Found this. The only one i would say that is ok to have continuity with the case is the GND. If any of the other pins have continuity then i would try it outside of the case and see if the printer then functions correctly.
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USB 2 vs USB 3 pin layout: https://i1.wp.com/www.isumsoft.com/it/wp-content/uploads/2016/09/pin.png?w=584&ssl=1 1
I have taked the PC down, dusted it and tidied up some routing.
The USB port shield no longer connects to the case. It does ground to the PSU…I think the components are isolated from the case. They are now at least.
The Shield connects to the ground pin, which is a black lead where I stripped off a test cable. None of the others; red, green white…connects to the shield or case.
I checked to see if anything was solved. Not yet.
One thing I checked just recently…
I plugged the USB cable into the Printer and touched the shield of the cable to the shield of the port.
When the PC is off, nothing happens…improvement. It used to kick on the hotend.
When the PC is on, problem repeats.
I hate to take up all your time. I’ll get a PCI USB card and a port tester and see if that tells me anything and check back.
Not at all, i do tech support as a hobby as i have nothing better to do. First time doing 3D printer tech support though xD This is a very interesting issue and i am happy to try and help as i also learn form the experience 
If it’s now all clean though and the stand offs aren’t shorting anything to the case then i am actually qwite perplexed myself at this point. If you have an old spare PSU it may be worth just plugging in enough to power up the board and see if the issue still persists. Otherwise yes, try the PCI.
Note: there are much cheaper PCI cards out there with less ports on but i sent that one since it as actually more useful to use after solving this issue
I might know someone who’ll have a couple lying around.
I just can’t figure out what I could have done to cause this and how to undo it!!!
When I gather some more tools, I will update you.
Thank you so much again.
Might not have done anything. Components degrade over time which can make strange things happen seemingly out of nowhere.
Good luck, hope u get it fixed, look forward to hearing your results
Sounds like you have run a number of different scenarios with only the printer being the common item.
That would leave me to believe that the issue is in the printer. I think it is safe to say you have eliminated the PC as a problem.
Have you done a reset of the printer back to its factory defaults?
Have you done anything to the printer? Check for any wires related to the hot end that may be grounding out.
whirlybird: I have not done anything to the printer recently. The last thing I did to the system was to put TL smoothers in line with the steppers and it worked fine with them for the last 4 months. When the problem started, I replaced the printer motherboard and that didn’t solve a thing. I have never touched the firmware or modified anything else electronic.
TehEmoGurl: I had an idea and found something new…I think the problem may be in the printer after all. I put the multimeter to the shield coming off the printer cable to the PC USB shield and it reads 24v. The printer is the only thing running on a 24v supply.
What I’m thinking now is that some current not supposed to be flowing there is finding a path through the PC that netbook isolates somehow.
I don’t know if this is useful, but the problem began after changing out the nozzle. I considered the possibility that I may have touched the heat element or thermistor inappropriately during the procedure, but ruled that out upon testing with the netbook and SD card…these modes would not perform perfectly with a damaged element/sensor in my estimation. Had I damaged the board in the swap, the new board would have resolved it.
I’d unplug the heater and thermistor from the main board and see what happens.
If the issue started after changing the nozzle then that is a clue.
Unplug them and check the voltage through the shield? I can do that, but will that tell me about how to make it work properly when they are connected?
The idea is process of elimination. Yes you can check the voltage at the shield but also with both unplugged is the actual problem still present? Does it try to heat. I imagine not with the heater unplugged but does the display show anything odd or does it just show an error?
I’d also inspect the wires very carefully near the extruder/hot end to see if one broke or got pinched.
You can remove the heater and thermistor from the hot end to make sure they are not grounding out and see what happens.
You could also test for voltage at the heater terminal when the printer is hooked up to see.
The PC causing the issue doesn’t really make any sense. I feel a more likely scenario is a wire has grounded out on the printer and causing voltage to the heater.
Well if the heating element is disconnected, I won’t know if I still have the problem of it heating up without being told to. I doubt it will try to heat up when it’s disconnected. Also, this problem does not occur when I print from the SD card or when I connect it to a netbook. That’s why I suspected the PC in the first place, but that might have been wrong if 24 volts is in play…that’s the printer’s voltage.
Is it possible that the heating element is shorting to the printer frame somehow? Perhaps I should try and see if I remove it from the block and test it connected but unmounted? FYI, the thermistor (and my finger) is what I have been relying on to tell me it’s heating…and when running SD/Netbook everything is normal, I have full control.
Does the display show it heating when the issue occurs?
With the heater and thermistor unplugged does the display give an error or does it still show it trying to heat?
I would remove the heater and thermistor from the hot end and make sure they don’t touch any metal and see.
It is odd.
Are you using any USB hub, extension cable or anything like that?
I will try that, thanks for the suggestion.
I could not answer earlier, the board capped my replies.
Just unplug the heat cartridge then see if the 24v to the USB shield is still there.
Prolly against the rules, but I wanna curse my head off with triumph and joy.
My happiness could not have been restored without you guys helping me on this scary path!!!
Everything is back to normal.
Once i replace the cartridge, We’ll be good as new.