Someone gave me a used I/O Linc model 2450.

 

The relay seems to work - when I press the set button there is an audible click and the white LED by the set button lights up. Using a multimeter I can see that NO and NC have continuity with COM depending on if the white LED is lit or not.

 

However, I can't seem to get the Sense LED to light.

I shorted the GND & S terminals with a jumper wire, but the green Sense LED will not illuminate. I linked it with my ISY and it the Sensor says "off" no matter if I have the terminals shorted or not.

 

Is this a common problem/failure? Any ideas or just throw it in the trash?

This is the first report I have seen on the Sensor not working.

Since you have a multimeter. There should be +5 volts on the Sensor S terminal to the GND terminal. The voltage is through the LED and some pull up resistors.

The Sensor Input is designed for a dry contact to pull it down to GND.

 

It is possible a voltage higher than 5 volts was put into it and damaged the circuitry. I believe it can tolerate an external voltage of 5 volts or less on the Sensor Input to GND.

Edited December 6, 20159 yr by Brian H

This is the first report I have seen on the Sensor not working.

Since you have a multimeter. There should be +5 volts on the Sensor S terminal to the GND terminal. The voltage is through the LED and some pull up resistors.

The Sensor Input is designed for a dry contact to pull it down to GND.

 

It is possible a voltage higher than 5 volts was put into it and damaged the circuitry. I believe it can tolerate an external voltage of 5 volts or less on the Sensor Input to GND.

 

I just tested it and I get 4.7 volts between GND & S terminals.

If you short out sense (gnd>s) you can test the contacts to see if they're working.. and don't throw the iolinc away because there are uses for it other than using sense.

 

 

Jon...

Should probably also do a factory reset on it..

 

 

Jon...

If you short out sense (gnd>s) you can test the contacts to see if they're working.. and don't throw the iolinc away because there are uses for it other than using sense.

 

 

Jon...

 

Hi Jon,

Can you clarify what you mean by "test the contacts to see if they're working".

Which contacts? The NO/NC?

Should probably also do a factory reset on it..

 

 

Jon...

 

I should have mentioned in my first post - that was the first thing I did when I got the i/o linc.

The relay can be set to follow the sensor input.

Have you tried a Factory Reset? Will not correct the LED not lighting as it is on the Sensor terminal with a current limiting resistor but the the input to the controller chip may still work. Though the controllers pins have an internal set of diodes to protect the input. If one of those got shorted. The input will not work.

 

You can still use the relays NC and NO functions.

You need to link the IOlinc then set the options for Momentary C.  The contacts will then follow the sensor.  Once linked you can also observe it's status...

 

 

Jon...

The relay can be set to follow the sensor input.

Have you tried a Factory Reset? Will not correct the LED not lighting as it is on the Sensor terminal with a current limiting resistor but the the input to the controller chip may still work. Though the controllers pins have an internal set of diodes to protect the input. If one of those got shorted. The input will not work.

 

You can still use the relays NC and NO functions.

Yes, I did the factory rest before even testing it. Do you know if its possible to test the current limiting resistor? I popped the case apart, though I haven't pulled the pcb out yet.

Edited December 6, 20159 yr by fahrvergnuugen

You need to link the IOlinc then set the options for Momentary C. The contacts will then follow the sensor. Once linked you can also observe it's status...

 

 

 

 

Jon...

I guess that would make it easy to test the circuit separate from the led. Ill give it a try.

The verdict is in - a resistor between the sense input and the micro-controller was bad!

The verdict is in - a resistor between the sense input and the micro-controller was bad!

 

That's good troubleshooting and should be an easy fix!  Then you'll have a free IOLinc

 

 

Jon...