I have a set of CD decks from America, power rated at 115v.
I want to use them in Japan where the mains supply is 100v.
I bought a step up transformer 100v to 120v.
If I use the transformer, will my decks fry?
:)

Is it something like this:
JAPAN STEP UP / STEP DOWN TRANSFORMERS - 100 VOLT - 120 VOLT
You should be OK, If transformer can handle the load.