The hypernetted chain approximation is used to study the phase diagram of a
simple hardcore Yukawa model of a charge-stabilized colloids. We calculate
the static structure factor, the pair distribution function, and the colle
ctive mode energies over a wide range of parameters, and the results are us
ed for studying the freezing transition of the system. The resulting phase
diagram is in good agreement with the known estimates and the Monte Carlo s
imulations.