Of course!!!
Iron core transformers require a dimmer suitable for inductive loads and so a common light dimmer will not work.
SOME electronic transformers can be dimmed with a light dimmer, but most have a built in safety shut down feature and a voltage drop across the primary is often seen as a defective voltage and so the transformer may well just shut down.
My guess is that you read about the dimming on a US based site where UL listed transformers are common.. these are a high freq transformer with no safety features and can be dimmed. They are however, illegal to sell in Australia as they do not pass C tick compliance as a minimum.
There are some that have a dimmer built in. depending on the size of the sign, I may be able to get you one id required and if you feel brave enough to change it over..
Gav
