both of my extruder heater outputs are constantly on?
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noticed my extruder was heating while no temp was commanded and started to diagnose and noticed both e heater leds on the board are constantly lit
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Can you try removing your SD card from the board and powering up again? Do the heater still start in the powered state? If so that would indicate that the mosfets have failed. It would be odd for both to fail spontaneously. I think more likely would be a short causing damage or a configuration error causing the signal to be inverted.
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@phaedrux well i removed the sd card and both heater indicator lights are still lit. what kind of short would cause this sort of problem? because my config hasnt changed.
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Can you grab some photos of the board?
Do you see any damaged chips?
When and where did you purchase it?
Has any wiring changed recently?
Do the LEDs light up even with the heaters disconnected and the SD card removed?
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@phaedrux Wiring recently went through an overhaul so thats why im not surprised. yes both extruder leds are lit with sd card removed, havent tried with everything unhooked and i cant see anything that looks burnt on the board. I believe i purchased this from filastruder.
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@jcwild said in both of my extruder heater outputs are constantly on?:
havent tried with everything unhooked
Try unhooking everything and see how that goes. Maybe something is shorted there.
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@phaedrux no this board is dead, ive unhooked everything and same result
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Is this a new build or an existing build?
What changed before it stopped working?
When and where did you purchase the board? -
@phaedrux `existing build, all the wiring for the extruder/hotend was re-done, got the board from filastruder a while ago
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I'll see if there is any recommended means of repair. Otherwise you may be able to use external mosfets controlled by alternative heater output pins, either from them expansion connector directly, or via a Duex and the mosfets it provides.
I'd also give the wiring a close inspection to see if there is a cause for the short and resolve that so that it doesn't happen again.
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What Duet Board?
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@phaedrux maestro 2
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From DC42
It's rare for the heater mosfets to fail. On Duet 2s the driver chips can fail if there is a transient on the +5V rail. If it's the mosfet that has failed, it's possible to replace it using a hot plate and hot air desoldering tool.
To test whether it is the mosfet or the driver, the general approach is to identify the mosfet gate series resistor (which is close to the mosfet gate terminal) and measure the voltage between each end of it and ground. If both ends are at +5V then the driver is commanding the mosfet on, so either the driver IC or the MCU has failed (assuming it does this with no SD card, which you've already got him to check). If the driver end of the resistor is close to 0V then the driver is commanding the mosfet off, so it's the mosfet that has failed.
