Hi again,
Well it would be better if you already had a spare ATX to start with so you didnt have to buy one first.
43vac could just mean that there is some residual ac because the two are already isolated and the slight capacitance is allowing
some ac voltage across the two grounds. You need to connect a resistor next, as per the procedure i outlined in a previous post.
This will tell you if the voltage is real or just a by product of the small capacitance. You have to realize that the meter has a
high impedance so it can see these voltages even when they are not of sufficient power to maintain that voltage across a
relatively large value resistor. In other words, a 100k resistor would probably knock that voltage down quite a bit. If not,
then that means there could be something else causing the voltage and you would want to be very careful going to 10k.
If 10k doesnt do it, i'd probably not continue.
Sometimes even a finger across the grounds will knock it down, but you have to be careful about getting a shock.
One finger only
The resistors provide more positive results though.
Do you have any resistors around?
0.5v is almost nothing, so they are already almost equal.
For the 43 volter, you can also try rotating the wall wart so that the prongs go into different holes, if that is possible.