Vertex K8400- temperature drops

Hello, I’ve got this strange problem with my printer, when I set prints to temperature 200, it take so long to get that temprature, and when printer reaches this temperature and and nozzle start printing the temperature starts slowly drops to 187-189, when I raises the temperature to 210-212, it keeps printing at 199-200. But when I want change filament via printer interface, printer easly reaches 210C and keeps this tempreature during filament loading/unloading. I’ve tried use basic vertex software and simplyfy 3d. And printer screen don’t show ERR:MINTEMP.
Also I’ve change heater, and nothing has change. Please help!

Hello maciejprajzner,

please go through this post, you may find several ideas and possible solutions on this topic.

http://forum.velleman.eu/viewtopic.php?f=62&t=18021

This sounds like the thermistor is not in the correct position.