A search for stellar variability based on time resolved CCD observations for the open cluster NGC 6802, was conducted in June 1990 at the 2.5 Isaac Newton Telescope (INT), at the Observatorio del Roque de los Muchachos (ORM), La Palma, Canary Islands, Spain. The main goal of this kind of observations was the detection of p-modes in solar-like stars. We have not detected clear evidence of oscillations in any star of the open cluster, as the noise level attained is higher than the expected amplitudes for p-modes, which are about 50 μ magnitudes (Gilliland & Brown 1991), in the best cases. However, we can report the discovery of a very faint W UMa type system, because its amplitude in the spectrum is 0.1 magnitudes, which clearly raises above the noise level. From the characteristics of its light curve, we assume it to be a W Ursae Majoris type binary system, with a period of 7.22 hours.