Issues with Printer Bed on i3 Prusa Hephestos

[Cobra]

Is the hot bed thermistor fine? Can you get a stable resistance with multimeter?

Thanks for the reply.
How do I correctly measure its elelectornic resistance? I haven't used the multimeter on the heatbed.
I still find it strange that it works in the beginning and then stops and works again when I reset the printer.
The bad thing is, that I don't know what thermistor is installed on the heatbed. We bought the heatbed together with an old used 3d printer and moved it to the new printer when we got the new one.

I am close to just buy a new one and see if that one works, those heatbeds are not very expensive.

[wenganxiang]

Thanks for the reply.
How do I correctly measure its elelectornic resistance? I haven't used the multimeter on the heatbed.
I still find it strange that it works in the beginning and then stops and works again when I reset the printer.
The bad thing is, that I don't know what thermistor is installed on the heatbed. We bought the heatbed together with an old used 3d printer and moved it to the new printer when we got the new one.

I am close to just buy a new one and see if that one works, those heatbeds are not very expensive.

You can swap the connection of extruder thermistor with hot bed thermistor. If it displays other error about sensor instead of "bed sensor error", we can conclude the hot bed thermistor is bad.
I use MK2a hot bed with size 20x20cm, its thermistor is 1.2ohm.
There are 2 wires from hot bed (not thermistor wires), use multimeter to check the resistance of 2 ends of wires.
I use Geeetech Prusa i3, so I describe the steps according to my printer type, hope it fits yours too.