Marlin Firmware Update Hotend Heater Issues

Hello together, i have trouble when i Upload the newest Marin 2.0. bugfix (Compiled .bin)

- Board MKS SGEN L V1.0 LPC1768
- TMC2230 SPI


after the SD-Card Upload everything works. Only the Hotend heater does not Heat (the Mosfet on the Board doesn't get triggered)
first i though about a defective Board/Mosfet...
then i tried to Upload the Heater and Bed Pins in the Pins file (P2_05 and P2_07) switched => all Heaters work in swapped condition!
after i switch the Pins again and upload the FW everything works!
when i Upload the Firmware again i have the Problem that the Hotend heater doesn't work again!...(only after uploaded it with pins swapped and then upload in normal condition...)

the Other Problem that i've encountered is (The BTT TFT35 with Dual Mode comes 2 days after the Problems from above)
when i swap from Standard Screen to Touchscreen mode the Hotend heater doesn't work again.... (same thing when i Upload first the pins swapped and the swap it back and upload it again everything works fine)

I Checked everything,

it seems to have Problems with the 17-19 Degree Room Temperature, it's an Dyze Hotend with 500C Thermistor.
it doesn't turn on the Hotend. the MINTEMP is set to 18 degree. The Marlin Changes required from Dyze itself are implemented (Sensor Nr. 66, Consecutive Low Temp Errors enabled etc.)

When i connect a Dyze Spare Thermistor i can't heatup again.. BUT if i heatup the Bed and touch the Surface of the Bed with it (so that the Hotend Temp. raises from 20 to 25 degree, THEN
when i switch on the Hotend Heater it works!!!, i measuired the Resistance of the thermistor (and the Spare one) when everything is cold... about 5.6MOhm

i don't know why marlin is Blocking the Heatup, NO error is thrown.... it has worked fine with 1.1.9 and the first 2. Marlin Versions, but now with 2.0.7 it won't work!

Edited 1 time(s). Last edit at 01/22/2021 03:20AM by NeueKlasse.

Thermistor table 66 ?

if so in Marlin/src/module/thermistor/thermistor_66.h

Find at the end

  { OV(  1022),  25 },
  { OV(  1023),  20 }
};

and try this

  { OV(1023) - 1, 25},
  { OV(  1023),  20}
};

But basically this thermistor is a really high start end and a cold room will cause issues.

Edited 2 time(s). Last edit at 01/22/2021 05:17AM by Dust.

Hi, Thank you for your answer,

i tried to Change the Line and compiled the FW again.
after Updating on the Printer the Problem still occurs,

The Bed (Roomtemperature) is at about 17°C on the Display, the Hotend at about 20°C (it doesn't change if i disconnect the Thermistor.. (66)... resistance to high...)
(but that's the same as with Marlin 1.1.9 before...where i still could heat up.. i thought #define MAX_CONSECUTIVE_LOW_TEMPERATURE_ERROR_ALLOWED 10 and #define MILLISECONDS_PREHEAT_TIME 30000 would Bridge the Error... )


if i set my Target Temperature the Hotend is still not Heating...
after 30s i get: Heating failed E1
Please Reset Printer

if i set the Thermistor Low Temp to 18 degree (lower than the minimal 20 Degree that could be displayed i get a low temp error immediately after start to heat up...

is it Possible to change the Marlin Code? (i don't know where to find the Thermal Protection Code...)

Edited 2 time(s). Last edit at 01/22/2021 07:10AM by NeueKlasse.

Had this problem a long time ago found that if add 2.5 to this line the problem went away.

#define MAX_REDUNDANT_TEMP_SENSOR_DIFF 12.5 // originally 10

Do not know if this was a correct way of dealing with this problem thou it has work for me for over a year.
Reason I changed this line for my 3D Printers are in a cold basement.

Edited 1 time(s). Last edit at 01/22/2021 07:43AM by Roberts_Clif.

---

Computer Programmer / Electronics Technician

The line I showed you is the only difference between 1.1.9 and marlin 2 temperature tables.

The lowest temperature that thermistor can read is 20C (its not a display issue, its the thermistor itself) so setting mintemp lower than 20 will instantly cause a mintemp error

the only way I know around it is to fake a curve in the table

so 20c reads 0 etc and it only reads correctly over 100c

Try this new attached thermistor table, and remember all readings below 100 will be higher than it shows

Edited 2 time(s). Last edit at 01/22/2021 07:49AM by Dust.

i tried the Thermistor Table, the Hotend will still not heat. i noticed that i can't crank up the Temperature over 485 degree!!.. Max Temp in Marlin is set to 500?!?!

the second thing i tried is to setup #define MAX_REDUNDANT_TEMP_SENSOR_DIFF 12.5
it doesn't work either :-/

Marlin (MKS SGEN L V1.0) thinks at these Thermistor resistance (above 5Mohm) there's no Thermistor Connected... why you can't Switch that "is Thermistor Connected" OFF?!
if i disable the Thermal Runaway Protection the Problem still exists... above the Runaway Protection there's a Comment in Marlin that says

/**
* Thermal Protection provides additional protection to your printer from damage
* and fire. Marlin always includes safe min and max temperature ranges which
* protect against a broken or disconnected thermistor wire.


I don't want that "always"....

Hey Guys, i found the Problem myself...

i tested around and had a Hard time totally pissed off..., FINALLY after Adding a extra Line and Change 2 Temperatures Below in the thermistor_66.h Temptable (Changes in Red) everything works just fine.
Marlin lacks of the ADC Value 1024! thats the Problem for the High Resistance Thermistor!!!!!

  { OV(  1022),  25 },
  { OV(  1023),  22 },
  { OV(  1024),  19 }
};