"alitonto" wrote in message
oups.com...
Hello,
I am trying to work out in particular which component is most likely to
cause a reduced voltage at the supply point to its circuit. I suspect
there is something pulling too much current ahead, becuase when I
disconnect the circuit then the supplied voltage returns to normal
measurement.

Generally, three things can be considered here. (1) V=IR so if I, the
current, or R, the resistance is too high, V, the voltage drop, will be
excessive. (2) Some power supplies use current limiting which kicks in at a
given point and then they switch over to a constant current mode (as opposed
to constant voltage mode). (3) Some power supplies use fold-back current
limiting which also kicks in at a given point but the current folds back
which makes the voltage drop at the load even more severe.

Could be the load is partly shorted, or a series resistance has gone up in
value, or a faulty connection, or a faulty power supply. Troubleshooting is
usually a process of elimination.