Failure to dim up

Discussion in 'C-Bus Wired Hardware' started by pmfortune, Jun 8, 2026.

  1. pmfortune

    pmfortune

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    I've recently updated my 5508D1A dimmers to 5508D1Ds. All channel are programmed to use trailing edge and all drivers for LED are electronic (all the same type).

    In one room, when the lights haven't been on for a while and a scene is triggered, one channel doesn't light. As soon as it's toggled off then on again it lights. It's constant on a single channel.

    I have found if I set a minimum level of 4% on the channel the light goes off OK but then always goes on when expected.

    Any thoughts?

    Thanks
     
    pmfortune, Jun 8, 2026
    #1
  2. pmfortune

    Trevor

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    try swapping the 2 of the outputs (Hardware) the dimmer controls and see if the fault moves with that.
    Also try swapping the 2 inputs (Software) to them as well.
     
    Trevor, Jun 8, 2026
    #2
  3. pmfortune

    Tension

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    Press the relevant channel key on the unit twice to disable auto detection. It'll flash quickly to confirm.
     
    Tension, Jun 8, 2026
    #3
  4. pmfortune

    NickD Moderator

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    This is not quite correct.

    Just for the record here for anyone that comes across this in the future..

    There is no "Auto Detection" on the new digital dimmers. They will never change mode automatically.

    Out of the box, the digital dimmers have a dimming profile enabled called "Load Detection Mode", that allows for safe detection of inductive loads. This profile has an extremely long soft turn on, as well as a very low minimum level.

    When the dimmer is first installed and the load has been connected, the installer needs to turn each channel on using the buttons on the front panel, and then either confirm that TE mode is OK, or change to LE mode if it's not.

    The channel will start in TE mode, using this safe profile. If it does not detect an inductive load, the channel will turn on successfully and the channel indicator will illuminate solid yellow. At this point, double clicking the channel key confirms that the load is OK for TE mode and deactivates the Load Detection mode and enables the normal TE dimming profile.

    If, however, there is an inductive load detected, the channel will shut down and the channel indicator will flash red slowly, indicating a mode error. If this happens, the installer needs to change the channel to LE mode using an extra long press. Turning the channel on again will illuminate the channel indicator in green. If it still flashes red then the load is not compatible with the default LE mode profile. It may be possible to make it work with a custom load profile.

    Note that changing to LE mode and back to TE mode will reset the mode confirmation flag so you would have to re-do the mode confirm procedure.

    Nick
     
    NickD, Jun 15, 2026
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  5. pmfortune

    NickD Moderator

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    This is why the dimmer has customisable load profiles.

    If you open the properties for that channel from the network, and go to the "Advanced" section, you can assign one the custom load profiles to it. In the dialog that opens where you can edit the custom load profile, there is a "Testing" tab, which will let you experiment with different settings for minimum level, as well as finding a maximum, without having to go back and forth deploying different settings to the unit and fiddle with the light switch. Once this is done, the dimmer then scales the C-Bus control range of 0-255 over the resulting range of the dimmer channel, so you don't lose any control.

    Nick
     
    NickD, Jun 15, 2026
    #5
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