TL431 circuit redundant?
Currently only 12V_OK LED works when 12V output is present but the current consumption of that LED is not enough to keep both RaToPUS turned on. DC-DC requires current consumption of ~(10-20mA) on 12V and 5V to be turned on.
That can be achieved on 12V rail by modifying resistors R44 & R50, but on 5V rail LED only somewhat works when there is no R80 #35
Another possibility is to replace TL431 with LD1 in series with current limiting resistor plus adding additional resistor in parallel to constantly sink 10mA in case LD1 stops working in radiation. (That can be used on 12V and 5V rail)
Once that's implemented we no longer need additional load board to keep the RaToPUS on.
Also #29 wouldn't be a problem anymore