An inexpensive automated DLTS system has been developed in modular form consisting of modules such as a capacitance meter, pulse generator, DLTS system timing controller, data acquisition system, PID temperature controller, cryostat with LN2 flow control facility, etc. These modules, except the capacitance meter and pulse generator, have been designed and fabricated in the laboratory. Further they are integrated and interfaced to PC AT/386 computer. Software has been developed to run the spectrometer, collect data and off-line data processing for the deep level parameters such as activation energy, capture cross-section and density. The system has been used to study the deep levels of platinum in n-type silicon and their passivation by atomic hydrogen. The estimated activation energy of the two acceptor levels are Ec-0.280 eV and Ec-0.522 eV and their capture cross sections are 2.2E-15 cm-2 and 4.3E-15 cm-2 respectively. These levels are found to be reactivated when the hydrogenated samples are annealed in the temperature range 350 - 500 degrees Celsius. The mechanism of passivation and reactivation of these levels are discussed.