Often the low voltage side of the transformer is fused with a small glass / ceramic filled fuse. If you have a careful look at the transformer casing there may be a removable part of the cover which you can take off to inspect.
If the is not obvious sign of one it may be because its an "electronic" transformer - it usually states and you can usually tell because it is very light, not feeling much heavier than a mobile phone. These don't usually have fused outputs. If it is much heaver, then it probably is a real transformer and is more than likely fused.
If there is no fuse and the unit has died, you can replace just the transformer bit. B&Q and the like (or any proper electrical wholesaler) sells replacement low voltage transformers. All you need to know is the VA rating. On a single light fitting, this could be anything from maybe 10 to 200VA. It will be stated on the case. If it is not, count up your lamp bulbs and multiply by the wattage of each bulb (i.e. if there are 5 of 20W lamps you need a 100VA transformer)
Please take care to turn the power off at the mains before you poke, especially as you don't know whether the switch is off or not. A torch will be essential!
Pete K, January 2006
