CC125/180 with limiter
The CC125 (or CC180) is perhaps our most common controller. It is neither opto-coupled like the Schulze or Hacker Master 195, nor directly connected like the Kontronik FAI and most cheaper BEC controllers. Instead it has two filter components, said to be inductors, in the BEC power lines, most notably the ground (black() line. I measure the resistance of this to be 0.1 ohm, but Steve Neu has reported seeing much higher resistance.
Most sensors, eg voltage sensor for the limiter, rpm sensor on the Unilog, require a solid ground connection. In the case of opto-coupled controllers this is achieved by connecting the blue wire (Neu) or brownie-black wire (Unilog) to some point on the power negative which becomes the ground reference. In the case of the Kontronik and most other BEC controllers this connection is made within the controller and the Blue/black connection is not necessary, in fact not desirable as two ground connections can lead to ground loops.
For the CC125 the situation is more complex. It normally works with either configuration but Neu now recommend connecting the blue wire (black on the Unilog). Without it voltages developed across the inductor can interfere with the sensor readings. But with it voltages across the inductor, or developed across the wiring ,can damage the inductor or even cause the controller to mal-function.
An alternative approach, avoiding ground loops and simplifying the installation, is shown below. This involves removing the inductor from the circuit, thus making the CC125 the same as the Kontronik or normal BEC controllers. This removes the filtering effect of course, making an optocoupler to the receiver even more of a necessity. Connecting the blue/black wire also removes the filtering. Removing the inductor requires uncovering the controller and some fine soldering so can only be undertaken by those with electronic experience and capability.
Most sensors, eg voltage sensor for the limiter, rpm sensor on the Unilog, require a solid ground connection. In the case of opto-coupled controllers this is achieved by connecting the blue wire (Neu) or brownie-black wire (Unilog) to some point on the power negative which becomes the ground reference. In the case of the Kontronik and most other BEC controllers this connection is made within the controller and the Blue/black connection is not necessary, in fact not desirable as two ground connections can lead to ground loops.
For the CC125 the situation is more complex. It normally works with either configuration but Neu now recommend connecting the blue wire (black on the Unilog). Without it voltages developed across the inductor can interfere with the sensor readings. But with it voltages across the inductor, or developed across the wiring ,can damage the inductor or even cause the controller to mal-function.
An alternative approach, avoiding ground loops and simplifying the installation, is shown below. This involves removing the inductor from the circuit, thus making the CC125 the same as the Kontronik or normal BEC controllers. This removes the filtering effect of course, making an optocoupler to the receiver even more of a necessity. Connecting the blue/black wire also removes the filtering. Removing the inductor requires uncovering the controller and some fine soldering so can only be undertaken by those with electronic experience and capability.
The picture above left shows the CC125 control board in its original state.the inductor is the component above right of the black wire. It can simply be shorted out, as done by the USA F5B team I believe. Another way, simpler and more reversible is shown in the next two images. The real ground of the CC125 is just to the right of the black wire connection, so just scrape it and tin it as shown in the middle image above, then solder the black wire there or to both the old and the new as shown above right. The wire can be re-soldered into its original position and the excess solder removed thus returning the device to it original condition. Full size pictures are available by clicking on the thumbnail above. Electronic expertise is required, all at your own risk of course, but already done by two other UK group members with no problems.