Bed temperature going up in the beginning of a print  

Re: Bed temperature going up in the beginning of a print

➡ does this only happen when the bed moves, or even when it's static ?

if it's static:

💡 can you monitor the psu voltage as well as the temperatures with a multimeter ? does the voltage correlate to the raise of temperature ?

maybe the power supply is not as stable as it should be and it might be that the electrolytic capacitors inside are at the end of their lifespan and you're close to a psu failure (unfortunately the voltage starts to raise up then in many cases).

❓ how old is your printer ? and how often is it powered up ?

Re: Bed temperature going up in the beginning of a print

I have only noted this when starting a print, so with a moving bed. Have to try the static option when the current print is done.

The printer is about 2 months old and I have used it every now and then. Not even near 24/7 usage. Can't go to the statistics either with the ongoing print but I don't think it should be broken with the usage I have had with it (unless it was somewhat broken when new).

After that first temp bump, it goes to the correct 55 deg in this case and stays very stable to the end of the print.

Re: Bed temperature going up in the beginning of a print

hmmm... hard to tell. only four more speculations:

1. might be as well a bad thermal contact between the temperature sensor and the bed. usually there is some kind of kapton tape underneath the heated bed with which the sensor is fixed.
simply a defective bed sensor (2.).
or (3.) it might be related to a bad soldering joint at the n-channel mosfet for the heated bed (Q5) or the power connector.
another idea would be the 15amp fuse (4.) or its socket.

just try to check these points.

in fact, when you've checked the stability of the supply voltage and it's still ok, you shouldn't be concerned about it.