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Switching on the heated bed disconnect usb connection to my pc

Posted by Eldaoud 
Switching on the heated bed disconnect usb connection to my pc
March 28, 2014 03:35AM
I have been playing around with my new ormerod printer and it worked like a charm. After about 1 week intensive printing and playing around something very strange happened. As soon as I heat up the heated bed the usb connection is lost to my pc and windows come up with a usb not recognised error. If I heat up the hot head it heats up but while heating up there is like a interference on my pc screen lines and all but the usb connection is not broken.

I looked around on the forum and it sounds like the power supply, but measuring the 2 power pins supplying power it does not even drop .5 volts from 12.3 volts. Also when I connect the usb cable all seems fine, when I switch on the power supply then it look like a spike comes through to my pc’s screen but just for a split second. Also when the printer is connected and just left with the power on and usb connected it seems every now and then it spikes my pc.

Any help will be appreciated.
Re: Switching on the heated bed disconnect usb connection to my pc
March 28, 2014 04:27AM
It could be a dodgy 0V connection between the ATX PSU and the Duet. Here are some suggestions:

1. Check the 2-core wire that carries the 12V supply between the ATX board and the Duet, in particular make sure the screws in the terminal blocks are still tight.

2. Put a ferrite core around the USB cable.

3. If you have another ATX power supply that can handle 20A on the 12V rail, try it in place of the one supplied.

Edited 1 time(s). Last edit at 03/28/2014 04:27AM by dc42.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Switching on the heated bed disconnect usb connection to my pc
March 28, 2014 04:51AM
Thank you dc42,

The 0v lead was melted in side the connecter, so I just stripped and reconnected the wire and all seem well.
Re: Switching on the heated bed disconnect usb connection to my pc
March 28, 2014 05:05AM
It's hard to get reliable connections using the wire supplied. If you use the ferrules, then you really need the correct crimping tool for them. If you tin the wires instead, then the solder will soften over time and you need to re-tighten the screws regularly. If you do neither, then the terminal block doesn't clamp the stranded wire very well. Also, the wire is IMO under-sized for the job. I now connect to the terminal block using the red and black wires out of a short piece of old 30A ring main cable.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
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