Short to ground driver 3 Duet 3 mini wifi 5+ on a V-core 3 build

RatRig0331

I’ve had everything up and running with my v-core 3 even had two good prints run over night 8+ hours than the next print I go to run some strange things started to happen first after the machine homed out and heated up as normal when it came to the point the print should have started the head goes to the far left corner and starts to extrude with out moving and the bed drops slowly to the bottom max travel. So I reset clean everything up and try to run the same code.

On the second run everything started fine and started to print the first layer just fine with no issues but x and y seemed to be moving slower than normal. After the first layer there was a massive 200mm x and y shift for the second layer. So I cancel the print clean the plate and reset

On the third try everything started fine first layer goes down and the second layer is just about finished when I get a “short to ground driver 3” alarm and the print head gust goes back-and-forth in a diagonal line vs the round shape it should be making. So I clean and reset the bed restart the machine the alarm is still there and x and y are not moving as they should with the alarm still there.

I shut down the machine over night and power it on in the morning and the alarm is gone but x and y still are not moving as they should

I checked the wires there is no shorts
I checked the steppers they tested out fine
I changed the wire with a stock untrimmed one from rat rig with no change

From what I’m reading in others on here it sounds like the driver went bad

dc42

@ratrig0331 please switch the drivers to spreadCycle mode using M569 P# D2 (where # is the driver number) and try again. Short-to-ground reports can be caused by using stealthChop mode either at too high a speed, or without doing the required tuning move during the homing procedure.

RatRig0331

@dc42

So right now that driver is at:
“ M569 P0.3 S1 D3”
Your saying to change d3 to d2 or to add a second line at the end?

dc42

@ratrig0331 change it to D2. If that avoids the problem, then you may be able to revert to stealthChop mode if you do the proper tuning move in the homing scripts.

RatRig0331

@dc42

I’ve read that people added “v21” at the end of that driver script what dose that do set the voltage to 21? Or turn on something else to quiet the steppers? Is it ok to do good to do or bad to do?

dc42

@ratrig0331 the V21 parameter changes the speed at which the drivers switch from stealthChop to spreadCycle, so that they only switch to spreadCycle at very high speeds (if at all). If you do that then it is even more important to execute the correct tuning move during homing.

RatRig0331

@dc42

How would you do that?

dc42

@ratrig0331 from https://duet3d.dozuki.com/Wiki/Tuning_Stepper_Motor_Drivers#Section_Considerations:

You must execute the proper tuning sequence after switching to stealthChop. This means: apply motor current, pause for more than 130ms, then execute a move at reasonable speed.

So homeall.g could be something like this, assuming RRF 3.3 or later:

M17 X Y Z ; enable XYZ motors
G4 P150 ; wait 150ms
<rest of homeall.g follows including G1 moves at reasonable speed>

RatRig0331

@dc42

Home all

; BLTouch
M280 P0 S160 ; Precautionary alarm release
M280 P0 S90 ; Ensure the pin is raised

G91 ; relative positioning
G1 H2 Z5 F6000 ; lift Z relative to current position
G1 H1 X-625 F1800 ; move quickly to X axis endstop and stop there (first pass)
G1 H2 X5 F6000 ; go back a few mm
G1 H1 X-625 F360 ; move slowly to X axis endstop once more (second pass)
G1 H2 X25 F6000 ; go back so not on endstop
G1 H1 Y605 F1800 ; move quickly to Y axis endstop and stop there (first pass)
G1 Y-5 F6000 ; go back a few mm
G1 H1 Y605 F360 ; move slowly to Y axis endstop once more (second pass)
G1 Y-25 F6000 ; go back so noton endstop

G90 ; absolute positioning
G1 X250 Y250 F10000 ; go to first probe point
G30 ; home Z by probing the bed

G91 ; relative positioning
G1 Z5 F100 ; lift Z relative to current position
G90 ; absolute positioning

dc42

@ratrig0331 there's no point in sending two M280 commands to the BLTouch in quick succession, because the second one will take effect before the first one has had a chance to send a pulse to the BLTouch. Use a G4 delay between them.

RatRig0331

@dc42

So changing the d2 seemed to help all the axis moves as they should, and I started a new print after one two hours into the print there is a new alarm “motor phase A may be disconnected reported by driver(s) 3”

Once more resulting in a diagonal print line movement vs is round tool path

dc42

@ratrig0331 said in Short to ground driver 3 Duet 3 mini wifi 5+ on a V-core 3 build:

@dc42

So changing the d2 seemed to help all the axis moves as they should, and I started a new print after one two hours into the print there is a new alarm “motor phase A may be disconnected reported by driver(s) 3”

Once more resulting in a diagonal print line movement vs is round tool path

That's probably caused by a bad crimp connection in the stepper motor cable; but a hardware fault on the board (e.g. bad soldering of the motor output connector) can't be ruled out. The warning message indicates phase A, so check the phase A side of the cable crimps.