I have a version 1.3 of the OSPI board, so far always used Raspberry Pi 1 B. This now broke and I have to replace it – I would really like to replace it with a Raspberry Pi 3 and use that for multiple other things (WiFi AP in the garden, etc…).
As this is all in a box with underground cables attached, delivering the 24V and LAN, there is no (easy) way to get another 5V cable or 230V for powering the Micro USB. Also, the box is pretty crammed, there is not a lot more space available.

Therefore, powering the RaspberryPi 3 through the Ospi board may be my best (read: only) chance. The transformer I use to supply the 24V (hager ST312) delivers 25W, thus I guess that should not be the limiting factor.
Thus my question:
Can you help me identify what to change on board Ospi v. 1.3 in order not to limit the power delivery to the Pi? I did not find the resistor R3 you mentioned above.

Thanks for your support!!