One relay in an install occasionally turns all on

Hi guys.

Interesting issue for you. I have one four channel DIN relay in my install that very occasionally (say, once a month-ish) turns all of its channels on and becomes unresponsive to switch inputs and local override.

Install scenario: Two networks. One doing the house (8 units), the other connected via a bridge to an out-building (3 units). This relay is on the smaller network, and shares it with a bunch of switches/sensors, a General Input and an 8 channel relay.

When the all-on event occurs, it affects only the relay. The dimmer channels remain all off, indicating that it is not related to remote ON override. (In this network, all remote override connections are wired, but unused.) To get the relay to turn all its channels off, power must be cut to the unit (has its own breaker). On power up, all channels return to off, in line with power fail settings in the unit programming.

Status LEDs show C-Bus LED on, and unit LED blinking, almost like local or remote override has been set. (And not sure whether this next bit is relevent) I say 'almost', because when I use local override, the unit LED is flashing with a 90% on duty cycle, but after every thirteen cycles, it takes a rest from blinking and remains on for a second. When the unexplained all-on event occured a few days ago, the unit LED has 90% duty cycle blink, but takes a rest every twelve cycles...

Suspect this one is going to be quite nasty to diagnose, due to the infrequency of the condition. So any and all suggestions welcome!

Steve.

 

There are only two things that will result in this flash pattern. Either the unit is in local toggle mode or the unit has had it's remote override input activated. Since all 4 channels are being turned on at once, it is almost certainly the remote override that is being activated.

This is normal.

So, the situation is that the microprocessor in the unit is having it's remote override input triggered somehow, yet the wired connections to the unit are unlikely to be the source since only this unit is being affected. The most likely cause is some contamination inside the unit. Perhaps when the humidity is high there is sufficient leakage current across this contamination to activate the input internal to the unit. A common form of contamination is a copper strand off-cut from the end of multi-strand cable, although I did see a Pro series dimmer with a fried gecko inside it once. Another possibility is a bad solder joint on the circuit board somewhere.

If the unit is within the warranty period then you should be able to get it replaced. I'd also try shining a torch through the ventilation holes in the unit, looking at the circuit board that the C-Bus connectors are mounted on. A good blow out with some compressed air might also be the go.

 

Makes perfect sense. Regarding inputs & local override not working when the condition manifests, is this normal when a remote override is activated (even when the override is a momentary contact)? To be clear, is the only way to cancel a remote override ON by way of triggering a remote override OFF, or by powering off the unit?

 

Or by inserting a gecko for frying?

 

you must have small geckos.. : )

.. you're right about the remote override ON having higher priority than C-Bus group states or local toggle keys. Remote override OFF does have higher priority than override ON, so if you have both signals present at the same time, the relays will all be OFF.

The DIN units are sensitive to the LEVEL of the Remote ON (or OFF) signals; edges are not important, so normally when the override ON signal is removed, the outputs return to whatever state they were in before the remote override. In your case, the override ON seems to be 'sticking', which makes me think along the same lines as Newman.. there's something wrong IN your unit.

 

Brilliant replies, gents. Given warranty replacement is an avenue of pleasure now closed, I shall resort to a bit of compressed air to dislodge the copper or critter within, or invest in a replacement.

 

Clipsal has given warranty in the past well outside the expected period. For various reasons they are very generous in a number of cases.

 

Good to know, tobex. Thanks.

 

Did it again...

The relay did its magic trick of turning all channels on overnight, and this time I opened the unit status in toolkit while it was in this state, and sure enough the Remote On override was shown as active, supporting the Newman school of botanical or inorganic contamination.

From memory, this has only ever happened overnight, as it did last night, presumably when it gets cool. And it was a cool night in Melbourne.

Have not yet checked visually for contamination, but fully expect something to come at me when I do. Hope it's copper, and not wildlife.

 

Is the Relay unit the DIN only output unit on that network, or are there other output units on the same network? From your post above it's not clear whether the dimmers are on the same physical network or they're on the other network. Remote Override functions do not cross network bridges.

It's also not clear whether the 8-channel relay on the same network you refer to is a regular DIN unit or an ELV relay (which doesn't support remote overrides). If it's the case that the relay unit that's giving you grief is the only output unit on that network that will respond to remote overrides, the fault may be in the wiring external to the unit.

 

Hi Newman.

There are five DIN units on this physical network (253).
- 8 channel 1A DIN dimmer
- 12 channel DIN relay
- 4 channel DIN relay
- General Input Unit
- Bridge (over to network 254)

Mistake in my OP. The 8 channel unit is a DIN 1A dimmer, and not an 8 channel relay. Checking status of the 12 channel relay and 8 channel dimmer when the 4 channel relay turned all on indicated remote override only on the 4 channel relay. The other two units were not in override.

Cheers,
S.

 

Follow up message to this thread providing what (I hope!) was a resolution to the problem of all relay channels on a 5504 occasionally switching on. A big thank you to Newman for pointing me in the right direction.

It wasn't flora, fauna or wire involved. I believe it was an adhesive foam pad resting on a circuit board. I removed the unit from the switchboard, shook it over a white sheet of paper to see if anything came out, like wire or solder, or rattled in a dead-gecko-kind-of-way. Nothing. Then inspected inside with a torch and spied an unusual yellow pad. Some manipulation (with wooden skewers, tweezers, and gynaecological attitude), and the yellow sticky pad was liberated in short order. Followed it up with a blast of compressed air everywhere and another shake.

Well, it's been four months since, and no remote override switching all channels on. Used to happen every month or so.

Thanks again, chaps.