Gene Cafe - Dimmer Mod 2017

Gene Cafe CBR-101 modified with a voltage regulator and a power monitor display

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Following the gene-cafe-dimmer-control-mod-stage-1 instructions on this site and this article on Coffee Forums UK, I implemented my own variation of the dimmer control mod on the Gene Cafe. I initially published the instructions here. I have put a few kilos of coffee through the Gene Cafe CBR-101 with this mod in place and I can confirm it is working properly.

Please make sure you read this article gene-cafe-dimmer-control-mod-stage-1 before attempting this one and are familiarised with opening, closing and the internal components and wiring of your Gene Cafe.

This mod consists of having the ability to control the power of the heating element, but also combining a very useful power consumption display and a switch to bypass the dimmer switch all in one place.

DISCLAIMER: You will be doing this at your own risk and make sure you know exactly what you are doing. Please make sure you take all the appropriate safety measurements as you are dealing with mains AC electrics which can be fatal.

Tools required:

  • Crimping tool;
  • Multimeter;
  • Wire cutter;
  • Screw drivers;
  • Nose pliers;
  • Hacksaw;
  • A drill and drill bits;
  • Sand paper.

Materials required:

  • 5 metres, 5-core 1mm2 cable: Bought from Screw Fix for around £6. We only need 4 cores, but I couldn't source such cable. I've used the internal cores of this cable to do all the relevant wiring between the switch, the meter and the voltage regulator. You don't need 5 metres, but I'd rather have some to spare than run short.
  • 6 x 6.3mm insulated female spade terminals / crimp connectors (these were used to attach to the DPDT switch)
  • 2 x 6.3mm fully insulated female spade terminals / crimp connectors (these were used to attach to the Gene PCB board);
  • 2 x 6.3mm insulated male spade terminals / crimp connectors (these were used to attach to the heater wire connectors);
  • 1 x M18 Cable gland; (~ £3.50 from eBay for 3);
  • 1 x Project Box. Mine is made of ABS, 216x130x85mm. (~£14 from eBay). Maybe slightly on the bigger side. Also the box is quite thick, so you'll need to improvise and think outside the box when cutting and slotting the components. All I had available to me was a hacksaw, a drill, some bits and sand paper… I have read that acetone dissolves ABS, so you might consider using it for cutting the holes in the box.

Components required:

  • 1 x Dual Pole Dual Throw (DPDT) Rocker Switch; (~£3.50 from eBay);
  • 1 x Digital 20A AC multifunctional electric energy measuring power meter; (~£10 from eBay)
  • 1 x Adjustable Voltage Regulator 220V 2000W AC; (~£3 from eBay);
Wiring the Circuit
This is how the wiring of my circuit looks like:

Testing the Circuit
This follows the same approach as illustrated in gene-cafe-dimmer-control-mod-stage-1. The only difference is that, is that we need to grab a neutral wire so we can wire the display unit and return it. The other difference is that we are using a Dual Pole Dual throw switch. The routing of the life (phase) wire follows exactly the same principle.

With the 5 core cable, leaving the yellow and green core alone, I used the brown wire to denote "live" input. The blue wire to denote "neutral" input. They will be connected to the "heater" and "ter4" terminals on the Gene PCB respectively. Then pick any of the other core and put a brown sleeve around it, and on another one, put a "blue" sleeve on it. Those will be the return wires that will be connected to the heater element. Make sure that the heater element is connected with the same polarity back on the PCB.

Before you cut the box and plug your circuit to the Gene, it would be wise to make sure your circuit is correctly wired. To check that, you can use a multimeter to check for continuity WITHOUT the circuit being plugged into the mains. For instance:

  • Check that, with the switch in the DIR position, there's no current going through to the voltage regulator. This is effectively bypassing the voltage regulator.
  • Check that, with the switch in in the opposite position, there's current going through the dimmer switch.
  • Check that the input live wire (phase) is wired correctly
  • Check that the input neutral wire is wired correctly

Once you are happy with that, you may want to test your circuit connected to the mains and a light bulb instead of the Gene. Again, reminder about taking the relevant and adequate precautions when dealing with life electricity as it can be lethal.

Once you are happy with your testing, you may plug that into the Gene.

Plugging Into the Gene
On the Gene Circuit Board, unplug the "heater" terminal wire and connect the brown wire. Plug the return wire (it should have a brown sleeve) into the heater element terminal which has just been disconnected. Repeat the same for the "ter4" terminal and the neutral wire (blue). Make sure that the wires do not interfere with any of the moving parts or touch the heater element or it's assembly.

This is an optional step: Instead of using cable clips to secure the cable to the gene, I used a 12mm OD cable gland. a 14mm OD MIGHT also fit, but I am not quite sure. See image below.

Cutting the box:
You'll need to cut the box to place the switch, the display unit and the voltage regulator, as well as the cable which will link the Gene main unit to the new control box. Open the box and study where the controls will be placed, as well as where you want to position the mains cable. Find a layout which gives you space between the components so you can wire them neatly and also allows you easy access in case you need to undo or replace one of them.

Only use my version as guidelines, but not as an example, as I am not very good with this sort of thing.


Gene Cafe and Control Box
GeneControlBoxAttachedToGene.jpgGene Control Box On
GeneControlBoxOn.jpgInside the Gene
InsideTheGene.jpgInside the Control Box
InsideTheControlBox.jpgRear of the Gene

And you are ready! Happy Roasting!


  • Prices quoted were at the time when I built it.