Submitted by MrGreg on Tue, 11/20/2018 - 13:44
Forums:
I appreciate that a single ended psu > =750Watt is recommended.
However I'm not clear on alternative configurations, so a couple of Qs
1. Is a single ended PSU essential? Or is a dual rail OK if jss1 and jss2 are cut?
2. Are the 4pin inline molex connectors required? Or optional if the 6 mosfet outputs are not required?
3. WRT to Qs 1 & 2 If one is just using a simple mill config say 3 or 4 axis, then is a PSU that can supply 12 - 16 A from the main 24pin connector + the 4pin square (gpu/aux) connectors OK?.... And in this config does it matter if the PSU is single or dual rail? ( providing the 4inline connectors are not connected/used)
Cheers
MrGreg
SIngle Supply is best....
Although the board can be modified for up to a 3x12v rail system (gen1 did this), it is best to stick with the existing 1 rail (gen2/gen3) for a couple of reasons. Mostly, it helps the power supply stability, as the minimum-load requirement on ATX 12v1 is supplied by the steppers themselves. Also, it is less likely to have fault issues during later maintenance, and modifications.
However, for only 3-axis NEMA17 (around 3*2*2A=12A inductive loads) most 23A rated 12v ATX supply should suffice if 5vSB > 2.5A. Keep in mind the 24 pin header is best <=12A, each 4 pin (2x2 square) plug supplies up to 15A, and each classic 1x4 plug offers 5A each. "The more the merrier" as they say... as long as they share the same rail. ;-)
The 6 Mosfet outputs can remain dormant if not in use.
J
Thanks for the clarification
OK
Will double check that 24p and 12p sq are same rail and run with that for now. Will get a big single when needs be.
Cheers
MrGreg