Switches not working

Hi,

I have an old (about 9 years) installation of CBus and recently about 6 switches have gone crazy. All are toggle switches and when pressed sometimes work but mostly fail to activate the light instead the LED on the switch just flashes. The CBus software cannot talk to the switches and produce an error similar to "Unable to communicate with device XX" . I have tried replacing a couple of the switches with no success and also buzzed the wiring to confirm it's still ok. If the light is activated by another working switch then the LED on the faulty switch glows red as normal.

The sparky who installed it has gone awol and I am at a loss as to how to fix this .

Any help would be grately appreciated.

-Mark

 

Could it also be a faulty power supply, resulting in less than optimum power at certain points in the system?

I had a similar fault in my place, which is the same vintage, but in my case replacing the switch fixed the fault. Actually it happened twice within 6 weeks of each other and oddly or co-incidently in both cases the switches that failed were 2 button, the rest in my place are 1 or 4 button and have never had an issue.

 

Getting hold of a PC Interface and downloading the Diagnostic Utility from the website may also yield more clues.

 

Dead key inputs

As Ashleigh has said, it is most likely dead switches. Did they all fail at the same time???

If so, it may be the old 5100PS - power supply with the three pin flex.

If they have failed over a period of time, it will be the key inputs.

There was an issue with key inputs manufactured in mid to late 99, where a particular component - a capacitor, fails eventually.

 

Mark - you have provided some important clues.

The short answer is intermittent communications - The important question is what is causing this.

In the "old" days a flashing LED on a key input unit was a (feature) signal that the unit cannot communication on the bus.

Where you said you have tried replacing a couple of switches with no success then I am taking from that, that the replacement switches displayed the same intermittent failures ???

The above being the case suggest a more global problem, most probably an old 5100PS having thrown in the towel therefore not enough C-bus network power therefore marginal comms. Check with a volt meter that you have between 28-36 volts DC available at several points around the bus.

If the intermittent faults are contained to several units only then it could be the old C7 capacitor issue where the capacitor that decouples the comms signals off the DC bus have thrown in the towel.

At nine years old I would start with the power supplies.

PS. To test power supplies test voltage then disconnect a power supply one at a time and see if you can find a situation where the voltage does not drop ie, power supply not pulling its weight

I have seen a situation with a 5100PS where its filtering components had failed, was supplying power but also trashing the bus comms, so as you disconnect check to see if normal operation returns.

These are usually intermittent faults so can be very hard to pin down, in addition you can lead yourself up the garden path based on when things choose to play up.

Good luck - it will be something basic but no doubt tricky to nail...