DUE/RADDS with ATX power supply cycles on/off continuously when not plugged into USB

So when I first set up my RADDS with my ATX the 5v power from the ATX powered the DUE and kept the LCD on and When I toggled power on via LCD it powered everything on fine and I could power off again also.  I loved this feature.  I started using Repetier Server to control more than one printer and I love it.  Recently though if I unplug the USB cable or the power cycles (power outage) and the computer or Pi power down or reboot, my ATX power supply goes into an endless instant reboot over and over.  It powers on for less than a second then poweres off for less than a second and does this over and over.  

Is this an issue with the firmware or maybe the ATX is not very good and not supplying enough power or something went wrong somewhere.  If the ATX powers on, shouldn't it stay on?  If it powers off should't it stay off?  During the constant reboot the LCD is also power cycling and the firmware can't even load. 

I did add BLTouch and it does power on with USB even if the ATX is not on.  Maybe that is drawing too much power for the 5v from the ATX to handle?  I did the 3.3v mod to the BLTouch and it is powered from the Z endstop pin.

The only other thing I can think of is my LCD sometimes goes dim for no reason.  Maybe that is dying and the 5v being pulled by the RRDFGSC is pulling too much power for the limited 5v ATX (in power off mode).

Any suggestions/recommendations? 


  • Sounds in deed like 5V power vie unpowered ATX is not enough. As soon as you get extra power over usb it seems to work. As a counter test add a usb charger instead of the pi. Guess that should be legal. Then you know no communication is happening and if it stays stable and starts toggling once you unplug you know it is power related. 
    BLtouch adds 20mA and can draw <300mA as it states. I think when toggling state it might use the higher values. Try unplugging it and see if it stops.

    If that is the problem use the ATX as normal power device instead to keep it stable.
  • That's a good test.  I'll see what happens.  I may also see if it does it when I unplug the BLtouch.  I may just need to use an external source for my BLtouch power.  Thanks!
  • I think ATX also has 5V/3.3V lines that only get powered when the PSU is on full power. Use these for extra devices requiring much power in that case.
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