RFF 3.3 and unresponsive BLTOUCH

Siopshop

Oddly the same issues persist with the last known working config.

Will clean the probe and test out with another set of Bl touch wiring.

The wiring from bltouch follows the sam path as all the other wiring from my Hemera. Ive heard of interference issues but never had this issue in the past. But will isolate to make sure.

self test on start up works correctly

Side by side in notepad++ I cant see any differences but the pid values and the printer name.

Is there anything board side i should check for ?

T3P3Tony

@siopshop if there are no differences form a known working config (which also has the same issues now) other than the heater PID settings then its not the config that the cause.

Siopshop

@t3p3tony

Wow. It was an inteference issue. Shielded the bltoch cable and now works fine

Thanks for your time

T3P3Tony

@siopshop ok thats odd that it changed between configs - but good to know its resolved!

Siopshop

@t3p3tony
Unfortunatley it became unresponsive shortly after. Ive attached a pic of the board below and it looks like L5&L6 has burnt out. Could you confirm ?

IMG_0426.HEIC

Siopshop

@siopshop @T3P3Tony
Apologise foir the heic

T3P3Tony

@siopshop its hard to say from the image (although they don't look quite right). What is unresponsive, the whole board or the BL touch?

Siopshop

@t3p3tony

Compared with another duet 2 wifi I have, L6 and L5 are blacked out and it expelled a waft of “component pop” in the air when switched on.
The Bl touch no longer lights up and is unresponsive, previously the Bltouch would probe test on start up.
Multi meter has confirmed that these have blown. Currently looking at schem to see what else has been affected.
I think its a goner.

No amendments have been made to the wiring over the past 24hrs. Sheathed the bltouch cable with some paracord and recrimped is all. Red to 5v, yellow heater 3, black / brown to ground, white in. The bltouch is a 3.0 and my understanding is that the duet 2 is 5v tolerant.
This is my 3rd duet on one of my printers and I know the pin out pretty well… I’d be surprised if I had “F upped”

Ive never had an issue with a film resistor blowing like this out of the blue but im absolutely bemused to how this has happened and the gradual degradation ive seen over the past few days

Is it worth sending it over for inspection?

T3P3Tony

@siopshop said in RFF 3.3 and unresponsive BLTOUCH:

Thanks for the background, it difficult sometimes on here to tell how much familiarity people have with the boards.

Your report confirms that L6 and L5 are damaged, as you say its confirming what else is damaged and how. Those are ferrite beads, not resistors. L6 is used to filter VDDPLL from VDDOUT/VDDCORE. all of those are not directly exposed to any of the IO interfaces.
L5 is the filter between 3.3V and ADVREF.

I have not seen these ferrites damaged in the way you describe before, they are basically shorts at DC frequencies so if they have passed enough current to get damaged I would expect the MCU is also damaged.

Siopshop

@t3p3tony

Oh no bobbins.

Ill retrace my steps. I wouldn't say im 100% pcb literate but enough to say its likely goosed.
The printer still homes and is responsive via DWC. I’ll run a dry gcode and see its behaviour, report back

Would Duet recycle the board if i sent it back ?

T3P3Tony

@siopshop ahh that's interesting, if the Duet is still responsive then the mcu might not be damaged. that would indicate a different failure mode for those ferrites

Would be interesting to know if all the temperatures read correctly. Also if you have one to hand you can test the zprobe.in with a simple switch to see if its still working.

Phil333

For your checks, I would suggest to use a different pin and see if the BLtouch works as intended like:

M558 P9 C"^exp.4" 5 F60 T1000

And connect the white pin to the EXP-Pin 4.

Before, make sure that your BLtouch is giving out 0 and 3.3/5V on the white pin (check that with a multimeter). Just to be sure, the BLtouch has no weird short, that is damaging your board.

I'm pretty sure, that the BLtouch will give out 5V if its powered via 5V.
The duet exp pins are to my knowledge not 5V tolerant (only 0-3.3V), so you might need to put a level shifter or voltage divider in between.

As I cant find a documentation (nor here https://duet3d.dozuki.com/Wiki/Connecting_a_Z_probe neither there https://duet3d.dozuki.com/Wiki/Duet_Wiring_Diagrams) of how the Z_probe_in pin is implemented, I cant give you further help on that.

I hope this helps you to check and workaround this issue.