Uhh, nope. No extra capacitor. I said the power consumption occurs with just plain vanilla factory-made board without any external components. The only soldering made were pretty plain sockets for attaching cables from other PCBs which are to be driven from this one - and I double-checked those for short circuits.

I asked my friend who did a few projects like that and he says power consumption up to 0.5A is typical for such boards... should I trust him?