Xbox PSU and Power_ON "flickering" (4 replies)

Hi all,

I have a Xbox PSU 203W and want to use it with my Printer.
Currently I have it all wired and working fine BUT I also want to be able to control it's power using the M8[0-1] commands.

I did wired the Power_ON cable from the PSU to the RAMPs 1.4 and it effectively works but what happens is that the power is not stable.
The PSU led keeps flashing between green-red and the supply is clearly not constant I can hear the fans and even the steppers falling as if the power
is constantly changing between on and off. I can only describe it as flickering.

If I try to shunt the Power_on cable from the PSU to the 5V standby cable it works fine, solid green led and all working as it should.

It seems that the RAMPS/Firmware isn't keeping the Power_on Pin constantly pulled high, but I'm unsure how to tackle this.
Any ideas?

Thanks!