This is a control board for a pool salt-cell chlorinator. The system cell and connected pump is controlled by the timer, where a weekly schedule can be set. The lower button on the timer is a manual on/off switch.

I initially took apart the board, as there was no power to the timer, this is now rectified, the timer is working and when the on/off switch is pressed, the system switches on.

What I'm trying to understand is how the timer signals to the board to switch the system on and off. There is an input voltage of 1.5v across the red and black wires of the timer. Thought that was quite a low voltage, anyway.

When I remove the green wire from the terminal block, the system turns on. Is the green wire a signal wire? I set the meter to continuity and tested for a circuit between the green wire and red / black, but nothing changed here when the timer button was switched.

My goal is to remove the timer and replace it with a smart relay that I can control remotely, but with my limited knowledge here, I'm not clear how the timer signals on and off. Any guidance would be appreciated!

The timer connections on the board have terminals labelled BK GN RD. The back of the timer notes text AL-218 and 24v, I haven't been able to find anything online under this model number.





Timer connection at bottom:

 

When I remove the green wire from the terminal block, the system turns on. Is the green wire a signal wire? I set the meter to continuity and tested for a circuit between the green wire and red / black, but nothing changed here when the timer button was switched.

Sounds like it.

 

Easiest way to test is to remove the green wire and link the green terminal to the black and then to the red and see what happens, if it changes the relay state.

 

Before doing any cross-connections the first thing is to measure the voltages across the terminal strip, because that is the tier power source, unless there is another connection to the timer that we have not been told about. Just randomly short-circuiting terminals is an easy way to do serious damage that the TS will not be able to repair. Consider that disconnecting a power feed might activate the attached system, depending upon the unknown control scheme.
So post #3 is very poor advice!!!

It is probably a good idea to look at the connections at the timer end of those wires, in case there is more information than just the color provided. That may possibly provide the desired information.

 

Before doing any cross-connections the first thing is to measure the voltages across the terminal strip, because that is the tier power source, unless there is another connection to the timer that we have not been told about. Just randomly short-circuiting terminals is an easy way to do serious damage that the TS will not be able to repair. Consider that disconnecting a power feed might activate the attached system, depending upon the unknown control scheme.
So post #3 is very poor advice!!!

It is probably a good idea to look at the connections at the timer end of those wires, in case there is more information than just the color provided. That may possibly provide the desired information.

Thank you for this. I will look more closely at the timer side, there was some sealant over the connections, so reading the labels was a little difficult. I did measure the voltage across green and the other two terminals, when I had the probes attached, the relay switched on/off rapidly multiple times a second, which confused me.

 

Is there a model number for the control board?

 

Is there a model number for the control board?

This is a photo of the board with some IDs. It's from an Australian company, Zodiac.

 

Thank you for this. I will look more closely at the timer side, there was some sealant over the connections, so reading the labels was a little difficult. I did measure the voltage across green and the other two terminals, when I had the probes attached, the relay switched on/off rapidly multiple times a second, which confused me.

More questions:Is the system functioning correctly as it is now? Is the timer portion functioning correctly? If the relay is switching when the probes touch the terminals it is entirely possible that the solder connection on the back of the terminal has been broken by torque on the terminal screw. I have seen that in several instances. It is hard to spot but simple to repair. And if the system is not functioning perfectly then the solder connections are worth examining.