# Gaggia Classic Re-build



## It02s28 (Feb 24, 2019)

Hi all,

So some of you may have seem my other posts where I've enquired about what espresso machine and grinder to buy etc.

I emded up opting for a Gaggia Classic (2008, Italian made with the 1425W power rating) which I picked up off a fellow Forum member and also the Sage Smart Grinder Pro.

I stripped it all down earlier on in the week to fully descale/clean and replace all seals/gaskets/thermostats that come with the Service Pack sold by Espresso Shop. I also caught a bad case of upgraditus and bought the brass shower head, IMS shower screen, Happy Donkey bottomless portafilter and the parts required to build portafiler with pressure gauge to mod the OPV pressure - really nasty that upgraditus!!

So last night I re-assembled it all (including covering the two terminals on the boiler thermostat after the plastic cases snapped off), turned it on at the wall (all buttons on the GC in the off-position) and it tripped the 'Protected by RCD' fuse! I've read that one cause might be residual moisture around the boiler and to solve this, I could disconnect the earthing wire coming from the power socket to the metal lid and then turn it on again for 15 mins to effectively cause excess moisture to evaporate.

Any thoughts on this solution or does anyone else have any ideas on what is tripping my fuse and how to resolve it!? P.S It was working before I started taking bits off....

Thanks

Chris


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## El carajillo (Mar 16, 2013)

Did you get the boiler terminals wet while working on your machine ? If you did not then the problem / short could be elsewhere .

If it is wet terminals you will need to disconnect the main earth not just the one to the lid /top. â€‹âTake great care if you remove the earth, you will have no protection if you accidentally touch any parts


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## It02s28 (Feb 24, 2019)

El carajillo said:


> Did you get the boiler terminals wet while working on your machine ? If you did not then the problem / short could be elsewhere .
> 
> If it is wet terminals you will need to disconnect the main earth not just the one to the lid /top. â€‹âTake great care if you remove the earth, you will have no protection if you accidentally touch any parts


By 'terminals', are you referring to the four silver prongs pointing out the top? I was very careful with keeping them dry but fear my partner could have got them wet when she tipped the puly caff solution out the boiler...

So if I was to disconnect the main earth as you recommend, when would I know when to reconnect it?


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## El carajillo (Mar 16, 2013)

WARNING I have not had occasion to try this, from other forum members report's, you will hear fizzing and crackling, when this ceases the insulation should be dry. Switch off at wall socket and unplug. Reconnect all earth connections, plug in and carefully switch on. DO NOT TOUCH ANY METAL WORK.

If machine works OK proceed cautiously . If it trips again you have other problems. ( could still be a problem with the boiler ) or something else shorting to earth.


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## It02s28 (Feb 24, 2019)

El carajillo said:


> WARNING I have not had occasion to try this, from other forum members report's, you will hear fizzing and crackling, when this ceases the insulation should be dry. Switch off at wall socket and unplug. Reconnect all earth connections, plug in and carefully switch on. DO NOT TOUCH ANY METAL WORK.
> 
> If machine works OK proceed cautiously . If it trips again you have other problems. ( could still be a problem with the boiler ) or something else shorting to earth.


Thanks for that. I assume yoh reconnect the earth after?

After leaving it to stand for 3 days, i've just tried turning it on again before fiddling with the earth wires and now instead of it tripping when I turn it on at the wall, it's tripping when I press the power button on the machine.

I've bought a continuity tester and will check the wires when it arrives later. Any where in particular that I should start first?


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## El carajillo (Mar 16, 2013)

Disconnect the 4 wires to the boiler terminals (note their positions) On each side of the boiler you will see a 'U' shape, these are the heating elements.

Set your meter to lowest ohm =resistance setting .Touch the meter terminals together, this should give you a reading of zero.

Touch the test leads , one to each end of a 'U' s terminals, this should give a figured reading . Repeat this on the legs of the other terminal.

If no reading, try leads one to a terminal the other to the boiler case, if you now get a reading there is a short , a fault in the heating element.

Repeat same test on other 'U' to boiler case.


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## It02s28 (Feb 24, 2019)

Many thanks for your advice and patience. I have tested the ohm (resistance) between each set of terminals and they each settle at the same reading "21" (ohms). What does this tell us?


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## El carajillo (Mar 16, 2013)

Sounds as if the boiler is OK. Did you try terminal to case ? presumably a zero reading.

Look carefully for any bare wires / terminals touching the case or boiler.


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## It02s28 (Feb 24, 2019)

There was no reading at all when I tested it to the case.

I did have two of the steam thermastat plastic clips snap off so I covered them each with insulation tape. Shall I remove this and try again?

Also, are there any photos that I can provide you with that may help?


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## It02s28 (Feb 24, 2019)

Hopefully these of some assistance!!

