CBUS after the QLD flood. Options to fix/replace?

Hi,

Part of my house was flooded with the recent Queensland floods and unfortunately one of the rooms that was flooded also was the wiring room for with some (not all) of my house c-bus network.

Immediately after the flood with all the power disconnected I flushed the cbus relays with clean water before the muddy water could dry, then followed up with a healthy dose of contact cleaner. I hope that this stops any sediment from shorting the circuit board as the boards should dry clean. As I don't have power in that part of the house I'm crossing my fingers and hoping that they will fire up, and that clipsal used some form of epoxy/lacquer coating on the finished boards to protect them. I only had 1 switch that was flooded, and I flushed it with clean water and followed up with contact cleaner & a toothbrush to clean the circuit board and it now works, so there may be hope for the relay units.

As I don't have insurance and have other big bills to pay to fix & clean my house, if the CBUS relay units are dead, what option do I have to replace them cheaply? I originally in 2004 had my electrician purchase and install the 240v & cat5 side of the CBUS, and I did the programming to save $$ (been working fine for years now). I have not had a quote to replace the system but as CBUS was expensive back in 2004 I shudder at what the costs are now to replace, depressing really . Is it possible to purchase second hand? Or are the relays/dimmers serviceable (eg. swap out circuit boards)? I had a quick look at one of the relay modules and it looks like the blue top caps are glued on and not easy to open without destroying the blue covers, so I can't easily get to the circuit board with a toothbrush & contact cleaner like I could with the switch. Is there anything else I can do that might help to save the relay units before I fire them up again?

I also have a dimmer (with power supply) in another part of my house that did not get flooded but looks like the power supply has burnt out. With the dimmer connected to the rest of the CBUS wiring network, it drags the voltage down to about 16v, which makes the entire system unreliable (as expected). Is it possible to change out the power supply board in this unit, saving on the cost of replacing the entire unit?

One last question - I have water in both the cbus conduits and the 240v conduits. I believe the standard 240v cable is rated to be wet and a conduit is considered a wet location, but I'm not sure if its bad to leave water in the cbus LV wiring conduits. If I should remove the water, what is the best way (eg. blow out with a vacuum cleaner)? The voltage status on the units still connected varies between 18v and 21v which is a little low but within operating conditions (2 of the flooded relays had power supplies).

Thanks for your guidance.
Dean

 

Let me say that you did exactly the right thing by flushing the units with clean water before the mud could dry. You need to prevent that mud from drying and get it out of the unit wherever it lurks. Water is not the end of electronics as most people think; rather it's electronics being powered up when wet that's the problem. Going over your switch with a toothbrush & cleaning solution was the right way to go about it and, unless there's some hidden contamination that absorbs humidity, it should be fine.

There is definitely hope for your relay units, although there can be no guarantee about this. All it would take would for there to be some damp mud under one of the components to create a short-circuit and the unit may not work or be damaged if powered. The units need to be as free of contamination as it is physically possible to make them to have a good chance of resurrecting them.

You have no real alternative but to pull the units to pieces and go over them with a toothbrush. The mud will most likely have made it's way into all the different connectors, in between the pins of IC's, in between windings of inductors, under capacitors... just about every conceivable nook and cranny. I would not power them up until they have been completely disassembled and thoroughly scrubbed until no observable trace of mud remains.

If the power was off when the units went under water there's a reasonable chance that this will bring them back to life. The main outstanding concern would be the relays themselves. The top cover of the relay (white) on this vintage of units clips on to it's base but without a resin or adhesive seal. If mud has made it's way up inside the relay then it could prevent/interfere with the relay mechanism or leave contamination on the relay contacts. This may cause extra arcing or increase the contact resistance, leading to the relays getting hot. If you've got the time and patience, it may be worth removing the relays from the PCB and disassembling them further for extra cleaning.

There is a good thread here where another member of the forum successfully repaired a C-Bus dimmer, which will give you lots of valuable tips for disassembly. The construction of the relay units of the same era is the same, but with a relay output PCBA obviously.

C-Bus gear turns up on eBay all the time. Keep an eye out and you may be able to pick yourself up some replacement units at reasonable cost. This is probably a good idea anyway if you plan to disassemble your existing units with the intention to repair them.

If all else fails, then Clipsal have a return and repair service. You fill out a form at your C-Bus distributor's place and send them in. They will be analysed as either Beyond Economic Repair or be repaired for a price that is less than the cost of buying a new unit.

