http://dx.com/p/hk3ff-dc5v-shg-5-pin-po ... ece-134102
Now I can replace the receiver board's 24 volt relay with one of these and the conversion from 240 volt to 5 volt of the board is complete.
This is nearly what the board looked like before hacking-

I have taken nearly every part off the board, the 24 volt relay, the diodes, the red cap, the large cap and the 5 volt regulator. I feed a 5 volt supply in where the regulator was from the 5 volt standby supply on a 1.6 xbox power supply and change the 24 volt relay for one of the 5 volt ones and now the whole receiver works on 5 volts. The other problem is the board is a latching circuit and to get around this and turn it to a momentary devise to pulse the Xbox on or off, I connect the Xboxes power switch across the relay terminals. The 2 outside terminals of the relay's switch are connected to the Xbox's open switch terminal so when the relay is in either position, on or off, it does nothing however, when the relay changes state, the switching relay terminal which is connected to the Xboxes "other" switch wire is also connected to ground via a 20k resistor. What this does is ground the Xbox's switch wire whenever the relay changes state. The 20k resistor is there to prevent a short and only supply a ground signal whilst the relay changes state. I'll do a complete "How To" with pics when I have the relays and have tested the circuit. The best part about this mod is the receiver is a "learning IR receiver" so that means it can be tuned to work on any button on just about any IR remote. Once I have the 5 volt 1.6 version working, I'll have a look at how to get it working on the other Xbox versions.