There is a chance that I may have re-connected the wires the wrong way round on the steam thermostat. I don't think this would cause it to trip but very happy to be told differently!


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## ashcroc (Oct 28, 2016)

It02s28 said:


> Hopefully these of some assistance!!
> 
> There is a chance that I may have re-connected the wires the wrong way round on the steam thermostat. I don't think this would cause it to trip but very happy to be told differently!


The thermostat is omnidirectional (it's nothing more than a switch activated by heat) so it doesn't matter which side the wires go - so long as they're the right ones.


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## It02s28 (Feb 24, 2019)

Thanks Ashcroc, I thought that was the case. I am sure i've connected the right ones to it. The mystery continues...


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## El carajillo (Mar 16, 2013)

Boiler readings OK, swapped stat terminals does not matter, insulation on stat terminals for your safety.

RE-reading from the start, with both switches off and tripping RCD suggests a problem between plug and GC switches.

Check the wires in the plug for loose or stray ends and check the cable for damage ,check socket and wiring on rear of machine (all connections clean and tight no loose strands) Trace from rear socket to GC switch for any bare wire / loose strands.

The earth terminal on the rear socket looks as if it has been damp at some point. The live terminal looks slightly discoloured (but it may be shadow fro earth terminal in photo)


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## Agentb (Feb 11, 2017)

My GC solenoid has three connectors and only two need to be used, the third, unused one is an earth. I can't see from any of the photos which way that is wired. Good luck!


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## It02s28 (Feb 24, 2019)

Does anyone know what happens when you press the power switch? It seems to me that the fault is likely to relate to whatever it is linked to.

Here is a better photo of the solenoid valve which shows that the middle pin is the only one that doesn't have a plug on it, whereas the pins either side do - one with two wires coming off it and the other with just one wire coming off it.


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## It02s28 (Feb 24, 2019)

Disaster! Pushed the switch assembly back in and the thing practically exploded in my hand. 'Straw that broke the camel's back' comes to mind... absolutely gutted.

So in summary; i've got a GC fully cleaned, descaled, fitted with new gaskets/seals/thermostats, a brand new IMS shower screen with brass shower head, bought a brand new spanner set, adjustable wrench set, PTFE and insulation tape, a multimeter, bottomless portafilter, pressure gauge ready to do the OPV mod and spent £160 on a Smart Grinder Pro...and now i'm going to have to admit defeat and send it somewhere to get it working (which will invariably involve a new button assembly plus other parts).

Where should I send it to guys??


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## MrShades (Jul 29, 2009)

The central metal rod holds the entire switch together. If you pull it out at either end then it'll explode in a mass of small springs and bits of metal.

It's reasonably straightforward to put it back together again - but it does take some skill and patience.

You may find more about the Gaggia switchbank and reassembly if you google or look on YouTube.

Good luck - it's quite good fun and quite satisfying to get it all back and working again - honest


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## L&R (Mar 8, 2018)

You will need a new switch because yours is cracked, you can't assemble it back with broken back panel.


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## ashcroc (Oct 28, 2016)

MrShades said:


> The central metal rod holds the entire switch together. If you pull it out at either end then it'll explode in a mass of small springs and bits of metal.
> 
> It's reasonably straightforward to put it back together again - but it does take some skill and patience.
> 
> ...


Look closely at the first pic. The casing of the switch is broken on the left hand side where the rod goes.


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## MrShades (Jul 29, 2009)

Ah yes - good point... it's bust!

So now you have a simpler but significantly more expensive task - as they're about £45


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## El carajillo (Mar 16, 2013)

Contact [email protected] on the forum, £ ??


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## L&R (Mar 8, 2018)

Or buy this unit for spares

https://www.ebay.co.uk/itm/Gaggia-Selecta-Deluxe-Espresso-machine-not-working/123673016146


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## It02s28 (Feb 24, 2019)

L&R said:


> Or buy this unit for spares
> 
> https://www.ebay.co.uk/itm/Gaggia-Selecta-Deluxe-Espresso-machine-not-working/123673016146


Not a bad idea! I assume it's the same switch configration?


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## MrShades (Jul 29, 2009)

Yes


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## It02s28 (Feb 24, 2019)

Thanks both. I may or may not be bidding for this...


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## It02s28 (Feb 24, 2019)

Well that could have gone better...!









I'm just going to spend the £40 on a brand new switch from Mr Bean 2 Cup, plus the plastic steam wand protection and steam knob.

If I can't locate the fault, i'll have no option but to send it away and get someone who know's what they're doing to open her up and get her working


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## MartinB (May 8, 2011)

Where are you based? Happy to take a look if you're anywhere near Oxfordshire. I may have a spare switch bank as well.


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## Agentb (Feb 11, 2017)

It02s28 said:


> Here is a better photo of the solenoid valve which shows that the middle pin is the only one that doesn't have a plug on it, whereas the pins either side do - one with two wires coming off it and the other with just one wire coming off it.


