MINTEMP but hotend temp stays 0 after swapping thermistors
As the subject says: after swapping the hotend thermistor on my MK3S+ the printer a mintemp error and the readout says 0 degC. First I measured the resistance at the connector side and I can happily see the heating up between my fingers. So next I swapped the hotend and heated bed connectors on the Einsy, it now shows the temp just fine on the heatbed readout and the hotend readout stays on 0 degC.
How to proceed with fault-finding?
RE: MINTEMP but hotend temp stays 0 after swapping thermistors
Update: I soldered a 100k resistor to a header and plugged this in both ports (for the bed and for the hotend). The bed readout shows 25 degC as expected, the hotend readout shows 0 degC and throws the MINTEMP error.
So I guess this malfunction is within the Einsy? Is it possible to check if the sensor is correctly read by the ADC on the Einsy?
RE: MINTEMP but hotend temp stays 0 after swapping thermistors
Ok, I have no idea what caused the T0 hotend thermistor to not work anymore but I solved it by plugging the hotend thermistor in T1 and swapping T0 and T1 in software, since T1 is available on the Einsy but not used by the MK3S+. Solution follows in case it is of any use for someone else having the same problem.
See Einsy-RAMBo connections and schematic:
Schematic, see sheet 3/sheet 11:
(I know that the schematic is for 1.1, I assumed this part was not changed between 1.0 and 1.1).
The I fetched the PrusaFirmware sources, edited pins_Einsy_1_0.h:
#define HEATER_0_PIN 3 //PE5 #define TEMP_0_PIN 1 //A1, was A0 #define HEATER_1_PIN -1 #define TEMP_1_PIN 0 //A0, was A1
Build, flash, hopsakee it works. Everything seems to work fine now. I have to do some more maintenance and calibration before I can do a full testprint.
Again, this is a weird failure that I didn't expect.
RE: MINTEMP but hotend temp stays 0 after swapping thermistors
I seem to running into this exact same issue. I've had a mk3s that's been broken for months and I haven't been able to fix it because of the mintemp thing. Put in a new hotend/thermistor, same mintemp issue. Appears like I have a broken port like you do. I've been so pissed at the printer that I've relegated it to paperweight status and printed everything on my not so great but reliable qidi machine. I don't know how to build the software, but I will attempt to go that route if it might fix this issue.
@at93850 Contact Prusa Support: Log into your Eshop account, navigate to support and live chat is at bottom right in most browsers. If not you may need to disable your ad-blocker temporarily.
Cheerio,
RE: MINTEMP but hotend temp stays 0 after swapping thermistors
Thanks for the follow-up and sharing your fix! You probably saved me countless hours, if not months, by pointing out where to tweak the firmware. I got a raw deal on a used MK3 with a fried hotend thermistor pin (instead of a bad thermistor as described), but your firmware workaround saved my investment. I thought I'd have to wait for my 3.5 upgrade since I'm clueless about fixing boards, but a quick Google search led me here. So, big thanks again!
Ok, I have no idea what caused the T0 hotend thermistor to not work anymore but I solved it by plugging the hotend thermistor in T1 and swapping T0 and T1 in software, since T1 is available on the Einsy but not used by the MK3S+. Solution follows in case it is of any use for someone else having the same problem.
See Einsy-RAMBo connections and schematic:
Schematic, see sheet 3/sheet 11:
(I know that the schematic is for 1.1, I assumed this part was not changed between 1.0 and 1.1).
The I fetched the PrusaFirmware sources, edited pins_Einsy_1_0.h:
#define HEATER_0_PIN 3 //PE5 #define TEMP_0_PIN 1 //A1, was A0 #define HEATER_1_PIN -1 #define TEMP_1_PIN 0 //A0, was A1Build, flash, hopsakee it works. Everything seems to work fine now. I have to do some more maintenance and calibration before I can do a full testprint.
Again, this is a weird failure that I didn't expect.