@gloomyandy i tried your suggested steps and here is the result :

Boot duet and sbc Turn on heater from dwc panel The fan don't turn on I turn off the heater wait for the temperature to go under 70°C hit emergency stop turn on heater fan don't turn on emergency stop (heater hot) fan turn on wait for the temperature to go under 70°C fan turn off Turn heater on Fan don't turn on

Here's the output of the M122 command :

=== Diagnostics === RepRapFirmware for Duet 3 MB6HC version 3.3 (2021-06-15 21:45:47) running on Duet 3 MB6HC v1.01 or later (SBC mode) Board ID: 08DJM-956L2-G43S8-6JTD6-3SS6K-KA1AH Used output buffers: 1 of 40 (14 max) === RTOS === Static ram: 150904 Dynamic ram: 62348 of which 0 recycled Never used RAM 140940, free system stack 202 words Tasks: SBC(ready,5.0%,330) HEAT(delaying,0.0%,325) Move(notifyWait,0.0%,302) CanReceiv(notifyWait,0.0%,908) CanSender(notifyWait,0.0%,374) CanClock(delaying,0.0%,339) TMC(notifyWait,7.1%,93) MAIN(running,87.7%,1250) IDLE(ready,0.1%,29), total 100.0% Owned mutexes: HTTP(MAIN) === Platform === Last reset 00:01:43 ago, cause: power up Last software reset at 2021-09-29 11:43, reason: StuckInSpinLoop, GCodes spinning, available RAM 143016, slot 2 Software reset code 0x4083 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0040080f BFAR 0x00000000 SP 0x2041970c Task IDLE Freestk 43 ok Stack: 00479e85 0047a862 61000000 a5a5a5a5 00479e85 a5a5a5a5 a5a5a5a5 2041ad9c 0000aaea 20432ac4 20424c74 20419728 20424c6c 00000004 2042cda0 2042cda0 20419728 00000000 00000001 20419784 4e49414d 00000000 00000000 00000001 00000001 00eec918 00000000 Error status: 0x00 Step timer max interval 154 MCU temperature: min 35.8, current 36.5, max 47.7 Supply voltage: min 24.3, current 24.4, max 24.4, under voltage events: 0, over voltage events: 0, power good: yes 12V rail voltage: min 12.0, current 12.0, max 12.0, under voltage events: 0 Heap OK, handles allocated/used 0/0, heap memory allocated/used/recyclable 0/0/0, gc cycles 0 Driver 0: position 0, standstill, reads 53339, writes 15 timeouts 0, SG min/max 0/0 Driver 1: position 0, standstill, reads 53339, writes 15 timeouts 0, SG min/max 0/0 Driver 2: position 0, standstill, reads 53339, writes 15 timeouts 0, SG min/max 0/0 Driver 3: position 0, standstill, reads 53340, writes 15 timeouts 0, SG min/max 0/0 Driver 4: position 0, standstill, reads 53340, writes 15 timeouts 0, SG min/max 0/0 Driver 5: position 0, standstill, reads 53341, writes 14 timeouts 0, SG min/max 0/0 Date/time: 2021-09-29 11:52:03 Slowest loop: 0.46ms; fastest: 0.04ms === Storage === Free file entries: 10 SD card 0 not detected, interface speed: 37.5MBytes/sec SD card longest read time 0.0ms, write time 0.0ms, max retries 0 === Move === DMs created 125, maxWait 0ms, bed compensation in use: none, comp offset 0.000 === MainDDARing === Scheduled moves 0, completed moves 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1 === AuxDDARing === Scheduled moves 0, completed moves 0, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1 === Heat === Bed heaters = 0 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1, chamberHeaters = 1 -1 -1 -1 === GCodes === Segments left: 0 Movement lock held by null HTTP* is doing "M122" in state(s) 0 Telnet is idle in state(s) 0 File is idle in state(s) 0 USB is idle in state(s) 0 Aux is idle in state(s) 0 Trigger* is idle in state(s) 0 Queue is idle in state(s) 0 LCD is idle in state(s) 0 SBC is idle in state(s) 0 Daemon is idle in state(s) 0 Aux2 is idle in state(s) 0 Autopause is idle in state(s) 0 Code queue is empty. === CAN === Messages queued 844, received 8, lost 0, longest wait 1ms for reply type 6018, peak Tx sync delay 607, free buffers 49 (min 48), ts 517/516/0 Tx timeouts 0,0,0,0,0,0 === SBC interface === State: 4, failed transfers: 1, checksum errors: 0 Last transfer: 1ms ago RX/TX seq numbers: 2731/2870 SPI underruns 0, overruns 0 Disconnects: 1, timeouts: 0, IAP RAM available 0x2c810 Buffer RX/TX: 0/0-0 === Duet Control Server === Duet Control Server v3.3.0 Code buffer space: 4096 Configured SPI speed: 8000000Hz Full transfers per second: 15.42, max wait times: 4.7ms/0.0ms Codes per second: 0.01 Maximum length of RX/TX data transfers: 3579/64

That's what I figured.

I'll just set the temp trigger to ~52* for both hot end and MCU. That will make sure that the fan is on during any print and cooldown period, plus if it is idle and gets hot for some reason.

Thanks!

@samlogan87 As well as the "L" parameter, there is also the "X" parameter which will limit the maximum fan speed. It might be worth having a play around with that to see if you can get adequate cooling at a lower (and therefore quieter) speed.

BTW - do you have any details of the air pump you are using for part cooling.? It's something I am considering doing and I've been looking at pond air pumps but noise level data is a scarce.

Sorry for reopening this again - however with the Revo Micro and it's 5V heatsink fan coming up - is that 5V fan okay to use with the provided buck converter from the HF output on the Smart Effector?

Skimming through this thread again - I'd say no - correct?

What are my options?
(apart from finding a (probably impossible to source) 12V/24V 20x20 fan with enough CFM and pressure..)

Do I need to run the full length of 1m wire directly to my Duet Wifi?

May we get lucky and just stick a standard V6 30mm duct with a 30mm fan on it..?