Looking at your circuit, I assume that a 240v mains supply is connected to "live240v" and "Neutral", and that a 115v mains supply is connected to "Live115v" and "Neutral", but not at the same time!
You show and incoming earth connection connected to chassis(?), also the 0v line connected to chassis.
With a circuit like this that is very wrong.
Depending on what voltage is on the neutral, the diode between neutral and 0v will get fried.
When making the (confusing) measurements, what are you using for the reference point, Earth, or the 0v line?
I suspect that you were using Earth.
To faultfind this circuit correctly, the -ve probe of you meter should be connected to the 0v line (ie the -ve side of C5), and not Earth. They are not (or at least should not) be the same point.
Try measuring again, and beware that the circuit is not isolated from the mains.
JimB