This has come up a few times, but it might be handy for some of you. If you have "PRO" dimmers on a site; L5104D5 L5102D10 L5101D20 and they stop dimming, ie: they only switch ON/OFF. This is typically caused by a built in Feature of the PRO dimmer. If the incoming frequency shifts outside of certain tolerances, the dimmer automatically switches over to a ON/OFF switching mode. To reset the dimmer you must turn off the incoming mains to it, then re-apply the mains. The dimmer should return to normal dimming operation. As the Research and development process for CIS is an on-going process you may find that very early PRO dimmers may be less tolerant of incoming frequency shift. This feature is not present in the DIN series dimmers
