EC meter make Arduino 5V drops to 3 ish V

wmfairuz:
I've bought this EC meter https://www.dfrobot.com/product-1123.html.

I have water temperature, EC, PH, ambient temperature sensor and a 20x4 LCD attached to the Arduino. When I check this morning, the EC meter dropped the whole Arduino Mega Vcc to 3 ish Volts and make it hangs.

I thought all the sensors are drawing too much current from the Arduino and decides to detach all sensors except the EC sensor. But same thing happens. (note: the LCD is still attached but with external power)

Does it indicate a faulty sensor board? What can I do to debug in this case.

Thanks!

You failed to mention the power supply for your project. Why are you powering the sensors from the Arduino?

Paul