Heating bed temperature increases without heating bed

alankilian

People are going to want to see your config.g and config_overrides.g files.
Post them with the "code" wrapping so people can see them in the post.

Also, almost always someone asks for the output of

M98 P"config.g"
M115

droftarts

@HansDuet3D if it starts at 80C, you’ve almost certainly got the wrong thermistor value; it’s probably 10k, not 100k.

Ian

HansDuet3D

Hi Ian,
Thank you for your message. Unfortunately, this is not the case. I measured the NTC beforehand and it had around 150k ohms at around 15 °. That would be fine.
In addition, the display of the heating bed and of course also the heating bed works if I configure e1temp instead of bedtem and connect accordingly.

Hans

HansDuet3D

Hi,
Yes. here are the two issue.

I have attached two zip files:
Config (39), here the heating bed is configured at e1temp and everything works.
Config (38) is exactly the same configuration, but the heating bed is configured at bedtemp. here the temperature display shows steadily, with and without a connected thermistor. See also the output of M98 P "config.g"
[1_1616613897073_Config(38).zip](Uploading 100%) [0_1616613897068_config (39).zip](Uploading 100%)
24.3.2021, 19:51:22: m98 P "config.g": HTTP is enabled on port 80
FTP is disabled
TELNET is disabled
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 365C
Warning: Heater 0 appears to be over-powered. If left on at full power, its temperature is predicted to reach 237C
24.3.2021, 19:51:33: M115: FIRMWARE_NAME: RepRapFirmware for Duet 2 WiFi / Ethernet FIRMWARE_VERSION: 3.1.1 ELECTRONICS: Duet WiFi 1.02 or later FIRMWARE_DATE: 2020-05-19b2

Phaedrux

Sorry zip files are not supported by the forum software. Please just copy and paste the text of the config.g so we can see it easily.

HansDuet3D

OK,
the two texts.

Config.g BEDHEAT dont't work

; Heaters
M308 S0 P"e1temp" Y"thermistor" T100000 B3950      ; configure sensor 0 as thermistor on pin e1temp
M950 H0 C"bedheat" T0                              ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00                                   ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B3950      ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                               ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00                                   ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                       ; set temperature limit for heater 1 to 280C

Config.g e1temp, work

; Heaters
M308 S0 P"bedtemp" Y"thermistor" T100000 B3950     ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0                              ; create bed heater output on bedheat and map it to sensor 0
M307 H0 B1 S1.00                                   ; enable bang-bang mode for the bed heater and set PWM limit
M140 H0                                            ; map heated bed to heater 0
M143 H0 S120                                       ; set temperature limit for heater 0 to 120C
M308 S1 P"e0temp" Y"thermistor" T100000 B3950      ; configure sensor 1 as thermistor on pin e0temp
M950 H1 C"e0heat" T1                               ; create nozzle heater output on e0heat and map it to sensor 1
M307 H1 B0 S1.00                                   ; disable bang-bang mode for heater  and set PWM limit
M143 H1 S280                                       ; set temperature limit for heater 1 to 280C

Phaedrux

I'm still confused. Can you show a photo of the wiring at the board indicating what is connected where and what that results in?

droftarts

@HansDuet3D it sounds like there’s something shorting on the board, possibly on the pins of the MCU where the thermistors connect, or in the thermistor circuit. Can you take a good, clear picture of both sides of the board, and post the images here. When and where did you purchase the board?

Ian

HansDuet3D

@droftarts
Hello,
In the last few days I have checked and measured all of my cabling. I did not find a bug. If the temperature sensor is connected to e1temp and configured, everything works fine.

The board was part of a kit for a BLV MGN.

I also looked at the circuit diagram.
If I understand correctly, the VSSA pin goes to GND. I measured it, it fits (green).
I measured C19 buffers against GND, it fits (green).
C19 goes to pin 19, I measured it, fits (green).
The R (th) goes via R 12 on pin 19 to U1 or to C19, and there I have no passage (red).
But I have to admit that the connection from R 12 to Pin 19 or C19 is difficult to measure.
I measured pin 19 against GND, no connection, paast.

The question now is whether this can be the cause of the error?

Here are a few pictures of the board?

Screenshot 2021-03-30 212925.jpg

droftarts

@hansduet3d unfortunately, you have a clone Duet, not produced by Duet3D. I can’t really comment on what might be wrong with it; I don’t know if they have change the circuit. If it was one of our boards, we would most likely replace it under warranty. But you need to contact the seller of your board and see if you can get a replacement, if you don’t want to repair it yourself. It does sound likely that the part of the circuit you have identified is faulty; possibly R12 just needs reflowing or replacing, but I really don’t know.

Ian

HansDuet3D

@alankilian said in Heating bed temperature increases without heating bed:

M98 P "config.g"

Hello,
I have now removed and disposed of the board. I'm looking forward to my original duet.
As hands off Chinese scrap.
Thanks again