Electrical noise with ASIAir Plus powering the mount?

WhatMattHerrs

I have a CGEM II mount, which usually makes a quiet electrical whining sounds while it's on, which I understand to be typical. However, if I am powering the CGEM II through one of the ASIAir Plus' power outputs, the whining noise in the mount gets really loud as soon as I plug in the usb connection via the hand controller. The volume also increases (though not by as much) if I even just make metal to metal contact between the USB plug and port.

I have experimented with two different power supplies (both 12V, one 5A and the other 3A) and it happens with both. I also repeated while plugging in to outlets on separate circuits in my house for good measure.

However, this issue doesn't happen if I power the ASIAir Plus and the CGEM II with separate power supplies (under this condition, when I plug in the usb to the hand controller, I can tell that the electrical noise changes pitch slightly, but that's it).

I have seen mixed information about whether people are powering their mounts through the ASIAir power outputs. But given that this noise issue is happening then the mount isn't using a lot of power (ie, not slewing), I wonder if there may be a grounding issue with the unit.

What do you think?

wizzlebippi

WhatMattHerrs It's because you're either powering the mount through both the hand controller and the 12V jack, or you're grounding through the hand controller. Try adding a USB power blocker between the hand controller and ASIAIR. If that doesn't work, the ground on the 12V jack might be weak.

I actually found an electrical issue with my AVX due to something similar. The problem turned out to be a bad crimp on the ground wire to the 12V jack.

WhatMattHerrs

Thanks for the feedback! Never would have thought about a USB power blocker. Can you describe your issue with the bad crimp? Where was that crimp? In the actual 12V wire that went between the ASIAir and the mount, or somewhere else?

wizzlebippi

WhatMattHerrs The bad crimp was on the plug that connected the 5.5mm barrel jack to the power distribution board. There was a measurable resistance on the ground wire, which probably made the ground through the hand controller's USB port a better path. I discovered this as a result of my mount not working correctly unless the power was connected to a 12V outlet on the ASIAIR, and the had controller was connected to a USB port. Without the hand controller's USB port connected, there was a good chance that the mount would not boot. Being a used mount, I used parts on hand and replaced the barrel jack and associated wiring.