Fan stoped working
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@bearer
But the mosfed is still adjustable, the voltage drops down to 11-12V when I reduce the fan to 86%. I have never seen a mosfet working like that when it is broken, did you?
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can't say i have but as the source goes straight to ground and you're dropping 12v between drain and ground then the options are limited?
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@bearer
It is official now: I'm totally confused now.
I have 20V on gate. 20? How? I would have expected 24V here, am I right?
(Yes, it is accurate, only the 3rd digit after the "dot" is going up and down one micro volt. Yes, I trust my Keithley multi meter.) -
@Chriss said in Fan stoped working:
I have 20V on gate. 20? How? I would have expected 24V here, am I right?
check your wiring - the gate is driven from the ATSAM directly (through a small resistance), so 3.3v max
ref https://github.com/T3P3/Duet/raw/master/Duet2/Duet2v1.04/Duet2_1.04c_Schematic.pdf
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@bearer
You where right... I know now where the 20V came from. Let us forget that post, please.You are right, there are 3,3V on the gate when I have the fan at max and close to 0 when the fan is at 0%. Let me guess: The mostfet has passed away too?
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either the mosfet is dropping 12v drain to source, or the board is dropping 12v from source to ground - either way something needs fixing as far as I can tell.
less than 1v drain to ground when on and loaded is okay
i suppose you could power down and see if you can measure any resistance from drain to source, or source to ground.
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@bearer
Source to ground: 93Ohm, this are my wires.
Drain to source: 24,7kOhm -
@bearer @Phaedrux
Just as an idea: Can I use the "ground" from a fan on the expansion (configured to provide 12V) board and VIN (24V) to control the 24 fan?
I need to get that fan back working and it seems to me like all three pwm's on the mainboard ore dead.
Cheers, Chriss
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Sure, the Duex and Duet should have a common ground anyway, so wiring the fan between Vfan/Vin on the Duet and Fan- on the Duex should work. But determining what shorted out the other mosfets in the first place might be prudent. (ofc sometimes things just fail because reasons)
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@bearer Cool... I will follow that way. I need that printer to continue the other build. I can debug the other problem in the future if I have some spare time.
I was a very good idea to by the Duex. That saved my ass a couple of times now.
Thanks for you help!
Cheers, Chriss
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Use Vfan if you can, it gives you the benefit of the 1A fuse for the fans, or add your own fuse.
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@bearer
This is, indeed, a very good idea.