Blown fan MOSFET, using different pin on RRF2.x

[supermarioprof]

I'm subscribing to "Stupid Guys Blowing MOSFET on Duet - Club".
Modifying a delta 3D printer effector I probably shorted FAN1 and FAN0 on an old Duet 3D board v1.03, inverting polarity, so now this is what I'm facing:

• FAN0 not working in any way
• FAN1 not working in any way
• FAN2 seems to work but it never stops

3D printer still works, I had to print some PLA and connected fans to "Always on" pins and it worked, but, ok, it is not a real solution.

I did some test, using Test Fan macro and a multimeter, shorting on endstop because I removed Duet board from 3D printer, and these are voltages I collected

MOSFETs seem to be good at first sight (see photo)

I made also measures about gate to source on MOSFET, results on the first image.

My question: is this weird behaviour probably due to damaged MOSFETs?
since it is difficult to change them I would like to know more before starting desoldering,
Or could I use some PWM pin on expansion port? I had some readings but I didn't understand if this is possible

[Phaedrux]

It does sound like the mosfets are damaged. The expansion port pins are not meant to carry a load directly.

[supermarioprof]

@Phaedrux I'm gonna changing them, with the aid of a local laboratory.

Concerning expansion port, I know I can't use for a direct load,
so I should use a simple Fotek SSR.
But...which command and which pin?

It should be M42, but I'm having difficulties in order to understand the online guide and docs, which pin is available of PWM and pin numbering,
so any help will be appreciated, at least an example (ok, I don't want to get out of contest, here we are for mosfets)

[droftarts]

@supermarioprof Assuming you're using RRF 3.x, most ports are available. However, only some offer PWM. See the list here https://docs.duet3d.com/Duet3D_hardware/Duet_2_family/Duet_2_WiFi_Ethernet_Hardware_Overview#inputoutput

So for PWM, it's bedheat, e[0-1]heat, exp.heater[3-7], or fan[0-2]. For example, you could use HEATER3, which is pin 8 on the Expansion header, pin name 'exp.heater3'. Define it with M950, then set PWM with M42, eg:

M950 P0 C"exp.heater3" Q100 ; create output/servo port 0 attached to heater 3 pin on expansion connector, 100Hz PWM frequency
M42 P0 S0.5                                 ; set 50% PWM on GPIO port 0

Ian

[supermarioprof]

@droftarts thanks for your help!
I understand your code, the problem is I'm under RRF 2.05.
Yes I know I should upgrade, it will be the next step.

But: what to do with pins, PWM and expansion port under RRF 2.x?
I know about M42 but, obviously, I get an error, like

M42 P3 I1 S240 --> Error: M42: Logical pin X is not available for writing

this sounds ok, since I didn't define that pin with M950 like you did,
but M950 is for RRF 3.x only.
Which command for RRF 2.x?

[droftarts]

@supermarioprof see the notes under the pin table. In RRF 2, pins are pre assigned, so you need to unassign them first:

RRF 2.x - Disable a heater using M307 H# A-1 C-1 D-1 to make the pin available, where # is the heater number, and make sure that no tool is configured to use that heater.
RRF 2.x - Disable a fan using M106 P# I-1 to make the pin available, where # is the fan number.

https://docs.duet3d.com/Duet3D_hardware/Duet_2_family/Duet_2_WiFi_Ethernet_Hardware_Overview#inputoutput

Ian

[supermarioprof]

@droftarts Oh my god I totally missed that line in the guide!
so, if I correctly understood:

say I wanna use pin 8 <--> HEATER3

this should be these gcodes:
M307 H3 A-1 C-1 D-1
M42 P3 I1 S240

I can't try right now, my damaged Duet3D is still under repair, but I will try as soon as possible.

Last question:
I will need to change my gcodes and my slicer settings, will I?
because FAN0, FAN1 e FAN2 are connected to specific pins (20-22), but my new fan1 should be pin 8, so what?

p.s.: I would like to change the thread title so that it will be more inherent with current content, but....is it possible? I can't find any button or settings

[Phaedrux]

Is there a reason to stay on RRF2?

[droftarts]

@supermarioprof said in FAN mosfet probably blown:

I will need to change my gcodes and my slicer settings, will I?
because FAN0, FAN1 e FAN2 are connected to specific pins (20-22), but my new fan1 should be pin 8, so what?

Are you going to have an external MOSFEt? Pin 8, and all expansion pins, are 3.3V signalling, ie not enough to run a fan directly. You can control it with M106, by using the A parameter in RRF 2.x, see https://docs.duet3d.com/User_manual/Reference/Gcodes#m106-fan-on and the notes:

The A parameter can be used to assign a fan to a different output pin, for example a spare heater output (use a M307 command to disable the heater and free up the pin first).

p.s.: I would like to change the thread title so that it will be more inherent with current content, but....is it possible? I can't find any button or settings

Edit the first post, you can change the thread title there.

Ian

[supermarioprof]

@Phaedrux Summer laziness, now I need my 3d printer to be working reliably for a while. during Christmas holiday I will upgrade to RRF3

[supermarioprof]

@droftarts sure I can use an external MOSFET or a Fotek SSR.
thank you very much, M106... A is exactly what I was looking for!

[supermarioprof]

@droftarts said in FAN mosfet probably blown:

Edit the first post, you can change the thread title there.
Ian

impossible, too late... 🥺

[droftarts]

@supermarioprof Okay, I can, what do you want it to say?

Ian

[supermarioprof]

@droftarts "Fan MOSFET blown - using different pin on RRF2.x" could be good, or something like that, it's up to you, thanks!

[droftarts]

@supermarioprof Done, going to mark as solved too.

Ian