Ramps 1.4 Diode (7 replies)

Morning all. Please forgive me if this has been asked before but I cannot find an answer

I have a CTC printer but I am making my own (I find making stuff myself somewhat rewarding)
Don't have all the items yet but have started with the brains. I will be using a Arduino mega2560 and a RAMPS 1.4 (from the bay) and a smart controller with LCD but I have concerns about the ramps, inperlicular the Diode's
D2 is in place but no D1. I have read this (http://reprap.org/wiki/RAMPS_1.4) but I’m a little confused

It says
" D1 should only be installed if the 5A rail is powered by 12V. It can be omitted and the Arduino will be powered from USB. You will want D1 installed if you add components to print without a PC. To reiterate, D1 MUST be omitted if you are powering the 5A rail by more than 12V, or the power is not absolutely clean, otherwise you may damage your ramps. "


I plane to run both boards from a converted PC power supply

My ? is do I need to install D1? If so can anyone tell me the value please (D2 is fitted with the value face down)
I have 4001 and 4007 but I think it may need a 4004

Can someone please advise me as to whether it should be fitted or not and if fitted the value?

Thanks for looking