Not uncommon for motors to be pulling constant amperage when on to maintain position or braking. .45A at 24V is ~11W, or ~21W at 48V. Not a huge draw for these motors, and to be expected.
Ok makes sense. The motor housing only gets about 8 degrees warmer than ambient temperature on idle. Also noticed the amp draw when idle can change based on what the printer last did or where it idles - carriage in the front waiting for a Rasterlink job to start is lower than parked at the origin. There's no consistent draw.
Max current on jobs today was was 4.5A for forward travel, 3.7A reverse. Doesn't sound like it's too bad there.
Servo motors draw current to remain in position unlike standard motors. Hence the small current draw. See if the current increases if you push it with your finger.. It shouldn't move and the current should rise.
Test the psu voltages in AC mode.. Make sure no caps have failed.. Shouldn't have much AC present on dc lines. If you do, could be a bad psu
I think you're getting me to check for an AC ripple? Will try that when I get some time.
am i incorrect they would draw current to stay in position AGAINST A LOAD? for instance if the movement was vertical and gravity acted on carriage weight.
1/2 amp is a fair amount of heat to "piss away" standing still.
you mention a really good point, though, is this a situation where some of the caps (or just one) has high ESR?
do you think it would help if i offered to loan him an analog ESR meter (there is a lot to be said for a simple GO - NO GO test)
Thank you but I'm afraid I wouldn't be able to use it correctly, there are about 20 caps inside the power supply housing. All previous tests I did on the supply it seemed fine for stable DC output under a fake load.
Unfortunately it's not that simple as if you touch a servo motor you'll notice a slight vibration - this is because the motor is trying to move to the commanded position, yet there's always a slight overshot (inertia of mechanical components) - so it's usually never "Exactly" at the right point so oscillates slightly (fractions of a mm) - whilst a stepper motor has discrete steps.
500ma is nothing when you consider the moving mass it's constantly trying to keep in position - even if it's not "moving".
An ESR Tester would be a good idea.. Most issues usually have a PSU fault to start with.
I really appreciate all yalls help on this!
