Fan stoped working
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@Chriss said in Fan stoped working:
So no need to put any pressure her, as long as I do not mess up the last remaining.
if it ain't broke .. you're not trying hard enough!
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@bearer
Sooooo true...I hope that somebody will jump in and help me to understand the voltage problem. I'm very confused about all of that. The fan was working very fine till yesterday. I printed a holder for the ir-probe for the new corexy and realized that the fan is not working any more. And I have two problems now? Very unlikely.....
Cheers, Chriss
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@Chriss said in Fan stoped working:
I hope that somebody will jump in and help me to understand the voltage problem.
you should probably elaborate a little on where the measurement is done. if between the two pins on the fan output then a failed mosfet can explain it.
if you're measuring Vfan with respect to ground on say Vin then the only thing between Vin an Vfan is a fuse and a jumper - measure the resistance in that path.
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@bearer
I hoped that I was clear enough but sure, I can elaborate it more:
I connected the fan to "FAN2" now, (because FAN[0|1])are gone. I used only some jumper wires and have the multi meter connected parallel to the fan.
Regular setup = 12-13V
Between FAN2- and VIN = 12-13V
Between FAN2+ and GND = 24VI jumperd the Duex to supply 12V for the fans. My former experience was that the the Duet provided 24V because the fan was spinning. But I see 12V now. Does that makes sense to you?
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Not unless Fan2 has also failed, just less spectacularly.
There aren't any other connections between the Duet and the Duex than the ribbon cable, 24v and ground? Having Vfan in the Duex set to 12v shouldn't affect the Duet2 Vfan unless there is a short in wiring somewhere afaik. (though that might explain the failure in the first place)
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@bearer said in Fan stoped working:
Not unless Fan2 has also failed, just less spectacularly.
That should not be the case, I measure 12V there.
There aren't any other connections between the Duet and the Duex than the ribbon cable, 24v and ground?
Nope, no connection
Having Vfan in the Duex set to 12v shouldn't affect the Duet2 Vfan unless there is a short in wiring somewhere afaik. (though that might explain the failure in the first place)
And it worked till yesterday....
I may have blown up the mosfet while I tried to debug the "not so spinning fan". But that was the only change I know about. -
@Chriss said in Fan stoped working:
That should not be the case, I measure 12V there.
they don't always fail as a a short or open circuit. if you measure the gate signal to be doing the correct thing but not the drain then its probaly done for.
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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.
