My Hictop Prusa i3 temp sensors not working(Err: MINTEMP)

[bluetangkid]

I finally got an actual print out of my printer, but it just suddenly started reporting 0C(MINTEMP) for the extruder temp sensor later that night while i left it idle. I checked both of the temp sensors which report 100k Ohms of resistance. Checked marlin(i'm running v1.0.5 r-2) and the sensor settings are correct. I tried plugging a backup temp sensor into the port which had the old temp sensor, and it still reports MINTEMP. Any suggestions?

Side note: i had to redo the connection on the bed sensor by taping aluminum foil to the + side, and for some reason it fixed the bed temp sensor(it reads correctly now). The extruder one still doesnt

Edit: I would like to use the other temp sensor port i have, bit i dont know how to edit the pins.h or any of that stuff.

[printbus]

The typical thermistors are negative temperature coefficient, meaning the resistance goes down with an increase in temperature. Your MINTEMP error is suggesting that the thermistor has unusually high resistance, as in an open connection somewhere between the thermistor and the input circuit on the electronics. It sounds like you've checked the thermistor, so I'd double check where you're connecting the hot end thermistor on the electronics.

FWIW, you could try applying a short between the two thermistor pins on the electronics. The short should cause a MAXTEMP error, since the electronics would be reading an unusually low resistance.

If you're positive you're connecting the thermistor properly, the electronics may be suspect. Are the thermistor leads fully insulated at the hot end? A common way that electronics gets damaged is a faulty hot end heater inadvertently applying 12V onto an inadequately insulated thermistor lead. The electronics board won't like that.

[bluetangkid]

Thanks for the reply. I think the socket is damaged since the short did not give a maxtemp error, and this happened when the extruder was on. What I want to do is use the other socket on the board, how would I go about that? Also what would you suggest for preventing repetition of this incident if this was the culprit?

[printbus]

...What I want to do is use the other socket on the board, how would I go about that?

You haven't indicated what the electronics is, and Marlin has been evolving as far as how the pin mapping is accomplished. If your Marlin source code includes only one pin file (pin.h), you'll have to find where in that file the pins for your motherboard type are defined, and make sure TEMP_1_PIN is configured to what the second temp sensor input is on your electronics. If there are multiple pin files in your source code, you look at the pin file applicable for your electronics type . You may find that the second sensor pin is already mapped - it was for some electronics types in older Marlin, and I think newer versions of Marlin have added the mapping for the second sensor on, for example, a MEGA2560 board with RAMPS shield.

Once the pin mapping is set, then you should only have to modify configuration.h. Find the #define statements for TEMP_SENSOR_0 and TEMP_SENSOR_1. A #define value of 0 disables that sensor, while a value of 1 enables it. So, if TEMP_SENSOR_0 is set to 1 in your firmware, change it to 0 and change TEMP_SENSOR_1 to 1.

I haven't used Marlin in over a year - I hope I haven't left out something else.

...what would you suggest for preventing repetition of this incident if this was the culprit?

That's hard to say since we don't know exactly what happened. I'd start by making sure the thermistor leads and wiring are fully insulated.

[bluetangkid]

You haven't indicated what the electronics is, and Marlin has been evolving as far as how the pin mapping is accomplished. If your Marlin source code includes only one pin file (pin.h), you'll have to find where in that file the pins for your motherboard type are defined, and make sure TEMP_1_PIN is configured to what the second temp sensor input is on your electronics. If there are multiple pin files in your source code, you look at the pin file applicable for your electronics type . You may find that the second sensor pin is already mapped - it was for some electronics types in older Marlin, and I think newer versions of Marlin have added the mapping for the second sensor on, for example, a MEGA2560 board with RAMPS shield.

Once the pin mapping is set, then you should only have to modify configuration.h. Find the #define statements for TEMP_SENSOR_0 and TEMP_SENSOR_1. A #define value of 0 disables that sensor, while a value of 1 enables it. So, if TEMP_SENSOR_0 is set to 1 in your firmware, change it to 0 and change TEMP_SENSOR_1 to 1.

I haven't used Marlin in over a year - I hope I haven't left out something else.



That's hard to say since we don't know exactly what happened. I'd start by making sure the thermistor leads and wiring are fully insulated.

Sorry, I use a mega 2560 with an integrated ramps board. Ill look at pins.h and see if i can fix it