![I've been Printing PPE on my IDEX 3d printer recently. This ends up being a bit of torture test for the Meastro and expansion as I have all 7 steppers going constantly for 2 hours.

The last couple of prints I had "P5 short circuit" errors that would trigger about 30min into a print after the controller and motors warmed up. But the prints would complete with almost no change to the motion of the extruder on P5. The extruder did stop for 5-10 seconds 2-3 times during the later prints, but re-started and completed the prints with no other issues.

I assume that poor current loop stability can trigger a short circuit flag, so I went ahead and did a similar fix to what you suggested DC42. Only had a chance to do one test print with P5 in spread-cycle mode, but the short circuit errors are gone. I'll do more test prints in stealth-chop mode tonight to confirm.

Attached are the front and back of my modified expansion.

Looking at the layout render, it looks like the culprit is the Vin trace to C6. It cuts off the direct path to ground and forces current from R3 to loop around the outside of the pcb. Personally, I'd put R3 and R2 between the TMC chip and stepper connector and give them 2-4 vias to the ground plane and the thermal die pad of the TMC. The motor phase connections can then sneak under or around the 805 resistor.

@zapta I store and print out of "dry cartridges" with A4 Molecular sieve desiccant. https://www.thingiverse.com/thing:3225037 I've made 8 so far.

They're a one time cost as the desiccant generally lasts years and can be recharged if needed. (rapid temperature cycling will pump air into the cartridge and saturate the desiccant)

I print PETG on PEI sheets or powder coat. The key is to print the first layer cold and pick the temperature based on how you want it to stick. Hotter sticks harder and colder pops off easier. I typically start at 60C for the first layer then switch to 80C for the rest of the layers to minimize warping. You'll need to tune this for your specific print bed.

I also run the hot end <230C on the first layer to avoid damaging the PEI, then ramp up the temperature for the rest of the print. I typically run 245-265C with fan for speed, overhangs, and layer adhesion. Then keep stringing in check with aggressive filament drying.

I do see some differences in the expansion board schematic. The 470pF ESD capacitors on the motor outputs have different voltage ratings. If the Duet 2 has NPO caps while the Expansion has Y5V (or even X7R) this might cause some noise as the higher capacitance capacitor dialectics are non-linear and piezoelectric while the NPO dialectic is nearly ideal.

I'd also look closely at the grounding and parasitics of the current sense resistors on P5. That current wave-form sure looks like the current loop has started to go unstable. Might not need much series inductance to drive it over the edge. (the TMC2224 data sheet even warns about stray inductance on this circuit) Also check the supply decoupling for stray inductance or capacitor dialectic differences as these could can easily couple back into the loop.

Replacing the controller on a Chinese IDEX printer with a Duet 2 Maestro + Stepper Driver Expansion and I've run into this same problem. P5 is VERY noisy when it switches to SpreadCycle mode. Sounds almost like the stepper is stalled and you can feel the carriage vibrate while moving. (double checked the wiring, haven't crossed anything...) I'm using the same stepper motor on the P0 channel, and P0 is silent.

Anyone figured out what's wrong with the P5 stepper driver on the expansion? Does it need some components replaced? (wrong Capacitor or resistor somewhere?)

For now I've worked around it by setting the "V" parameter to 25 so it says in Stealth chop for most moves. It also got better when I swapped the X1 and X2 motors and wires. The motors are the same part number but, the X2 motor has longer wires.

M569 P5 S1 D3 V25                                 	; physical drive 5 goes forwards E2 (Very noisy!)