Ticking sound from a power supply can indicate short circuit, supply tries to start but as soon as voltages raises, a protection kicks in and shuts off it again in constant loop (well this is what happens with a Toshiba T5100 "laptop"). Start to check with multimeter if any of the power pins have shorts to each other or ground. If not, then it could be the supply not handling full load due old n' dry electrolytics.