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I have three 150kg servos installed in a robot arm. I have tested them successfully when connected to a servo driver hat on a raspberry pi zero 2w (image). However, they were under-powered because the servo driver hat regulates everything at 5v and these servos are rated from 6v-12v.

To solve the under-power issue, I connected the positive and negative servo wires to the positive and negative output terminals of a Mean Well 12v power supply. So now only the yellow control wires of the servos are going to the hat; the positive and negative wires are connected to the power supply directly. Images here and here. I also have a GND wire connecting the GND on the power supply and the GND on the servo driver hat.

However, the servos don't respond at all (as if they're not getting a signal). I used a multimeter to test the power coming off the power supply jumper cables and it's registering at approx 12v as it should so the servos should be getting power. I've tried removing the GND connection between the power supply and servo hat but that had no effect. What else can I try?

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  • $\begingroup$ Please edit and upload and add any photos to the question. People are more likely to view them in the question than having to click a link. $\endgroup$ Feb 7 at 23:15

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Ground on the power supply is probably just the chassis/mains AC safety ground. Check the datasheet to be sure, but the V+/V- outputs are likely not referenced with respect to the chassis. So at the moment, you don't have a complete circuit for your PWM signal.

The common "ground" for your servo, hat, and power supply should be the V- terminal of the power supply.

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