 

Thanks Newman. Some great tips in your post about disassembly, eBay and confirming that I have taken the right approach. Although I used a guerney to force the clean water into the units (and gave them a really good flush), you are correct that the mud does get everywhere. I'll take the same approach that I took with the switch that got submerged but now working happily, use a toothbrush and contact cleaner as a final clean.

I did turn off all the power before the flood and the units have not been powered on since, even after flushing with clean water. So its good to know that there is a good chance of survival if I can clean them well.

Now if only there was an easy way to take off the purple fronts....

 

Thanks Ashleigh,

I have managed to pop off the purple plastic covers, the trick is to lever them up with an appropriately sized screwdriver on the ends of the covers. The first one was very difficult to remove so I thought the others would be as well, but thankfully the covers on the other relays popped off quite easily. Some of the covers are damaged but not significantly and should glue back OK. The purple plastic also has a "memory" and will spring back to the original shape which is useful.

I have disassembled all the units and there is very little contamination in them. I popped open a couple of the relay covers and the relay insides looked very clean & shiny so I won't bother cleaning them. At first I thought the second contact inside the relay was faulty as it had a little black bubble on the contact, but the second relay I opened also had it, and upon closer inspection it looks like the bubble is some form of arc suppressant (??) so I left it alone. The largest mess inside the modules is actually from gekos and mud-wasps!

All the circuit boards are on my workbench waiting for the cleaning treatment. I don't have any isopropyl alcohol, will metho do instead?

I will fire them up on a workbench and cross my fingers for no fireworks....

Luckly I only have 2 cbus conduits which will be full of water (apart from the mains conduits) so will try the vaccum trick today.

Thanks for the advice.

Dean

 

Finished cleaning & re-assembling. 4 out of 5 working

OK, here is the outcome after a day of dismantling 5 units, scrubbing the circuit boards with metho then contact cleaner (metho leaves a white residue although harmless the contact cleaner gets it clean).

After reassembling the units I have 4 out of the 5 working. Originally 2 did not fire up but I swapped the modules until I got a working combination.

I have a power supply that I'm fairly sure is dead, its the only unit that was flooded with a 200mA power supply (unenergised when it flooded). The power supply fuse is intact, the caps don't look bloated and nothing went "pop" or is charred. Any recommendations on how to troubleshoot a power supply?

In the broken unit I also have a CPU module that lights up the "unit" LED but won't recognise the CBUS network (CBUS LED won't light when plugged into an active CBUS plug) when I swapped it into one of the working units. Upon further inspection I found the thin wire around the inductor near the cbus connectors to be broken from my toothbrush cleaning, and also one of the connections in the flat cable connecting the relay board to the CPU board was twisted. Fixed both of these problems so I think the CPU module is OK but I can't test until I get the power supply in the unit working (and I've had enough with disassembing / assembling one of the working ones today to check it in a working unit....).

Is it possible to purchase the power supply and any maybe a CPU module direct from Clipsal?

So far I'm pretty happy I could get 4 out 5 working.

 

Great work! All your efforts thus far have saved you a lot of money, which is always satisfying.

I take it this means that the other 4 units were 'P' version units, i.e. units that don't provide 200mA to C-Bus?

There are actually 2 fuses if you look closely, although that may not be the problem. All I can suggest is that you get out the magnifying glass and go over it with a very careful eye, looking for contamination still lurking where it shouldn't, or evidence of cracked solder joints. A component may also have been dislodged from the board during cleaning so keep an eye out for pads on the circuit board that look like a component was once soldered there. Switch mode power supplies need most things to be right before they'll fire up. Debugging a 240V power supply whilst it's connected to mains can be a dangerous business so I'd suggest you avoid that at all costs.

Clipsal do not sell the individual modules within a product. If you want replacement circuit boards from Clipsal the only way is to return the unit for repair.

 

All working now!

Newman, thanks for the tips. I found a resistor that had been dislodged by the cleaning on the power supply module, and along with re-soldering the wire for the inductor on the CPU module, the last non working unit fired up and is active on the network.

I'm very happy - all the CBUS units are working now. Now to re-assemble them back into their panels and to get my sparky to give them a final 240v check before bringing them back online for the house.

So it is possible to "drown" the CBUS relays and bring them back to life!

Regards
Dean