be the rubber or fibre version?

















Thanks everyone.


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## jimbojohn55 (Jan 15, 2016)

if there is a groove then it needs the modern O ring type - I think that the model you have is half way to the pressed steel element type that has the O ring as well. Cant think why it didn't flood unless someone had used thread sealant on the boiler.

Couple of things re the amount of pressure when you tested it

Blow through the pressure stat pipe to check it is not blocked, the pressurestat it self could be faulty or its been adjusted by someone - you wont know till you have the new gauge on it, also disassemble and clean the safety pressure release valve at the top of the machine.

Re the thermal fuse, I think your type can be seen in this page by Fransesco - Im pretty sure its the same size as the modern type but without the bracket to hold it in place. Much of what Pavoni did at the time was look at ways to speed up production and reduce costs, hence moving to a surface mounted element as it was easier and quicker to fit

http://www.francescoceccarelli.eu/La_Pavoni/Faidate/termostato_eng.htm


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## Batian (Oct 23, 2017)

The latest update.....

The gasket/seal groove referred to above (with pic) is not as it looks! Some scratching of the surface verdigris revealed the remnants of a gasket/glue. I have cleaned it all out with a Dremmel fitted with a brass wire brush.

I have dismantled the pressure stat diaphragm.

It was full of crud and well corroded. The conical spring was corroded in place.

It did 'brush up' but I am still left me thinking, in view of its age and the behaviour of the machine pre dismantling, that for the sake of a few £s the peace of mind would be worth it.

Re @jimbojohn55 comments on the safety valve.

I had already dismantled that as the seller had reported he could not stop it leaking. I found no leak on the test , but I took it off anyway , mainly so the exhaust pipe was not damaged whilst I worked on the machine.

It is (no surprises) different to the one on my other La Pav which has a plastic 'float'.

This one is a ball bearing and spring.

Should I go the whole hog and replace the safety valve innards while I am at it?


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## jimbojohn55 (Jan 15, 2016)

Safety valve should be fine as long as its clean, with no scale

agree pressure stat should be replaced some bits cant be repaired,


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## Batian (Oct 23, 2017)

Update.

Cleaned down the few rust spots on the underside of the base and treated prior 3 coats of Hammerite.

Banksy need not worry.


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## Batian (Oct 23, 2017)

coffeechap said:


> I believe it's a thermal fuse as opposed to a stat, a resettable one one be better provided it fits, I can check for you on Monday and let you know


The bits and pieces arrived from The Espresso Shop today.

The Espresso Shop gent told me that the thermal fuse does not fit the hole. He agreed with my original plan to use one of the heater holding hex bolts to secure the fuse with the supplied yoke.

I offered it up with this in mind, but the contours of the base of the heater would mean it necessary ro make a new yoke.

However, it's only a gnats whisker to tight in the hole. So I used a Dremmel type tool to ream it out a tad. Drop of epoxy resin (good to 177C) and crossed fingers.

The other minor worry is that the fuse reset button is on the squiffy. It may have been damaged in the post?


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## jimbojohn55 (Jan 15, 2016)

a quality solution


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## ashcroc (Oct 28, 2016)

Looking good. Hope you checked for continuity before glueing it in.


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## Batian (Oct 23, 2017)

ashcroc said:


> Looking good. Hope you checked for continuity before glueing it in.


I did!

With aforethought, I should have checked the fuse and reset worked by using a cigarette lighter. But by the time I had thought of that, the glue was set.

Amateurs huh?


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## Batian (Oct 23, 2017)

Update...

The wiring has been refitted. What a pile of spaghetti. The more I looked at the wiring diagram (above) and the mass of wires of seemingly inconsistent colours the more confused I became. In the end, I took the base plate of my other La Pav and copied that. A quick check around with the multi meter and a current detector and I fired the boiler up. It heated OK but as the bits and pieces were not attached, I could not test the new stats.

Next job was some polishing. SolVol Autosol on the back of a piece of leather has done a reasonable job. The grooves were done in a similar way by cutting a piece of leather to fit and pushing it round with a bamboo kebab stick! The piston shaft channel was done with a cotton bud.









The piston has had some abuse. I suspect that someone had clamped it in a vice (to undo the shaft) without protecting the brass. The worst scoring was on the leading rim of the piston and can just be seen in the picture. I am hoping that as it is clear of the bore, it will not be a problem.


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## jimbojohn55 (Jan 15, 2016)

Looking good, I think the piston will be fine - there is no sign of scoring in the cylinder so the new seals should keep it clear,


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## Batian (Oct 23, 2017)

Advice please @jimbojohn55

The seller reported a leak at the top of the sight glass/pressure gauge nut.

When I fired up the machine pre disassembly no leak was apparent. However on dismantling, the Teflon washer was in pieces. So I have purchased a new washer, nut and gauge.

