I´ve slightly modified a ph sensor module to use it as a measuring device for ORP levels.
To implement this, I desoldered the potentiometer closest to the BNC socket, like mentioned somewhere else (see picture).
The Arduino and the module are supplied by an external power supply, the positive pole of the USB cable has been removed.
Most of the time, it works perfectly fine, but I´ve stumbled over a very strange problem:
Every time I remove the sensor from the solution and put it back in again, the readings are completely off. If I remove the BNC connector and put it back in, everything is fine again.
As I´m no electronics expert, I wonder, what the reason might be and if that might also happen during normal operation.
I expect it has something to do with your sensor or its interface board. Without a schematic for it I cannot guess what is going on. Maybe you have to reset it?
Thanks a lot for the reply.
I´ve found some schematics of the interface (PH-4502C by Diy More) here.
Please see also attachment.
Reseting the ph module/interface is not possible as there is no button, switching of doesn´t work. Just removing the ORP sensor from the BNC interface solves the problem.
But even if reseting might be possible, during normal operation one doesn´t realise, that it´s necessary, as you don´t know, if the values are correct or not, as you don´t know the correct value.
You can only detect it by putting the sensor into the calibration solution.
I´ve just realised, that the pin layout within the schematic is not correct as the TO and DO are switched compared to my part and the pictures within the post --> I´m not 100% sure about the schematic mentioned in the post
To proceed any further a annotated schematic is needed. It appears you may have one as you are removing parts. We know it works with the pot, put it back. We can play guessing games for a long time and never find it.
