Extruder does not stay hot when printing

Dear Forum,
Another problem. When starting a new job, the extruder gets nicely hot at the right temperature, but after printing has started, the heating stops, so the Extruder temperature does not stay hot during printing. With Preheat, the temperature remains at the right height.
What is going on here? Software or hardware?
Greetings Auke

Hello @Auke-3D

Edit : Oups sorry ! K8400 ?

This is for a delta : maybe you will find some answers in :

But this, work also for k8400 :
Could be a bad cable loom (cable with sectional strands creating random continuity faults depending on its positioning) , or bad connector connection, or sensor or heatcarridge default …

supposing you stell have an original firmware from velleman !

As you are recovering from a burned connector on the head, the cable loom seem to be the culprit …

Hop you will find the solution, have a nice day !

The problem is not resolved. I had already printed several parts here in a few days and all of a sudden I get this problem on the same day. What I now also see that the display blinks (as if you blink your eyes). Now I see that when changing the time, the second, happens. After a while between 8 and 15 minutes, one time the temperature suddenly drops and another time the printer crashes / stops abruptly and another time the layers have shifted 4mm in the meantime. What is going on here? best regards Auke

You should check everything, start by testing the power supply (correct output voltage? do you have a multimeter to measure and do you know how to do that? beware risk of electrocution!)

keep only the minimum (no led strip, no second head, no second extruder, …)
Look closely at the motherboard, no burnt trace?
Check all connections …

Hi Pacc, The output voltage from the power supply to the motherboard is 15V DC. Measured the red and the black wire. Now I see that on the back of the plug that comes from the extruder board, there is a scorch mark. There is the purple thread and it is precisely from the heather. Do I now have to replace the entire wiring harness or just the plug? To be fair, I replaced the three boards of the stepper motors earlier that apparently had a short circuit. Kind regards, Auke

IMG_4711

For me, replacing the cable and thoroughly cleaning the connector which has had a heat stroke seems obligatory.
(it must create false contact and have greater resistance).

Replacing the cable will eventually allow if the problem disappears to know without too much doubt if the motherboard is ok or not.

Hoping that the change of cable solves the problem, have a good day or night!

Thanks for the advice. Here at 20:30 so you can still do a few more hours of hobby. Sincerely, Auke

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