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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.

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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.

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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?

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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.

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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.

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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?

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I will try that, thanks for the suggestion.
I could not answer earlier, the board capped my replies.

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Just unplug the heat cartridge then see if the 24v to the USB shield is still there.

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That’ll be the second thing I try when I get home.
First I’ll take it out of the block and test it, in the event there’s a short between the coil and the case surrounding the ceramic…if that makes any difference. The MK10 hotend block I’ve got doesn’t clamp it, it’s held with a setscrew which could have pierced. Dunno if that would do this, I have not messed with it since installation, but it’s a straw to grasp at.

Thank you. We haven’t fixed it, but with your help I feel we’re making progress ruling stuff out.

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I think we found it.
I disconnected the heater cartridge to see if the shield still carried 24v.
I found the wires to the heater were pinched and the insulation exposed. Very bad thing, very good possibility that’s where the root cause is.
First, disconnecting the heater cartridge removed the 24v from being carried on the shield.
Second, reconnecting the heater cartridge, protecting the exposed conductors AND THE PROBLEM DID NOT REPEAT!

I think I am in business.

You have been great!
wirlybird has been great.

I cannot thank you enough!
I will replace the heater cartridge and find a way to route the wires so this never happens again.

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Yaaaay! Glad it’s fixed! Happy printing :slight_smile:

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Good job. Happy you got it going.

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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.

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