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I did a search on this and I found two threads, one where the RAMBO was apparently fried and another where it may or may not have been. I just started getting this error tonight. I guess I will tear down my hotend again, wish I'd put connectors on for the fan/thermistor/resitors, guess I'll do that this time. Other than checking the thermistor connections anything else I should look for before just replacing the RAMBO? Ironically I just received my thermocouple today and had just verified that the temp readings I was getting from the hotend were accurate..

cpunches wrote:I did a search on this and I found two threads, one where the RAMBO was apparently fried and another where it may or may not have been. I just started getting this error tonight. I guess I will tear down my hotend again, wish I'd put connectors on for the fan/thermistor/resitors, guess I'll do that this time. Other than checking the thermistor connections anything else I should look for before just replacing the RAMBO? Ironically I just received my thermocouple today and had just verified that the temp readings I was getting from the hotend were accurate..

Before I dropped the cash on a new board I would...

1. Verify that I was getting appropriate resistance across the thermistor leads. Check for a short.

2. Swap my bed and hot end thermistors at the board to make sure the issue stays on the hot end.

3. Give serious thought as to how far out my use of dual extruders is, and whether or not I can get by until then by using the ext 1 connections and switching the pins in the firmware.

Thanks for the suggestions Foshon. I'm really hoping it's not the Rambo. The print job will start and run for a few minutes (and that just started last night) so I'm hopeful it's the thermistor connection that's maybe screwed up.

Strangely the issue hasn't re-occurred tonight and I've run several test prints - at varying degrees of success so at least I'm back where I was lol.

I really hate intermittent problems like this. I'll probably go ahead and tear the hotend apart just to check the connections to the thermistor.

If it's intermittent it's probably not the RAMBO board, the common failure case destroys the input pin on the arduino.
My guess would be bad connection somewhere.

I think it might be due to my low-tech solution for keeping the bowden tub from flopping over onto the Z tower cheapskate. I have a string that only becomes taut at z0 and keeps the tube off the cheapskate. When the string is slack the loop can travel a bit up and down the flex tubing. I think maybe it was pulling on the flex tube that houses the wires running to the hotend and maybe causing a problem.

Again, thanks all for the suggestions.

It turns out one of the leads to the thermistor had broken and when I would increase the speed the additional movement was enough to trigger the temp sensor defect error. I've torn the hot end apart again and will hopefully be able to get the thermistor hooked up properly again.

I did break down and go ahead and order the E3D hot end kit. I think in the long run it'll be a better hot end for me. I also ordered the new EZ-Struder from SeeMeCNC and looking forward to getting it setup too. I'm actually getting some decent prints when the hotend is working properly So hopefully between a new hotend and the new ez-struder I might finally get consistent prints!