Hi,
Just finished putting together my Anet A8. When I select preheat, the bed goes to 60C, but the hotend tops out at 40C (laser thermometer), even though the display says 190C. I checked the resistance of the thermistor and it checks out at 90K Ohms. I was going to replace the hotend, but the replacement thermistor reads 86K ohms, and have heard about 100K ohms is normal. So I don’t think it is thermistor. Is this a motherboard problem? Or a software problem? Your advise is greatly appreciated! thank you! Eric
Does the resistance of the thermistor change with temperature ?
gikam
July 4, 2017, 8:45am
3
I think your laser thermometer is wrong.
try touching the nozzle with a drop of water. does it boil/sizzle?
try touching the nozzle with a bit of PLA filament. does it melt?
i think your display 190 is correct.
I would also test the real temperature of the nozzle. If the thermistor is defekt, it should either show nothing or something like over 700 degrees.
If the temperature is going up in the display, I would assume the thermistor is working.
Besides that, I would upload the latest Skynet3d software (there is an instruction document in their download). This firmware is based on the latest Marlin release which has a lot of bugfixes, features and changes for your printer.
Try checking that your heating element is secured tightly in the nozzle block and the thermistor is properly inserted into the small hole in the aluminum block.
My bet is it’s not and it’s reading the air temp next to the block.
