2 year+ arduino MEGA is beginning to have trouble in terrarium installation

Hello. I build a terrarium (vivarium) for dart frogs. For this system, I have following hooked up in an 8x realy module.

  • 2x 12V PC vents
  • 2x 12V LED light
  • 1x 230V LED light
  • 1x 230V Pump for misting
  • 1x 230V Pump for waterfall
  • 2x 12V LED light
  • 1x 230V Heat-blower (if temp drops below 19C)

Its all connected in a suitable box with an LCD display showing time, temp and humid

My code is like 600 lines and it has all worked perfectly for the last two years. However lately it is not able to run all the things together at ones.

Normally the only thing running at daytime constantly is daylights (1x 12V + 1x 230V LED) and the waterfall (pump). The fans will spin every 20min for 3 mins, or so they should. They have stopped working when the pump for the waterfall is turned on.

Another thing that has changed is the LCD display.
The LCD display is starting to dim so much I can't read anything on it.
Lately, the daylight (230V) won't run either when the waterfall is on.

I have taken the box apart and the connections are fine.

Could one of my resistors be a problem? I have tried to change power source for the Arduino and use my back-up files for it without any luck.

Post the project details.

If the electronics are exposed to moisture or condensation, you will see fuzzy growths on PCB tracks and solder joints, especially near power connections. Careful cleaning with a fine brush and rubbing alcohol, plus resoldering connections might be able to fix it, temporarily.

Another possibility is that you don't have sufficient electrical transient protection on pumps, motors and relays, lack of which will eventually lead to complete destruction of the Arduino.

An example would be the flyback diode D1 on the motor (or relay) connection in the diagram below.

Do the relay module LEDs light when they're supposed too? If so, does the load the relay is switching work? Could be worn relay contacts or worn fan motor bearings. If the fan motor bearings are dragging, that could cause higher current demand and pull down the voltage to other components. Same thing with pump motor.