Duet 3 6HC Rev. 1.01 Faulty

NeueKlasse

Bed is the Original 24V Bed from Anycubic.
Mosfets are the Original Ones either..

Today i made the conversion from Mosfets to the V_OUT Connections on the
Duet itself... maybe the Mosfets are faulty....
but after Powering the Printer and looking on DWC now i get
lots of Communication Lost Errors (see above...) WITHOUT Powering the bed?! i Checked everything again... no Issue there.

dc42

It sounds to me that there is a ground loop in the power wiring. Please provide photos showing how you are providing power to the Pi, the Duet, and the bed heater circuit. Also please confirm that you do not have any independently-powered devices (for example a PC) connected to the Duet or the Pi via USB.

NeueKlasse

@dc42 Thanks, below some Pictures of the Wiring!

Power Supply 3 Rows 24V

Row Bed Heater Mosfets
Row Pi Powersupply 15W
Row to Duet Board

!

on Bottom Right you see the Power Supply for the Pi, i also tried another Pi Power Supply
direct driven from the Wall Outlet without any Changes....

Now i've the Mosfets back in the Cabinet... the 15A Fuse of the Duet seems to weak for the bed and blows after 10-20 degree heatup....
after having the Mosfets back in the Printer the Connection Loss Issues are still
high frequently.....

!

Nothing else is powered / Connected from the Pi or from the Duet! only everything
on the Photos...

NeueKlasse

I Have disconnected everything from the Board except the Ribbon Cable to the Pi
and the PanelDue.
The Communication Errors are still coming every Second!
Connection Lost, Connection Established... and so on and so on...

Tried with another Pi and another Ribbon Cable! Same Thing

I am wondering why they doesn't came that frequently yesterday night....????
they almost just came when i heated up the bed.... but now it's horrible

is it possible to get another Board to confirm that's not the Board? maybe Repair?

dc42

Thanks for the pictures. Your power wiring looks OK to me. I really don't think it's the Duet that is the problem.

Are you sure that the PSU is capable of driving that bed heater? If it was blowing the fuse on the Duet quite quickly, it must have been taking 20A or more. Perhaps the PSU is cutting out and the Duet is resetting.
Could there be a short in the bed heater, or between the bed heater element and the aluminium bed plate of you have one? What type of bed heater is it?
When the connection is lost, does the bed heater turn off?

NeueKlasse

When the communication gets lost the Heater is still Heating, although M303 is working with all that Communication Loss Errors (no Header)

The PSU is the Original One so i think there must be plenty of Room for the Power...
(1000W 24V)
i was also surprised that the fuse was blown... i dont measured the Bed Amps but
i found that the Bed must have around 300-400W (i hope that's correct)
so around 12-16A

The Thing is it doesn't matter if all is connected to the board or when i disconnect everything from the Board.... i have Communication loss Errors every second!

So the Bed Heater doesn't have to Play with it to get hundreds of Errors...
(yesterday i thought so... but today i'm not sure what to think...)

Veti

@NeueKlasse said in Duet 3 6HC Rev. 1.01 Faulty:

i found that the Bed must have around 300-400W (i hope that's correct)
so around 12-16A

the max current on the bed is 15A. So you ware most likely exceeding that.

measure the resistance of the bed and subtract the resistance of the multimeter with no connection

NeueKlasse

@Veti

Yep the Fuse is only 15A (Mosfet on the Duet is rated for 18A i think) but even with
that (i had just tested the Option without extra Mosfets...) i had Communication Errors..

Measured the Bed... 1.5 to 1.6 Ohm, so at 1.6 V/A ... the Bed drawn Current must be around 15A

NeueKlasse

This post is deleted!

NeueKlasse

What does the Point SPI Overruns/Underruns say? (M122)

NeueKlasse

Although, is it possible to exchange the board? I need the Printer to work..

NeueKlasse

I remembered that i had connected the Duet and Pi4 in that way that the Duet supplies the Pi 5V before i put everything in the printer...
Then i wanted a extra Powersupply to not overload the Duet...

Today i disconnected the Pi Powersupply and added the needed Jumper... et voila... problems seem gone.

I don’t understand why? I tried the original Pi power supply and even with this i had communication losses ....

I hope the board is tough enough...

jay_s_uk

the board was originally designed with the pi 3 in mind and not the pi 4. The pi 4 requires more power compared to the pi 3 so its really advised to use a separate psu to power the pi

NeueKlasse

@jay_s_uk

The problem is it doesn’t work with my board ..
and i don’t understand why ..

Maybe it’s possible to cut the int5V and use the external 15W Powersupply together mit the 5Vext connector??

NeueKlasse

So.. how much Current is the Int 5V capable of?
and how much current does the Board in Ext 5V Mode work with? The documentation lacks of information there

The Communication Errors are completely gone with the Int 5V Jumper! 10Hour Print without Problems... the Toolchange is slow (directly switch from t1 to t0 without waiting for temps (pre and past toolchange script empty) gcode file without additional commands... the change can take from 3s to 20s

dc42

@NeueKlasse said in Duet 3 6HC Rev. 1.01 Faulty:

So.. how much Current is the Int 5V capable of?
and how much current does the Board in Ext 5V Mode work with? The documentation lacks of information there

https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview#Section_Operating_limits

@NeueKlasse said in Duet 3 6HC Rev. 1.01 Faulty:

the Toolchange is slow (directly switch from t1 to t0 without waiting for temps (pre and past toolchange script empty) gcode file without additional commands... the change can take from 3s to 20s

Have you anything in the tfree files?

NeueKlasse

@dc42
Oh Thanks, 5V3A mentioned... and what about external 5V power, is it the same thing there?

dc42

If you are applying external power, then the current taken is the quoted 200-300mA from the Duet itself, plus anything you have connected to the IOx, LED strip or Laser/VFD connectors that draws power from them.

NeueKlasse

@dc42

But what Amperage can the Duet handle via Ext 5V?

My target is to get the int5V overload risks
out of the way while powering the SBC from the Duet otherwise it doesn’t work for me (communication problems)

dc42

@NeueKlasse said in Duet 3 6HC Rev. 1.01 Faulty:

I remembered that i had connected the Duet and Pi4 in that way that the Duet supplies the Pi 5V before i put everything in the printer...
Then i wanted a extra Powersupply to not overload the Duet...

Today i disconnected the Pi Powersupply and added the needed Jumper... et voila... problems seem gone.

I don’t understand why? I tried the original Pi power supply and even with this i had communication losses ....

I hope the board is tough enough...

Somehow there was differential noise between the ground of the Pi and the Duet ground when the bed heater was operating. However, from your wiring photos, I can't see the source of that, because you have connected the power wires to the bed heater mosfet directly to the PSU.

I have a few other suggestions to try, with the 5V_INT jumper removed and the Pi powered from the buck converter:

Temporarily disconnect both power input wires to mosfet switch. Then check with a multimeter that there is no connection between the bed heater output wires and the negative output terminals of the PSU. Assuming there is none, reconnect those wires and proceed to #2.
Currently you have the red and black input wires to the buck regulator connected directly to the middle pair of output terminals of the PSU. Try removing those two spade terminals from those PSU outputs and connect them instead to the same outputs as the Duet, leaving the middle output terminals free. It's possible to fit two spade terminals under one screw, but you may have to bend one of the spade terminals a little.
If #2 doesn't help, connect those two buck regulator input wires directly to the VIN terminals of the Duet instead, along with the two power wires.