AC/DC converter problem
That circuit is a joke.  As Andy mentioned in a comment, 1N4001 diodes are inappropriate here.  They should be 1N4004 at least.  The rest of the circuit is nothing to be proud of either, unless you're the manufacturer and you're raking in the extra few pennies per unit you saved by buying cheap parts and hiring incompetent engineers, and your business model is to dump cheap crap out there, then run away before it catches up with you.  Take a look at the unit and see if there is even a manufacturer listed.  Even if there is, see if you can find them.  Probably not.

To answer your question about voltage: The input voltage is 239 V, but that's a sine wave.  When you measure AC voltage like that, you get the RMS value.  The peak value of a sine wave is sqrt(2) higher than the RMS.  The peaks of your input power is therefore 338 V.  You are only seeing 292 V because various parts of this circuit drop some voltage.