Hot End and Heated Bed Temps Wrong

I just finished building my printer and hooking up all of the wiring and now I am on to testing all of the equipment. My thermistors for both my hot end and heated bed are reporting wrong temperatures. They both always report -59C no matter if I am powering from USB or the power supply. Also, they are not changing at all when I turn the respective parts on; they are constantly at -59. I checked all of my wiring and everything seems to be in order. What else could be going wrong? Any troubleshooting tips? Thanks.

Normally you see a minus value from the thermistors if they are not being seen by the duet.

I used to have this problem with the hot end due to a poor crimp at the connector block that joins it to the hot end loom.

It always used to be the case that you got a reading of -273C if the thermistors are not connected; but maybe that has changed in RRP's 0.78 firmware. I'm fairly sure my 0.78a-dc42 still shows -273, however my fork does the temperature readings differently.

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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].

Quote
dc42
It always used to be the case that you got a reading of -273C if the thermistors are not connected; but maybe that has changed in RRP's 0.78 firmware. I'm fairly sure my 0.78a-dc42 still shows -273, however my fork does the temperature readings differently.

No, it doesn't :-)

After loading your latest experimental firmware and fitting your differential board, I did a preliminary test with the bed ribbon cable unplugged. I was expecting to see a bed temperature of -273 with the bed thermistor disconnected, but in fact it was reporting -53, so something has changed!

The reported temps with the thermistor connected appear to be the same as always.

Dave
(#106)

Interesting, my second hot nozzle thermistor reading with the second nozzle disconnected is reading -273.1C, as I expected. Perhaps your SAM3X has a small ADC offset.

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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].

Quote
dc42
Interesting, my second hot nozzle thermistor reading with the second nozzle disconnected is reading -273.1C, as I expected. Perhaps your SAM3X has a small ADC offset.

No idea - it always read -273 before with disconnected thermistors. Maybe quickly try unplugging your bed ribbon as I did and see what bed reading you get.

Having thought a bit, I am having second thoughts about what firmware I installed. I definitely used your config & homing files, and your latest web interface (it has the new speed & extrusion controls). But now I am wondering whether I inadvertently downloaded RRP firmware instead of yours - I won't have access to my Ormerod till tonight to check. Would your differential board and Z homing work with RRP firmware and your config files? OTOH I am sure I would have noticed any major difference in the firmware filename - I keep all versions in the same directory and a different name format would have stuck out.

Dave
(#106)

Dave, my web interface won't work with RRP firmware because it uses the new status command to get extra info and cumulative filament extrusion. So you must be running my firmware fork. The differential board does work with RRP firmware, although the backup mode is unavailable, and RRP firmware doesn't slow down Z homing when the Z probe reading goes above 90% of the threshold set by G31.

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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].

Problem solved! It was just due to poor crimping, but I sodered and fixed the problem. Thanks for the advice!