Gaggiuino installation manual
Wiring your Gaggia, without the guesswork
Pick your machine above. Every diagram and table below follows it.
Read this first
- Unplug it. Empty the boiler. Keep it unplugged for the whole build.
- Earth every metal part. Buzz the chain out before you plug in.
- Never run the boiler dry. Fill and prime before any heat test.
- First power-on through an RCD/GFCI outlet.
- If your machine doesn’t match a diagram, stop. Trust the machine, not the picture.
Mains voltage kills. If you are not confident, have an electrician do the high-voltage work. This mod voids the machine’s warranty.
Made for PEAK
Six parts in your kit are not off-the-shelf. They are made to our own specification, so if you ever replace one, match the spec below rather than the nearest generic equivalent.
Ceramic thermal fuseexclusive
185 °C · 16 A · M4 · re-settable
A second layer of protection on top of the coffee machine standard. Unlike the stock one-shot part, you reset it by hand instead of stranding the machine.
Thermocouplecustom
Type K · ungrounded · M4 × 6 mm
Made to our own thread and length, so it drops into the stock boiler position with no adapter and no drilling.
Pressure sensorfood grade
0–1.2 MPa · G1/4
It sits in the brew water, so every wetted surface is food grade — not an industrial sensor reused for coffee.
Control boardgold plated
Gold-plated contacts
Thermocouple and pressure signals are millivolts. Gold plating keeps noise out, so the temperature graph does not jump.
Teflon display cablehigh temp
Teflon insulated · pre-terminated
Our own cable for the display run, insulated in high-temperature Teflon so it survives inside a hot machine instead of going brittle.
Scales converter hubno solder
Hub + cable · terminated both ends
The converter hub for the scales module and its cable. The scales plug straight in — nothing in this build needs a soldering iron.
The ceramic thermal fuse is fitted, not optional. It is a safety part, and the build below assumes it is in place.
Wiring schematic
The whole circuit, redrawn for the screen in your hand and split the same way the machine is: the mains side that can hurt you, and the signal side that cannot.
High voltage — mains
Low voltage — signals
Wiring loom
Ships ready-made — 22 wires. Each row is one wire and both ends.
Identify wires by where their ends land — never by colour. The colours here match the demo loom in the photos, and cable colours differ between production batches. The terminals on each end are what defines a wire. And never mix looms from different voltages — the wrong one still fits.
Swatches show the demo loom’s colours, for matching against the photos below — your batch may differ.
Wire by part
The same wires, grouped by the part in your hand. Work through one card, then move on.
Earth chain
Buzz out every link before you plug in. Probe from the plug’s earth pin to the warming plate, boiler body, 3-way valve and frame. All must beep. Get this wrong and the machine still makes coffee — which is what makes it dangerous.
Switch panel
Boiler & fuse
Two elements, 2 mm pin receptacles — not spades. Earth stud takes a 6.3 mm spade. Thermocouple is Type K, ungrounded, M4 × 6 mm — custom made for these kits. Thermal paste, hand tight only.
The ceramic thermal fuse is fitted, not optional. PEAK Coffee has this part made exclusively for these kits — a re-settable 185 °C, 16 A, M4 ceramic fuse that drops into the stock position. It is a second layer of protection on top of the coffee machine standard, and unlike the stock one-shot part you reset it by hand instead of stranding the machine.
Never bypass the fuse. It is the last thing between a stuck SSR and a dry boiler glowing red.
Connections
| Terminal | Goes to | Type |
|---|---|---|
| J10 | AC neutral — N-In | 6.3 mm spade |
| J11 | AC line — L-In | 6.3 mm spade |
| J12 | Pump — P-Out | 6.3 mm spade |
| J13 | 3-way valve — 3-Out | 6.3 mm spade |
| J4 | Thermocouple — Type K, ungrounded, 6 mm | polarised |
| J6 | Pressure sensor — food grade, 0–1.2 MPa | 5V · GND · P |
| J9 | SSR control — watch polarity | GND · R1 · R2 |
| J7 | Brew + steam switches | JST-PH 2 mm |
| J1 | Display — TX goes to RX | GND · TX · RX · 5V |
| J8 | Scales | D2 · 5V · GND · CLK · D1 |
| J5 | Extra IO | GND · B15 · A12 |
| J27 | Programming / UART | header |
Red-edged rows carry mains. Keep signal wires away from the mains bundle or temperature readings wander.
Install order
- Unplug, drain, cool.
- Photograph the stock wiring from three angles.
- Strip the old harness — thermostats and their wiring come out.
- Fit the thermocouple with paste, hand tight.
- Mount the SSR on metal for heatsinking. Fork spades on all four terminals.
- Mount the board clear of the boiler and steam path.
- Build the earth chain first — then buzz it out.
- Neutral star from the socket to board, boiler, pump, valve.
- Live path socket → switch → SSR and board.
- Low voltage — thermocouple, transducer, switches, display.
- Tug-test every crimp. Re-check the earth chain.
- Fill and prime before any heat test.
You’ll want: 6.3 mm crimp tool · fork spades · 2 mm pin receptacles · thermal paste · multimeter with continuity buzzer · nut drivers · Torx set.
First power-on
- Before plugging in: continuity from plug earth to every metal part — all must beep.
- Before plugging in: no continuity L to N, or either to earth.
- Boiler full. Display comes up, temperature climbs smoothly to setpoint.
- Pump test with the portafilter out.
- Valve test — pressure should dump to the drip tray when brewing stops.
Troubleshooting
| Symptom | Check first |
|---|---|
| Nothing powers up | Thermal fuse; live path socket → L-In |
| Board alive, screen black | RX/TX swapped at J1 |
| Temperature jumps around | Signal wires next to mains; loose or grounded probe |
| Boiler heats and never stops | SSR failed closed — unplug now |
| Boiler never heats | SSR polarity at J9; thermal fuse |
| Pump runs constantly | P-Out wired to a permanent live |
| No pressure release | Valve live at 3-Out; valve earth |
| Pressure reads zero | 5 V and signal at J6; G1/4 seal |
| RCD/GFCI trips | Stop. Live-to-earth fault. Do not retry |
Original diagrams
The full-detail originals for your machine, for the bench rather than the phone. Tap to open at full size.