Zone

A whole new line called ACTION MASTERS makes its appearance - these are articulated action figures based on TRANSFORMERS characters both old and new. OPTIMUS PRIME has brought back an experimental form of energy called Nucleon to super-fuel his troops with incredible powers. The DECEPTICONS steal this resource and the battle rages anew. But this energy source comes with a price - it makes the TRANSFORMERS robots unable to change! That power is given instead to their weapons and assistant drones.
More MICROMASTER figures are released, including MICROMASTERS COMBINERS, an interconnecting series of micro-vehicles.

But all good things must come to an end, and so it is with the first generation of TRANSFORMERS figures; 1990 is their last year of production in the U.S. The Transformers line continues overseas however.