Three AM12's dead after winter in my shed. Too cold?

[ChrisGUK]

I installed six AM12's in my shed last spring to control my garden lighting. It all worked very well all summer even though the shed probably reaches 35°C or more some days. But I came to fire everything up today and three of the six AM12's are dead. The shed is perfectly dry but would have got down to about -8°C a few times over the winter. The power to the shed was off all winter so it's not a power problem.

I brought them all indoors, double checked everything, and tried the dead ones with various different addresses. No signs of life at all, so I opened one up and everything looks fine, all clean, no signs of corrosion, burning, or dry joints. Power is getting to the circuit board but they just don't respond to commands.

Does anyone know what could have happened? Or how I might be able to repair these? Is X10 viable for this environment or should I be looking for something else?

[Boiler]

Hello Chris,

Welcome to the forum.

Unfortunately, this forum is based in the States and we do not have much direct experience with the Marmitek units.

None the less, your AM12's should be somewhat similar to our AM486 units in the States.  That being the case, there isn't much in the unit that should be susceptible to cold or high temperature (up to 50C).  If the relay were to ingest moisture the contacts could degrade over time.  Since you lost functionality in three units in a short period of time, that doesn't sound like your failure mode.

Instead, I would suggest that your units were damaged during the previous year (when power was applied) due to an electrical "event".  Assuming that your units are somewhat similar to ours, the susceptible components would be the fuse (likely a "link" on the pcb), the varistor (transient suppression) or the output relay itself (less likely).

There are some schematics on the IdoBartana site (these are US models) that may be of some use in identifying the components: AM486 Schematic

Best of luck,
Boiler

[ChrisGUK]

Many thanks for the reply Boiler. I don't think it was a power event because the units all worked up until the end of the summer and then the power was off all winter. There is a tiny fuse link on the board but it's intact. Varistors usually show visible damage when blown but there is none.

It's an odd one, for sure. Anyway, I will replace them although they are fairly expensive here in France, equivalent to over US$30 each. And next winter I will bring them into the house and keep them warm..

Monitoring this thread so will always be interested to hear more opinions or similar experiences. Thanks again.

[dave w]

Chris,

I imagine you already checked this, but your solenoid relays aren't simply "stuck" are they?

X10 puts a dab of grease on the cam mechanism...maybe it thickened in the cold with no regular operation?

OK I'll go back to sleep now.

[ChrisGUK]

Hi Dave, yes that had occurred to me so on the one I opened up I operated the relay escapement manually a few times just in case so I don't think it's that. Thanks for the thought though.

[Boiler]

Chris,

I imagine you already checked this, but your solenoid relays aren't simply "stuck" are they?

X10 puts a dab of grease on the cam mechanism...maybe it thickened in the cold with no regular operation?

OK I'll go back to sleep now.

Talk about going to sleep, I had totally forgotten that these units use the ratcheting mechanism on the contacts (not a sealed unit). 

I've used these units both in my garage and back patio.  The garage rarely gets below 0C, but the patio spent a good amount of time at -20C this winter (units are powered but rarely activated).  Haven't seen this type of failure in either location.

Blown coil on the relay?

[dave w]

Blown coil on the relay?

Yeah, or the SCR that fires the solenoid, or (I suppose) the chip, but gee what would cause three failures all at the same time.

Chris, besides rotating the cam, did you check the solenoid armature (piston)? I use a dental pick, but if you don't have one, a stiff wire will do it. Insert the pick in the end of the solenoid with the spring, going down through the center of the spring and gently push the armature until you see the pawl rotate the cam. You should be able to feel if the armature/pawl is sticking.

Good luck

[ChrisGUK]

Wow, I really do appreciate all this help. You guys really care! Good idea on the solenoid but tried and no luck I'm afraid. I also determined that no power is applied to the solenoid when commands are sent. 

[dave w]

Well other than bad connections on HCUC dials, I'm out of ideas, relative to cold and being dormant.

[Brian H]

Oh yes. As dave w suggested. If you have not tried it yet. Rotate the House and Unit Code wheels a few turns. The maybe making a bad connection and the address has shifted. I have actually gotten a few NEW X10 Modules where the dials where flaky and rotating them corrected the problem.

[ChrisGUK]

That was one of the first things I tried, lots of different house and unit codes. Somewhere a long time ago I saw the address that a module has with no address wheels fitted but I can't find it now. Anyway I don't think it's that.

[Brian H]

M13 is no dials.

[ChrisGUK]

Thanks Brian, just tried that but no dice. Time to admit defeat, I think. At least I know I'm not missing anything obvious!

[dave w]

Thanks Brian, just tried that but no dice. Time to admit defeat, I think. At least I know I'm not missing anything obvious!

No Chris, you forgot "Xorcism"! 


"I don't care who you are, now that's funny"

[ChrisGUK]

Ah, well I haven't tried that .. yet!