Non reactive hotend thermistor stuck at around 50degrees

General Discussion
1

Basic Information:

Printer Model: ender 3v2
MCU / Printerboard: mks genl 2.1
Host / SBC linux mint
klippy(2).zip (1.6 MB)

After i was done making all my axis move the way i wanted, i tried to check my hotend and bed heater.
My bed heater detected the correct temperatures and was able to heat properly.
My hotend however showed around 50 degrees even without anything done to it, and when i tried to increase it to 200 degrees it didn’t budge.
Even tho it showed 50 degrees the hotend was cool to the touch also.

2

Can someone please help me out? I cant figure this one out on my own T_T

3

You most likely have a defective hot end thermistor.

You’re going to have to replace it. After wiring in the new one and before you mount it, check that it’s reading a reasonable temperature - like 20C for the room.

4

I don’t think it’s the thermistor: i managed to get it to work by inverting the sensor pin from the bed and the hotend. When i heat the hotend it now reacts accordingly and detects temperature normally but now my bed sensor doesn’t work. There should be 2 sensor pins for heat detection and i can only find one T_T

5

Can you draw out your wiring and post your latest printer.cfg? " i managed to get it to work by inverting the sensor pin from the bed and the hotend" doesn’t make any sense.

Along with that, I don’t know what you mean by “There should be 2 sensor pins for heat detection and i can only find one T_T”.

When I look at the schematic - there is nothing unusual about the Thermistor interface:

image
image462×672 10.3 KB

There are three thermistor inputs, each going to a 2Pin JST HX connector - one pin being the pull up to 3V3 as well as the MCU’s ADC pin and the other going to ground. I presume the pull-ups (R25, R26 & R27) are all 4k7.

6

Okay here is my printer.cfg
printer.cfg (1.9 KB)
Im not able to express myself very well because i don’t know much about what im doing lol!
From what i had gathered my cfg doesn’t use the initial name of the pins of my board but uses the auto translated names of the mainsail cfg for the pins. i have been fiddling in blind for most of this

7

Your printer.cfg looks fine. You are specifying the extruder heater on MCU pin PK6 which is connected to A14_THERM1 in the schematic fragment above. I imagine that on the board, it is labeled “THERM1”.

Can you provide some pictures of your main controller board and the connection to the hot end thermistor?

I have no idea what this means. Can you explain where you “gathered” this information?

8

472789053_555806727449839_8572216744660464534_n
472789053_555806727449839_8572216744660464534_n1537×2048 369 KB

This is my board, the hotend thermistor is the white one on the bottom left, the black one is the bed thermistor.
canvas
canvas2000×1413 438 KB

(dont pay attention to the ones circled in red)
This is the pinout i found online for the board, but my cfg didn’t work at first so i added the top line of my printer.cfg, it’s along the lines of
[include mainsail.cfg] or something

9

Okay, Here is the processor wiring diagram from the schematic:

image
image633×854 73 KB

You can see that:

  • A15_THERMO is connected to PK7
  • A14_THERMO is connected to PK6
  • A13_THERMO is connected to PK5

and, going back to the Thermistor wiring I posted above:

image
image462×672 10.3 KB

  • TH2 is connected to A15_THERMO which is connected to PK7
  • TB is connected to A14_THERMO which is connected to PK6
  • TH1 is connected to A13_THERMO which is connected to PK5

So, you should have your bed thermistor connected to PK6 and your extruder thermistor connected to PK5.

Now, looking at your photograph:

image
image1537×2048 414 KB

and cross referencing it to your pinout diagram:

image
image2000×1413 401 KB

The white wire, which you have indicated is the extruder thermistor, is plugged into TH1 (which is PK5) and the bed thermistor is plugged into TB (which is PK6).

Now, in your printer.cfg, you have the following specified connections:

[extruder]
step_pin: PA1
dir_pin: PA3
enable_pin: !PA7
microsteps: 16
rotation_distance: 33.500
nozzle_diameter: 0.400
filament_diameter: 1.750
heater_pin: PH5
sensor_type: EPCOS 100K B57560G104F
sensor_pin: PK6  #$# <=== Specified Thermistor
control: pid
pid_Kp: 22.2
pid_Ki: 1.08
pid_Kd: 114
min_temp: 0
max_temp: 250

#[extruder1]
#step_pin: PC1
#dir_pin: PC3
#enable_pin: !PC7
#heater_pin: PH6
#sensor_pin: PK7
#...

[heater_bed]
heater_pin: PH6
sensor_type: EPCOS 100K B57560G104F
sensor_pin: PK1  #$# <=== Specified Thermistor
control: watermark
min_temp: 0
max_temp: 130

Your heater thermistor should be PK5 (Not PK6 as in your printer.cfg) and your bed thermistor should be PK6' (not PK1as in yourprinter.cfg`). You need to change to the correct pins.

The reason why you’re always getting a constant temperature for the extruder is because you’re not reading the extruder thermistor.

I’m not sure why you’re reading 50C as you’re using standard thermistors. I suspect that the thermistor pull ups are not the standard 4.7k - you’ll have to find out what they actually are and specify them in you printer.cfg.

10

ohhhh this would explain why i can only read from the bed thermistor and not the hotend thermistor! The bed one is stock but not the hotend one. I thought it was the same model but maybe not! thanks alot i’ll try it and come back

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