hot end stop heating after print start

[3DAngel]

hello to all,

just put the printer all together and it heats up both bed and hotend. normal no issue.
this is not my first printer.... so I know how to check voltage , cable, connectors,...etc
this unit came with Marlin 1.1.8

preheating PLA default works correctly and holds normally
as soon as I print from SD, the printer starts, but it stops heating the hotend and I have temp runaway error and needs to restart.

using S3D, Cura and both the same symptom.

do I have a buggy FW or the main board is loosing its logic gate when printing?

anyone had this type of issue?

thanks in advance

PS:
I have arduino 1.8.9 and 1.1.9 Marlin FW ready to be upload, but I don't think it is the FW rather other thing.....

mainly suspecting the GT 2560 V3.\\\\ not happy.... kindly asking for your help and feedback

thanks again

[William]

Hi, You can check if your hot end thermistor wiring is fully connected.
The thermistor can be measured after full access.

[3DAngel]

thanks.
the thermistor is acting correctly all the way up and holding when idle.
as soon as the print starts, the hotend stops heating. and you can see the thermistor reports back the actual drops of temperature.

[3DAngel]

read in some post here there, and it mentioned thin wall printing; which I was.
but the latest print, I sliced it to be a calibration cube 20x20, and yet it fails same way

[William]

Hi, does this happens when you print all models?
You can try to update the firmware. If this happens after the update,
You may need to replace the motherboard.

[3DAngel]

thank you William.

I just solved my issue.
1- the hot end connector: who ever tied those two screws did not screw them tight!!!
as soon as the movement of the printer head stars, it would not provide the good contact, therefore heater can not heat
2- the provided fan duct was blowing directly toward the hot end/nozzle, @ 100% the heating element cannot keep up with the heat loss.

tight the two screws back (the cable was black already, had to brush the oxidation off)
hot air and wood work iron to change the fan duct's air flow's angle and now , even at 100% full blast the heater rise the temperature normally.

now trying to print the calibration cube..... will see... if issue persist, will come back here and post update.

hope this can help someone one day......
cheers

[William]

Thanks for your share.

[3DAngel]

well.... i do not understand how this could have happened.
all was nice and I just pushed manually the hot end (not in operation) and the nozzle hit the metal clip on the hot bed and PUUF!!!!!
a short between the nozzle and the clip!! WTxxxxxxxx......
now the board is shorted, the extruder extension board too..... the two extruder's fans are not operational... their 24 V gone, but fan are still good.

all other are good ... will have to bring power from other pins.......