Gaggia have changed the wiring colours a few times, but that looks correct. The earth is the one at the bottom.

Returning to the switch, do you think it may have been broken before it fell apart ?


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## It02s28 (Feb 24, 2019)

Thanks Martin, very kind of you. I live I Bristol not a million miles away although I have already placed the order now for the switch bank plus 2 other steam wand related items that needed replacing.

I noticed before the switch bank broke that the third plug down on the left hand side i.e.. bottom of the power switch rocker, the switch was perhaps only 90% of the way in so it might be as simple as that - although I imagine it will have worked if in that far.

I'm looking at 2-5 days before I get the new switch bank, so i'm parking it until that arrives and I can re-test.


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## MartinB (May 8, 2011)

That's a shame, I used to live in Bristol as well!

Best of luck with it. If you need any details then I'm more than happy to whip the lid off my Classic and take any pictures for you regarding wiring.


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## It02s28 (Feb 24, 2019)

Oh no, that is a shame! Well i'm at my witts end with this machine so I may take you up on your offer  all the gear no idea springs to mind!!

Will let you know how I get on with the new switch bank...


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## It02s28 (Feb 24, 2019)

Hey all!

I received the switchbank as well as a replacement steam knob and the black protective disc yesterday. However! In fitting the latter 2 items, I somehow managed to trap and fray the cable that leads from the bottom of the brew button to one of the boiler terminals and the top thermostat  I managed to repair it but then discovered the 13A fuse in the power plug went! Fixed that and now it's up and running...at long last 

So first and foremost thank you to all the contributors to this thread, really appreciate your comments and assistance.

I have now moved onto the OPV - I adjusted it counter clockwise 270 degrees and this is what happens to my gauge:

https://www.dropbox.com/s/wxfq3h8i5grx2w4/20190316_153323_2.mp4?dl=0

I then pulled a shot using a bottomless portafilter and this was the result - see video here p.s. it's not pretty:

https://www.dropbox.com/s/l7r6zwfwc3avt3i/20190316_153730.mp4?dl=0

Think i've got a fair bit of work to do...

I'm grinding 20g on setting 9 on my Smart Grinder Pro and paying alot of attention on getting an even tamp.

Any pointers ?


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## It02s28 (Feb 24, 2019)

I've resolved the issue of the needle in my gauge vibrating by not pre-filling the basket with water prior to flicking the brew switch - it's now resting at 10 bar nicely.

Although it doesn't seem to have made much difference to the finished shot; still producing a disappointing amount of crema as well as still spitting a bit and a pretty 'soupy' puck - latest video here: https://www.dropbox.com/s/ob2tvisgtf3gqrc/20190316_162959.mp4?dl=0


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## L&R (Mar 8, 2018)

Lower the pressure to 9bar and try again.


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## It02s28 (Feb 24, 2019)

Thnaks L&R - Is this close enough?


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## L&R (Mar 8, 2018)

Looks perfect, now play with your grind settings and amount of coffee u use for the shots.


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## ashcroc (Oct 28, 2016)

Isn't static pressure approximately 1 bar higher than flowing peessure? Sure I was advised to set the portafilter gauge to 10 bar for a 9 bar shot.


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## L&R (Mar 8, 2018)

Actually the difference is ~0.5 bar, it will be ok with lower pressure, I use often 7.2 bar for extraction with nice results.


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## ashcroc (Oct 28, 2016)

L&R said:


> Actually the difference is ~0.5 bar, it will be ok with lower pressure, I use often 7.2 bar for extraction with nice results.


Interesting. Wonder when the difference changed. Either way (& regardless of getting ok results at lower pressures) a static pressure of 9 bar won't give the 9 bar shot that was being aimed for here.


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## It02s28 (Feb 24, 2019)

ashcroc said:


> Interesting. Wonder when the difference changed. Either way (& regardless of getting ok results at lower pressures) a static pressure of 9 bar won't give the 9 bar shot that was being aimed for here.


What am I measuring with the pressure gauge? Static pressure?


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## ashcroc (Oct 28, 2016)

It02s28 said:


> What am I measuring with the pressure gauge? Static pressure?


Yes. There's no flow through the portafilter with the gauge attached.


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## It02s28 (Feb 24, 2019)

So should I have kept it at 10 bar?


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## L&R (Mar 8, 2018)

try to make some shots with low pressure and compare the result


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## ashcroc (Oct 28, 2016)

It02s28 said:


> So should I have kept it at 10 bar?


Up to you. If you're getting good results where it's set I'd be inclined to leave it as is.


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## It02s28 (Feb 24, 2019)

What's the general consensus on which variables are the most impactful in creating a good shot? If you were to rank them, might it be something like this:

1. Grind

2. Dose

3. Brew pressure

4. Temperature

5. Bean freshness

I ask this because i'm not sure which of the variables to fix/keep constant and which to vary when dialling my shot in.


