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Thread: Relay Failure

  1. #1
    Automated Home Sr Member danward79's Avatar
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    Default Relay Failure

    Hi

    I seem to be suffering with an AM12 hardwired module, it would appear that the relay is sticking, leaving me with a high resistance contact rather than a fully open contact.

    The symptoms are that the lights (fluro), come on in the middle of the night without the module activating. I have also noticed that with the module off the starter on the lights, sometimes glows, this can only be seen in the dark. This would tend to suggest some leakage from the module.

    The module has been in use for about 2 years now. It is activated twice a day, once on and once off.

    Has anyone else seen this before?

    Any advice?
    Cheers

    Dan

  2. #2

    Default Re: Relay Failure

    Hi Dan,

    The only time relays tend to get "high resistance contacts" is when they should be closed and the contacts are contaminated. This leads to less power than there should be when the relay is on and the contacts will get hot.

    What you are noticing is the slight leakage current that is used for local control of the module.

    Devices that take very little current can end up being powered all the time.

    The symptoms are that the lights (fluro), come on in the middle of the night without the module activating.
    When you say it "comes on", do you mean a brief flash, or that it comes on and stays on. If it stays on, do you have to send a command to turn it off.

    I have also noticed that with the module off the starter on the lights, sometimes glows, this can only be seen in the dark. This would tend to suggest some leakage from the module.
    Definately the local control sensing current causing this.

    The reason the light comes on fully (if that is what is happening) is that the leakage current causes the starter to heatup at which point its contacts close. the change in current is sensed by the module and it switches on.

    I had the same problem a couple of years ago with some Christmas lights. When the module was off there was sufficient leakage to charge up the PIC based controller after about 15 seconds. The PIC then started its sequence and the increaded load as soon as the first set of light was turned on resulted in a "click" as the module came on.

    You CAN disable local control but it involves opening the unit and cutting a diode or pin on the chip. Dont have the mod details to hand but google for

    X10 disable local control

    and you should find the info required.

    Hope that helps

    Keith
    KAT5.tv - affordable high quality AV Distribution
    http://www.kat5.tv

  3. #3
    Automated Home Sr Member danward79's Avatar
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    Default Re: Relay Failure

    Hi Keith,

    Thanks for the responce. Couple of questions do appliance modules have local control? Secondly why has this only started happening more recently?
    Cheers

    Dan

  4. #4

    Default Re: Relay Failure

    Quote Originally Posted by danward79
    Couple of questions do appliance modules have local control?
    Definately. My Xmas light were on a AM12 as was my previous dishwasher (the current one has a built in delay feature). After I had loaded the dishwasher I could operate the ON button without tripping local control but if I had forgotten to put something in and opened the door that was enough to trip the module on so I disabled local control.

    The kettle is on an AM12 which cuts the power at 10pm until getting up time. If I want to use the kettle in the meantime I have to flick the kettle ON-OFF-ON to get the module to come on. (There is a scheduled HomeVision event which turns it off every half hour from 10pm until getting up time so I dont need to manually turn it off again)

    Quote Originally Posted by danward79
    Secondly why has this only started happening more recently?
    Ah! the 64 million dollar question.... Dunno!

    Has ANYTHING changed,eg new lamp, new starter etc.

    Is there more than one lamp on the circuit? If so, has one of them failed.

    If you put a small tungsten lamp eg 15W pygmy bulb across the circuit as well that should maintain enough load on the sensing circuit to effectively disable it.

    Regards

    Keith
    KAT5.tv - affordable high quality AV Distribution
    http://www.kat5.tv

  5. #5
    Automated Home Sr Member danward79's Avatar
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    Default

    No nothing at all has changed on the circuit, no new tubes, starters, etc.

    I will try disabling the local control.

    I found this article. Looks ok to me.

    http://www.x10ideas.com/articles/dis...trol%20Feature
    Cheers

    Dan

  6. #6

    Default

    Quote Originally Posted by danward79
    I found this article. Looks ok to me.

    http://www.x10ideas.com/articles/dis...trol%20Feature
    Looks OK to me too. IIRC I actually cut the IC pin on one module I modified as it was quicker than fully disassembling

    Keith
    KAT5.tv - affordable high quality AV Distribution
    http://www.kat5.tv

  7. #7
    Automated Home Sr Member danward79's Avatar
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    Default Re: Relay Failure

    Ok Thanks for that.

    Out of interest why do you have an appliance module on your kettle? :roll:
    Cheers

    Dan

  8. #8

    Default Re: Relay Failure

    Quote Originally Posted by danward79
    Out of interest why do you have an appliance module on your kettle? :roll:
    Actually, the question you should be asking (or I should) is "Why do I STILL have an appliance module on the kettle?"

    The reason for its existance is that when I worked for BT at Martlesham I had to get up VERY early in the morning and was totally unable to function until after a large mug of coffee.

    By having the kettle on an appliance module I could fill the kettle anytime after 10pm and flick the switch to ON. Because the AM had disconnected the power the kettle would not boil.

    Then at 05:40 Mon-Fri, Homevision would turn the kettle on so that when I got downstairs at 05:45 ish all I had to do was pour the hot water into the cup. It gave me an extra 5 minutes in bed which may not sound a lot but as I was only getting just over 5 hours sleep every night every little helps.

    I also had a small lamp in the bedroom which would come on at low brightness so I could see to walk round the bedroom without disturbing Sharon.

    The two table lamps in the lounge also came on so that when I got downstairs the lounge was lit. When it was time to leave, one of the lamps would flash and a few minutes after I was supposed to have left, they went out.

    Hope that makes it clearer

    Keith
    KAT5.tv - affordable high quality AV Distribution
    http://www.kat5.tv

  9. #9
    Automated Home Sr Member danward79's Avatar
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    Default

    Ah I thought as much
    Cheers

    Dan

  10. #10
    Automated Home Sr Member danward79's Avatar
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    Default Re: Relay Failure

    And of course all this now explains why the NTL cable box comes on in the night!
    Cheers

    Dan

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