I think this person is looking at the AC voltage across the capacitor under actual circuit load. The 470nF capacitor is just to eliminate the DC voltage across the capacitor under test.
Richard
Hi Richard.
Well this method it supposed to be used on analogue TV sets,
usually the low voltage set like 150V 20V 12V 9V comes from an simple transformer and the AC to DC conversion,
it is made just by a simple diode ( not bridge).
Theoretically speaking, what it would be the AC voltage that a single diode will not convert in to DC,
if the source is 150V ?
Its known that the capacitor acts as filter so to eliminate the called ripple.
Your estimation about test at full load must be correct.
Alm is correct , that he is trying to measure ripple.
The first conclusion could be that if the capacitor falls sort under load so to eliminate an major part of ripple,
it should be damaged.
And now the new question would be how much ripple per volt is acceptable ?
Can we make a rule of the thump about it ?