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## Agentb (Feb 11, 2017)

Well done on getting it working, I kept thinking of "Trigger's Broom" you've done more plumbing than i have.

You asked about variables ... all need to be right(ish)!

Thanks for posting the videos, i have seen worse - and my sink has had a coffee habit in the past.

You don't say what volume but my reaction was "too fast" - i would go a lot tighter on the grind.

You also don't have a PID ? - trust me it helps - a lot (best mod i have bought). The Gaggia without one goes up and down temperature a lot probably +/- 10C or more. You can temperate surf, basically pull some water, wait until the light goes off - load the PF as boiler is heating. When the light comes on the heating element goes off and the boiler is cooling - count to 5 (you can vary this) and start the extraction. Time the extraction from the time of the switch i think is the convention.

Also you say 20g - I don't know what size basket you are using (?) but I'm using 17-18 in a VST 18 basket.

My extraction times tend to go slowly some thing like 36-40g out in 40-50 seconds sometime. I hope that helps.

Good luck.


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## It02s28 (Feb 24, 2019)

Haha love that AgentB. I certainly have learnt a few things since working on my machine.

I've been considering buying a new basket - i'm still using what looks to be the original double basket. Would you buy your 18g VST again? Did you go ridgeless?

I will shoot another video tomorrow with my scales.

I am keen on getting a PID but it's an expense I can't afford right now having blew a small fortune just on getting my machine functioning. Did you opt for MrShades? I've heard lots of good things about it.


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## Agentb (Feb 11, 2017)

It02s28 said:


> I've been considering buying a new basket - i'm still using what looks to be the original double basket. Would you buy your 18g VST again? Did you go ridgeless?


Good question, probably. I have started to learn the more you change everything changes again, one step forward N steps back.

I wouldn't buy another one, unless i had to, they are pricey.

Would i buy ridged, i did but that wasn't me thinking properly. you get a litle bit of coffee in the ridge and so when you knock it out its not as clean as a ridgeless i think. If i was making 100 a day, different story as the ridge helps lock it in.

You mentioned you had an original basket, i don't know what size that is but 20g seems a bit high. You need to try the 5p test and see if that is too much, if it is drop the dose down.


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## It02s28 (Feb 24, 2019)

Here is the latest video I took at lunch today: https://www.dropbox.com/s/lx8cub4lx6bnzcq/20190320_111038.mp4?dl=0

This was by far my tastiest shot which I achieved through upping my dose to 20g but most importantly switching the beans out to a lighter roast. This has resulted in more crema and a more rounded flavour.

I did notice however that water was flowing through the return pipe - which you can hear it dropping into the reservoir in the video. Could this suggest my grind might be too fine and/or tamp too hard?


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## L&R (Mar 8, 2018)

If there wasn't returning water, I would think of a problem or wrongly adjusted expansion valve.

BR


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## ashcroc (Oct 28, 2016)

It02s28 said:


> Here is the latest video I took at lunch today: https://www.dropbox.com/s/lx8cub4lx6bnzcq/20190320_111038.mp4?dl=0
> 
> This was by far my tastiest shot which I achieved through upping my dose to 20g but most importantly switching the beans out to a lighter roast. This has resulted in more crema and a more rounded flavour.
> 
> I did notice however that water was flowing through the return pipe - which you can hear it dropping into the reservoir in the video. Could this suggest my grind might be too fine and/or tamp too hard?


It's just the pump delivering at a higher pressure than your OPV is set at. I take it as a sign the puck is creating enough pressure in the system for a proper brew.


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## It02s28 (Feb 24, 2019)

ashcroc said:


> It's just the pump delivering at a higher pressure than your OPV is set at. I take it as a sign the puck is creating enough pressure in the system for a proper brew.


Ahh now that makes sense - I didn't notice it (probably because it wasn't happening) before I adjusted the OPV.


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## It02s28 (Feb 24, 2019)

What do we think of my latest shot? 18g in, 40g out in 25 seconds

https://www.dropbox.com/s/rzofk0z48c7z15a/20190325_190124.mp4?dl=0

Contemplating upgrading the basket to an 18g ridgeless VST


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## Agentb (Feb 11, 2017)

How does it taste?

I'd certainly not sink that one.







although i've learnt at this time of night it's risky business playing with coffee..

When are you starting the clock?- it sounds like when the extraction starts, i think the convention here is when the switch goes on.

You have to love bottomless PFs.

I did notice it seems to start on one side and then make it's way across, sorry about the small screenshot but needs must...









I don't know why that is - possibly not even distribution? - someone who knows may be along soon.

Getting there...


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## JojoS (Oct 1, 2014)

Distribution issue most likely and too much headspace. Dose a bit higher and wdt might improve extraction.


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