Last night my cctv tripped the main mcb in the house, we only knew something was wrong when the alarm on the charger for the stair lift went off ( audible ) normally if there is a power outage the cctv re-set its self, but all i was getting was the bank of lights just flash on then back off & the hard drive did not kick in, i have now taken the lid off & given it a good blow out to remove the accumulated dust, re-coupled the wires back in and nothing, shake the power supply lead & i get the odd bleep, i suspect that this is the problem, but i cant see how i could check it with a meter as it has got four pins, ( Power Requirements DC 12V 10A SWITCH POWER )