No here is the problem. The first part of the female thread seems to have been stripped. With the Teflon washer in place there is no 'bite'. With the washer removed it tightens well.

Should I use some thread lock, and if so what is recommended?

I have a set of taps and dies---should I re cut the thread, and if so you wouldn't happen to know the size needed?

Or should I forget the Teflon washer and use some form of liquid gasket in place of....?

Thanks in advance...


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## jimbojohn55 (Jan 15, 2016)

Batian said:


> Advice please @jimbojohn55
> 
> The seller reported a leak at the top of the sight glass/pressure gauge nut.
> 
> ...


It's 11mm, pavoni made it an awkward size to stop people adding gauges to euros easily,

Not sure what thread lock you would use but try PTFE without the washer, ?


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## Batian (Oct 23, 2017)

Advice (again!) please @jimbojohn55

This machine is fitted with an early type steam wand---not the bayonet fitting. An earlier user has fitted a single hole tip.

It is a rather crude gruesome device.

It has also 'modified' the thread such that a new replacement 3 hole tip will not screw on! He ho.

My best hope will be to find a new (economic) replacement, but ...............

Can you tell me the thread size please and I will have a stab at it. I have limited ability and a basic die set M3 to M10!


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## Batian (Oct 23, 2017)

Update @jimbojohn55 see above!)

Looking closer ar the steam pipe thread I could see only half the length had been butchered, So I cut the bad piece of and Dremmeled the cut surface free of swarf and bevelled it. The La Pav 3 hole tip now goes on to what remains of the thread, but more of that later.









Above is a pic of the shower screen, after a wipe and before the Pulycaff. It is being replaced anyway so I was not to bothered.. The portafilter and basket were much the same.

I wonder what the last cup of coffee from this machine tasted like?

I have now reassembled the machine and fired it up. The pressure stat cut in at 1 Bar. I repeatedly tested this until the full tank had flushed the system. The only little niggly leak is at the steam tip that allows a slow drip to form when in use. I expect there is not enough thread left after my chop. I tried some PTFE tape with no improvement. So I expect it needs to be cut back some more? @jimbojohn55)

Rather pleasingly, the vacuum created when cooling made the lever rise...just as if it was the 'barista of pulls past' come to haunt.......

So I can assume the seal replacements and cleaning and polishing have been a success.


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## jimbojohn55 (Jan 15, 2016)

Have you changed the fat washer in the steam valve? The other thing it could be is if the metal end of the steam valve rod is deformed at the chamfered end. Also try tightening the coller nut on the steam valve as it makes the fat washer seal.

Cheers jim


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## jimbojohn55 (Jan 15, 2016)

I meant to say above extending the thread on the steam arm is fairly straightforward just Dremel of the chrome a bit first and use oil as you cut


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## Batian (Oct 23, 2017)

jimbojohn55 said:


> I meant to say above extending the thread on the steam arm is fairly straightforward just Dremel of the chrome a bit first and use oil as you cut


Thanks...but what size die Jim?

Re the dribble at the steam tip..

Just a refresh The steam wand is the old fashioned type, NOT the bayonet fitting. It only shows when the steam valve is opened and steam is gushing under pressure from the tip. It is exuding from the thread.

So can I assume that the washers at the valve and the connection of the pipe to valve are OK?


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## jimbojohn55 (Jan 15, 2016)

I think the steam arm is m5 or m6 find a couple of m5 and m6 bolts and see what fits the new steam tip


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## jimbojohn55 (Jan 15, 2016)

Batian said:


> Thanks...but what size die Jim?
> 
> Re the dribble at the steam tip..
> 
> ...


its hard to say, if its just coming from the thread then try some ptfe tape - if its the joint of the arm to the valve then you need a small o-ring - I think both halfords and toolstation sell mixed box,s


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## Batian (Oct 23, 2017)

jimbojohn55 said:


> I think the steam arm is m5 or m6 find a couple of m5 and m6 bolts and see what fits the new steam tip


Done. For future reference, it is M6.


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## Batian (Oct 23, 2017)

I have put a new thread on the steam wand. This was the first time I have used the cheap 'tap and die' set I bought in Aldi several years ago on the basis of 'they will come in useful one day. It was also the first time I had done any thread cutting since skule........

For the benefit of those who, like me, do not have an engineering background, here are a couple of pointers.

The steam wand is chrome plated brass and therefore quite soft. I think this softness actually made it difficult to start using the M6 die. I could not get it started and keep square to the wand. So I went up a size to M7, cut the length and then re cut with the M6.

I used some oil (3 in 1) as @jimbojohn55 instruction, and a 'cut and back, cut and back' action to keep the swarf clear.


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## jimbojohn55 (Jan 15, 2016)

Looks fine to me, god bless the Aldi god's, almost makes up for their bean barrels ;-)


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