Repairing a Xanura SAIX module (or Marmitek AWM2)

[MindBender]

Broke a Xanura SAIX module or a Marmitek AWM2 module? And 'no user serviceable parts inside' doesn't stop you? Then crack it open and repair it yourself: These modules too have a fuse inside, but you need a soldering iron to replace it because it's just a piece of thin (fuse) wire. Make sure to replace it with equally thin fure wire!

Here's a close-up of the fuse:


Here's where to look for it:


(Note: The AMW2 module doens't have the TRAIC that's floating above it populated)

[Bwired]

Hi Robert
Thanks, I have a couple xanura modules which are defect, I will check it out and if possible repair them.

www.bwired.nl Online Domotica, Home Automation house.

[Han]

If somebody wants me to do some repair work on defect X10/A10 units, you can contact me by email. It gives me a chance to look at the electronics insite the units and see how some isues are solved.

Han Alink

[Consultant]

[:(!] Don't try to repair modules!!!
You lose all warranty issues and no one will help you in case of fire.
Send the defect modules back to the supplier!

[MindBender]

As I posted earlier, Xanura modules don't last very long. At the worst years, I had a drop-out of 20% of my modules. At that time, that was compensated by Eaton's very liberal replacement policy. Now the worst modules have been replaced and the new ones don't seem to break that easily, but things are still breaking down in my installation, so I decided to investigate.

When taking out the module, I notice some local discoloration of the plastic on most of the modules, indicating long term heating. Got to wonder how much energy they consume in order to get that warm and how you can every save energy by using these...

The internals of the module look like this:

Internals of a SAIX module

Module internals.JPG (78.14 KiB) Viewed 19748 times

The discolored area of the casing covers the top-left quadrant. In this area, there's a capacitor of 1uF/400v. This capacitor is a vital part of the module's power supply and it's a well known fact that capacitor dry out when exposed to heat for a long time. Tere have also been reports of poor batches supplied by manufacturers.

A closed inspection of the bottom of the capacitor shows that it has been leaking some electrolyte:

Capacitor bottom.JPG (45.65 KiB) Viewed 19748 times

When looking closely at the top, you can see it is bulging up a little:

Capacitor top.JPG (65.05 KiB) Viewed 19748 times

Verifying the capacitor's actual capacity confirms it being defective:

Capacitor degraded capacity

Capacitor capacity.JPG (71.21 KiB) Viewed 19748 times

Where it's capacity should be 1000nF, all that is left is 80nF.

But the proof of the pudding is in the eating, so I replaced it with a new capacitor (nl.farnell.com/jsp/search/productdetail ... ku=9693319) and tested it out: The module is now fully functional again!
When replacing this capacitor, make sure you pick one rated for a temperature up to 105 degrees Celsius.

So far I have repaired 2 modules this way. Three others are a bit harder to take out, but I think I can repair them this way too. Hopefully this helps others to give their modules a longer life span.

[Bwired]

Great!
I frequently get some mails about this subject, and refer then to this topic.
The SAIX12 does not have this problem anymore (promised by Eaton)
so far i they are right about it, but my Saix12 collection (20) are only a couple of years old yet

[Mdamen]

[offtopic]Very nice multimeter you got there![/offtopic]

[MindBender]

If your module is broken and the capacitor looks fine, you might want to check the series resistor (circled in red) of it's internal power supply. It's an 100 Ohm resistor, SMT package 2512 of 1 or 1.5 Watt (http://nl.farnell.com/jsp/search/produc ... ku=1887761). It's located under the TO-220 triac:

Internal power supply series resistor

resistor.jpg (120.27 KiB) Viewed 19683 times

You can bend up the triac, but that's not recommended because the pins will easily break. Unfortunately removing it isn't very easy either, because one of the leads has been bent flat to thicken one of the PCB traces. But if you accidentally break the triac, you don't really have to replace it, as the module will work fine without it. It's a little helper to the relay, preventing sparks on the contacts, uprating it from 10A to 16A. If you don't attach such heavy loads, your module is fine without it. Marmitek brand modules don't even have this component placed.
If the resistor is the problem, I always recommend you to replace the capacitor anyway: It's a small extra effort when the unit is opened up on your workbench.

[MindBender]

[offtopic]Very nice multimeter you got there![/offtopic]

Thanks. I'm very happy with it, but I am disappointed by the it's battery consumption, slow startup time and early auto power-off.

[MindBender]

Another Xanura SAIX bites the dust. I noticed the module squeeling louder than usual and no lamp was mounted on the junction box, so I noticed the LED blinking erratically. The module was warm too, it's plastic housing showed brown discolouring and signs of melting. So without checking if the device still worked, I removed it from my installation and opened it up:

Xanura SAIX running hot

Xanura SAIX running hot.jpg (173.34 KiB) Viewed 19623 times

I checked the capacitor, the series resistor and even the fuse I described above, but all checked out ok. The resistor marked 473 got a little hot (duhuh) and out-of-circuit it measures 35kOhm, where it should be 47kOhm. That's 24% less than it's rated value, but I think this more of an effect than a cause.

Does anybody encounter a similar defect, or have an idea of what's wrong with this module?