signs of a failing mosfet on e0 heater?
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My custom printer was down for a couple of months, I made some mods to it and didnt have the time to tune/configure it. Last weekend I finally got around to getting it running again. The controller is a duet 2 wifi running the latest release firmware: 3.4.6, with a single hot end. part of my rebuilding I changed the heat cartridge and the thermistor.
The printer seemed to pick up right where I left it, but in my last couple of prints I have had heater failures on E0. The weird thing is they are over temp warnings. generally, 20+ degrees over what it is set at. I have been able to reset the fault, bring the hot end temp back up, and resume the print. it runs for another 30 minutes to 4 hours, and then it faults again with the same error, 15-20 degrees over for 5 seconds. When it faults it successfully shuts off the heater.
The heat cartridge and thermistor are new and came from slice engineering. I put a new nozzle on when I got the printer running again and ran a PID tune which was successful.
I am wondering if this is a sign that the mosfet on e0 is going bad? Or is there something else I should suspect? I was planning on changing it so the cartridge was plugged in to the e1 heater instead… but before I do, I wanted to know if there is anything else I should suspect.
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@AlexZ, it is unlikely to be the mosfet. Generally when they fail they do so permanently.
Is the new heater a high wattage heater (more than 40W)? Is your heat block a copper block rather than aluminum? In both cases I have found that standard PiD tuning is less than ideal and needs hand tweaking.
Also, the actual temperature graph may tell you more about what is happening.
