Circolo Espresso Maker Tweaking

Just some exploration and tweaking of this old workhorse. First to determine whether it already has a PID controller, and if it'd help any.

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Applies to at least Nescafé Dolce Gusto Circolo Manual EDG600, EDG600WH and EDG600R. With the automatic model having been out for a good while, the manual model is kind of obsolete but tempting to attempt to mod. In fact, where I'm located the automatic model costs about 250 EUR while thee manual one can be had for 50 EUR new, and used ones for free.

Googling up for the details turned up a dearth of information on modding or hacking this attractive looking piece of equipment, so I decided to try to fill some of those details. First order of priority will be determining whether the machine already comes with PID, and if the heat-block design would in fact benefit from a PID at all.

Besides the obvious PID, I'm also looking for USB connection with temperature logging and remote control, including automatic water stop to program the brewing amount and optional pre-infusion for those so desiring. Other hacks might present itself as I progress through this.

Taking the espresso machine apart proved slightly challenging. As always, live parts inside, so don't let them get away (or to bite you!). There's a good blow-apart picture set at - unfortunately the guys there (In German no less) can't remember or seem to be able to explain just how they got it apart. "Tab manipulation" indeed.

The back plate of the device is held down by six, long screws looking like security hex key 10, or maybe 15. I had a security torx 15 at hand, but it was just slightly too large. Fortunately, the security screws are no match for a flat screwdriver head of requisite width. The two bottom ones open upwards towards the roof of the brewing cavity, so a shorter screwdriver comes handy.

After the screws are off comes the hard part. It's hard to figure what part comes off next. In fact, nothing really seems to come off easy, but pulling the inner shroud of the brewing cavity outwards - with the screws removed, again - firmly enough should allow it dislodge. However, do disconnect the led-light connector on the back first so it doesn't get torn off. The four tabs visible just around the cavity on the back side aren't actually holding them down, they're just for alignment, as well as a fifth one just visible on the top of the cavity. The small holes on the drip-shelf grooves are there just for distraction as well.

There are four tabs holding it in place, however, but those are inaccessible from the outside, so your best bet is to just apply firm but gentle pull on it. Mine came off easiest from the bottom end, and from the shape of it that might be the case in general. Pulling the bottom end out and slightly upwards might be best strategy. After the shroud is off, now is your last opportunity to just wash it and put it back in if you're not qualified for working with mains voltage; the pump and heater inside operate on it and have many exposed terminals.

If you DO decide to carry on, the side panels can come off next. Start with the one opposite to power-button, again starting from the bottom. The attachment mechanism should be self-evident from looking at the bottom of the thing; just lift the plastic ring over the peg until you can slide it off. The side panels are also connected shallow tabs on their edges at the upper and lower ends, but those should offer little resistance.

Getting off the side panels reveals the innards. The electronics are labeled as "APOLLO Mainboard v2.4". Googling up on this turns up quite a few decent images labeled as Krups Nespresso KP5002 as well as a service manual for Krups Cube Nespresso XN5005. Unfortunately none of these look very useful for modders, although I'm keeping them in mind, and will also have to see if there are already mod instructions for those models!

Closely examining the electronics mainboard does reveal some useful things, however. The pump and heat block are ran off the mains power, good choice but awkward for hobbyist modder. There's a clear separation of the mains voltage and low voltage on the backside of the main board, however, so keeping connections clear to the low power side and hands off powered device should help avoid sudden death.

Switching mains power to the heater and pump from the low power side is handled by two MOC3063 opto-couplers with zero-crossing circuit. The hard way to mod this would be to lift off the low-power side legs and connect my own controller, however at present I'm looking whether I can effect a less destructive modding employing the existing circuitry. Taking control of the inputs including what's labeled as a NTC thermistor should do that, although if there's already PID inside, the effect on that will be useless at best.

On the flip-side of the mainboard there's a small SOIC16 that looks to be the brains of the operation, upper row reads F8212 and lower row looks like IO4pm19, with a five pin programming header connected to it. My uneducated...

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  • First look at the lay of the land

    BadgerBadgerMushroom03/03/2015 at 23:11 0 comments

    Added some reference images off my bench. These images are for educational and reference use ONLY. Taking a look at the mechanical parts, you can see there's a two-position switch that the lever will push as well, for hot and cold dispensing. Is there an electrical difference to the two? The cold dispense doesn't need to reheat the heat-block afterwards, so maybe that's what it's it.

    The pump is on the right hand side in the image, along the pipe rising from bottom of the water reservoir. There's a T-junction on the pipe, the other branch going directly the the water-dispenser, the other taking a long detour to the heat-block on the left hand side and back. The mechanical action of the lever blocks either one of these tubes as time along with toggling the two position switch shown. For fully automatic dispensing, the cold tube would need to be blocked, or a mechanical actuator added to choose between the tubes. In that case, a divert could be added as well to allow pre-heating (or cooling) the tubes and the water in them by letting it briefly run off, or back into the water reservoir (which would heat water there, making cold drinks even warmer...). Especially since there's no divert, the tubes could use with some insulation to keep them at desired temperature. Failing both of these, you might want to just let water run off the machine with no capsule inserted for a while before dispensing.

    There's a close up of the back-side of the low-voltage circuitry, where you almost make out the writing on the SOIC16 mentioned in the details. R20 hooks up heater, R19 hooks up water pump, the other side of the opto-isolators can be seen going direct to the microcontroller, which might be helpful for a reverse-engineering and re-programming project. But this isn't one. Worst come to worst, cutting up those thin traces going to the microcontroller and hooking up our own controller would let us in direct control. Near L2 at upper left is the hookup for the NTC thermistor though; we can see a lot of discrete components involved, and the traces go under the microcontroller, so it's not easy to figure out how it works right away. That is something I may have to focus on, though.

    Finally, there's a picture of the optocouplers from the front so you can see the model and roughly how they line up. It also has J12 marked as ground, so we have our ground and can see it circling the edges of the low volatage side and the hole at the middle. Just a reminder, when that thing is hooked up to the wall, a lot of the connectors will have deadly levels of current on them, so hands off when it's hooked up, and make sure nothing you add or change bridges the upper and lower side of the board, divided through those two optocoupplers and the power-suppply feedback optocoupler in the middle.

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