Re: Mach2 USB

Dale Ghent

With these cameras, and certainly with the ASI183, t's important to note that they have two power sources.

The logic board that drives the sensor and the USB controller on the camera is juiced via the USB's own 5V power. The 12V power on these cameras is solely for operating the TEC. This is why you can plug just a USB cable into the camera and it'll work.

USB's 5V DC power follows the same laws of physics that the 12V does and there will certainly be voltage drop over the cable length between source and device. This voltage drop can be more precipitous even when the USB cable is the same length as your 12V, only because the power-carrying pair of conductors in the USB cable are in all likelihood a smaller gauge (ca. 28-30awg vs. a 12V feeds typical 16-18awg.) We've found that USB cables that are too long can induce spontaneous device resets due to a low voltage condition.

My general advice, like others have echoed here, is to keep USB runs short for power and other reasons. The most reliable way to address this issue is to put a powered (12V) USB hub on the telescope itself and run all devices up there - camera, focuser, and whatever other USB-having accoutrements you might have to that. This would also mean you would need a 12V power hub of some sort with it, so that the thru-mount 12V power can power multiple devices.


On Jul 16, 2022, at 21:39, prestoncheatham <holmescheatham@...> wrote:

No, I hadn't thought of that. I will check the 12 volt with a meter. The camera is a ZWO ASI 183MC PRO.

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Sent: Jul 16, 2022 2:20 PM
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Subject: Re: [ap-gto] Mach2 USB

On Sat, Jul 16, 2022 at 11:29 AM, prestoncheatham wrote:
The flat cable is plugged into the USB on the camera and the USB on the mount. The round cable supplies the 12v DC for the camera cooler.
... also, have you checked your 12 volt cable at the camera with a voltmeter to make sure you don't have a bad connection or cable somewhere along the line? I can't see the name of the camera in the photo but the newer ZWO cameras with the larger detectors need to have 12 volts all the time to work.

Dean Jacobsen
Astrobin Image Gallery -

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