hot end problem

Hi all

I have just finished a 1st time build of a RepRapPro (ex RS components), took about 14 hours. All is working except the hot end temp which shows -273 no matter what I do. The temp sensor reads around 116K at ambient of 20C.
I fitted a variable resistance of 70K to 150K but it always shows -273. Any idea where to look for the problem?. Where can I find the circuit diagram so I can poke a round a bit?. I and very familiar with microprocessors, but I have no experience with the ardinuo boards.

thanks for any help
Mike

My 2 cent
the duet is not getting a readout on the pin.
Could be a loose connection on or off the board (are you using the right pin ?), before error-checking the board have you tried connecting the resistor directly to to Duet pins (as to eliminate problems in the wiring), if that still does not work, you could (if you know your way around arduino) change the temp pin in software to another pin nr.

On my Duet i noticed some black plastic over some of the pins. I cleaned it with a knife and after that my bed thermistor read normal.

Hi

I am connecting directly to the pins on the board. The 2 wires go to a pot of 50K and a 100K in series, so I can adjust 100-150K range

Are these the correct pins to use in the attached picture ?

any idea where I can download the circuit diagram for the PCB ?

mike

It does sound like you have a faulty Duet board. The board schematic and PCB files are at [github.com].

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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].

Try warming the hot end with a hair dryer or a hot air gun for a few seconds. Always works for mine.