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charlieRC
Related question (I hope)? I am building my second reprap with a rambo using a 24 volt p/s. Since I want to limit the amount of damage if I discover something about the 24 volt under fire, I wanted to get my hot end and bed working without the motors connected (foolishly or not, I figured that might protect the motor drivers). I knew as mentioned above not to unplug the motors under power. My question is.....what about powering up the rambo with no motors conected (or maybe one for the extruder)? Is that likely to cause problems even if I don't plug anything in under power?
As mentioned by others, no problem.
If you have an older version of RAMBo with PTC fuses (orangey-yellow blade-like components), replace the 11A PTC fuse with a proper fuse before moving to 24V. The 11A PTC fuses are only rated to 16V, and can cause all sorts of issues at higher voltages.
With the motors, always a good idea to test them with a multimeter before you plug them in the first time. Had a friend buy 5 motors, and after plugging them in his Z stepper died. Turns out one of the Z motors had a shorted coil, and this took out the driver (it was a RAMPS board, so it was an A4988). The resistance of a stepper motor coil should be low, but it's unlikely to be less than a 1 ohm (usually listed on the spec sheet), and a stepper motor has 2 such coils. It's a simple test that avoids costly driver replacements.