Just built a Anet printer. When powered up for the first time the extruded temp was at 91 and kept going up and down. After powering off a few times for setting up the bed the temp is now displaying as 231. I have swapped the temp sensor for the extruder with the hotbed and the makes no difference. When swapped the temp on the hotbed is displayed correctly. So I don’t think it’s the sensor.

Anybody have any other ideas. I think it’s the main board

Why you guys all buy Anet A8, since A6 is newer and better (and cheaper)?!?

all connections in correctly? i had something kinda similar while back ended up being bad thermistor. Have you updated firmware also?

Yes all connections in fine. The only firmware I can find is a v1 on the suppliers site.