Rocket Giotto lost heat & pressure, won't reach normal levels

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
ProfessorEspresso

#1: Post by ProfessorEspresso »

New poster here. I have a machine that gets regular daily use and maintenance. I back flush, replace shower screens and group head gasket, and I am experienced in repairs and diagnostics as well (mostly on larger commercial machines).

However, yesterday I noticed that the boiler pressure was only 0.5 bars (left gauge), and I could touch the group head without burning my hand. Steam wand releases no steam. If I engage the group head, the motor works and dispenses water, but is not reaching the correct pressure and temperature to brew. I did try brewing espresso under these conditions as a test, and with coffee in the portafilter it did reach 8 bars of pressure (right gauge).

So I have some ideas, but maybe you can help me narrow things down before I take things apart and get into it:
(forgive me as I may use incorrect part names, but I'll try to be as clear as possible)

I initially thought it could be the pressure seal valve at the top. It had previously been hissing slightly while the machine was on and I put off the repair too long. However, the steam wand was also putting out wet steam at that time. So...now I'm not sure. Could it be the water level sensor in the boiler? Then I thought it could be the heating element, because it wasn't getting as hot as it should.

Now I'm worried it's multiple parts that have failed, including the pressure seal valve and the heating element.

Any tips on figuring out what's gone wrong here? Is there a test I can run to narrow things down? I'm comfortable working with any part of the machine, I'd just prefer to have a clearer picture of the problem before I start dismantling and replacing parts. Thanks everyone!

JRising
Team HB

#2: Post by JRising »

Well, if you already know that the vacuum breaker is leaking, replace it. When it's out you can look into the hole toi see if the boiler is terribly over-filled. If the boiler iis overfilled, remove and clean your boiler-fill probe. Put the boiler fill probe and new vacuum breaker in and begin looking for the problem with your boiler not heating.

Before bothering to work live to check voltages, you should unplug the machine, take the body panels off and simply test resistance across the element, then from each element terminal to boiler-ground. Resistance through element should be about 10 to 15. Element to ground should be infinite/open-circuit at your multimeter's highest range.

When working on a live machine you must be very careful. DO NOT work on a live machine unless you're certain how to use your multimeter and any other tools you will be using.

Turn the machine on, check for voltage across the element terminals. It's nice and easy on a giotto, the element sticks out the side where you can easily check it with a multi-meter. Since it does begin heating normally, you should see mains voltage across the element, 110 to 114VAC or something.
Wait for it to stop heating, then check the element again, it will probably be way lower than 110V, work away from the element along the black wire to see where the voltage drop is, first component along the wire will be the safety thermostat on top of the boiler. Since they're such easy access, you might as well move your blue wire's probe up to the blue wire's safety thermostat also, to check it.
If your Giotto has the 2-pole Sirai pressostat, you can move along to that, etc.

If the element is good and getting power, it will heat the water in the boiler. If it's not heating the boiler in the water, find out what component is preventing it from getting power. If you get all the way back to the Gicar/ProElind board and voltage between Resistenza and Blue Neutral is not 110VAC, then assume the large relay on the powerboard is the issue.

ProfessorEspresso (original poster)

#3: Post by ProfessorEspresso (original poster) »

JRising,

Thanks so much for your detailed reply! So, fun update: I powered on the machine today in an attempt to record the symptoms and after a couple minutes hearing the little tings of the boiler heating up, I hear a pop and sparks start coming out of the frame! Yep, pretty stupid of me to push my luck. So now I have a new problem.

After removing the machine frame, I can confirm that the heating element is indeed shot, as are the terminals and connected wires. I don't see any evidence of additional electrical or fire damage, but I'm at a bit of a loss now. Can the wiring be replaced? I'm comfortable soldering simple projects, but this seems a bit above my skill level. And there's no point in proceeding with the other problems until I can get the wiring situation sorted. What a pickle.

Ideally, I'd like to just purchase a new set of wiring for the machine and swap it, as well as the vacuum seal and heating element. I tried searching online, but I can't seem to find any place that sells just the bundle of wires that connects everything inside the machine. I can buy the power boxes, but from photos it doesn't seem like any wiring is included.

Any ideas?

Cheers,
-In Over My Head, aka Now I've Done It

JRising
Team HB

#4: Post by JRising »

You can get wire and terminals from any electronics store. Just replace the burnt wires. 14 gauge, high temperature wire. With a deep socket and impact gun the element comes out easily (you'll want to drain the boiler first and/or lean the machine at an angle so that it doesn't dump all that mineral rich boiler water inside the machine.

Or take the machine to a place that services Rockets. The element will be about $100 - $120, Labour will be whatever the shop's minimum is, probably 2 hours.